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diff --git a/doc/pcre2.txt b/doc/pcre2.txt index 9df2d47..8f4e8a1 100644 --- a/doc/pcre2.txt +++ b/doc/pcre2.txt @@ -377,6 +377,8 @@ PCRE2 NATIVE API SERIALIZATION FUNCTIONS PCRE2 NATIVE API AUXILIARY FUNCTIONS + pcre2_code *pcre2_code_copy(const pcre2_code *code); + int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer, PCRE2_SIZE bufflen); @@ -487,10 +489,10 @@ PCRE2 API OVERVIEW pcre2_jit_stack_assign() in order to control the JIT code's memory usage. - JIT matching is automatically used by pcre2_match() if it is available. - There is also a direct interface for JIT matching, which gives improved - performance. The JIT-specific functions are discussed in the pcre2jit - documentation. + JIT matching is automatically used by pcre2_match() if it is available, + unless the PCRE2_NO_JIT option is set. There is also a direct interface + for JIT matching, which gives improved performance. The JIT-specific + functions are discussed in the pcre2jit documentation. A second matching function, pcre2_dfa_match(), which is not Perl-com- patible, is also provided. This uses a different algorithm for the @@ -523,76 +525,113 @@ PCRE2 API OVERVIEW return a copy of the subject string with substitutions for parts that were matched. - Finally, there are functions for finding out information about a com- - piled pattern (pcre2_pattern_info()) and about the configuration with + Functions whose names begin with pcre2_serialize_ are used for saving + compiled patterns on disc or elsewhere, and reloading them later. + + Finally, there are functions for finding out information about a com- + piled pattern (pcre2_pattern_info()) and about the configuration with which PCRE2 was built (pcre2_config()). + Functions with names ending with _free() are used for freeing memory + blocks of various sorts. In all cases, if one of these functions is + called with a NULL argument, it does nothing. + STRING LENGTHS AND OFFSETS - The PCRE2 API uses string lengths and offsets into strings of code - units in several places. These values are always of type PCRE2_SIZE, - which is an unsigned integer type, currently always defined as size_t. - The largest value that can be stored in such a type (that is - ~(PCRE2_SIZE)0) is reserved as a special indicator for zero-terminated - strings and unset offsets. Therefore, the longest string that can be + The PCRE2 API uses string lengths and offsets into strings of code + units in several places. These values are always of type PCRE2_SIZE, + which is an unsigned integer type, currently always defined as size_t. + The largest value that can be stored in such a type (that is + ~(PCRE2_SIZE)0) is reserved as a special indicator for zero-terminated + strings and unset offsets. Therefore, the longest string that can be handled is one less than this maximum. NEWLINES PCRE2 supports five different conventions for indicating line breaks in - strings: a single CR (carriage return) character, a single LF (line- + strings: a single CR (carriage return) character, a single LF (line- feed) character, the two-character sequence CRLF, any of the three pre- - ceding, or any Unicode newline sequence. The Unicode newline sequences - are the three just mentioned, plus the single characters VT (vertical + ceding, or any Unicode newline sequence. The Unicode newline sequences + are the three just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029). - Each of the first three conventions is used by at least one operating + Each of the first three conventions is used by at least one operating system as its standard newline sequence. When PCRE2 is built, a default - can be specified. The default default is LF, which is the Unix stan- - dard. However, the newline convention can be changed by an application + can be specified. The default default is LF, which is the Unix stan- + dard. However, the newline convention can be changed by an application when calling pcre2_compile(), or it can be specified by special text at the start of the pattern itself; this overrides any other settings. See the pcre2pattern page for details of the special character sequences. - In the PCRE2 documentation the word "newline" is used to mean "the + In the PCRE2 documentation the word "newline" is used to mean "the character or pair of characters that indicate a line break". The choice - of newline convention affects the handling of the dot, circumflex, and + of newline convention affects the handling of the dot, circumflex, and dollar metacharacters, the handling of #-comments in /x mode, and, when - CRLF is a recognized line ending sequence, the match position advance- + CRLF is a recognized line ending sequence, the match position advance- ment for a non-anchored pattern. There is more detail about this in the section on pcre2_match() options below. - The choice of newline convention does not affect the interpretation of + The choice of newline convention does not affect the interpretation of the \n or \r escape sequences, nor does it affect what \R matches; this has its own separate convention. MULTITHREADING - In a multithreaded application it is important to keep thread-specific - data separate from data that can be shared between threads. The PCRE2 - library code itself is thread-safe: it contains no static or global - variables. The API is designed to be fairly simple for non-threaded - applications while at the same time ensuring that multithreaded appli- + In a multithreaded application it is important to keep thread-specific + data separate from data that can be shared between threads. The PCRE2 + library code itself is thread-safe: it contains no static or global + variables. The API is designed to be fairly simple for non-threaded + applications while at the same time ensuring that multithreaded appli- cations can use it. There are several different blocks of data that are used to pass infor- mation between the application and the PCRE2 libraries. - (1) A pointer to the compiled form of a pattern is returned to the user + The compiled pattern + + A pointer to the compiled form of a pattern is returned to the user when pcre2_compile() is successful. The data in the compiled pattern is - fixed, and does not change when the pattern is matched. Therefore, it - is thread-safe, that is, the same compiled pattern can be used by more - than one thread simultaneously. An application can compile all its pat- - terns at the start, before forking off multiple threads that use them. - However, if the just-in-time optimization feature is being used, it - needs separate memory stack areas for each thread. See the pcre2jit - documentation for more details. - - (2) The next section below introduces the idea of "contexts" in which + fixed, and does not change when the pattern is matched. Therefore, it + is thread-safe, that is, the same compiled pattern can be used by more + than one thread simultaneously. For example, an application can compile + all its patterns at the start, before forking off multiple threads that + use them. However, if the just-in-time optimization feature is being + used, it needs separate memory stack areas for each thread. See the + pcre2jit documentation for more details. + + In a more complicated situation, where patterns are compiled only when + they are first needed, but are still shared between threads, pointers + to compiled patterns must be protected from simultaneous writing by + multiple threads, at least until a pattern has been compiled. The logic + can be something like this: + + Get a read-only (shared) lock (mutex) for pointer + if (pointer == NULL) + { + Get a write (unique) lock for pointer + pointer = pcre2_compile(... + } + Release the lock + Use pointer in pcre2_match() + + Of course, testing for compilation errors should also be included in + the code. + + If JIT is being used, but the JIT compilation is not being done immedi- + ately, (perhaps waiting to see if the pattern is used often enough) + similar logic is required. JIT compilation updates a pointer within the + compiled code block, so a thread must gain unique write access to the + pointer before calling pcre2_jit_compile(). Alternatively, + pcre2_code_copy() can be used to obtain a private copy of the compiled + code. + + Context blocks + + The next main section below introduces the idea of "contexts" in which PCRE2 functions are called. A context is nothing more than a collection of parameters that control the way PCRE2 operates. Grouping a number of parameters together in a context is a convenient way of passing them to @@ -605,44 +644,45 @@ MULTITHREADING threads. However, if any thread needs to change any value in a context, it must make its own thread-specific copy. - (3) The matching functions need a block of memory for working space and - for storing the results of a match. This includes details of what was + Match blocks + + The matching functions need a block of memory for working space and for + storing the results of a match. This includes details of what was matched, as well as additional information such as the name of a - (*MARK) setting. Each thread must provide its own version of this mem- - ory. + (*MARK) setting. Each thread must provide its own copy of this memory. PCRE2 CONTEXTS - Some PCRE2 functions have a lot of parameters, many of which are used - only by specialist applications, for example, those that use custom - memory management or non-standard character tables. To keep function - argument lists at a reasonable size, and at the same time to keep the - API extensible, "uncommon" parameters are passed to certain functions - in a context instead of directly. A context is just a block of memory - that holds the parameter values. Applications that do not need to - adjust any of the context parameters can pass NULL when a context + Some PCRE2 functions have a lot of parameters, many of which are used + only by specialist applications, for example, those that use custom + memory management or non-standard character tables. To keep function + argument lists at a reasonable size, and at the same time to keep the + API extensible, "uncommon" parameters are passed to certain functions + in a context instead of directly. A context is just a block of memory + that holds the parameter values. Applications that do not need to + adjust any of the context parameters can pass NULL when a context pointer is required. - There are three different types of context: a general context that is - relevant for several PCRE2 operations, a compile-time context, and a + There are three different types of context: a general context that is + relevant for several PCRE2 operations, a compile-time context, and a match-time context. The general context - At present, this context just contains pointers to (and data for) - external memory management functions that are called from several + At present, this context just contains pointers to (and data for) + external memory management functions that are called from several places in the PCRE2 library. The context is named `general' rather than - specifically `memory' because in future other fields may be added. If - you do not want to supply your own custom memory management functions, - you do not need to bother with a general context. A general context is + specifically `memory' because in future other fields may be added. If + you do not want to supply your own custom memory management functions, + you do not need to bother with a general context. A general context is created by: pcre2_general_context *pcre2_general_context_create( void *(*private_malloc)(PCRE2_SIZE, void *), void (*private_free)(void *, void *), void *memory_data); - The two function pointers specify custom memory management functions, + The two function pointers specify custom memory management functions, whose prototypes are: void *private_malloc(PCRE2_SIZE, void *); @@ -650,16 +690,16 @@ PCRE2 CONTEXTS Whenever code in PCRE2 calls these functions, the final argument is the value of memory_data. Either of the first two arguments of the creation - function may be NULL, in which case the system memory management func- - tions malloc() and free() are used. (This is not currently useful, as - there are no other fields in a general context, but in future there - might be.) The private_malloc() function is used (if supplied) to - obtain memory for storing the context, and all three values are saved + function may be NULL, in which case the system memory management func- + tions malloc() and free() are used. (This is not currently useful, as + there are no other fields in a general context, but in future there + might be.) The private_malloc() function is used (if supplied) to + obtain memory for storing the context, and all three values are saved as part of the context. - Whenever PCRE2 creates a data block of any kind, the block contains a - pointer to the free() function that matches the malloc() function that - was used. When the time comes to free the block, this function is + Whenever PCRE2 creates a data block of any kind, the block contains a + pointer to the free() function that matches the malloc() function that + was used. When the time comes to free the block, this function is called. A general context can be copied by calling: @@ -674,7 +714,7 @@ PCRE2 CONTEXTS The compile context - A compile context is required if you want to change the default values + A compile context is required if you want to change the default values of any of the following compile-time parameters: What \R matches (Unicode newlines or CR, LF, CRLF only) @@ -684,11 +724,11 @@ PCRE2 CONTEXTS The maximum length of the pattern string An external function for stack checking - A compile context is also required if you are using custom memory man- - agement. If none of these apply, just pass NULL as the context argu- + A compile context is also required if you are using custom memory man- + agement. If none of these apply, just pass NULL as the context argu- ment of pcre2_compile(). - A compile context is created, copied, and freed by the following func- + A compile context is created, copied, and freed by the following func- tions: pcre2_compile_context *pcre2_compile_context_create( @@ -699,33 +739,33 @@ PCRE2 CONTEXTS void pcre2_compile_context_free(pcre2_compile_context *ccontext); - A compile context is created with default values for its parameters. + A compile context is created with default values for its parameters. These can be changed by calling the following functions, which return 0 on success, or PCRE2_ERROR_BADDATA if invalid data is detected. int pcre2_set_bsr(pcre2_compile_context *ccontext, uint32_t value); - The value must be PCRE2_BSR_ANYCRLF, to specify that \R matches only - CR, LF, or CRLF, or PCRE2_BSR_UNICODE, to specify that \R matches any + The value must be PCRE2_BSR_ANYCRLF, to specify that \R matches only + CR, LF, or CRLF, or PCRE2_BSR_UNICODE, to specify that \R matches any Unicode line ending sequence. The value is used by the JIT compiler and - by the two interpreted matching functions, pcre2_match() and + by the two interpreted matching functions, pcre2_match() and pcre2_dfa_match(). int pcre2_set_character_tables(pcre2_compile_context *ccontext, const unsigned char *tables); - The value must be the result of a call to pcre2_maketables(), whose + The value must be the result of a call to pcre2_maketables(), whose only argument is a general context. This function builds a set of char- acter tables in the current locale. int pcre2_set_max_pattern_length(pcre2_compile_context *ccontext, PCRE2_SIZE value); - This sets a maximum length, in code units, for the pattern string that - is to be compiled. If the pattern is longer, an error is generated. - This facility is provided so that applications that accept patterns - from external sources can limit their size. The default is the largest + This sets a maximum length, in code units, for the pattern string that + is to be compiled. If the pattern is longer, an error is generated. + This facility is provided so that applications that accept patterns + from external sources can limit their size. The default is the largest number that a PCRE2_SIZE variable can hold, which is effectively unlim- ited. @@ -733,38 +773,38 @@ PCRE2 CONTEXTS uint32_t value); This specifies which characters or character sequences are to be recog- - nized as newlines. The value must be one of PCRE2_NEWLINE_CR (carriage + nized as newlines. The value must be one of PCRE2_NEWLINE_CR (carriage return only), PCRE2_NEWLINE_LF (linefeed only), PCRE2_NEWLINE_CRLF (the - two-character sequence CR followed by LF), PCRE2_NEWLINE_ANYCRLF (any + two-character sequence CR followed by LF), PCRE2_NEWLINE_ANYCRLF (any of the above), or PCRE2_NEWLINE_ANY (any Unicode newline sequence). When a pattern is compiled with the PCRE2_EXTENDED option, the value of - this parameter affects the recognition of white space and the end of + this parameter affects the recognition of white space and the end of internal comments starting with #. The value is saved with the compiled - pattern for subsequent use by the JIT compiler and by the two inter- + pattern for subsequent use by the JIT compiler and by the two inter- preted matching functions, pcre2_match() and pcre2_dfa_match(). int pcre2_set_parens_nest_limit(pcre2_compile_context *ccontext, uint32_t value); This parameter ajusts the limit, set when PCRE2 is built (default 250), - on the depth of parenthesis nesting in a pattern. This limit stops + on the depth of parenthesis nesting in a pattern. This limit stops rogue patterns using up too much system stack when being compiled. int pcre2_set_compile_recursion_guard(pcre2_compile_context *ccontext, int (*guard_function)(uint32_t, void *), void *user_data); - There is at least one application that runs PCRE2 in threads with very - limited system stack, where running out of stack is to be avoided at - all costs. The parenthesis limit above cannot take account of how much - stack is actually available. For a finer control, you can supply a - function that is called whenever pcre2_compile() starts to compile a - parenthesized part of a pattern. This function can check the actual + There is at least one application that runs PCRE2 in threads with very + limited system stack, where running out of stack is to be avoided at + all costs. The parenthesis limit above cannot take account of how much + stack is actually available. For a finer control, you can supply a + function that is called whenever pcre2_compile() starts to compile a + parenthesized part of a pattern. This function can check the actual stack size (or anything else that it wants to, of course). - The first argument to the callout function gives the current depth of - nesting, and the second is user data that is set up by the last argu- - ment of pcre2_set_compile_recursion_guard(). The callout function + The first argument to the callout function gives the current depth of + nesting, and the second is user data that is set up by the last argu- + ment of pcre2_set_compile_recursion_guard(). The callout function should return zero if all is well, or non-zero to force an error. The match context @@ -778,10 +818,10 @@ PCRE2 CONTEXTS The limit for calling match() recursively A match context is also required if you are using custom memory manage- - ment. If none of these apply, just pass NULL as the context argument + ment. If none of these apply, just pass NULL as the context argument of pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match(). - A match context is created, copied, and freed by the following func- + A match context is created, copied, and freed by the following func- tions: pcre2_match_context *pcre2_match_context_create( @@ -792,7 +832,7 @@ PCRE2 CONTEXTS void pcre2_match_context_free(pcre2_match_context *mcontext); - A match context is created with default values for its parameters. + A match context is created with default values for its parameters. These can be changed by calling the following functions, which return 0 on success, or PCRE2_ERROR_BADDATA if invalid data is detected. @@ -800,96 +840,96 @@ PCRE2 CONTEXTS int (*callout_function)(pcre2_callout_block *, void *), void *callout_data); - This sets up a "callout" function, which PCRE2 will call at specified + This sets up a "callout" function, which PCRE2 will call at specified points during a matching operation. Details are given in the pcre2call- out documentation. int pcre2_set_offset_limit(pcre2_match_context *mcontext, PCRE2_SIZE value); - The offset_limit parameter limits how far an unanchored search can - advance in the subject string. The default value is PCRE2_UNSET. The - pcre2_match() and pcre2_dfa_match() functions return - PCRE2_ERROR_NOMATCH if a match with a starting point before or at the + The offset_limit parameter limits how far an unanchored search can + advance in the subject string. The default value is PCRE2_UNSET. The + pcre2_match() and pcre2_dfa_match() functions return + PCRE2_ERROR_NOMATCH if a match with a starting point before or at the given offset is not found. For example, if the pattern /abc/ is matched - against "123abc" with an offset limit less than 3, the result is - PCRE2_ERROR_NO_MATCH. A match can never be found if the startoffset + against "123abc" with an offset limit less than 3, the result is + PCRE2_ERROR_NO_MATCH. A match can never be found if the startoffset argument of pcre2_match() or pcre2_dfa_match() is greater than the off- set limit. - When using this facility, you must set PCRE2_USE_OFFSET_LIMIT when - calling pcre2_compile() so that when JIT is in use, different code can - be compiled. If a match is started with a non-default match limit when + When using this facility, you must set PCRE2_USE_OFFSET_LIMIT when + calling pcre2_compile() so that when JIT is in use, different code can + be compiled. If a match is started with a non-default match limit when PCRE2_USE_OFFSET_LIMIT is not set, an error is generated. - The offset limit facility can be used to track progress when searching - large subject strings. See also the PCRE2_FIRSTLINE option, which + The offset limit facility can be used to track progress when searching + large subject strings. See also the PCRE2_FIRSTLINE option, which requires a match to start within the first line of the subject. If this - is set with an offset limit, a match must occur in the first line and - also within the offset limit. In other words, whichever limit comes + is set with an offset limit, a match must occur in the first line and + also within the offset limit. In other words, whichever limit comes first is used. int pcre2_set_match_limit(pcre2_match_context *mcontext, uint32_t value); - The match_limit parameter provides a means of preventing PCRE2 from + The match_limit parameter provides a means of preventing PCRE2 from using up too many resources when processing patterns that are not going - to match, but which have a very large number of possibilities in their - search trees. The classic example is a pattern that uses nested unlim- + to match, but which have a very large number of possibilities in their + search trees. The classic example is a pattern that uses nested unlim- ited repeats. - Internally, pcre2_match() uses a function called match(), which it - calls repeatedly (sometimes recursively). The limit set by match_limit - is imposed on the number of times this function is called during a + Internally, pcre2_match() uses a function called match(), which it + calls repeatedly (sometimes recursively). The limit set by match_limit + is imposed on the number of times this function is called during a match, which has the effect of limiting the amount of backtracking that - can take place. For patterns that are not anchored, the count restarts - from zero for each position in the subject string. This limit is not + can take place. For patterns that are not anchored, the count restarts + from zero for each position in the subject string. This limit is not relevant to pcre2_dfa_match(), which ignores it. - When pcre2_match() is called with a pattern that was successfully pro- + When pcre2_match() is called with a pattern that was successfully pro- cessed by pcre2_jit_compile(), the way in which matching is executed is - entirely different. However, there is still the possibility of runaway - matching that goes on for a very long time, and so the match_limit - value is also used in this case (but in a different way) to limit how + entirely different. However, there is still the possibility of runaway + matching that goes on for a very long time, and so the match_limit + value is also used in this case (but in a different way) to limit how long the matching can continue. - The default value for the limit can be set when PCRE2 is built; the - default default is 10 million, which handles all but the most extreme - cases. If the limit is exceeded, pcre2_match() returns - PCRE2_ERROR_MATCHLIMIT. A value for the match limit may also be sup- + The default value for the limit can be set when PCRE2 is built; the + default default is 10 million, which handles all but the most extreme + cases. If the limit is exceeded, pcre2_match() returns + PCRE2_ERROR_MATCHLIMIT. A value for the match limit may also be sup- plied by an item at the start of a pattern of the form (*LIMIT_MATCH=ddd) - where ddd is a decimal number. However, such a setting is ignored - unless ddd is less than the limit set by the caller of pcre2_match() + where ddd is a decimal number. However, such a setting is ignored + unless ddd is less than the limit set by the caller of pcre2_match() or, if no such limit is set, less than the default. int pcre2_set_recursion_limit(pcre2_match_context *mcontext, uint32_t value); The recursion_limit parameter is similar to match_limit, but instead of - limiting the total number of times that match() is called, it limits - the depth of recursion. The recursion depth is a smaller number than - the total number of calls, because not all calls to match() are recur- + limiting the total number of times that match() is called, it limits + the depth of recursion. The recursion depth is a smaller number than + the total number of calls, because not all calls to match() are recur- sive. This limit is of use only if it is set smaller than match_limit. Limiting the recursion depth limits the amount of system stack that can - be used, or, when PCRE2 has been compiled to use memory on the heap - instead of the stack, the amount of heap memory that can be used. This - limit is not relevant, and is ignored, when matching is done using JIT + be used, or, when PCRE2 has been compiled to use memory on the heap + instead of the stack, the amount of heap memory that can be used. This + limit is not relevant, and is ignored, when matching is done using JIT compiled code or by the pcre2_dfa_match() function. - The default value for recursion_limit can be set when PCRE2 is built; - the default default is the same value as the default for match_limit. - If the limit is exceeded, pcre2_match() returns PCRE2_ERROR_RECURSION- - LIMIT. A value for the recursion limit may also be supplied by an item + The default value for recursion_limit can be set when PCRE2 is built; + the default default is the same value as the default for match_limit. + If the limit is exceeded, pcre2_match() returns PCRE2_ERROR_RECURSION- + LIMIT. A value for the recursion limit may also be supplied by an item at the start of a pattern of the form (*LIMIT_RECURSION=ddd) - where ddd is a decimal number. However, such a setting is ignored - unless ddd is less than the limit set by the caller of pcre2_match() + where ddd is a decimal number. However, such a setting is ignored + unless ddd is less than the limit set by the caller of pcre2_match() or, if no such limit is set, less than the default. int pcre2_set_recursion_memory_management( @@ -898,21 +938,21 @@ PCRE2 CONTEXTS void (*private_free)(void *, void *), void *memory_data); This function sets up two additional custom memory management functions - for use by pcre2_match() when PCRE2 is compiled to use the heap for + for use by pcre2_match() when PCRE2 is compiled to use the heap for remembering backtracking data, instead of recursive function calls that - use the system stack. There is a discussion about PCRE2's stack usage - in the pcre2stack documentation. See the pcre2build documentation for + use the system stack. There is a discussion about PCRE2's stack usage + in the pcre2stack documentation. See the pcre2build documentation for details of how to build PCRE2. - Using the heap for recursion is a non-standard way of building PCRE2, - for use in environments that have limited stacks. Because of the + Using the heap for recursion is a non-standard way of building PCRE2, + for use in environments that have limited stacks. Because of the greater use of memory management, pcre2_match() runs more slowly. Func- - tions that are different to the general custom memory functions are - provided so that special-purpose external code can be used for this - case, because the memory blocks are all the same size. The blocks are + tions that are different to the general custom memory functions are + provided so that special-purpose external code can be used for this + case, because the memory blocks are all the same size. The blocks are retained by pcre2_match() until it is about to exit so that they can be - re-used when possible during the match. In the absence of these func- - tions, the normal custom memory management functions are used, if sup- + re-used when possible during the match. In the absence of these func- + tions, the normal custom memory management functions are used, if sup- plied, otherwise the system functions. @@ -920,75 +960,75 @@ CHECKING BUILD-TIME OPTIONS int pcre2_config(uint32_t what, void *where); - The function pcre2_config() makes it possible for a PCRE2 client to - discover which optional features have been compiled into the PCRE2 - library. The pcre2build documentation has more details about these + The function pcre2_config() makes it possible for a PCRE2 client to + discover which optional features have been compiled into the PCRE2 + library. The pcre2build documentation has more details about these optional features. - The first argument for pcre2_config() specifies which information is - required. The second argument is a pointer to memory into which the - information is placed. If NULL is passed, the function returns the - amount of memory that is needed for the requested information. For - calls that return numerical values, the value is in bytes; when - requesting these values, where should point to appropriately aligned - memory. For calls that return strings, the required length is given in + The first argument for pcre2_config() specifies which information is + required. The second argument is a pointer to memory into which the + information is placed. If NULL is passed, the function returns the + amount of memory that is needed for the requested information. For + calls that return numerical values, the value is in bytes; when + requesting these values, where should point to appropriately aligned + memory. For calls that return strings, the required length is given in code units, not counting the terminating zero. - When requesting information, the returned value from pcre2_config() is - non-negative on success, or the negative error code PCRE2_ERROR_BADOP- - TION if the value in the first argument is not recognized. The follow- + When requesting information, the returned value from pcre2_config() is + non-negative on success, or the negative error code PCRE2_ERROR_BADOP- + TION if the value in the first argument is not recognized. The follow- ing information is available: PCRE2_CONFIG_BSR - The output is a uint32_t integer whose value indicates what character - sequences the \R escape sequence matches by default. A value of + The output is a uint32_t integer whose value indicates what character + sequences the \R escape sequence matches by default. A value of PCRE2_BSR_UNICODE means that \R matches any Unicode line ending - sequence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR, + sequence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR, LF, or CRLF. The default can be overridden when a pattern is compiled. PCRE2_CONFIG_JIT - The output is a uint32_t integer that is set to one if support for + The output is a uint32_t integer that is set to one if support for just-in-time compiling is available; otherwise it is set to zero. PCRE2_CONFIG_JITTARGET - The where argument should point to a buffer that is at least 48 code - units long. (The exact length required can be found by calling - pcre2_config() with where set to NULL.) The buffer is filled with a - string that contains the name of the architecture for which the JIT - compiler is configured, for example "x86 32bit (little endian + - unaligned)". If JIT support is not available, PCRE2_ERROR_BADOPTION is - returned, otherwise the number of code units used is returned. This is + The where argument should point to a buffer that is at least 48 code + units long. (The exact length required can be found by calling + pcre2_config() with where set to NULL.) The buffer is filled with a + string that contains the name of the architecture for which the JIT + compiler is configured, for example "x86 32bit (little endian + + unaligned)". If JIT support is not available, PCRE2_ERROR_BADOPTION is + returned, otherwise the number of code units used is returned. This is the length of the string, plus one unit for the terminating zero. PCRE2_CONFIG_LINKSIZE The output is a uint32_t integer that contains the number of bytes used - for internal linkage in compiled regular expressions. When PCRE2 is - configured, the value can be set to 2, 3, or 4, with the default being - 2. This is the value that is returned by pcre2_config(). However, when - the 16-bit library is compiled, a value of 3 is rounded up to 4, and - when the 32-bit library is compiled, internal linkages always use 4 + for internal linkage in compiled regular expressions. When PCRE2 is + configured, the value can be set to 2, 3, or 4, with the default being + 2. This is the value that is returned by pcre2_config(). However, when + the 16-bit library is compiled, a value of 3 is rounded up to 4, and + when the 32-bit library is compiled, internal linkages always use 4 bytes, so the configured value is not relevant. The default value of 2 for the 8-bit and 16-bit libraries is sufficient - for all but the most massive patterns, since it allows the size of the + for all but the most massive patterns, since it allows the size of the compiled pattern to be up to 64K code units. Larger values allow larger - regular expressions to be compiled by those two libraries, but at the + regular expressions to be compiled by those two libraries, but at the expense of slower matching. PCRE2_CONFIG_MATCHLIMIT - The output is a uint32_t integer that gives the default limit for the - number of internal matching function calls in a pcre2_match() execu- + The output is a uint32_t integer that gives the default limit for the + number of internal matching function calls in a pcre2_match() execu- tion. Further details are given with pcre2_match() below. PCRE2_CONFIG_NEWLINE - The output is a uint32_t integer whose value specifies the default - character sequence that is recognized as meaning "newline". The values + The output is a uint32_t integer whose value specifies the default + character sequence that is recognized as meaning "newline". The values are: PCRE2_NEWLINE_CR Carriage return (CR) @@ -997,56 +1037,56 @@ CHECKING BUILD-TIME OPTIONS PCRE2_NEWLINE_ANY Any Unicode line ending PCRE2_NEWLINE_ANYCRLF Any of CR, LF, or CRLF - The default should normally correspond to the standard sequence for + The default should normally correspond to the standard sequence for your operating system. PCRE2_CONFIG_PARENSLIMIT - The output is a uint32_t integer that gives the maximum depth of nest- + The output is a uint32_t integer that gives the maximum depth of nest- ing of parentheses (of any kind) in a pattern. This limit is imposed to - cap the amount of system stack used when a pattern is compiled. It is - specified when PCRE2 is built; the default is 250. This limit does not - take into account the stack that may already be used by the calling - application. For finer control over compilation stack usage, see + cap the amount of system stack used when a pattern is compiled. It is + specified when PCRE2 is built; the default is 250. This limit does not + take into account the stack that may already be used by the calling + application. For finer control over compilation stack usage, see pcre2_set_compile_recursion_guard(). PCRE2_CONFIG_RECURSIONLIMIT - The output is a uint32_t integer that gives the default limit for the - depth of recursion when calling the internal matching function in a - pcre2_match() execution. Further details are given with pcre2_match() + The output is a uint32_t integer that gives the default limit for the + depth of recursion when calling the internal matching function in a + pcre2_match() execution. Further details are given with pcre2_match() below. PCRE2_CONFIG_STACKRECURSE - The output is a uint32_t integer that is set to one if internal recur- - sion when running pcre2_match() is implemented by recursive function - calls that use the system stack to remember their state. This is the - usual way that PCRE2 is compiled. The output is zero if PCRE2 was com- - piled to use blocks of data on the heap instead of recursive function + The output is a uint32_t integer that is set to one if internal recur- + sion when running pcre2_match() is implemented by recursive function + calls that use the system stack to remember their state. This is the + usual way that PCRE2 is compiled. The output is zero if PCRE2 was com- + piled to use blocks of data on the heap instead of recursive function calls. PCRE2_CONFIG_UNICODE_VERSION - The where argument should point to a buffer that is at least 24 code - units long. (The exact length required can be found by calling - pcre2_config() with where set to NULL.) If PCRE2 has been compiled - without Unicode support, the buffer is filled with the text "Unicode - not supported". Otherwise, the Unicode version string (for example, - "8.0.0") is inserted. The number of code units used is returned. This + The where argument should point to a buffer that is at least 24 code + units long. (The exact length required can be found by calling + pcre2_config() with where set to NULL.) If PCRE2 has been compiled + without Unicode support, the buffer is filled with the text "Unicode + not supported". Otherwise, the Unicode version string (for example, + "8.0.0") is inserted. The number of code units used is returned. This is the length of the string plus one unit for the terminating zero. PCRE2_CONFIG_UNICODE - The output is a uint32_t integer that is set to one if Unicode support - is available; otherwise it is set to zero. Unicode support implies UTF + The output is a uint32_t integer that is set to one if Unicode support + is available; otherwise it is set to zero. Unicode support implies UTF support. PCRE2_CONFIG_VERSION - The where argument should point to a buffer that is at least 12 code - units long. (The exact length required can be found by calling - pcre2_config() with where set to NULL.) The buffer is filled with the + The where argument should point to a buffer that is at least 12 code + units long. (The exact length required can be found by calling + pcre2_config() with where set to NULL.) The buffer is filled with the PCRE2 version string, zero-terminated. The number of code units used is returned. This is the length of the string plus one unit for the termi- nating zero. @@ -1060,58 +1100,74 @@ COMPILING A PATTERN void pcre2_code_free(pcre2_code *code); - The pcre2_compile() function compiles a pattern into an internal form. - The pattern is defined by a pointer to a string of code units and a - length, If the pattern is zero-terminated, the length can be specified - as PCRE2_ZERO_TERMINATED. The function returns a pointer to a block of - memory that contains the compiled pattern and related data. The caller - must free the memory by calling pcre2_code_free() when it is no longer - needed. + pcre2_code *pcre2_code_copy(const pcre2_code *code); + + The pcre2_compile() function compiles a pattern into an internal form. + The pattern is defined by a pointer to a string of code units and a + length. If the pattern is zero-terminated, the length can be specified + as PCRE2_ZERO_TERMINATED. The function returns a pointer to a block of + memory that contains the compiled pattern and related data, or NULL if + an error occurred. + + If the compile context argument ccontext is NULL, memory for the com- + piled pattern is obtained by calling malloc(). Otherwise, it is + obtained from the same memory function that was used for the compile + context. The caller must free the memory by calling pcre2_code_free() + when it is no longer needed. + + The function pcre2_code_copy() makes a copy of the compiled code in new + memory, using the same memory allocator as was used for the original. + However, if the code has been processed by the JIT compiler (see + below), the JIT information cannot be copied (because it is position- + dependent). The new copy can initially be used only for non-JIT match- + ing, though it can be passed to pcre2_jit_compile() if required. The + pcre2_code_copy() function provides a way for individual threads in a + multithreaded application to acquire a private copy of shared compiled + code. NOTE: When one of the matching functions is called, pointers to the compiled pattern and the subject string are set in the match data block - so that they can be referenced by the extraction functions. After run- - ning a match, you must not free a compiled pattern (or a subject - string) until after all operations on the match data block have taken - place. - - If the compile context argument ccontext is NULL, memory for the com- - piled pattern is obtained by calling malloc(). Otherwise, it is - obtained from the same memory function that was used for the compile - context. - - The options argument contains various bit settings that affect the com- - pilation. It should be zero if no options are required. The available - options are described below. Some of them (in particular, those that - are compatible with Perl, but some others as well) can also be set and - unset from within the pattern (see the detailed description in the - pcre2pattern documentation). - - For those options that can be different in different parts of the pat- - tern, the contents of the options argument specifies their settings at - the start of compilation. The PCRE2_ANCHORED and PCRE2_NO_UTF_CHECK + so that they can be referenced by the substring extraction functions. + After running a match, you must not free a compiled pattern (or a sub- + ject string) until after all operations on the match data block have + taken place. + + The options argument for pcre2_compile() contains various bit settings + that affect the compilation. It should be zero if no options are + required. The available options are described below. Some of them (in + particular, those that are compatible with Perl, but some others as + well) can also be set and unset from within the pattern (see the + detailed description in the pcre2pattern documentation). + + For those options that can be different in different parts of the pat- + tern, the contents of the options argument specifies their settings at + the start of compilation. The PCRE2_ANCHORED and PCRE2_NO_UTF_CHECK options can be set at the time of matching as well as at compile time. - Other, less frequently required compile-time parameters (for example, + Other, less frequently required compile-time parameters (for example, the newline setting) can be provided in a compile context (as described above). If errorcode or erroroffset is NULL, pcre2_compile() returns NULL imme- - diately. Otherwise, if compilation of a pattern fails, pcre2_compile() - returns NULL, having set these variables to an error code and an offset - (number of code units) within the pattern, respectively. The - pcre2_get_error_message() function provides a textual message for each - error code. Compilation errors are positive numbers, but UTF formatting - errors are negative numbers. For an invalid UTF-8 or UTF-16 string, the - offset is that of the first code unit of the failing character. - - Some errors are not detected until the whole pattern has been scanned; - in these cases, the offset passed back is the length of the pattern. - Note that the offset is in code units, not characters, even in a UTF + diately. Otherwise, the variables to which these point are set to an + error code and an offset (number of code units) within the pattern, + respectively, when pcre2_compile() returns NULL because a compilation + error has occurred. The values are not defined when compilation is suc- + cessful and pcre2_compile() returns a non-NULL value. + + The pcre2_get_error_message() function (see "Obtaining a textual error + message" below) provides a textual message for each error code. Compi- + lation errors have positive error codes; UTF formatting error codes are + negative. For an invalid UTF-8 or UTF-16 string, the offset is that of + the first code unit of the failing character. + + Some errors are not detected until the whole pattern has been scanned; + in these cases, the offset passed back is the length of the pattern. + Note that the offset is in code units, not characters, even in a UTF mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char- acter. - This code fragment shows a typical straightforward call to pcre2_com- + This code fragment shows a typical straightforward call to pcre2_com- pile(): pcre2_code *re; @@ -1125,208 +1181,211 @@ COMPILING A PATTERN &erroffset, /* for error offset */ NULL); /* no compile context */ - The following names for option bits are defined in the pcre2.h header + The following names for option bits are defined in the pcre2.h header file: PCRE2_ANCHORED If this bit is set, the pattern is forced to be "anchored", that is, it - is constrained to match only at the first matching point in the string - that is being searched (the "subject string"). This effect can also be - achieved by appropriate constructs in the pattern itself, which is the + is constrained to match only at the first matching point in the string + that is being searched (the "subject string"). This effect can also be + achieved by appropriate constructs in the pattern itself, which is the only way to do it in Perl. PCRE2_ALLOW_EMPTY_CLASS - By default, for compatibility with Perl, a closing square bracket that - immediately follows an opening one is treated as a data character for - the class. When PCRE2_ALLOW_EMPTY_CLASS is set, it terminates the + By default, for compatibility with Perl, a closing square bracket that + immediately follows an opening one is treated as a data character for + the class. When PCRE2_ALLOW_EMPTY_CLASS is set, it terminates the class, which therefore contains no characters and so can never match. PCRE2_ALT_BSUX - This option request alternative handling of three escape sequences, - which makes PCRE2's behaviour more like ECMAscript (aka JavaScript). + This option request alternative handling of three escape sequences, + which makes PCRE2's behaviour more like ECMAscript (aka JavaScript). When it is set: (1) \U matches an upper case "U" character; by default \U causes a com- pile time error (Perl uses \U to upper case subsequent characters). (2) \u matches a lower case "u" character unless it is followed by four - hexadecimal digits, in which case the hexadecimal number defines the - code point to match. By default, \u causes a compile time error (Perl + hexadecimal digits, in which case the hexadecimal number defines the + code point to match. By default, \u causes a compile time error (Perl uses it to upper case the following character). - (3) \x matches a lower case "x" character unless it is followed by two - hexadecimal digits, in which case the hexadecimal number defines the - code point to match. By default, as in Perl, a hexadecimal number is + (3) \x matches a lower case "x" character unless it is followed by two + hexadecimal digits, in which case the hexadecimal number defines the + code point to match. By default, as in Perl, a hexadecimal number is always expected after \x, but it may have zero, one, or two digits (so, for example, \xz matches a binary zero character followed by z). PCRE2_ALT_CIRCUMFLEX In multiline mode (when PCRE2_MULTILINE is set), the circumflex - metacharacter matches at the start of the subject (unless PCRE2_NOTBOL - is set), and also after any internal newline. However, it does not + metacharacter matches at the start of the subject (unless PCRE2_NOTBOL + is set), and also after any internal newline. However, it does not match after a newline at the end of the subject, for compatibility with - Perl. If you want a multiline circumflex also to match after a termi- + Perl. If you want a multiline circumflex also to match after a termi- nating newline, you must set PCRE2_ALT_CIRCUMFLEX. PCRE2_ALT_VERBNAMES - By default, for compatibility with Perl, the name in any verb sequence - such as (*MARK:NAME) is any sequence of characters that does not - include a closing parenthesis. The name is not processed in any way, - and it is not possible to include a closing parenthesis in the name. - However, if the PCRE2_ALT_VERBNAMES option is set, normal backslash - processing is applied to verb names and only an unescaped closing - parenthesis terminates the name. A closing parenthesis can be included - in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED + By default, for compatibility with Perl, the name in any verb sequence + such as (*MARK:NAME) is any sequence of characters that does not + include a closing parenthesis. The name is not processed in any way, + and it is not possible to include a closing parenthesis in the name. + However, if the PCRE2_ALT_VERBNAMES option is set, normal backslash + processing is applied to verb names and only an unescaped closing + parenthesis terminates the name. A closing parenthesis can be included + in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED option is set, unescaped whitespace in verb names is skipped and #-com- ments are recognized, exactly as in the rest of the pattern. PCRE2_AUTO_CALLOUT - If this bit is set, pcre2_compile() automatically inserts callout + If this bit is set, pcre2_compile() automatically inserts callout items, all with number 255, before each pattern item. For discussion of the callout facility, see the pcre2callout documentation. PCRE2_CASELESS - If this bit is set, letters in the pattern match both upper and lower - case letters in the subject. It is equivalent to Perl's /i option, and + If this bit is set, letters in the pattern match both upper and lower + case letters in the subject. It is equivalent to Perl's /i option, and it can be changed within a pattern by a (?i) option setting. PCRE2_DOLLAR_ENDONLY - If this bit is set, a dollar metacharacter in the pattern matches only - at the end of the subject string. Without this option, a dollar also - matches immediately before a newline at the end of the string (but not - before any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored - if PCRE2_MULTILINE is set. There is no equivalent to this option in + If this bit is set, a dollar metacharacter in the pattern matches only + at the end of the subject string. Without this option, a dollar also + matches immediately before a newline at the end of the string (but not + before any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored + if PCRE2_MULTILINE is set. There is no equivalent to this option in Perl, and no way to set it within a pattern. PCRE2_DOTALL - If this bit is set, a dot metacharacter in the pattern matches any - character, including one that indicates a newline. However, it only + If this bit is set, a dot metacharacter in the pattern matches any + character, including one that indicates a newline. However, it only ever matches one character, even if newlines are coded as CRLF. Without this option, a dot does not match when the current position in the sub- - ject is at a newline. This option is equivalent to Perl's /s option, + ject is at a newline. This option is equivalent to Perl's /s option, and it can be changed within a pattern by a (?s) option setting. A neg- ative class such as [^a] always matches newline characters, independent of the setting of this option. PCRE2_DUPNAMES - If this bit is set, names used to identify capturing subpatterns need + If this bit is set, names used to identify capturing subpatterns need not be unique. This can be helpful for certain types of pattern when it - is known that only one instance of the named subpattern can ever be - matched. There are more details of named subpatterns below; see also + is known that only one instance of the named subpattern can ever be + matched. There are more details of named subpatterns below; see also the pcre2pattern documentation. PCRE2_EXTENDED - If this bit is set, most white space characters in the pattern are - totally ignored except when escaped or inside a character class. How- - ever, white space is not allowed within sequences such as (?> that + If this bit is set, most white space characters in the pattern are + totally ignored except when escaped or inside a character class. How- + ever, white space is not allowed within sequences such as (?> that introduce various parenthesized subpatterns, nor within numerical quan- - tifiers such as {1,3}. Ignorable white space is permitted between an - item and a following quantifier and between a quantifier and a follow- + tifiers such as {1,3}. Ignorable white space is permitted between an + item and a following quantifier and between a quantifier and a follow- ing + that indicates possessiveness. - PCRE2_EXTENDED also causes characters between an unescaped # outside a - character class and the next newline, inclusive, to be ignored, which + PCRE2_EXTENDED also causes characters between an unescaped # outside a + character class and the next newline, inclusive, to be ignored, which makes it possible to include comments inside complicated patterns. Note - that the end of this type of comment is a literal newline sequence in + that the end of this type of comment is a literal newline sequence in the pattern; escape sequences that happen to represent a newline do not - count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be + count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be changed within a pattern by a (?x) option setting. Which characters are interpreted as newlines can be specified by a set- - ting in the compile context that is passed to pcre2_compile() or by a - special sequence at the start of the pattern, as described in the sec- - tion entitled "Newline conventions" in the pcre2pattern documentation. + ting in the compile context that is passed to pcre2_compile() or by a + special sequence at the start of the pattern, as described in the sec- + tion entitled "Newline conventions" in the pcre2pattern documentation. A default is defined when PCRE2 is built. PCRE2_FIRSTLINE - If this option is set, an unanchored pattern is required to match - before or at the first newline in the subject string, though the - matched text may continue over the newline. See also PCRE2_USE_OFF- - SET_LIMIT, which provides a more general limiting facility. If - PCRE2_FIRSTLINE is set with an offset limit, a match must occur in the - first line and also within the offset limit. In other words, whichever + If this option is set, an unanchored pattern is required to match + before or at the first newline in the subject string, though the + matched text may continue over the newline. See also PCRE2_USE_OFF- + SET_LIMIT, which provides a more general limiting facility. If + PCRE2_FIRSTLINE is set with an offset limit, a match must occur in the + first line and also within the offset limit. In other words, whichever limit comes first is used. PCRE2_MATCH_UNSET_BACKREF - If this option is set, a back reference to an unset subpattern group - matches an empty string (by default this causes the current matching - alternative to fail). A pattern such as (\1)(a) succeeds when this - option is set (assuming it can find an "a" in the subject), whereas it - fails by default, for Perl compatibility. Setting this option makes + If this option is set, a back reference to an unset subpattern group + matches an empty string (by default this causes the current matching + alternative to fail). A pattern such as (\1)(a) succeeds when this + option is set (assuming it can find an "a" in the subject), whereas it + fails by default, for Perl compatibility. Setting this option makes PCRE2 behave more like ECMAscript (aka JavaScript). PCRE2_MULTILINE - By default, for the purposes of matching "start of line" and "end of - line", PCRE2 treats the subject string as consisting of a single line - of characters, even if it actually contains newlines. The "start of - line" metacharacter (^) matches only at the start of the string, and - the "end of line" metacharacter ($) matches only at the end of the + By default, for the purposes of matching "start of line" and "end of + line", PCRE2 treats the subject string as consisting of a single line + of characters, even if it actually contains newlines. The "start of + line" metacharacter (^) matches only at the start of the string, and + the "end of line" metacharacter ($) matches only at the end of the string, or before a terminating newline (except when PCRE2_DOL- - LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set, + LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set, the "any character" metacharacter (.) does not match at a newline. This behaviour (for ^, $, and dot) is the same as Perl. - When PCRE2_MULTILINE it is set, the "start of line" and "end of line" - constructs match immediately following or immediately before internal - newlines in the subject string, respectively, as well as at the very - start and end. This is equivalent to Perl's /m option, and it can be + When PCRE2_MULTILINE it is set, the "start of line" and "end of line" + constructs match immediately following or immediately before internal + newlines in the subject string, respectively, as well as at the very + start and end. This is equivalent to Perl's /m option, and it can be changed within a pattern by a (?m) option setting. Note that the "start of line" metacharacter does not match after a newline at the end of the - subject, for compatibility with Perl. However, you can change this by - setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a - subject string, or no occurrences of ^ or $ in a pattern, setting + subject, for compatibility with Perl. However, you can change this by + setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a + subject string, or no occurrences of ^ or $ in a pattern, setting PCRE2_MULTILINE has no effect. PCRE2_NEVER_BACKSLASH_C - This option locks out the use of \C in the pattern that is being com- - piled. This escape can cause unpredictable behaviour in UTF-8 or - UTF-16 modes, because it may leave the current matching point in the - middle of a multi-code-unit character. This option may be useful in - applications that process patterns from external sources. Note that + This option locks out the use of \C in the pattern that is being com- + piled. This escape can cause unpredictable behaviour in UTF-8 or + UTF-16 modes, because it may leave the current matching point in the + middle of a multi-code-unit character. This option may be useful in + applications that process patterns from external sources. Note that there is also a build-time option that permanently locks out the use of \C. PCRE2_NEVER_UCP - This option locks out the use of Unicode properties for handling \B, + This option locks out the use of Unicode properties for handling \B, \b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as - described for the PCRE2_UCP option below. In particular, it prevents - the creator of the pattern from enabling this facility by starting the - pattern with (*UCP). This option may be useful in applications that + described for the PCRE2_UCP option below. In particular, it prevents + the creator of the pattern from enabling this facility by starting the + pattern with (*UCP). This option may be useful in applications that process patterns from external sources. The option combination PCRE_UCP and PCRE_NEVER_UCP causes an error. PCRE2_NEVER_UTF - This option locks out interpretation of the pattern as UTF-8, UTF-16, + This option locks out interpretation of the pattern as UTF-8, UTF-16, or UTF-32, depending on which library is in use. In particular, it pre- - vents the creator of the pattern from switching to UTF interpretation - by starting the pattern with (*UTF). This option may be useful in - applications that process patterns from external sources. The combina- + vents the creator of the pattern from switching to UTF interpretation + by starting the pattern with (*UTF). This option may be useful in + applications that process patterns from external sources. The combina- tion of PCRE2_UTF and PCRE2_NEVER_UTF causes an error. PCRE2_NO_AUTO_CAPTURE If this option is set, it disables the use of numbered capturing paren- - theses in the pattern. Any opening parenthesis that is not followed by - ? behaves as if it were followed by ?: but named parentheses can still - be used for capturing (and they acquire numbers in the usual way). - There is no equivalent of this option in Perl. + theses in the pattern. Any opening parenthesis that is not followed by + ? behaves as if it were followed by ?: but named parentheses can still + be used for capturing (and they acquire numbers in the usual way). + There is no equivalent of this option in Perl. Note that, if this + option is set, references to capturing groups (back references or + recursion/subroutine calls) may only refer to named groups, though the + reference can be by name or by number. PCRE2_NO_AUTO_POSSESS @@ -1461,11 +1520,12 @@ COMPILING A PATTERN COMPILATION ERROR CODES There are over 80 positive error codes that pcre2_compile() may return - if it finds an error in the pattern. There are also some negative error - codes that are used for invalid UTF strings. These are the same as - given by pcre2_match() and pcre2_dfa_match(), and are described in the - pcre2unicode page. The pcre2_get_error_message() function can be called - to obtain a textual error message from any error code. + (via errorcode) if it finds an error in the pattern. There are also + some negative error codes that are used for invalid UTF strings. These + are the same as given by pcre2_match() and pcre2_dfa_match(), and are + described in the pcre2unicode page. The pcre2_get_error_message() func- + tion (see "Obtaining a textual error message" below) can be called to + obtain a textual error message from any error code. JUST-IN-TIME (JIT) COMPILATION @@ -1487,53 +1547,53 @@ JUST-IN-TIME (JIT) COMPILATION void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack); - These functions provide support for JIT compilation, which, if the - just-in-time compiler is available, further processes a compiled pat- + These functions provide support for JIT compilation, which, if the + just-in-time compiler is available, further processes a compiled pat- tern into machine code that executes much faster than the pcre2_match() - interpretive matching function. Full details are given in the pcre2jit + interpretive matching function. Full details are given in the pcre2jit documentation. - JIT compilation is a heavyweight optimization. It can take some time - for patterns to be analyzed, and for one-off matches and simple pat- - terns the benefit of faster execution might be offset by a much slower - compilation time. Most, but not all patterns can be optimized by the + JIT compilation is a heavyweight optimization. It can take some time + for patterns to be analyzed, and for one-off matches and simple pat- + terns the benefit of faster execution might be offset by a much slower + compilation time. Most, but not all patterns can be optimized by the JIT compiler. LOCALE SUPPORT - PCRE2 handles caseless matching, and determines whether characters are - letters, digits, or whatever, by reference to a set of tables, indexed - by character code point. This applies only to characters whose code - points are less than 256. By default, higher-valued code points never - match escapes such as \w or \d. However, if PCRE2 is built with UTF - support, all characters can be tested with \p and \P, or, alterna- - tively, the PCRE2_UCP option can be set when a pattern is compiled; - this causes \w and friends to use Unicode property support instead of + PCRE2 handles caseless matching, and determines whether characters are + letters, digits, or whatever, by reference to a set of tables, indexed + by character code point. This applies only to characters whose code + points are less than 256. By default, higher-valued code points never + match escapes such as \w or \d. However, if PCRE2 is built with UTF + support, all characters can be tested with \p and \P, or, alterna- + tively, the PCRE2_UCP option can be set when a pattern is compiled; + this causes \w and friends to use Unicode property support instead of the built-in tables. - The use of locales with Unicode is discouraged. If you are handling - characters with code points greater than 128, you should either use + The use of locales with Unicode is discouraged. If you are handling + characters with code points greater than 128, you should either use Unicode support, or use locales, but not try to mix the two. - PCRE2 contains an internal set of character tables that are used by - default. These are sufficient for many applications. Normally, the + PCRE2 contains an internal set of character tables that are used by + default. These are sufficient for many applications. Normally, the internal tables recognize only ASCII characters. However, when PCRE2 is built, it is possible to cause the internal tables to be rebuilt in the default "C" locale of the local system, which may cause them to be dif- ferent. - The internal tables can be overridden by tables supplied by the appli- - cation that calls PCRE2. These may be created in a different locale - from the default. As more and more applications change to using Uni- + The internal tables can be overridden by tables supplied by the appli- + cation that calls PCRE2. These may be created in a different locale + from the default. As more and more applications change to using Uni- code, the need for this locale support is expected to die away. - External tables are built by calling the pcre2_maketables() function, - in the relevant locale. The result can be passed to pcre2_compile() as - often as necessary, by creating a compile context and calling - pcre2_set_character_tables() to set the tables pointer therein. For - example, to build and use tables that are appropriate for the French - locale (where accented characters with values greater than 128 are + External tables are built by calling the pcre2_maketables() function, + in the relevant locale. The result can be passed to pcre2_compile() as + often as necessary, by creating a compile context and calling + pcre2_set_character_tables() to set the tables pointer therein. For + example, to build and use tables that are appropriate for the French + locale (where accented characters with values greater than 128 are treated as letters), the following code could be used: setlocale(LC_CTYPE, "fr_FR"); @@ -1542,15 +1602,15 @@ LOCALE SUPPORT pcre2_set_character_tables(ccontext, tables); re = pcre2_compile(..., ccontext); - The locale name "fr_FR" is used on Linux and other Unix-like systems; - if you are using Windows, the name for the French locale is "french". - It is the caller's responsibility to ensure that the memory containing + The locale name "fr_FR" is used on Linux and other Unix-like systems; + if you are using Windows, the name for the French locale is "french". + It is the caller's responsibility to ensure that the memory containing the tables remains available for as long as it is needed. The pointer that is passed (via the compile context) to pcre2_compile() - is saved with the compiled pattern, and the same tables are used by - pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com- - pilation, and matching all happen in the same locale, but different + is saved with the compiled pattern, and the same tables are used by + pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com- + pilation, and matching all happen in the same locale, but different patterns can be processed in different locales. @@ -1558,13 +1618,13 @@ INFORMATION ABOUT A COMPILED PATTERN int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where); - The pcre2_pattern_info() function returns general information about a + The pcre2_pattern_info() function returns general information about a compiled pattern. For information about callouts, see the next section. - The first argument for pcre2_pattern_info() is a pointer to the com- + The first argument for pcre2_pattern_info() is a pointer to the com- piled pattern. The second argument specifies which piece of information - is required, and the third argument is a pointer to a variable to - receive the data. If the third argument is NULL, the first argument is - ignored, and the function returns the size in bytes of the variable + is required, and the third argument is a pointer to a variable to + receive the data. If the third argument is NULL, the first argument is + ignored, and the function returns the size in bytes of the variable that is required for the information requested. Otherwise, The yield of the function is zero for success, or one of the following negative num- bers: @@ -1574,9 +1634,9 @@ INFORMATION ABOUT A COMPILED PATTERN PCRE2_ERROR_BADOPTION the value of what was invalid PCRE2_ERROR_UNSET the requested field is not set - The "magic number" is placed at the start of each compiled pattern as - an simple check against passing an arbitrary memory pointer. Here is a - typical call of pcre2_pattern_info(), to obtain the length of the com- + The "magic number" is placed at the start of each compiled pattern as + an simple check against passing an arbitrary memory pointer. Here is a + typical call of pcre2_pattern_info(), to obtain the length of the com- piled pattern: int rc; @@ -1593,12 +1653,17 @@ INFORMATION ABOUT A COMPILED PATTERN PCRE2_INFO_ARGOPTIONS Return a copy of the pattern's options. The third argument should point - to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the - options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP- - TIONS returns the compile options as modified by any top-level option - settings such as (*UTF) at the start of the pattern itself. For exam- - ple, if the pattern /(*UTF)abc/ is compiled with the PCRE2_EXTENDED - option, the result is PCRE2_EXTENDED and PCRE2_UTF. + to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the + options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP- + TIONS returns the compile options as modified by any top-level (*XXX) + option settings such as (*UTF) at the start of the pattern itself. + + For example, if the pattern /(*UTF)abc/ is compiled with the + PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is + PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can + change within a pattern do not affect the result of PCRE2_INFO_ALLOP- + TIONS, even if they appear right at the start of the pattern. (This was + different in some earlier releases.) A pattern compiled without PCRE2_ANCHORED is automatically anchored by PCRE2 if the first significant item in every top-level branch is one of @@ -2038,62 +2103,70 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION The unused bits of the options argument for pcre2_match() must be zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_NOTBOL, - PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, + PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PARTIAL_SOFT. Their action is described below. Setting PCRE2_ANCHORED at match time is not supported by the just-in- time (JIT) compiler. If it is set, JIT matching is disabled and the - normal interpretive code in pcre2_match() is run. The remaining options - are supported for JIT matching. + normal interpretive code in pcre2_match() is run. Apart from + PCRE2_NO_JIT (obviously), the remaining options are supported for JIT + matching. PCRE2_ANCHORED The PCRE2_ANCHORED option limits pcre2_match() to matching at the first - matching position. If a pattern was compiled with PCRE2_ANCHORED, or - turned out to be anchored by virtue of its contents, it cannot be made - unachored at matching time. Note that setting the option at match time + matching position. If a pattern was compiled with PCRE2_ANCHORED, or + turned out to be anchored by virtue of its contents, it cannot be made + unachored at matching time. Note that setting the option at match time disables JIT matching. PCRE2_NOTBOL This option specifies that first character of the subject string is not - the beginning of a line, so the circumflex metacharacter should not - match before it. Setting this without having set PCRE2_MULTILINE at + the beginning of a line, so the circumflex metacharacter should not + match before it. Setting this without having set PCRE2_MULTILINE at compile time causes circumflex never to match. This option affects only the behaviour of the circumflex metacharacter. It does not affect \A. PCRE2_NOTEOL This option specifies that the end of the subject string is not the end - of a line, so the dollar metacharacter should not match it nor (except - in multiline mode) a newline immediately before it. Setting this with- - out having set PCRE2_MULTILINE at compile time causes dollar never to + of a line, so the dollar metacharacter should not match it nor (except + in multiline mode) a newline immediately before it. Setting this with- + out having set PCRE2_MULTILINE at compile time causes dollar never to match. This option affects only the behaviour of the dollar metacharac- ter. It does not affect \Z or \z. PCRE2_NOTEMPTY An empty string is not considered to be a valid match if this option is - set. If there are alternatives in the pattern, they are tried. If all - the alternatives match the empty string, the entire match fails. For + set. If there are alternatives in the pattern, they are tried. If all + the alternatives match the empty string, the entire match fails. For example, if the pattern a?b? - is applied to a string not beginning with "a" or "b", it matches an + is applied to a string not beginning with "a" or "b", it matches an empty string at the start of the subject. With PCRE2_NOTEMPTY set, this - match is not valid, so pcre2_match() searches further into the string + match is not valid, so pcre2_match() searches further into the string for occurrences of "a" or "b". PCRE2_NOTEMPTY_ATSTART - This is like PCRE2_NOTEMPTY, except that it locks out an empty string + This is like PCRE2_NOTEMPTY, except that it locks out an empty string match only at the first matching position, that is, at the start of the - subject plus the starting offset. An empty string match later in the - subject is permitted. If the pattern is anchored, such a match can + subject plus the starting offset. An empty string match later in the + subject is permitted. If the pattern is anchored, such a match can occur only if the pattern contains \K. + PCRE2_NO_JIT + + By default, if a pattern has been successfully processed by + pcre2_jit_compile(), JIT is automatically used when pcre2_match() is + called with options that JIT supports. Setting PCRE2_NO_JIT disables + the use of JIT; it forces matching to be done by the interpreter. + PCRE2_NO_UTF_CHECK When PCRE2_UTF is set at compile time, the validity of the subject as a @@ -2322,13 +2395,14 @@ OTHER INFORMATION ABOUT A MATCH ERROR RETURNS FROM pcre2_match() If pcre2_match() fails, it returns a negative number. This can be con- - verted to a text string by calling pcre2_get_error_message(). Negative - error codes are also returned by other functions, and are documented - with them. The codes are given names in the header file. If UTF check- - ing is in force and an invalid UTF subject string is detected, one of a - number of UTF-specific negative error codes is returned. Details are - given in the pcre2unicode page. The following are the other errors that - may be returned by pcre2_match(): + verted to a text string by calling the pcre2_get_error_message() func- + tion (see "Obtaining a textual error message" below). Negative error + codes are also returned by other functions, and are documented with + them. The codes are given names in the header file. If UTF checking is + in force and an invalid UTF subject string is detected, one of a number + of UTF-specific negative error codes is returned. Details are given in + the pcre2unicode page. The following are the other errors that may be + returned by pcre2_match(): PCRE2_ERROR_NOMATCH @@ -2336,19 +2410,19 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_PARTIAL - The subject string did not match, but it did match partially. See the + The subject string did not match, but it did match partially. See the pcre2partial documentation for details of partial matching. PCRE2_ERROR_BADMAGIC PCRE2 stores a 4-byte "magic number" at the start of the compiled code, - to catch the case when it is passed a junk pointer. This is the error + to catch the case when it is passed a junk pointer. This is the error that is returned when the magic number is not present. PCRE2_ERROR_BADMODE - This error is given when a pattern that was compiled by the 8-bit - library is passed to a 16-bit or 32-bit library function, or vice + This error is given when a pattern that was compiled by the 8-bit + library is passed to a 16-bit or 32-bit library function, or vice versa. PCRE2_ERROR_BADOFFSET @@ -2362,35 +2436,35 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_BADUTFOFFSET The UTF code unit sequence that was passed as a subject was checked and - found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the - value of startoffset did not point to the beginning of a UTF character + found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the + value of startoffset did not point to the beginning of a UTF character or the end of the subject. PCRE2_ERROR_CALLOUT - This error is never generated by pcre2_match() itself. It is provided - for use by callout functions that want to cause pcre2_match() or - pcre2_callout_enumerate() to return a distinctive error code. See the + This error is never generated by pcre2_match() itself. It is provided + for use by callout functions that want to cause pcre2_match() or + pcre2_callout_enumerate() to return a distinctive error code. See the pcre2callout documentation for details. PCRE2_ERROR_INTERNAL - An unexpected internal error has occurred. This error could be caused + An unexpected internal error has occurred. This error could be caused by a bug in PCRE2 or by overwriting of the compiled pattern. PCRE2_ERROR_JIT_BADOPTION - This error is returned when a pattern that was successfully studied - using JIT is being matched, but the matching mode (partial or complete - match) does not correspond to any JIT compilation mode. When the JIT - fast path function is used, this error may be also given for invalid + This error is returned when a pattern that was successfully studied + using JIT is being matched, but the matching mode (partial or complete + match) does not correspond to any JIT compilation mode. When the JIT + fast path function is used, this error may be also given for invalid options. See the pcre2jit documentation for more details. PCRE2_ERROR_JIT_STACKLIMIT - This error is returned when a pattern that was successfully studied - using JIT is being matched, but the memory available for the just-in- - time processing stack is not large enough. See the pcre2jit documenta- + This error is returned when a pattern that was successfully studied + using JIT is being matched, but the memory available for the just-in- + time processing stack is not large enough. See the pcre2jit documenta- tion for more details. PCRE2_ERROR_MATCHLIMIT @@ -2399,10 +2473,10 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_NOMEMORY - If a pattern contains back references, but the ovector is not big - enough to remember the referenced substrings, PCRE2 gets a block of + If a pattern contains back references, but the ovector is not big + enough to remember the referenced substrings, PCRE2 gets a block of memory at the start of matching to use for this purpose. There are some - other special cases where extra memory is needed during matching. This + other special cases where extra memory is needed during matching. This error is given when memory cannot be obtained. PCRE2_ERROR_NULL @@ -2411,12 +2485,12 @@ ERROR RETURNS FROM pcre2_match() PCRE2_ERROR_RECURSELOOP - This error is returned when pcre2_match() detects a recursion loop - within the pattern. Specifically, it means that either the whole pat- + This error is returned when pcre2_match() detects a recursion loop + within the pattern. Specifically, it means that either the whole pat- tern or a subpattern has been called recursively for the second time at - the same position in the subject string. Some simple patterns that - might do this are detected and faulted at compile time, but more com- - plicated cases, in particular mutual recursions between two different + the same position in the subject string. Some simple patterns that + might do this are detected and faulted at compile time, but more com- + plicated cases, in particular mutual recursions between two different subpatterns, cannot be detected until matching is attempted. PCRE2_ERROR_RECURSIONLIMIT @@ -2424,6 +2498,27 @@ ERROR RETURNS FROM pcre2_match() The internal recursion limit was reached. +OBTAINING A TEXTUAL ERROR MESSAGE + + int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer, + PCRE2_SIZE bufflen); + + A text message for an error code from any PCRE2 function (compile, + match, or auxiliary) can be obtained by calling pcre2_get_error_mes- + sage(). The code is passed as the first argument, with the remaining + two arguments specifying a code unit buffer and its length, into which + the text message is placed. Note that the message is returned in code + units of the appropriate width for the library that is being used. + + The returned message is terminated with a trailing zero, and the func- + tion returns the number of code units used, excluding the trailing + zero. If the error number is unknown, the negative error code + PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes- + sage is truncated (but still with a trailing zero), and the negative + error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are + very long; a buffer size of 120 code units is ample. + + EXTRACTING CAPTURED SUBSTRINGS BY NUMBER int pcre2_substring_length_bynumber(pcre2_match_data *match_data, @@ -2794,7 +2889,8 @@ CREATING A NEW STRING WITH SUBSTITUTIONS used in an assertion). As for all PCRE2 errors, a text message that describes the error can be - obtained by calling pcre2_get_error_message(). + obtained by calling the pcre2_get_error_message() function (see + "Obtaining a textual error message" above). DUPLICATE SUBPATTERN NAMES @@ -2802,56 +2898,56 @@ DUPLICATE SUBPATTERN NAMES int pcre2_substring_nametable_scan(const pcre2_code *code, PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last); - When a pattern is compiled with the PCRE2_DUPNAMES option, names for - subpatterns are not required to be unique. Duplicate names are always - allowed for subpatterns with the same number, created by using the (?| - feature. Indeed, if such subpatterns are named, they are required to + When a pattern is compiled with the PCRE2_DUPNAMES option, names for + subpatterns are not required to be unique. Duplicate names are always + allowed for subpatterns with the same number, created by using the (?| + feature. Indeed, if such subpatterns are named, they are required to use the same names. Normally, patterns with duplicate names are such that in any one match, - only one of the named subpatterns participates. An example is shown in + only one of the named subpatterns participates. An example is shown in the pcre2pattern documentation. - When duplicates are present, pcre2_substring_copy_byname() and - pcre2_substring_get_byname() return the first substring corresponding - to the given name that is set. Only if none are set is - PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name() + When duplicates are present, pcre2_substring_copy_byname() and + pcre2_substring_get_byname() return the first substring corresponding + to the given name that is set. Only if none are set is + PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name() function returns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate names. - If you want to get full details of all captured substrings for a given - name, you must use the pcre2_substring_nametable_scan() function. The - first argument is the compiled pattern, and the second is the name. If - the third and fourth arguments are NULL, the function returns a group + If you want to get full details of all captured substrings for a given + name, you must use the pcre2_substring_nametable_scan() function. The + first argument is the compiled pattern, and the second is the name. If + the third and fourth arguments are NULL, the function returns a group number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise. When the third and fourth arguments are not NULL, they must be pointers - to variables that are updated by the function. After it has run, they + to variables that are updated by the function. After it has run, they point to the first and last entries in the name-to-number table for the - given name, and the function returns the length of each entry in code - units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are + given name, and the function returns the length of each entry in code + units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are no entries for the given name. The format of the name table is described above in the section entitled - Information about a pattern. Given all the relevant entries for the - name, you can extract each of their numbers, and hence the captured + Information about a pattern. Given all the relevant entries for the + name, you can extract each of their numbers, and hence the captured data. FINDING ALL POSSIBLE MATCHES AT ONE POSITION - The traditional matching function uses a similar algorithm to Perl, - which stops when it finds the first match at a given point in the sub- + The traditional matching function uses a similar algorithm to Perl, + which stops when it finds the first match at a given point in the sub- ject. If you want to find all possible matches, or the longest possible - match at a given position, consider using the alternative matching - function (see below) instead. If you cannot use the alternative func- + match at a given position, consider using the alternative matching + function (see below) instead. If you cannot use the alternative func- tion, you can kludge it up by making use of the callout facility, which is described in the pcre2callout documentation. What you have to do is to insert a callout right at the end of the pat- - tern. When your callout function is called, extract and save the cur- - rent matched substring. Then return 1, which forces pcre2_match() to - backtrack and try other alternatives. Ultimately, when it runs out of + tern. When your callout function is called, extract and save the cur- + rent matched substring. Then return 1, which forces pcre2_match() to + backtrack and try other alternatives. Ultimately, when it runs out of matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH. @@ -2863,26 +2959,26 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION pcre2_match_context *mcontext, int *workspace, PCRE2_SIZE wscount); - The function pcre2_dfa_match() is called to match a subject string - against a compiled pattern, using a matching algorithm that scans the - subject string just once, and does not backtrack. This has different - characteristics to the normal algorithm, and is not compatible with - Perl. Some of the features of PCRE2 patterns are not supported. Never- - theless, there are times when this kind of matching can be useful. For - a discussion of the two matching algorithms, and a list of features + The function pcre2_dfa_match() is called to match a subject string + against a compiled pattern, using a matching algorithm that scans the + subject string just once, and does not backtrack. This has different + characteristics to the normal algorithm, and is not compatible with + Perl. Some of the features of PCRE2 patterns are not supported. Never- + theless, there are times when this kind of matching can be useful. For + a discussion of the two matching algorithms, and a list of features that pcre2_dfa_match() does not support, see the pcre2matching documen- tation. - The arguments for the pcre2_dfa_match() function are the same as for + The arguments for the pcre2_dfa_match() function are the same as for pcre2_match(), plus two extras. The ovector within the match data block is used in a different way, and this is described below. The other com- - mon arguments are used in the same way as for pcre2_match(), so their + mon arguments are used in the same way as for pcre2_match(), so their description is not repeated here. - The two additional arguments provide workspace for the function. The - workspace vector should contain at least 20 elements. It is used for + The two additional arguments provide workspace for the function. The + workspace vector should contain at least 20 elements. It is used for keeping track of multiple paths through the pattern tree. More - workspace is needed for patterns and subjects where there are a lot of + workspace is needed for patterns and subjects where there are a lot of potential matches. Here is an example of a simple call to pcre2_dfa_match(): @@ -2902,45 +2998,45 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION Option bits for pcre_dfa_match() - The unused bits of the options argument for pcre2_dfa_match() must be - zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_NOTBOL, + The unused bits of the options argument for pcre2_dfa_match() must be + zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, PCRE2_PARTIAL_SOFT, - PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but the last four of - these are exactly the same as for pcre2_match(), so their description + PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but the last four of + these are exactly the same as for pcre2_match(), so their description is not repeated here. PCRE2_PARTIAL_HARD PCRE2_PARTIAL_SOFT - These have the same general effect as they do for pcre2_match(), but - the details are slightly different. When PCRE2_PARTIAL_HARD is set for - pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the + These have the same general effect as they do for pcre2_match(), but + the details are slightly different. When PCRE2_PARTIAL_HARD is set for + pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the subject is reached and there is still at least one matching possibility that requires additional characters. This happens even if some complete - matches have already been found. When PCRE2_PARTIAL_SOFT is set, the - return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL - if the end of the subject is reached, there have been no complete + matches have already been found. When PCRE2_PARTIAL_SOFT is set, the + return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL + if the end of the subject is reached, there have been no complete matches, but there is still at least one matching possibility. The por- - tion of the string that was inspected when the longest partial match + tion of the string that was inspected when the longest partial match was found is set as the first matching string in both cases. There is a - more detailed discussion of partial and multi-segment matching, with + more detailed discussion of partial and multi-segment matching, with examples, in the pcre2partial documentation. PCRE2_DFA_SHORTEST - Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to + Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to stop as soon as it has found one match. Because of the way the alterna- - tive algorithm works, this is necessarily the shortest possible match + tive algorithm works, this is necessarily the shortest possible match at the first possible matching point in the subject string. PCRE2_DFA_RESTART - When pcre2_dfa_match() returns a partial match, it is possible to call + When pcre2_dfa_match() returns a partial match, it is possible to call it again, with additional subject characters, and have it continue with the same match. The PCRE2_DFA_RESTART option requests this action; when - it is set, the workspace and wscount options must reference the same - vector as before because data about the match so far is left in them + it is set, the workspace and wscount options must reference the same + vector as before because data about the match so far is left in them after a partial match. There is more discussion of this facility in the pcre2partial documentation. @@ -2948,8 +3044,8 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION When pcre2_dfa_match() succeeds, it may have matched more than one sub- string in the subject. Note, however, that all the matches from one run - of the function start at the same point in the subject. The shorter - matches are all initial substrings of the longer matches. For example, + of the function start at the same point in the subject. The shorter + matches are all initial substrings of the longer matches. For example, if the pattern <.*> @@ -2964,17 +3060,17 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION <something> <something else> <something> - On success, the yield of the function is a number greater than zero, - which is the number of matched substrings. The offsets of the sub- - strings are returned in the ovector, and can be extracted by number in - the same way as for pcre2_match(), but the numbers bear no relation to - any capturing groups that may exist in the pattern, because DFA match- + On success, the yield of the function is a number greater than zero, + which is the number of matched substrings. The offsets of the sub- + strings are returned in the ovector, and can be extracted by number in + the same way as for pcre2_match(), but the numbers bear no relation to + any capturing groups that may exist in the pattern, because DFA match- ing does not support group capture. - Calls to the convenience functions that extract substrings by name - return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used + Calls to the convenience functions that extract substrings by name + return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used after a DFA match. The convenience functions that extract substrings by - number never return PCRE2_ERROR_NOSUBSTRING, and the meanings of some + number never return PCRE2_ERROR_NOSUBSTRING, and the meanings of some other errors are slightly different: PCRE2_ERROR_UNAVAILABLE @@ -2984,64 +3080,64 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION PCRE2_ERROR_UNSET - There is a slot in the ovector for this substring, but there were + There is a slot in the ovector for this substring, but there were insufficient matches to fill it. - The matched strings are stored in the ovector in reverse order of - length; that is, the longest matching string is first. If there were - too many matches to fit into the ovector, the yield of the function is + The matched strings are stored in the ovector in reverse order of + length; that is, the longest matching string is first. If there were + too many matches to fit into the ovector, the yield of the function is zero, and the vector is filled with the longest matches. - NOTE: PCRE2's "auto-possessification" optimization usually applies to - character repeats at the end of a pattern (as well as internally). For - example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA - matching, this means that only one possible match is found. If you - really do want multiple matches in such cases, either use an ungreedy - repeat auch as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when + NOTE: PCRE2's "auto-possessification" optimization usually applies to + character repeats at the end of a pattern (as well as internally). For + example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA + matching, this means that only one possible match is found. If you + really do want multiple matches in such cases, either use an ungreedy + repeat auch as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when compiling. Error returns from pcre2_dfa_match() The pcre2_dfa_match() function returns a negative number when it fails. - Many of the errors are the same as for pcre2_match(), as described + Many of the errors are the same as for pcre2_match(), as described above. There are in addition the following errors that are specific to pcre2_dfa_match(): PCRE2_ERROR_DFA_UITEM - This return is given if pcre2_dfa_match() encounters an item in the - pattern that it does not support, for instance, the use of \C in a UTF + This return is given if pcre2_dfa_match() encounters an item in the + pattern that it does not support, for instance, the use of \C in a UTF mode or a back reference. PCRE2_ERROR_DFA_UCOND - This return is given if pcre2_dfa_match() encounters a condition item - that uses a back reference for the condition, or a test for recursion + This return is given if pcre2_dfa_match() encounters a condition item + that uses a back reference for the condition, or a test for recursion in a specific group. These are not supported. PCRE2_ERROR_DFA_WSSIZE - This return is given if pcre2_dfa_match() runs out of space in the + This return is given if pcre2_dfa_match() runs out of space in the workspace vector. PCRE2_ERROR_DFA_RECURSE - When a recursive subpattern is processed, the matching function calls + When a recursive subpattern is processed, the matching function calls itself recursively, using private memory for the ovector and workspace. - This error is given if the internal ovector is not large enough. This + This error is given if the internal ovector is not large enough. This should be extremely rare, as a vector of size 1000 is used. PCRE2_ERROR_DFA_BADRESTART - When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option, - some plausibility checks are made on the contents of the workspace, - which should contain data about the previous partial match. If any of + When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option, + some plausibility checks are made on the contents of the workspace, + which should contain data about the previous partial match. If any of these checks fail, this error is given. SEE ALSO - pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3), + pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3), pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2stack(3), pcre2unicode(3). @@ -3055,8 +3151,8 @@ AUTHOR REVISION - Last updated: 16 December 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 17 June 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ @@ -3383,6 +3479,15 @@ USING EBCDIC CODE an EBCDIC environment. +PCRE2GREP SUPPORT FOR EXTERNAL SCRIPTS + + By default, on non-Windows systems, pcre2grep supports the use of call- + outs with string arguments within the patterns it is matching, in order + to run external scripts. For details, see the pcre2grep documentation. + This support can be disabled by adding --disable-pcre2grep-callout to + the configure command. + + PCRE2GREP OPTIONS FOR COMPRESSED FILE SUPPORT By default, pcre2grep reads all files as plain text. You can build it @@ -3410,7 +3515,7 @@ PCRE2GREP BUFFER SIZE --with-pcre2grep-bufsize=50K to the configure command. The caller of pcre2grep can override this - value by using --buffer-size on the command line.. + value by using --buffer-size on the command line. PCRE2TEST OPTION FOR LIBREADLINE SUPPORT @@ -3539,8 +3644,8 @@ AUTHOR REVISION - Last updated: 16 October 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 01 April 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ @@ -4218,49 +4323,52 @@ UNSUPPORTED OPTIONS AND PATTERN ITEMS PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PARTIAL_SOFT. The PCRE2_ANCHORED option is not supported at match time. - The only unsupported pattern items are \C (match a single data unit) - when running in a UTF mode, and a callout immediately before an asser- + If the PCRE2_NO_JIT option is passed to pcre2_match() it disables the + use of JIT, forcing matching by the interpreter code. + + The only unsupported pattern items are \C (match a single data unit) + when running in a UTF mode, and a callout immediately before an asser- tion condition in a conditional group. RETURN VALUES FROM JIT MATCHING When a pattern is matched using JIT matching, the return values are the - same as those given by the interpretive pcre2_match() code, with the - addition of one new error code: PCRE2_ERROR_JIT_STACKLIMIT. This means - that the memory used for the JIT stack was insufficient. See "Control- + same as those given by the interpretive pcre2_match() code, with the + addition of one new error code: PCRE2_ERROR_JIT_STACKLIMIT. This means + that the memory used for the JIT stack was insufficient. See "Control- ling the JIT stack" below for a discussion of JIT stack usage. - The error code PCRE2_ERROR_MATCHLIMIT is returned by the JIT code if - searching a very large pattern tree goes on for too long, as it is in - the same circumstance when JIT is not used, but the details of exactly - what is counted are not the same. The PCRE2_ERROR_RECURSIONLIMIT error + The error code PCRE2_ERROR_MATCHLIMIT is returned by the JIT code if + searching a very large pattern tree goes on for too long, as it is in + the same circumstance when JIT is not used, but the details of exactly + what is counted are not the same. The PCRE2_ERROR_RECURSIONLIMIT error code is never returned when JIT matching is used. CONTROLLING THE JIT STACK When the compiled JIT code runs, it needs a block of memory to use as a - stack. By default, it uses 32K on the machine stack. However, some - large or complicated patterns need more than this. The error - PCRE2_ERROR_JIT_STACKLIMIT is given when there is not enough stack. - Three functions are provided for managing blocks of memory for use as - JIT stacks. There is further discussion about the use of JIT stacks in + stack. By default, it uses 32K on the machine stack. However, some + large or complicated patterns need more than this. The error + PCRE2_ERROR_JIT_STACKLIMIT is given when there is not enough stack. + Three functions are provided for managing blocks of memory for use as + JIT stacks. There is further discussion about the use of JIT stacks in the section entitled "JIT stack FAQ" below. - The pcre2_jit_stack_create() function creates a JIT stack. Its argu- - ments are a starting size, a maximum size, and a general context (for - memory allocation functions, or NULL for standard memory allocation). + The pcre2_jit_stack_create() function creates a JIT stack. Its argu- + ments are a starting size, a maximum size, and a general context (for + memory allocation functions, or NULL for standard memory allocation). It returns a pointer to an opaque structure of type pcre2_jit_stack, or - NULL if there is an error. The pcre2_jit_stack_free() function is used - to free a stack that is no longer needed. (For the technically minded: + NULL if there is an error. The pcre2_jit_stack_free() function is used + to free a stack that is no longer needed. (For the technically minded: the address space is allocated by mmap or VirtualAlloc.) - JIT uses far less memory for recursion than the interpretive code, and - a maximum stack size of 512K to 1M should be more than enough for any + JIT uses far less memory for recursion than the interpretive code, and + a maximum stack size of 512K to 1M should be more than enough for any pattern. - The pcre2_jit_stack_assign() function specifies which stack JIT code + The pcre2_jit_stack_assign() function specifies which stack JIT code should use. Its arguments are as follows: pcre2_match_context *mcontext @@ -4269,7 +4377,7 @@ CONTROLLING THE JIT STACK The first argument is a pointer to a match context. When this is subse- quently passed to a matching function, its information determines which - JIT stack is used. There are three cases for the values of the other + JIT stack is used. There are three cases for the values of the other two options: (1) If callback is NULL and data is NULL, an internal 32K block @@ -4287,34 +4395,34 @@ CONTROLLING THE JIT STACK return value must be a valid JIT stack, the result of calling pcre2_jit_stack_create(). - A callback function is obeyed whenever JIT code is about to be run; it + A callback function is obeyed whenever JIT code is about to be run; it is not obeyed when pcre2_match() is called with options that are incom- - patible for JIT matching. A callback function can therefore be used to - determine whether a match operation was executed by JIT or by the + patible for JIT matching. A callback function can therefore be used to + determine whether a match operation was executed by JIT or by the interpreter. You may safely use the same JIT stack for more than one pattern (either - by assigning directly or by callback), as long as the patterns are + by assigning directly or by callback), as long as the patterns are matched sequentially in the same thread. Currently, the only way to set - up non-sequential matches in one thread is to use callouts: if a call- - out function starts another match, that match must use a different JIT + up non-sequential matches in one thread is to use callouts: if a call- + out function starts another match, that match must use a different JIT stack to the one used for currently suspended match(es). - In a multithread application, if you do not specify a JIT stack, or if - you assign or pass back NULL from a callback, that is thread-safe, - because each thread has its own machine stack. However, if you assign - or pass back a non-NULL JIT stack, this must be a different stack for + In a multithread application, if you do not specify a JIT stack, or if + you assign or pass back NULL from a callback, that is thread-safe, + because each thread has its own machine stack. However, if you assign + or pass back a non-NULL JIT stack, this must be a different stack for each thread so that the application is thread-safe. - Strictly speaking, even more is allowed. You can assign the same non- - NULL stack to a match context that is used by any number of patterns, - as long as they are not used for matching by multiple threads at the - same time. For example, you could use the same stack in all compiled - patterns, with a global mutex in the callback to wait until the stack + Strictly speaking, even more is allowed. You can assign the same non- + NULL stack to a match context that is used by any number of patterns, + as long as they are not used for matching by multiple threads at the + same time. For example, you could use the same stack in all compiled + patterns, with a global mutex in the callback to wait until the stack is available for use. However, this is an inefficient solution, and not recommended. - This is a suggestion for how a multithreaded program that needs to set + This is a suggestion for how a multithreaded program that needs to set up non-default JIT stacks might operate: During thread initalization @@ -4326,7 +4434,7 @@ CONTROLLING THE JIT STACK Use a one-line callback function return thread_local_var - All the functions described in this section do nothing if JIT is not + All the functions described in this section do nothing if JIT is not available. @@ -4335,20 +4443,20 @@ JIT STACK FAQ (1) Why do we need JIT stacks? PCRE2 (and JIT) is a recursive, depth-first engine, so it needs a stack - where the local data of the current node is pushed before checking its + where the local data of the current node is pushed before checking its child nodes. Allocating real machine stack on some platforms is diffi- cult. For example, the stack chain needs to be updated every time if we - extend the stack on PowerPC. Although it is possible, its updating + extend the stack on PowerPC. Although it is possible, its updating time overhead decreases performance. So we do the recursion in memory. (2) Why don't we simply allocate blocks of memory with malloc()? - Modern operating systems have a nice feature: they can reserve an + Modern operating systems have a nice feature: they can reserve an address space instead of allocating memory. We can safely allocate mem- - ory pages inside this address space, so the stack could grow without + ory pages inside this address space, so the stack could grow without moving memory data (this is important because of pointers). Thus we can - allocate 1M address space, and use only a single memory page (usually - 4K) if that is enough. However, we can still grow up to 1M anytime if + allocate 1M address space, and use only a single memory page (usually + 4K) if that is enough. However, we can still grow up to 1M anytime if needed. (3) Who "owns" a JIT stack? @@ -4356,8 +4464,8 @@ JIT STACK FAQ The owner of the stack is the user program, not the JIT studied pattern or anything else. The user program must ensure that if a stack is being used by pcre2_match(), (that is, it is assigned to a match context that - is passed to the pattern currently running), that stack must not be - used by any other threads (to avoid overwriting the same memory area). + is passed to the pattern currently running), that stack must not be + used by any other threads (to avoid overwriting the same memory area). The best practice for multithreaded programs is to allocate a stack for each thread, and return this stack through the JIT callback function. @@ -4365,36 +4473,36 @@ JIT STACK FAQ You can free a JIT stack at any time, as long as it will not be used by pcre2_match() again. When you assign the stack to a match context, only - a pointer is set. There is no reference counting or any other magic. + a pointer is set. There is no reference counting or any other magic. You can free compiled patterns, contexts, and stacks in any order, any- - time. Just do not call pcre2_match() with a match context pointing to + time. Just do not call pcre2_match() with a match context pointing to an already freed stack, as that will cause SEGFAULT. (Also, do not free - a stack currently used by pcre2_match() in another thread). You can - also replace the stack in a context at any time when it is not in use. + a stack currently used by pcre2_match() in another thread). You can + also replace the stack in a context at any time when it is not in use. You should free the previous stack before assigning a replacement. - (5) Should I allocate/free a stack every time before/after calling + (5) Should I allocate/free a stack every time before/after calling pcre2_match()? - No, because this is too costly in terms of resources. However, you - could implement some clever idea which release the stack if it is not - used in let's say two minutes. The JIT callback can help to achieve + No, because this is too costly in terms of resources. However, you + could implement some clever idea which release the stack if it is not + used in let's say two minutes. The JIT callback can help to achieve this without keeping a list of patterns. - (6) OK, the stack is for long term memory allocation. But what happens - if a pattern causes stack overflow with a stack of 1M? Is that 1M kept + (6) OK, the stack is for long term memory allocation. But what happens + if a pattern causes stack overflow with a stack of 1M? Is that 1M kept until the stack is freed? - Especially on embedded sytems, it might be a good idea to release mem- - ory sometimes without freeing the stack. There is no API for this at - the moment. Probably a function call which returns with the currently - allocated memory for any stack and another which allows releasing mem- + Especially on embedded sytems, it might be a good idea to release mem- + ory sometimes without freeing the stack. There is no API for this at + the moment. Probably a function call which returns with the currently + allocated memory for any stack and another which allows releasing mem- ory (shrinking the stack) would be a good idea if someone needs this. (7) This is too much of a headache. Isn't there any better solution for JIT stack handling? - No, thanks to Windows. If POSIX threads were used everywhere, we could + No, thanks to Windows. If POSIX threads were used everywhere, we could throw out this complicated API. @@ -4403,18 +4511,18 @@ FREEING JIT SPECULATIVE MEMORY void pcre2_jit_free_unused_memory(pcre2_general_context *gcontext); The JIT executable allocator does not free all memory when it is possi- - ble. It expects new allocations, and keeps some free memory around to - improve allocation speed. However, in low memory conditions, it might - be better to free all possible memory. You can cause this to happen by - calling pcre2_jit_free_unused_memory(). Its argument is a general con- + ble. It expects new allocations, and keeps some free memory around to + improve allocation speed. However, in low memory conditions, it might + be better to free all possible memory. You can cause this to happen by + calling pcre2_jit_free_unused_memory(). Its argument is a general con- text, for custom memory management, or NULL for standard memory manage- ment. EXAMPLE CODE - This is a single-threaded example that specifies a JIT stack without - using a callback. A real program should include error checking after + This is a single-threaded example that specifies a JIT stack without + using a callback. A real program should include error checking after all the function calls. int rc; @@ -4442,19 +4550,20 @@ EXAMPLE CODE JIT FAST PATH API Because the API described above falls back to interpreted matching when - JIT is not available, it is convenient for programs that are written + JIT is not available, it is convenient for programs that are written for general use in many environments. However, calling JIT via pcre2_match() does have a performance impact. Programs that are written - for use where JIT is known to be available, and which need the best - possible performance, can instead use a "fast path" API to call JIT - matching directly instead of calling pcre2_match() (obviously only for + for use where JIT is known to be available, and which need the best + possible performance, can instead use a "fast path" API to call JIT + matching directly instead of calling pcre2_match() (obviously only for patterns that have been successfully processed by pcre2_jit_compile()). - The fast path function is called pcre2_jit_match(), and it takes + The fast path function is called pcre2_jit_match(), and it takes exactly the same arguments as pcre2_match(). The return values are also the same, plus PCRE2_ERROR_JIT_BADOPTION if a matching mode (partial or - complete) is requested that was not compiled. Unsupported option bits - (for example, PCRE2_ANCHORED) are ignored. + complete) is requested that was not compiled. Unsupported option bits + (for example, PCRE2_ANCHORED) are ignored, as is the PCRE2_NO_JIT + option. When you call pcre2_match(), as well as testing for invalid options, a number of other sanity checks are performed on the arguments. For exam- @@ -4481,8 +4590,8 @@ AUTHOR REVISION - Last updated: 14 November 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 05 June 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ @@ -6229,17 +6338,21 @@ MATCHING A SINGLE CODE UNIT possible to build PCRE2 with the use of \C permanently disabled. PCRE2 does not allow \C to appear in lookbehind assertions (described - below) in a UTF mode, because this would make it impossible to calcu- - late the length of the lookbehind. Neither the alternative matching - function pcre2_dfa_match() not the JIT optimizer support \C in a UTF - mode. The former gives a match-time error; the latter fails to optimize - and so the match is always run using the interpreter. + below) in UTF-8 or UTF-16 modes, because this would make it impossible + to calculate the length of the lookbehind. Neither the alternative + matching function pcre2_dfa_match() nor the JIT optimizer support \C in + these UTF modes. The former gives a match-time error; the latter fails + to optimize and so the match is always run using the interpreter. + + In the 32-bit library, however, \C is always supported (when not + explicitly locked out) because it always matches a single code unit, + whether or not UTF-32 is specified. In general, the \C escape sequence is best avoided. However, one way of - using it that avoids the problem of malformed UTF characters is to use - a lookahead to check the length of the next character, as in this pat- - tern, which could be used with a UTF-8 string (ignore white space and - line breaks): + using it that avoids the problem of malformed UTF-8 or UTF-16 charac- + ters is to use a lookahead to check the length of the next character, + as in this pattern, which could be used with a UTF-8 string (ignore + white space and line breaks): (?| (?=[\x00-\x7f])(\C) | (?=[\x80-\x{7ff}])(\C)(\C) | @@ -8254,8 +8367,8 @@ AUTHOR REVISION - Last updated: 13 November 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 20 June 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ @@ -8460,7 +8573,7 @@ DESCRIPTION This set of functions provides a POSIX-style API for the PCRE2 regular expression 8-bit library. See the pcre2api documentation for a descrip- tion of PCRE2's native API, which contains much additional functional- - ity. There is no POSIX-style wrapper for PCRE2's 16-bit and 32-bit + ity. There are no POSIX-style wrappers for PCRE2's 16-bit and 32-bit libraries. The functions described here are just wrapper functions that ultimately @@ -8478,8 +8591,8 @@ DESCRIPTION easier to slot in PCRE2 as a replacement library. Other POSIX options are not even defined. - There are also some other options that are not defined by POSIX. These - have been added at the request of users who want to make use of certain + There are also some options that are not defined by POSIX. These have + been added at the request of users who want to make use of certain PCRE2-specific features via the POSIX calling interface. When PCRE2 is called via these functions, it is only the API that is @@ -8530,11 +8643,11 @@ COMPILING A PATTERN REG_NOSUB - The PCRE2_NO_AUTO_CAPTURE option is set when the regular expression is - passed for compilation to the native function. In addition, when a pat- - tern that is compiled with this flag is passed to regexec() for match- - ing, the nmatch and pmatch arguments are ignored, and no captured - strings are returned. + When a pattern that is compiled with this flag is passed to regexec() + for matching, the nmatch and pmatch arguments are ignored, and no cap- + tured strings are returned. Versions of the PCRE library prior to 10.22 + used to set the PCRE2_NO_AUTO_CAPTURE compile option, but this no + longer happens because it disables the use of back references. REG_UCP @@ -8653,43 +8766,44 @@ MATCHING A PATTERN If the pattern was compiled with the REG_NOSUB flag, no data about any matched strings is returned. The nmatch and pmatch arguments of - regexec() are ignored. - - If the value of nmatch is zero, or if the value pmatch is NULL, no data - about any matched strings is returned. - - Otherwise,the portion of the string that was matched, and also any cap- - tured substrings, are returned via the pmatch argument, which points to - an array of nmatch structures of type regmatch_t, containing the mem- - bers rm_so and rm_eo. These contain the byte offset to the first char- - acter of each substring and the offset to the first character after the - end of each substring, respectively. The 0th element of the vector - relates to the entire portion of string that was matched; subsequent + regexec() are ignored (except possibly as input for REG_STARTEND). + + The value of nmatch may be zero, and the value pmatch may be NULL + (unless REG_STARTEND is set); in both these cases no data about any + matched strings is returned. + + Otherwise, the portion of the string that was matched, and also any + captured substrings, are returned via the pmatch argument, which points + to an array of nmatch structures of type regmatch_t, containing the + members rm_so and rm_eo. These contain the byte offset to the first + character of each substring and the offset to the first character after + the end of each substring, respectively. The 0th element of the vector + relates to the entire portion of string that was matched; subsequent elements relate to the capturing subpatterns of the regular expression. Unused entries in the array have both structure members set to -1. - A successful match yields a zero return; various error codes are - defined in the header file, of which REG_NOMATCH is the "expected" + A successful match yields a zero return; various error codes are + defined in the header file, of which REG_NOMATCH is the "expected" failure code. ERROR MESSAGES The regerror() function maps a non-zero errorcode from either regcomp() - or regexec() to a printable message. If preg is not NULL, the error + or regexec() to a printable message. If preg is not NULL, the error should have arisen from the use of that structure. A message terminated - by a binary zero is placed in errbuf. If the buffer is too short, only + by a binary zero is placed in errbuf. If the buffer is too short, only the first errbuf_size - 1 characters of the error message are used. The - yield of the function is the size of buffer needed to hold the whole - message, including the terminating zero. This value is greater than + yield of the function is the size of buffer needed to hold the whole + message, including the terminating zero. This value is greater than errbuf_size if the message was truncated. MEMORY USAGE - Compiling a regular expression causes memory to be allocated and asso- - ciated with the preg structure. The function regfree() frees all such - memory, after which preg may no longer be used as a compiled expres- + Compiling a regular expression causes memory to be allocated and asso- + ciated with the preg structure. The function regfree() frees all such + memory, after which preg may no longer be used as a compiled expres- sion. @@ -8702,8 +8816,8 @@ AUTHOR REVISION - Last updated: 29 November 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 31 January 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ @@ -8722,12 +8836,12 @@ PCRE2 SAMPLE PROGRAM documentation. If you do not have a copy of the PCRE2 distribution, you can save this listing to re-create the contents of pcre2demo.c. - The demonstration program, which uses the PCRE2 8-bit library, compiles - the regular expression that is its first argument, and matches it - against the subject string in its second argument. No PCRE2 options are - set, and default character tables are used. If matching succeeds, the - program outputs the portion of the subject that matched, together with - the contents of any captured substrings. + The demonstration program compiles the regular expression that is its + first argument, and matches it against the subject string in its second + argument. No PCRE2 options are set, and default character tables are + used. If matching succeeds, the program outputs the portion of the sub- + ject that matched, together with the contents of any captured sub- + strings. If the -g option is given on the command line, the program then goes on to check for further matches of the same regular expression in the same @@ -8735,38 +8849,45 @@ PCRE2 SAMPLE PROGRAM bility of matching an empty string. Comments in the code explain what is going on. - If PCRE2 is installed in the standard include and library directories + The code in pcre2demo.c is an 8-bit program that uses the PCRE2 8-bit + library. It handles strings and characters that are stored in 8-bit + code units. By default, one character corresponds to one code unit, + but if the pattern starts with "(*UTF)", both it and the subject are + treated as UTF-8 strings, where characters may occupy multiple code + units. + + If PCRE2 is installed in the standard include and library directories for your operating system, you should be able to compile the demonstra- - tion program using this command: + tion program using a command like this: - gcc -o pcre2demo pcre2demo.c -lpcre2-8 + cc -o pcre2demo pcre2demo.c -lpcre2-8 If PCRE2 is installed elsewhere, you may need to add additional options - to the command line. For example, on a Unix-like system that has PCRE2 - installed in /usr/local, you can compile the demonstration program + to the command line. For example, on a Unix-like system that has PCRE2 + installed in /usr/local, you can compile the demonstration program using a command like this: - gcc -o pcre2demo -I/usr/local/include pcre2demo.c \ - -L/usr/local/lib -lpcre2-8 + cc -o pcre2demo -I/usr/local/include pcre2demo.c \ + -L/usr/local/lib -lpcre2-8 - - Once you have compiled and linked the demonstration program, you can - run simple tests like this: + Once you have built the demonstration program, you can run simple tests + like this: ./pcre2demo 'cat|dog' 'the cat sat on the mat' ./pcre2demo -g 'cat|dog' 'the dog sat on the cat' - Note that there is a much more comprehensive test program, called - pcre2test, which supports many more facilities for testing regular - expressions using the PCRE2 libraries. The pcre2demo program is pro- - vided as a simple coding example. + Note that there is a much more comprehensive test program, called + pcre2test, which supports many more facilities for testing regular + expressions using all three PCRE2 libraries (8-bit, 16-bit, and 32-bit, + though not all three need be installed). The pcre2demo program is pro- + vided as a relatively simple coding example. If you try to run pcre2demo when PCRE2 is not installed in the standard library directory, you may get an error like this on some operating systems (e.g. Solaris): - ld.so.1: a.out: fatal: libpcre2.so.0: open failed: No such file or - directory + ld.so.1: pcre2demo: fatal: libpcre2-8.so.0: open failed: No such file + or directory This is caused by the way shared library support works on those sys- tems. You need to add @@ -8785,8 +8906,8 @@ AUTHOR REVISION - Last updated: 20 October 2014 - Copyright (c) 1997-2014 University of Cambridge. + Last updated: 02 February 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ PCRE2SERIALIZE(3) Library Functions Manual PCRE2SERIALIZE(3) @@ -8822,6 +8943,15 @@ SAVING AND RE-USING PRECOMPILED PCRE2 PATTERNS using the 8-bit library. +SECURITY CONCERNS + + The facility for saving and restoring compiled patterns is intended for + use within individual applications. As such, the data supplied to + pcre2_serialize_decode() is expected to be trusted data, not data from + arbitrary external sources. There is only some simple consistency + checking, not complete validation of what is being re-loaded. + + SAVING COMPILED PATTERNS Before compiled patterns can be saved they must be serialized, that is, @@ -8915,11 +9045,12 @@ RE-USING PRECOMPILED PATTERNS ignored. The yield of the function is the number of decoded patterns, or one of the following negative error codes: - PCRE2_ERROR_BADDATA second argument is zero or less - PCRE2_ERROR_BADMAGIC mismatch of id bytes in the data - PCRE2_ERROR_BADMODE mismatch of variable unit size or PCRE2 version - PCRE2_ERROR_MEMORY memory allocation failed - PCRE2_ERROR_NULL first or third argument is NULL + PCRE2_ERROR_BADDATA second argument is zero or less + PCRE2_ERROR_BADMAGIC mismatch of id bytes in the data + PCRE2_ERROR_BADMODE mismatch of code unit size or PCRE2 version + PCRE2_ERROR_BADSERIALIZEDDATA other sanity check failure + PCRE2_ERROR_MEMORY memory allocation failed + PCRE2_ERROR_NULL first or third argument is NULL PCRE2_ERROR_BADMAGIC may mean that the data is corrupt, or that it was compiled on a system with different endianness. @@ -8951,8 +9082,8 @@ AUTHOR REVISION - Last updated: 03 November 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 24 May 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ @@ -9609,15 +9740,19 @@ WIDE CHARACTERS AND UTF MODES In UTF modes, the dot metacharacter matches one UTF character instead of a single code unit. - The escape sequence \C can be used to match a single code unit, in a - UTF mode, but its use can lead to some strange effects because it - breaks up multi-unit characters (see the description of \C in the - pcre2pattern documentation). The use of \C is not supported by the - alternative matching function pcre2_dfa_match() when in UTF mode. Its - use provokes a match-time error. The JIT optimization also does not - support \C in UTF mode. If JIT optimization is requested for a UTF - pattern that contains \C, it will not succeed, and so the matching will - be carried out by the normal interpretive function. + The escape sequence \C can be used to match a single code unit in a UTF + mode, but its use can lead to some strange effects because it breaks up + multi-unit characters (see the description of \C in the pcre2pattern + documentation). + + The use of \C is not supported by the alternative matching function + pcre2_dfa_match() when in UTF-8 or UTF-16 mode, that is, when a charac- + ter may consist of more than one code unit. The use of \C in these + modes provokes a match-time error. Also, the JIT optimization does not + support \C in these modes. If JIT optimization is requested for a UTF-8 + or UTF-16 pattern that contains \C, it will not succeed, and so when + pcre2_match() is called, the matching will be carried out by the normal + interpretive function. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly test characters of any code value, but, by default, the characters that @@ -9769,9 +9904,9 @@ VALIDITY OF UTF STRINGS The following negative error codes are given for invalid UTF-16 strings: - PCRE_UTF16_ERR1 Missing low surrogate at end of string - PCRE_UTF16_ERR2 Invalid low surrogate follows high surrogate - PCRE_UTF16_ERR3 Isolated low surrogate + PCRE2_ERROR_UTF16_ERR1 Missing low surrogate at end of string + PCRE2_ERROR_UTF16_ERR2 Invalid low surrogate follows high surrogate + PCRE2_ERROR_UTF16_ERR3 Isolated low surrogate Errors in UTF-32 strings @@ -9779,8 +9914,8 @@ VALIDITY OF UTF STRINGS The following negative error codes are given for invalid UTF-32 strings: - PCRE_UTF32_ERR1 Surrogate character (range from 0xd800 to 0xdfff) - PCRE_UTF32_ERR2 Code point is greater than 0x10ffff + PCRE2_ERROR_UTF32_ERR1 Surrogate character (0xd800 to 0xdfff) + PCRE2_ERROR_UTF32_ERR2 Code point is greater than 0x10ffff AUTHOR @@ -9792,8 +9927,8 @@ AUTHOR REVISION - Last updated: 16 October 2015 - Copyright (c) 1997-2015 University of Cambridge. + Last updated: 03 July 2016 + Copyright (c) 1997-2016 University of Cambridge. ------------------------------------------------------------------------------ |