diff options
author | Thomas Haller <thaller@redhat.com> | 2017-12-13 08:17:07 +0100 |
---|---|---|
committer | Sven Eden <yamakuzure@gmx.net> | 2017-12-13 08:17:07 +0100 |
commit | 8f0c163245883ed1e1fb1fb9b7bc65443e5ff01f (patch) | |
tree | fe69f835512f6de5bf70fe5365dcc1a912801995 /src/basic/macro.h | |
parent | 9c7f04ad328f82e5472d8f948b2d60e8218d9cc4 (diff) |
basic/macros: add STRLEN() to get length of string literal as constant expression
While the compiler likely optimizes strlen(x) for string literals,
it is not a constant expression.
Hence,
char buffer[strlen("OPTION_000") + 1];
declares a variable-length array. STRLEN() can be used instead
when a constant espression is needed.
It's not entirely identical to strlen(), as STRLEN("a\0") counts 2.
Also, it only works with string literals and the macro enforces
that the argument is a literal.
Diffstat (limited to 'src/basic/macro.h')
-rw-r--r-- | src/basic/macro.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/basic/macro.h b/src/basic/macro.h index c5671d7db..d73adc021 100644 --- a/src/basic/macro.h +++ b/src/basic/macro.h @@ -143,6 +143,14 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) { !__builtin_types_compatible_p(typeof(x), typeof(&*(x))), \ sizeof(x)/sizeof((x)[0]), \ (void)0)) + +/* + * STRLEN - return the length of a string literal, minus the trailing NUL byte. + * Contrary to strlen(), this is a constant expression. + * @x: a string literal. + */ +#define STRLEN(x) (sizeof(""x"") - 1) + /* * container_of - cast a member of a structure out to the containing structure * @ptr: the pointer to the member. |