diff options
Diffstat (limited to 'gl/lib/getcwd.c')
| -rw-r--r-- | gl/lib/getcwd.c | 84 |
1 files changed, 78 insertions, 6 deletions
diff --git a/gl/lib/getcwd.c b/gl/lib/getcwd.c index 113332f1..28f69133 100644 --- a/gl/lib/getcwd.c +++ b/gl/lib/getcwd.c @@ -1,4 +1,4 @@ -/* Copyright (C) 1991-2022 Free Software Foundation, Inc. +/* Copyright (C) 1991-2023 Free Software Foundation, Inc. This file is part of the GNU C Library. This file is free software: you can redistribute it and/or modify @@ -16,6 +16,7 @@ #if !_LIBC # include <config.h> +# include <stdio.h> # include <unistd.h> # include "pathmax.h" #else @@ -28,7 +29,6 @@ #include <errno.h> #include <sys/types.h> #include <sys/stat.h> -#include <stdbool.h> #include <stddef.h> #include <fcntl.h> /* For AT_FDCWD on Solaris 9. */ @@ -114,13 +114,21 @@ FIXME - if the kernel ever adds support for multi-thread safety for avoiding standard fds, then we should use opendir_safer and openat_safer. */ -#ifdef GNULIB_defined_opendir +#ifdef GNULIB_defined_DIR +# undef DIR # undef opendir -#endif -#ifdef GNULIB_defined_closedir # undef closedir +# undef readdir +# undef rewinddir +#else +# ifdef GNULIB_defined_opendir +# undef opendir +# endif +# ifdef GNULIB_defined_closedir +# undef closedir +# endif #endif - + #if defined _WIN32 && !defined __CYGWIN__ # if HAVE_MSVC_INVALID_PARAMETER_HANDLER static char * @@ -173,6 +181,9 @@ __getcwd_generic (char *buf, size_t size) #if HAVE_OPENAT_SUPPORT int fd = AT_FDCWD; bool fd_needs_closing = false; +# if defined __linux__ + bool proc_fs_not_mounted = false; +# endif #else char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1]; char *dotlist = dots; @@ -438,6 +449,67 @@ __getcwd_generic (char *buf, size_t size) thisdev = dotdev; thisino = dotino; + +#if HAVE_OPENAT_SUPPORT + /* On some platforms, a system call returns the directory that FD points + to. This is useful if some of the ancestor directories of the + directory are unreadable, because in this situation the loop that + climbs up the ancestor hierarchy runs into an EACCES error. + For example, in some Android app, /data/data/com.termux is readable, + but /data/data and /data are not. */ +# if defined __linux__ + /* On Linux, in particular, if /proc is mounted, + readlink ("/proc/self/fd/<fd>") + returns the directory, if its length is < 4096. (If the length is + >= 4096, it fails with error ENAMETOOLONG, even if the buffer that we + pass to the readlink function would be large enough.) */ + if (!proc_fs_not_mounted) + { + char namebuf[14 + 10 + 1]; + sprintf (namebuf, "/proc/self/fd/%u", (unsigned int) fd); + char linkbuf[4096]; + ssize_t linklen = readlink (namebuf, linkbuf, sizeof linkbuf); + if (linklen < 0) + { + if (errno != ENAMETOOLONG) + /* If this call was not successful, the next one will likely be + not successful either. */ + proc_fs_not_mounted = true; + } + else + { + dirroom = dirp - dir; + if (dirroom < linklen) + { + if (size != 0) + { + __set_errno (ERANGE); + goto lose; + } + else + { + char *tmp; + size_t oldsize = allocated; + + allocated += linklen - dirroom; + if (allocated < oldsize + || ! (tmp = realloc (dir, allocated))) + goto memory_exhausted; + + /* Move current contents up to the end of the buffer. */ + dirp = memmove (tmp + dirroom + (allocated - oldsize), + tmp + dirroom, + oldsize - dirroom); + dir = tmp; + } + } + dirp -= linklen; + memcpy (dirp, linkbuf, linklen); + break; + } + } +# endif +#endif } if (dirstream && __closedir (dirstream) != 0) |