| /* Determine current working directory. Linux version. |
| Copyright (C) 1997,1998,1999,2000,2002,2003,2006 |
| Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <assert.h> |
| #include <errno.h> |
| #include <limits.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| |
| #include <sysdep.h> |
| #include <sys/syscall.h> |
| #include <bp-checks.h> |
| |
| #include <kernel-features.h> |
| |
| |
| /* If we compile the file for use in ld.so we don't need the feature |
| that getcwd() allocates the buffers itself. */ |
| #ifdef IS_IN_rtld |
| # define NO_ALLOCATION 1 |
| #endif |
| |
| |
| #if __ASSUME_GETCWD_SYSCALL > 0 |
| /* Kernel 2.1.92 introduced a third way to get the current working |
| directory: a syscall. We've got to be careful that even when |
| compiling under 2.1.92+ the libc still runs under older kernels. */ |
| # define no_syscall_getcwd 0 |
| # define have_new_dcache 1 |
| /* This is a trick since we don't define generic_getcwd. */ |
| # define generic_getcwd getcwd |
| #else |
| /* The "proc" filesystem provides an easy method to retrieve the value. |
| For each process, the corresponding directory contains a symbolic link |
| named `cwd'. Reading the content of this link immediate gives us the |
| information. But we have to take care for systems which do not have |
| the proc filesystem mounted. Use the POSIX implementation in this case. */ |
| static char *generic_getcwd (char *buf, size_t size) internal_function; |
| |
| # if __NR_getcwd |
| /* Kernel 2.1.92 introduced a third way to get the current working |
| directory: a syscall. We've got to be careful that even when |
| compiling under 2.1.92+ the libc still runs under older kernels. */ |
| static int no_syscall_getcwd; |
| static int have_new_dcache; |
| # else |
| # define no_syscall_getcwd 1 |
| static int have_new_dcache = 1; |
| # endif |
| #endif |
| |
| char * |
| __getcwd (char *buf, size_t size) |
| { |
| char *path; |
| int n; |
| char *result; |
| |
| if (no_syscall_getcwd && !have_new_dcache) |
| return generic_getcwd (buf, size); |
| |
| #ifndef NO_ALLOCATION |
| size_t alloc_size = size; |
| if (size == 0) |
| { |
| if (buf != NULL) |
| { |
| __set_errno (EINVAL); |
| return NULL; |
| } |
| |
| alloc_size = MAX (PATH_MAX, __getpagesize ()); |
| } |
| |
| if (buf == NULL) |
| { |
| path = malloc (alloc_size); |
| if (path == NULL) |
| return NULL; |
| } |
| else |
| #else |
| # define alloc_size size |
| #endif |
| path = buf; |
| |
| #if defined __NR_getcwd || __LINUX_GETCWD_SYSCALL > 0 |
| if (!no_syscall_getcwd) |
| { |
| int retval; |
| |
| retval = INLINE_SYSCALL (getcwd, 2, CHECK_STRING (path), alloc_size); |
| if (retval >= 0) |
| { |
| # ifndef NO_ALLOCATION |
| if (buf == NULL && size == 0) |
| /* Ensure that the buffer is only as large as necessary. */ |
| buf = realloc (path, (size_t) retval); |
| |
| if (buf == NULL) |
| /* Either buf was NULL all along, or `realloc' failed but |
| we still have the original string. */ |
| buf = path; |
| # endif |
| |
| return buf; |
| } |
| |
| # if __ASSUME_GETCWD_SYSCALL |
| /* It should never happen that the `getcwd' syscall failed because |
| the buffer is too small if we allocated the buffer ourselves |
| large enough. */ |
| assert (errno != ERANGE || buf != NULL || size != 0); |
| |
| # ifndef NO_ALLOCATION |
| if (buf == NULL) |
| free (path); |
| # endif |
| |
| return NULL; |
| # else |
| if (errno == ENOSYS) |
| { |
| no_syscall_getcwd = 1; |
| have_new_dcache = 1; /* Now we will try the /proc method. */ |
| } |
| else if (errno != ERANGE || buf != NULL) |
| { |
| # ifndef NO_ALLOCATION |
| if (buf == NULL) |
| free (path); |
| # endif |
| return NULL; |
| } |
| # endif |
| } |
| #endif |
| |
| n = __readlink ("/proc/self/cwd", path, alloc_size - 1); |
| if (n != -1) |
| { |
| if (path[0] == '/') |
| { |
| if ((size_t) n >= alloc_size - 1) |
| { |
| #ifndef NO_ALLOCATION |
| if (buf == NULL) |
| free (path); |
| #endif |
| return NULL; |
| } |
| |
| path[n] = '\0'; |
| #ifndef NO_ALLOCATION |
| if (buf == NULL && size == 0) |
| /* Ensure that the buffer is only as large as necessary. */ |
| buf = realloc (path, (size_t) n + 1); |
| if (buf == NULL) |
| /* Either buf was NULL all along, or `realloc' failed but |
| we still have the original string. */ |
| buf = path; |
| #endif |
| |
| return buf; |
| } |
| #ifndef have_new_dcache |
| else |
| have_new_dcache = 0; |
| #endif |
| } |
| |
| #if __ASSUME_GETCWD_SYSCALL == 0 |
| /* Set to have_new_dcache only if error indicates that proc doesn't |
| exist. */ |
| if (errno != EACCES && errno != ENAMETOOLONG) |
| have_new_dcache = 0; |
| #endif |
| |
| #ifndef NO_ALLOCATION |
| /* Don't put restrictions on the length of the path unless the user does. */ |
| if (size == 0) |
| { |
| free (path); |
| path = NULL; |
| } |
| #endif |
| |
| result = generic_getcwd (path, size); |
| |
| #ifndef NO_ALLOCATION |
| if (result == NULL && buf == NULL && size != 0) |
| free (path); |
| #endif |
| |
| return result; |
| } |
| weak_alias (__getcwd, getcwd) |
| |
| #if __ASSUME_GETCWD_SYSCALL == 0 |
| /* Get the code for the generic version. */ |
| # define GETCWD_RETURN_TYPE static char * internal_function |
| # define __getcwd generic_getcwd |
| # include <sysdeps/posix/getcwd.c> |
| #endif |