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glibc/sysdeps/unix/sysv/linux/getcwd.c
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/* Determine current working directory. Linux version. | |
Copyright (C) 1997-2016 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, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <assert.h> | |
#include <errno.h> | |
#include <limits.h> | |
#include <stdlib.h> | |
#include <unistd.h> | |
#include <sys/param.h> | |
#include <sysdep.h> | |
#include <sys/syscall.h> | |
/* If we compile the file for use in ld.so we don't need the feature | |
that getcwd() allocates the buffers itself. */ | |
#if IS_IN (rtld) | |
# define NO_ALLOCATION 1 | |
#endif | |
/* 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; | |
char * | |
__getcwd (char *buf, size_t size) | |
{ | |
char *path; | |
char *result; | |
#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; | |
int retval; | |
retval = INLINE_SYSCALL (getcwd, 2, 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; | |
} | |
/* The system call cannot handle paths longer than a page. | |
Neither can the magic symlink in /proc/self. Just use the | |
generic implementation right away. */ | |
if (errno == ENAMETOOLONG) | |
{ | |
#ifndef NO_ALLOCATION | |
if (buf == NULL && 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; | |
} | |
/* 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; | |
} | |
weak_alias (__getcwd, getcwd) | |
/* Get the code for the generic version. */ | |
#define GETCWD_RETURN_TYPE static char * internal_function | |
#define __getcwd generic_getcwd | |
#include <sysdeps/posix/getcwd.c> |