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/* Determine current working directory. Linux version.
Copyright (C) 1997-2019 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
<https://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);
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 && path[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 either cannot handle paths longer than a page
or can succeed without returning an absolute path. Just use the
generic implementation right away. */
if (retval >= 0 || 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 *
#define __getcwd generic_getcwd
#include <sysdeps/posix/getcwd.c>
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