/* Determine current working directory.  Linux version.

   Copyright (C) 1997-2018 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);

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>