/* Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   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/>.  */

/* Wants:

   AC_STDC_HEADERS

   AC_DIR_HEADER

   AC_UNISTD_H

   AC_MEMORY_H

   AC_CONST

   AC_ALLOCA

 */

/* AIX requires this to be the first thing in the file.  */

#if defined _AIX && !defined __GNUC__

 #pragma alloca

#endif

#ifdef	HAVE_CONFIG_H

# include "config.h"

#endif

#include <errno.h>

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

#ifdef	STDC_HEADERS

# include <stddef.h>

#endif

#if !defined __GNU_LIBRARY__ && !defined STDC_HEADERS

extern int errno;

#endif

#ifndef __set_errno

# define __set_errno(val) errno = (val)

#endif

#ifndef	NULL

# define NULL	0

#endif

#if defined USGr3 && !defined DIRENT

# define DIRENT

#endif /* USGr3 */

#if defined Xenix && !defined SYSNDIR

# define SYSNDIR

#endif /* Xenix */

#if defined POSIX || defined DIRENT || defined __GNU_LIBRARY__

# include <dirent.h>

# ifndef __GNU_LIBRARY__

#  define D_NAMLEN(d) strlen((d)->d_name)

# else

#  define HAVE_D_NAMLEN

#  define D_NAMLEN(d) ((d)->d_namlen)

# endif

#else /* not POSIX or DIRENT */

# define dirent		direct

# define D_NAMLEN(d)	((d)->d_namlen)

# define HAVE_D_NAMLEN

# if defined USG && !defined sgi

#  if defined SYSNDIR

#   include <sys/ndir.h>

#  else /* Not SYSNDIR */

#   include "ndir.h"

#  endif /* SYSNDIR */

# else /* not USG */

#  include <sys/dir.h>

# endif /* USG */

#endif /* POSIX or DIRENT or __GNU_LIBRARY__ */

#if defined HAVE_UNISTD_H || defined __GNU_LIBRARY__

# include <unistd.h>

#endif

#if defined STDC_HEADERS || defined __GNU_LIBRARY__ || defined POSIX

# include <stdlib.h>

# include <string.h>

# define ANSI_STRING

#else	/* No standard headers.  */

# ifdef	USG

#  include <string.h>

#  ifdef NEED_MEMORY_H

#   include <memory.h>

#  endif

#  define	ANSI_STRING

# else	/* Not USG.  */

#  ifdef NeXT

#   include <string.h>

#  else	/* Not NeXT.  */

#   include <strings.h>

#   ifndef bcmp

extern int bcmp ();

#   endif

#   ifndef bzero

extern void bzero ();

#   endif

#   ifndef bcopy

extern void bcopy ();

#   endif

#  endif /* NeXT. */

# endif	/* USG.  */

extern char *malloc (), *realloc ();

extern void free ();

#endif /* Standard headers.  */

#ifndef	ANSI_STRING

# define memcpy(d, s, n)	bcopy((s), (d), (n))

# define memmove memcpy

#endif	/* Not ANSI_STRING.  */

#ifndef MAX

# define MAX(a, b) ((a) < (b) ? (b) : (a))

#endif

#ifdef _LIBC

# ifndef mempcpy

#  define mempcpy __mempcpy

# endif

# define HAVE_MEMPCPY	1

#endif

#if !defined __alloca && !defined __GNU_LIBRARY__

# ifdef	__GNUC__

#  undef alloca

#  define alloca(n)	__builtin_alloca (n)

# else	/* Not GCC.  */

#  if	defined sparc || defined HAVE_ALLOCA_H

#   include <alloca.h>

#  else	/* Not sparc or HAVE_ALLOCA_H.  */

#   ifndef _AIX

extern char *alloca ();

#   endif /* Not _AIX.  */

#  endif /* sparc or HAVE_ALLOCA_H.  */

# endif	/* GCC.  */

# define __alloca	alloca

#endif

#if defined HAVE_LIMITS_H || defined STDC_HEADERS || defined __GNU_LIBRARY__

# include <limits.h>

#else

# include <sys/param.h>

#endif

#if defined _LIBC

# include <not-cancel.h>

# include <kernel-features.h>

#else

# define __openat64_nocancel(dfd, name, mode) openat64 (dfd, name, mode)

# define __close_nocancel_nostatus(fd) close (fd)

#endif

#ifndef PATH_MAX

# ifdef	MAXPATHLEN

#  define PATH_MAX MAXPATHLEN

# else

#  define PATH_MAX 1024

# endif

#endif

#if !defined STDC_HEADERS && !defined __GNU_LIBRARY__

# undef	size_t

# define size_t	unsigned int

#endif

#ifndef __GNU_LIBRARY__

# define __lstat64	stat64

#endif

#ifndef _LIBC

# define __rewinddir	rewinddir

#endif

#ifndef _LIBC

# define __getcwd getcwd

#endif

#ifndef GETCWD_RETURN_TYPE

# define GETCWD_RETURN_TYPE char *

#endif

#ifdef __ASSUME_ATFCTS

# define __have_atfcts 1

#elif IS_IN (rtld)

static int __rtld_have_atfcts;

# define __have_atfcts __rtld_have_atfcts

#endif

/* Get the pathname of the current working directory, and put it in SIZE

   bytes of BUF.  Returns NULL if the directory couldn't be determined or

   SIZE was too small.  If successful, returns BUF.  In GNU, if BUF is

   NULL, an array is allocated with `malloc'; the array is SIZE bytes long,

   unless SIZE == 0, in which case it is as big as necessary.  */

GETCWD_RETURN_TYPE

__getcwd (char *buf, size_t size)

{

#ifndef __ASSUME_ATFCTS

  static const char dots[]

    = "../../../../../../../../../../../../../../../../../../../../../../../\

../../../../../../../../../../../../../../../../../../../../../../../../../../\

../../../../../../../../../../../../../../../../../../../../../../../../../..";

  const char *dotp = &dots[sizeof (dots)];

  const char *dotlist = dots;

  size_t dotsize = sizeof (dots) - 1;

#endif

  int prev_errno = errno;

  DIR *dirstream = NULL;

  bool fd_needs_closing = false;

  int fd = AT_FDCWD;

  char *path;

#ifndef NO_ALLOCATION

  size_t allocated = size;

  if (size == 0)

    {

      if (buf != NULL)

	{

	  __set_errno (EINVAL);

	  return NULL;

	}

      allocated = PATH_MAX + 1;

    }

  if (buf == NULL)

    {

      path = malloc (allocated);

      if (path == NULL)

	return NULL;

    }

  else

#else

# define allocated size

#endif

    path = buf;

  char *pathp = path + allocated;

  *--pathp = '\0';

  struct stat64 st;

  if (__lstat64 (".", &st) < 0)

    goto lose;

  dev_t thisdev = st.st_dev;

  ino_t thisino = st.st_ino;

  if (__lstat64 ("/", &st) < 0)

    goto lose;

  dev_t rootdev = st.st_dev;

  ino_t rootino = st.st_ino;

  while (!(thisdev == rootdev && thisino == rootino))

    {

      if (__have_atfcts >= 0)

	  fd = __openat64_nocancel (fd, "..", O_RDONLY | O_CLOEXEC);

      else

	fd = -1;

      if (fd >= 0)

	{

	  fd_needs_closing = true;

	  if (__fstat64 (fd, &st) < 0)

	    goto lose;

	}

#ifndef __ASSUME_ATFCTS

      else if (errno == ENOSYS)

	{

	  __have_atfcts = -1;

	  /* Look at the parent directory.  */

	  if (dotp == dotlist)

	    {

# ifdef NO_ALLOCATION

	      __set_errno (ENOMEM);

	      goto lose;

# else

	      /* My, what a deep directory tree you have, Grandma.  */

	      char *new;

	      if (dotlist == dots)

		{

		  new = malloc (dotsize * 2 + 1);

		  if (new == NULL)

		    goto lose;

#  ifdef HAVE_MEMPCPY

		  dotp = mempcpy (new, dots, dotsize);

#  else

		  memcpy (new, dots, dotsize);

		  dotp = &new[dotsize];

#  endif

		}

	      else

		{

		  new = realloc ((void *) dotlist, dotsize * 2 + 1);

		  if (new == NULL)

		    goto lose;

		  dotp = &new[dotsize];

		}

#  ifdef HAVE_MEMPCPY

	      *((char *) mempcpy ((char *) dotp, new, dotsize)) = '\0';

	      dotsize *= 2;

#  else

	      memcpy ((char *) dotp, new, dotsize);

	      dotsize *= 2;

	      new[dotsize] = '\0';

#  endif

	      dotlist = new;

# endif

	    }

	  dotp -= 3;

	  /* Figure out if this directory is a mount point.  */

	  if (__lstat64 (dotp, &st) < 0)

	    goto lose;

	}

#endif

      else

	goto lose;

      if (dirstream && __closedir (dirstream) != 0)

	{

	  dirstream = NULL;

	  goto lose;

       }

      dev_t dotdev = st.st_dev;

      ino_t dotino = st.st_ino;

      bool mount_point = dotdev != thisdev;

      /* Search for the last directory.  */

      if (__have_atfcts >= 0)

	dirstream = __fdopendir (fd);

#ifndef __ASSUME_ATFCTS

      else

	dirstream = __opendir (dotp);

#endif

      if (dirstream == NULL)

	goto lose;

      fd_needs_closing = false;

      struct dirent *d;

      bool use_d_ino = true;

      while (1)

	{

	  /* Clear errno to distinguish EOF from error if readdir returns

	     NULL.  */

	  __set_errno (0);

	  d = __readdir (dirstream);

	  if (d == NULL)

	    {

	      if (errno == 0)

		{

		  /* When we've iterated through all directory entries

		     without finding one with a matching d_ino, rewind the

		     stream and consider each name again, but this time, using

		     lstat64.  This is necessary in a chroot on at least one

		     system.  */

		  if (use_d_ino)

		    {

		      use_d_ino = false;

		      __rewinddir (dirstream);

		      continue;

		    }

		  /* EOF on dirstream, which means that the current directory

		     has been removed.  */

		  __set_errno (ENOENT);

		}

	      goto lose;

	    }

#ifdef _DIRENT_HAVE_D_TYPE

	  if (d->d_type != DT_DIR && d->d_type != DT_UNKNOWN)

	    continue;

#endif

	  if (d->d_name[0] == '.'

	      && (d->d_name[1] == '\0'

		  || (d->d_name[1] == '.' && d->d_name[2] == '\0')))

	    continue;

	  if (use_d_ino && !mount_point && (ino_t) d->d_ino != thisino)

	    continue;

	  if (__have_atfcts >= 0)

	    {

	      /* We don't fail here if we cannot stat64() a directory entry.

		 This can happen when (network) filesystems fail.  If this

		 entry is in fact the one we are looking for we will find

		 out soon as we reach the end of the directory without

		 having found anything.  */

	      if (__fstatat64 (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0)

		continue;

	    }

#ifndef __ASSUME_ATFCTS

	  else

	    {

	      char name[dotlist + dotsize - dotp + 1 + _D_ALLOC_NAMLEN (d)];

# ifdef HAVE_MEMPCPY

	      char *tmp = mempcpy (name, dotp, dotlist + dotsize - dotp);

	      *tmp++ = '/';

	      strcpy (tmp, d->d_name);

# else

	      memcpy (name, dotp, dotlist + dotsize - dotp);

	      name[dotlist + dotsize - dotp] = '/';

	      strcpy (&name[dotlist + dotsize - dotp + 1], d->d_name);

# endif

	      /* We don't fail here if we cannot stat64() a directory entry.

		 This can happen when (network) filesystems fail.  If this

		 entry is in fact the one we are looking for we will find

		 out soon as we reach the end of the directory without

		 having found anything.  */

	      if (__lstat64 (name, &st) < 0)

		continue;

	    }

#endif

	  if (S_ISDIR (st.st_mode)

	      && st.st_dev == thisdev && st.st_ino == thisino)

	    break;

	}

      size_t namlen = _D_EXACT_NAMLEN (d);

      if ((size_t) (pathp - path) <= namlen)

	{

#ifndef NO_ALLOCATION

	  if (size == 0)

	    {

	      size_t oldsize = allocated;

	      allocated = 2 * MAX (allocated, namlen);

	      char *tmp = realloc (path, allocated);

	      if (tmp == NULL)

		goto lose;

	      /* Move current contents up to the end of the buffer.

		 This is guaranteed to be non-overlapping.  */

	      pathp = memcpy (tmp + allocated - (path + oldsize - pathp),

			      tmp + (pathp - path),

			      path + oldsize - pathp);

	      path = tmp;

	    }

	  else

#endif

	    {

	      __set_errno (ERANGE);

	      goto lose;

	    }

	}

      pathp -= namlen;

      (void) memcpy (pathp, d->d_name, namlen);

      *--pathp = '/';

      thisdev = dotdev;

      thisino = dotino;

    }

  if (dirstream != NULL && __closedir (dirstream) != 0)

    {

      dirstream = NULL;

      goto lose;

    }

  if (pathp == &path[allocated - 1])

    *--pathp = '/';

#ifndef __ASSUME_ATFCTS

  if (dotlist != dots)

    free ((void *) dotlist);

#endif

  size_t used = path + allocated - pathp;

  memmove (path, pathp, used);

  if (size == 0)

    /* Ensure that the buffer is only as large as necessary.  */

    buf = realloc (path, used);

  if (buf == NULL)

    /* Either buf was NULL all along, or `realloc' failed but

       we still have the original string.  */

    buf = path;

  /* Restore errno on successful return.  */

  __set_errno (prev_errno);

  return buf;

 lose:;

  int save_errno = errno;

#ifndef __ASSUME_ATFCTS

  if (dotlist != dots)

    free ((void *) dotlist);

#endif

  if (dirstream != NULL)

    __closedir (dirstream);

  if (fd_needs_closing)

    __close_nocancel_nostatus (fd);

#ifndef NO_ALLOCATION

  if (buf == NULL)

    free (path);

#endif

  __set_errno (save_errno);

  return NULL;

}

#if defined _LIBC && !defined __getcwd

weak_alias (__getcwd, getcwd)

#endif