/* Provide a stub lchown function for systems that lack it.

   Copyright (C) 1998-1999, 2002, 2004, 2006-2007, 2009-2018 Free Software

   Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* written by Jim Meyering */

#include <config.h>

#include <unistd.h>

#include <errno.h>

#include <stdbool.h>

#include <string.h>

#include <sys/stat.h>

#if !HAVE_LCHOWN

/* If the system chown does not follow symlinks, we don't want it

   replaced by gnulib's chown, which does follow symlinks.  */

# if CHOWN_MODIFIES_SYMLINK

#  undef chown

# endif

/* Work just like chown, except when FILE is a symbolic link.

   In that case, set errno to EOPNOTSUPP and return -1.

   But if autoconf tests determined that chown modifies

   symlinks, then just call chown.  */

int

lchown (const char *file, uid_t uid, gid_t gid)

{

# if HAVE_CHOWN

#  if ! CHOWN_MODIFIES_SYMLINK

  struct stat stats;

  if (lstat (file, &stats) == 0 && S_ISLNK (stats.st_mode))

    {

      errno = EOPNOTSUPP;

      return -1;

    }

#  endif

  return chown (file, uid, gid);

# else /* !HAVE_CHOWN */

  errno = ENOSYS;

  return -1;

# endif

}

#else /* HAVE_LCHOWN */

# undef lchown

/* Work around trailing slash bugs in lchown.  */

int

rpl_lchown (const char *file, uid_t uid, gid_t gid)

{

  bool stat_valid = false;

  int result;

# if CHOWN_CHANGE_TIME_BUG

  struct stat st;

  if (gid != (gid_t) -1 || uid != (uid_t) -1)

    {

      if (lstat (file, &st))

        return -1;

      stat_valid = true;

      if (!S_ISLNK (st.st_mode))

        return chown (file, uid, gid);

    }

# endif

# if CHOWN_TRAILING_SLASH_BUG

  if (!stat_valid)

    {

      size_t len = strlen (file);

      if (len && file[len - 1] == '/')

        return chown (file, uid, gid);

    }

# endif

  result = lchown (file, uid, gid);

# if CHOWN_CHANGE_TIME_BUG && HAVE_LCHMOD

  if (result == 0 && stat_valid

      && (uid == st.st_uid || uid == (uid_t) -1)

      && (gid == st.st_gid || gid == (gid_t) -1))

    {

      /* No change in ownership, but at least one argument was not -1,

         so we are required to update ctime.  Since lchown succeeded,

         we assume that lchmod will do likewise.  But if the system

         lacks lchmod and lutimes, we are out of luck.  Oh well.  */

      result = lchmod (file, st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO

                                           | S_ISUID | S_ISGID | S_ISVTX));

    }

# endif

  return result;

}

#endif /* HAVE_LCHOWN */