/* Stub for readlink().

   Copyright (C) 2003-2007, 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/>.  */

#include <config.h>

/* Specification.  */

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/stat.h>

#if !HAVE_READLINK

/* readlink() substitute for systems that don't have a readlink() function,

   such as DJGPP 2.03 and mingw32.  */

ssize_t

readlink (const char *name, char *buf _GL_UNUSED,

          size_t bufsize _GL_UNUSED)

{

  struct stat statbuf;

  /* In general we should use lstat() here, not stat().  But on platforms

     without symbolic links, lstat() - if it exists - would be equivalent to

     stat(), therefore we can use stat().  This saves us a configure check.  */

  if (stat (name, &statbuf) >= 0)

    errno = EINVAL;

  return -1;

}

#else /* HAVE_READLINK */

# undef readlink

/* readlink() wrapper that uses correct types, for systems like cygwin

   1.5.x where readlink returns int, and which rejects trailing slash,

   for Solaris 9.  */

ssize_t

rpl_readlink (const char *name, char *buf, size_t bufsize)

{

# if READLINK_TRAILING_SLASH_BUG

  size_t len = strlen (name);

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

    {

      /* Even if name without the slash is a symlink to a directory,

         both lstat() and stat() must resolve the trailing slash to

         the directory rather than the symlink.  We can therefore

         safely use stat() to distinguish between EINVAL and

         ENOTDIR/ENOENT, avoiding extra overhead of rpl_lstat().  */

      struct stat st;

      if (stat (name, &st) == 0)

        errno = EINVAL;

      return -1;

    }

# endif /* READLINK_TRAILING_SLASH_BUG */

  return readlink (name, buf, bufsize);

}

#endif /* HAVE_READLINK */