libvirt/gnulib/lib/lstat.c

/* Work around a bug of lstat on some systems

   Copyright (C) 1997-1999, 2000-2006, 2008 Free Software Foundation, Inc.

   This program 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.

   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 Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* written by Jim Meyering */

#include <config.h>

/* Get the original definition of open.  It might be defined as a macro.  */
#define __need_system_sys_stat_h
#include <sys/types.h>
#include <sys/stat.h>
#undef __need_system_sys_stat_h

static inline int
orig_lstat (const char *filename, struct stat *buf)
{
  return lstat (filename, buf);
}

/* Specification.  */
#include <sys/stat.h>

#include <string.h>
#include <errno.h>

/* lstat works differently on Linux and Solaris systems.  POSIX (see
   `pathname resolution' in the glossary) requires that programs like
   `ls' take into consideration the fact that FILE has a trailing slash
   when FILE is a symbolic link.  On Linux and Solaris 10 systems, the
   lstat function already has the desired semantics (in treating
   `lstat ("symlink/", sbuf)' just like `lstat ("symlink/.", sbuf)',
   but on Solaris 9 and earlier it does not.

   If FILE has a trailing slash and specifies a symbolic link,
   then use stat() to get more info on the referent of FILE.
   If the referent is a non-directory, then set errno to ENOTDIR
   and return -1.  Otherwise, return stat's result.  */

int
rpl_lstat (const char *file, struct stat *sbuf)
{
  size_t len;
  int lstat_result = orig_lstat (file, sbuf);

  if (lstat_result != 0 || !S_ISLNK (sbuf->st_mode))
    return lstat_result;

  len = strlen (file);
  if (len == 0 || file[len - 1] != '/')
    return 0;

  /* FILE refers to a symbolic link and the name ends with a slash.
     Call stat() to get info about the link's referent.  */

  /* If stat fails, then we do the same.  */
  if (stat (file, sbuf) != 0)
    return -1;

  /* If FILE references a directory, return 0.  */
  if (S_ISDIR (sbuf->st_mode))
    return 0;

  /* Here, we know stat succeeded and FILE references a non-directory.
     But it was specified via a name including a trailing slash.
     Fail with errno set to ENOTDIR to indicate the contradiction.  */
  errno = ENOTDIR;
  return -1;
}