/* Open a stream to a file.

   Copyright (C) 2007-2015 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 <http://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */

/* If the user's config.h happens to include <stdio.h>, let it include only

   the system's <stdio.h> here, so that orig_fopen doesn't recurse to

   rpl_fopen.  */

#define __need_FILE

#include <config.h>

/* Get the original definition of fopen.  It might be defined as a macro.  */

#include <stdio.h>

#undef __need_FILE

static FILE *

orig_fopen (const char *filename, const char *mode)

{

  return fopen (filename, mode);

}

/* Specification.  */

/* Write "stdio.h" here, not <stdio.h>, otherwise OSF/1 5.1 DTK cc eliminates

   this include because of the preliminary #include <stdio.h> above.  */

#include "stdio.h"

#include <errno.h>

#include <fcntl.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/stat.h>

FILE *

rpl_fopen (const char *filename, const char *mode)

{

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

  if (strcmp (filename, "/dev/null") == 0)

    filename = "NUL";

#endif

#if FOPEN_TRAILING_SLASH_BUG

  /* If the filename ends in a slash and a mode that requires write access is

     specified, then fail.

     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>

     says that

       "A pathname that contains at least one non-slash character and that

        ends with one or more trailing slashes shall be resolved as if a

        single dot character ( '.' ) were appended to the pathname."

     and

       "The special filename dot shall refer to the directory specified by

        its predecessor."

     If the named file already exists as a directory, then if a mode that

     requires write access is specified, fopen() must fail because POSIX

     <http://www.opengroup.org/susv3/functions/fopen.html> says that it

     fails with errno = EISDIR in this case.

     If the named file does not exist or does not name a directory, then

     fopen() must fail since the file does not contain a '.' directory.  */

  {

    size_t len = strlen (filename);

    if (len > 0 && filename[len - 1] == '/')

      {

        int fd;

        struct stat statbuf;

        FILE *fp;

        if (mode[0] == 'w' || mode[0] == 'a')

          {

            errno = EISDIR;

            return NULL;

          }

        fd = open (filename, O_RDONLY);

        if (fd < 0)

          return NULL;

        if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))

          {

            close (fd);

            errno = ENOTDIR;

            return NULL;

          }

        fp = fdopen (fd, mode);

        if (fp == NULL)

          {

            int saved_errno = errno;

            close (fd);

            errno = saved_errno;

          }

        return fp;

      }

  }

# endif

  return orig_fopen (filename, mode);

}