/* truncate emulations for native Windows.
   Copyright (C) 2017-2021 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, 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/>.  */

/* If the user's config.h happens to include <unistd.h>, let it include only
   the system's <unistd.h> here, so that orig_faccessat doesn't recurse to
   rpl_faccessat.  */
#define _GL_INCLUDING_UNISTD_H
#include <config.h>

/* Specification.  */
#include <unistd.h>

#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#undef _GL_INCLUDING_UNISTD_H

#if TRUNCATE_TRAILING_SLASH_BUG
static int
orig_truncate (const char *filename, off_t length)
{
  return truncate (filename, length);
}
#endif

/* Write "unistd.h" here, not <unistd.h>, otherwise OSF/1 5.1 DTK cc
   eliminates this include because of the preliminary #include <unistd.h>
   above.  */
#include "unistd.h"

int
truncate (const char *filename, off_t length)
{
#if TRUNCATE_TRAILING_SLASH_BUG
  /* Use the original truncate(), but correct the trailing slash handling.  */
  size_t len = strlen (filename);
  if (len && filename[len - 1] == '/')
    {
      struct stat st;
      if (stat (filename, &st) == 0)
        errno = (S_ISDIR (st.st_mode) ? EISDIR : ENOTDIR);
      return -1;
    }
  return orig_truncate (filename, length);
#else
  int fd;

  if (length == 0)
    {
      fd = open (filename, O_WRONLY | O_TRUNC | O_CLOEXEC);
      if (fd < 0)
        return -1;
    }
  else
    {
      fd = open (filename, O_WRONLY | O_CLOEXEC);
      if (fd < 0)
        return -1;
      if (ftruncate (fd, length) < 0)
        {
          int saved_errno = errno;
          close (fd);
          errno = saved_errno;
          return -1;
        }
    }
  close (fd);
  return 0;
#endif
}
