lib/truncate.c

   1 /* truncate emulations for native Windows.
   2    Copyright (C) 2017-2018 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <unistd.h>
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24
  25 int
  26 truncate (const char *filename, off_t length)
  27 {
  28   int fd;
  29
  30   if (length == 0)
  31     {
  32       fd = open (filename, O_WRONLY | O_TRUNC);
  33       if (fd < 0)
  34         return -1;
  35     }
  36   else
  37     {
  38       fd = open (filename, O_WRONLY);
  39       if (fd < 0)
  40         return -1;
  41       if (ftruncate (fd, length) < 0)
  42         {
  43           int saved_errno = errno;
  44           close (fd);
  45           errno = saved_errno;
  46           return -1;
  47         }
  48     }
  49   close (fd);
  50   return 0;
  51 }