port.c

   1 /* portability functions */
   2
   3 /* Copyright (C) 2009 Keith Rarick
   4
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "t.h"
  20
  21 #ifdef _NEED_POSIX_FALLOCATE
  22 int
  23 posix_fallocate(int fd, off_t offset, off_t len)
  24 {
  25     off_t i;
  26     ssize_t w;
  27     off_t p;
  28     #define ZERO_BUF_SIZE 512
  29     char buf[ZERO_BUF_SIZE] = {}; /* initialize to zero */
  30
  31     /* we only support a 0 offset */
  32     if (offset != 0) return EINVAL;
  33
  34     if (len <= 0) return EINVAL;
  35
  36     if (len % 512 != 0) {
  37         len += 512 - len % 512;
  38     }
  39
  40     for (i = 0; i < len; i += w) {
  41         w = write(fd, &buf, ZERO_BUF_SIZE);
  42         if (w == -1) return errno;
  43     }
  44
  45     p = lseek(fd, 0, SEEK_SET);
  46     if (p == -1) return errno;
  47
  48     return 0;
  49 }
  50 #endif