lib/full-write.c

   1 /* full-write.c -- an interface to write that retries after interrupts
   2    Copyright (C) 1993, 1994, 1997, 1998, 2000 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 2, 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
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18    Copied largely from GNU C's cccp.c.
  19    */
  20
  21 #if HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <sys/types.h>
  26
  27 #if HAVE_UNISTD_H
  28 # include <unistd.h>
  29 #endif
  30
  31 #include <errno.h>
  32 #ifndef errno
  33 extern int errno;
  34 #endif
  35
  36 /* Write LEN bytes at PTR to descriptor DESC, retrying if interrupted.
  37    Return LEN upon success, write's (negative) error code otherwise.  */
  38
  39 int
  40 full_write (int desc, const char *ptr, size_t len)
  41 {
  42   int total_written;
  43
  44   total_written = 0;
  45   while (len > 0)
  46     {
  47       int written = write (desc, ptr, len);
  48       /* write on an old Slackware Linux 1.2.13 returns zero when
  49          I try to write more data than there is room on a floppy disk.
  50          This puts dd into an infinite loop.  Reproduce with
  51          dd if=/dev/zero of=/dev/fd0.  If you have this problem,
  52          consider upgrading to a newer kernel.  */
  53       if (written < 0)
  54         {
  55 #ifdef EINTR
  56           if (errno == EINTR)
  57             continue;
  58 #endif
  59           return written;
  60         }
  61       total_written += written;
  62       ptr += written;
  63       len -= written;
  64     }
  65   return total_written;
  66 }