lib/sh/zwrite.c

   1 /* zwrite - write contents of buffer to file descriptor, retrying on error */
   2
   3 /* Copyright (C) 1999-2002 Free Software Foundation, Inc.
   4
   5    This file is part of GNU Bash, the Bourne Again SHell.
   6
   7    Bash is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation, either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    Bash is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include <config.h>
  22
  23 #include <sys/types.h>
  24
  25 #if defined (HAVE_UNISTD_H)
  26 #  include <unistd.h>
  27 #endif
  28
  29 #include <errno.h>
  30
  31 #if !defined (errno)
  32 extern int errno;
  33 #endif
  34
  35 /* Write NB bytes from BUF to file descriptor FD, retrying the write if
  36    it is interrupted.  We retry three times if we get a zero-length
  37    write.  Any other signal causes this function to return prematurely. */
  38 int
  39 zwrite (fd, buf, nb)
  40      int fd;
  41      char *buf;
  42      size_t nb;
  43 {
  44   int n, i, nt;
  45
  46   for (n = nb, nt = 0;;)
  47     {
  48       i = write (fd, buf, n);
  49       if (i > 0)
  50         {
  51           n -= i;
  52           if (n <= 0)
  53             return nb;
  54           buf += i;
  55         }
  56       else if (i == 0)
  57         {
  58           if (++nt > 3)
  59             return (nb - n);
  60         }
  61       else if (errno != EINTR)
  62         return -1;
  63     }
  64 }