lib/safe-read.c

   1 /* safe-read.c -- an interface to read that retries after interrupts
   2    Copyright (C) 1993, 1994 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
  19 #if HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #include <sys/types.h>
  24
  25 #if HAVE_UNISTD_H
  26 # include <unistd.h>
  27 #endif
  28
  29 #include <errno.h>
  30 #ifndef errno
  31 extern int errno;
  32 #endif
  33
  34 /* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted.
  35    Return the actual number of bytes read, zero for EOF, or negative
  36    for an error.  */
  37
  38 int
  39 safe_read (desc, ptr, len)
  40      int desc;
  41      char *ptr;
  42      int len;
  43 {
  44   int n_chars;
  45
  46   if (len <= 0)
  47     return len;
  48
  49 #ifdef EINTR
  50   do
  51     {
  52       n_chars = read (desc, ptr, len);
  53     }
  54   while (n_chars < 0 && errno == EINTR);
  55 #else
  56   n_chars = read (desc, ptr, len);
  57 #endif
  58
  59   return n_chars;
  60 }