lib/safe-read.c

   1 /* safe-read.c -- an interface to read that retries after interrupts
   2    Copyright (C) 1993, 1994, 1998 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 #include "safe-read.h"
  35
  36 /* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted.
  37    Return the actual number of bytes read, zero for EOF, or negative
  38    for an error.  */
  39
  40 ssize_t
  41 safe_read (int desc, void *ptr, size_t len)
  42 {
  43   ssize_t n_chars;
  44
  45   if (len <= 0)
  46     return len;
  47
  48 #ifdef EINTR
  49   do
  50     {
  51       n_chars = read (desc, ptr, len);
  52     }
  53   while (n_chars < 0 && errno == EINTR);
  54 #else
  55   n_chars = read (desc, ptr, len);
  56 #endif
  57
  58   return n_chars;
  59 }