coreutils/lib/safe-read.c

/* safe-read.c -- an interface to read that retries after interrupts
   Copyright (C) 1993, 1994 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <errno.h>
#ifndef errno
extern int errno;
#endif

/* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted.
   Return the actual number of bytes read, zero for EOF, or negative
   for an error.  */

int
safe_read (desc, ptr, len)
     int desc;
     char *ptr;
     int len;
{
  int n_chars;

  if (len <= 0)
    return len;

#ifdef EINTR
  do
    {
      n_chars = read (desc, ptr, len);
    }
  while (n_chars < 0 && errno == EINTR);
#else
  n_chars = read (desc, ptr, len);
#endif

  return n_chars;
}