1 /* An interface to read() that retries after interrupts.
2 Copyright (C) 1993, 1994, 1998, 2002 Free Software Foundation, Inc.
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)
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.
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. */
23 #include "safe-read.h"
26 #include <sys/types.h>
38 /* We don't pass an nbytes count > SSIZE_MAX to read() - POSIX says the
39 effect would be implementation-defined. Also we don't pass an nbytes
40 count > INT_MAX but <= SSIZE_MAX to read() - this triggers a bug in
42 #define MAX_BYTES_TO_READ INT_MAX
44 /* Read up to COUNT bytes at BUF from descriptor FD, retrying if interrupted.
45 Return the actual number of bytes read, zero for EOF, or (size_t) -1
48 safe_read (int fd, void *buf, size_t count)
50 size_t total_read = 0;
54 char *ptr = (char *) buf;
57 size_t nbytes_to_read = count;
60 /* Limit the number of bytes to read in one round, to avoid running
61 into unspecified behaviour. But keep the file pointer block
62 aligned when doing so. */
63 if (nbytes_to_read > MAX_BYTES_TO_READ)
64 nbytes_to_read = MAX_BYTES_TO_READ & ~8191;
66 result = read (fd, ptr, nbytes_to_read);