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>
37 # define IS_EINTR(x) ((x) == EINTR)
39 # define IS_EINTR(x) 0
48 /* The extra casts work around common compiler bugs. */
49 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
50 /* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
51 It is necessary at least when t == time_t. */
52 #define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
53 ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
54 #define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
57 # define INT_MAX TYPE_MAXIMUM (int)
60 /* Read up to COUNT bytes at BUF from descriptor FD, retrying if interrupted.
61 Return the actual number of bytes read, zero for EOF, or SAFE_RW_ERROR
64 safe_read (int fd, void *buf, size_t count)
68 /* POSIX limits COUNT to SSIZE_MAX, but we limit it further, requiring
69 that COUNT <= INT_MAX, to avoid triggering a bug in Tru64 5.1.
70 When decreasing COUNT, keep the file pointer block-aligned.
71 Note that in any case, read may succeed, yet read fewer than COUNT
72 bytes, so the caller must be prepared to handle partial results. */
74 count = INT_MAX & ~8191;
78 result = read (fd, buf, count);
80 while (result < 0 && IS_EINTR (errno));
82 return (size_t) result;