1*946379e7Schristos /* An interface to read and write that retries after interrupts.
2*946379e7Schristos
3*946379e7Schristos Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005, 2006 Free
4*946379e7Schristos Software Foundation, Inc.
5*946379e7Schristos
6*946379e7Schristos This program is free software; you can redistribute it and/or modify
7*946379e7Schristos it under the terms of the GNU General Public License as published by
8*946379e7Schristos the Free Software Foundation; either version 2, or (at your option)
9*946379e7Schristos any later version.
10*946379e7Schristos
11*946379e7Schristos This program is distributed in the hope that it will be useful,
12*946379e7Schristos but WITHOUT ANY WARRANTY; without even the implied warranty of
13*946379e7Schristos MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14*946379e7Schristos GNU General Public License for more details.
15*946379e7Schristos
16*946379e7Schristos You should have received a copy of the GNU General Public License
17*946379e7Schristos along with this program; if not, write to the Free Software Foundation,
18*946379e7Schristos Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19*946379e7Schristos
20*946379e7Schristos #include <config.h>
21*946379e7Schristos
22*946379e7Schristos /* Specification. */
23*946379e7Schristos #ifdef SAFE_WRITE
24*946379e7Schristos # include "safe-write.h"
25*946379e7Schristos #else
26*946379e7Schristos # include "safe-read.h"
27*946379e7Schristos #endif
28*946379e7Schristos
29*946379e7Schristos /* Get ssize_t. */
30*946379e7Schristos #include <sys/types.h>
31*946379e7Schristos #include <unistd.h>
32*946379e7Schristos
33*946379e7Schristos #include <errno.h>
34*946379e7Schristos
35*946379e7Schristos #ifdef EINTR
36*946379e7Schristos # define IS_EINTR(x) ((x) == EINTR)
37*946379e7Schristos #else
38*946379e7Schristos # define IS_EINTR(x) 0
39*946379e7Schristos #endif
40*946379e7Schristos
41*946379e7Schristos #include <limits.h>
42*946379e7Schristos
43*946379e7Schristos #ifdef SAFE_WRITE
44*946379e7Schristos # define safe_rw safe_write
45*946379e7Schristos # define rw write
46*946379e7Schristos #else
47*946379e7Schristos # define safe_rw safe_read
48*946379e7Schristos # define rw read
49*946379e7Schristos # undef const
50*946379e7Schristos # define const /* empty */
51*946379e7Schristos #endif
52*946379e7Schristos
53*946379e7Schristos /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
54*946379e7Schristos interrupted. Return the actual number of bytes read(written), zero for EOF,
55*946379e7Schristos or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */
56*946379e7Schristos size_t
safe_rw(int fd,void const * buf,size_t count)57*946379e7Schristos safe_rw (int fd, void const *buf, size_t count)
58*946379e7Schristos {
59*946379e7Schristos /* Work around a bug in Tru64 5.1. Attempting to read more than
60*946379e7Schristos INT_MAX bytes fails with errno == EINVAL. See
61*946379e7Schristos <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
62*946379e7Schristos When decreasing COUNT, keep it block-aligned. */
63*946379e7Schristos enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
64*946379e7Schristos
65*946379e7Schristos for (;;)
66*946379e7Schristos {
67*946379e7Schristos ssize_t result = rw (fd, buf, count);
68*946379e7Schristos
69*946379e7Schristos if (0 <= result)
70*946379e7Schristos return result;
71*946379e7Schristos else if (IS_EINTR (errno))
72*946379e7Schristos continue;
73*946379e7Schristos else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
74*946379e7Schristos count = BUGGY_READ_MAXIMUM;
75*946379e7Schristos else
76*946379e7Schristos return result;
77*946379e7Schristos }
78*946379e7Schristos }
79