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9b36a80c LC |
1 | /* An interface to read and write that retries after interrupts. |
2 | ||
5e69ceb7 | 3 | Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2014 Free Software |
61cd9dc9 | 4 | Foundation, Inc. |
9b36a80c LC |
5 | |
6 | This program is free software: you can redistribute it and/or modify | |
7 | it under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #include <config.h> | |
20 | ||
21 | /* Specification. */ | |
22 | #ifdef SAFE_WRITE | |
23 | # include "safe-write.h" | |
24 | #else | |
25 | # include "safe-read.h" | |
26 | #endif | |
27 | ||
28 | /* Get ssize_t. */ | |
29 | #include <sys/types.h> | |
30 | #include <unistd.h> | |
31 | ||
32 | #include <errno.h> | |
33 | ||
34 | #ifdef EINTR | |
35 | # define IS_EINTR(x) ((x) == EINTR) | |
36 | #else | |
37 | # define IS_EINTR(x) 0 | |
38 | #endif | |
39 | ||
40 | #include <limits.h> | |
41 | ||
42 | #ifdef SAFE_WRITE | |
43 | # define safe_rw safe_write | |
44 | # define rw write | |
45 | #else | |
46 | # define safe_rw safe_read | |
47 | # define rw read | |
48 | # undef const | |
49 | # define const /* empty */ | |
50 | #endif | |
51 | ||
52 | /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if | |
53 | interrupted. Return the actual number of bytes read(written), zero for EOF, | |
54 | or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */ | |
55 | size_t | |
56 | safe_rw (int fd, void const *buf, size_t count) | |
57 | { | |
58 | /* Work around a bug in Tru64 5.1. Attempting to read more than | |
59 | INT_MAX bytes fails with errno == EINVAL. See | |
60 | <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>. | |
61 | When decreasing COUNT, keep it block-aligned. */ | |
62 | enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 }; | |
63 | ||
64 | for (;;) | |
65 | { | |
66 | ssize_t result = rw (fd, buf, count); | |
67 | ||
68 | if (0 <= result) | |
1cd4fffc | 69 | return result; |
9b36a80c | 70 | else if (IS_EINTR (errno)) |
1cd4fffc | 71 | continue; |
9b36a80c | 72 | else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count) |
1cd4fffc | 73 | count = BUGGY_READ_MAXIMUM; |
9b36a80c | 74 | else |
1cd4fffc | 75 | return result; |
9b36a80c LC |
76 | } |
77 | } |