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9b36a80c LC |
1 | /* An interface to read and write that retries (if necessary) until complete. |
2 | ||
3 | Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002, 2003, | |
4 | 2004, 2005, 2006 Free Software Foundation, Inc. | |
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 FULL_READ | |
23 | # include "full-read.h" | |
24 | #else | |
25 | # include "full-write.h" | |
26 | #endif | |
27 | ||
28 | #include <errno.h> | |
29 | ||
30 | #ifdef FULL_READ | |
31 | # include "safe-read.h" | |
32 | # define safe_rw safe_read | |
33 | # define full_rw full_read | |
34 | # undef const | |
35 | # define const /* empty */ | |
36 | #else | |
37 | # include "safe-write.h" | |
38 | # define safe_rw safe_write | |
39 | # define full_rw full_write | |
40 | #endif | |
41 | ||
42 | #ifdef FULL_READ | |
43 | /* Set errno to zero upon EOF. */ | |
44 | # define ZERO_BYTE_TRANSFER_ERRNO 0 | |
45 | #else | |
46 | /* Some buggy drivers return 0 when one tries to write beyond | |
47 | a device's end. (Example: Linux 1.2.13 on /dev/fd0.) | |
48 | Set errno to ENOSPC so they get a sensible diagnostic. */ | |
49 | # define ZERO_BYTE_TRANSFER_ERRNO ENOSPC | |
50 | #endif | |
51 | ||
52 | /* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if | |
53 | interrupted or if a partial write(read) occurs. Return the number | |
54 | of bytes transferred. | |
55 | When writing, set errno if fewer than COUNT bytes are written. | |
56 | When reading, if fewer than COUNT bytes are read, you must examine | |
57 | errno to distinguish failure from EOF (errno == 0). */ | |
58 | size_t | |
59 | full_rw (int fd, const void *buf, size_t count) | |
60 | { | |
61 | size_t total = 0; | |
62 | const char *ptr = (const char *) buf; | |
63 | ||
64 | while (count > 0) | |
65 | { | |
66 | size_t n_rw = safe_rw (fd, ptr, count); | |
67 | if (n_rw == (size_t) -1) | |
68 | break; | |
69 | if (n_rw == 0) | |
70 | { | |
71 | errno = ZERO_BYTE_TRANSFER_ERRNO; | |
72 | break; | |
73 | } | |
74 | total += n_rw; | |
75 | ptr += n_rw; | |
76 | count -= n_rw; | |
77 | } | |
78 | ||
79 | return total; | |
80 | } |