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9b36a80c LC |
1 | /* An interface to read and write that retries (if necessary) until complete. |
2 | ||
f0007cad | 3 | Copyright (C) 1993-1994, 1997-2006, 2009-2012 Free Software Foundation, Inc. |
9b36a80c LC |
4 | |
5 | This program is free software: you can redistribute it and/or modify | |
6 | it under the terms of the GNU Lesser General Public License as published by | |
7 | the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public License | |
16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
17 | ||
18 | #include <config.h> | |
19 | ||
20 | /* Specification. */ | |
21 | #ifdef FULL_READ | |
22 | # include "full-read.h" | |
23 | #else | |
24 | # include "full-write.h" | |
25 | #endif | |
26 | ||
27 | #include <errno.h> | |
28 | ||
29 | #ifdef FULL_READ | |
30 | # include "safe-read.h" | |
31 | # define safe_rw safe_read | |
32 | # define full_rw full_read | |
33 | # undef const | |
34 | # define const /* empty */ | |
35 | #else | |
36 | # include "safe-write.h" | |
37 | # define safe_rw safe_write | |
38 | # define full_rw full_write | |
39 | #endif | |
40 | ||
41 | #ifdef FULL_READ | |
42 | /* Set errno to zero upon EOF. */ | |
43 | # define ZERO_BYTE_TRANSFER_ERRNO 0 | |
44 | #else | |
45 | /* Some buggy drivers return 0 when one tries to write beyond | |
46 | a device's end. (Example: Linux 1.2.13 on /dev/fd0.) | |
47 | Set errno to ENOSPC so they get a sensible diagnostic. */ | |
48 | # define ZERO_BYTE_TRANSFER_ERRNO ENOSPC | |
49 | #endif | |
50 | ||
51 | /* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if | |
52 | interrupted or if a partial write(read) occurs. Return the number | |
53 | of bytes transferred. | |
54 | When writing, set errno if fewer than COUNT bytes are written. | |
55 | When reading, if fewer than COUNT bytes are read, you must examine | |
56 | errno to distinguish failure from EOF (errno == 0). */ | |
57 | size_t | |
58 | full_rw (int fd, const void *buf, size_t count) | |
59 | { | |
60 | size_t total = 0; | |
61 | const char *ptr = (const char *) buf; | |
62 | ||
63 | while (count > 0) | |
64 | { | |
65 | size_t n_rw = safe_rw (fd, ptr, count); | |
66 | if (n_rw == (size_t) -1) | |
1cd4fffc | 67 | break; |
9b36a80c | 68 | if (n_rw == 0) |
1cd4fffc LC |
69 | { |
70 | errno = ZERO_BYTE_TRANSFER_ERRNO; | |
71 | break; | |
72 | } | |
9b36a80c LC |
73 | total += n_rw; |
74 | ptr += n_rw; | |
75 | count -= n_rw; | |
76 | } | |
77 | ||
78 | return total; | |
79 | } |