summaryrefslogtreecommitdiffstats
path: root/lib/full-write.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/full-write.c')
-rw-r--r--lib/full-write.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/lib/full-write.c b/lib/full-write.c
new file mode 100644
index 0000000..1513705
--- /dev/null
+++ b/lib/full-write.c
@@ -0,0 +1,85 @@
1/* An interface to read and write that retries (if necessary) until complete.
2
3 Copyright (C) 1993, 1994, 1997-2003 Free Software Foundation, Inc.
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
8 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 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
18
19#if HAVE_CONFIG_H
20# include <config.h>
21#endif
22
23/* Specification. */
24#ifdef FULL_READ
25# include "full-read.h"
26#else
27# include "full-write.h"
28#endif
29
30#include <errno.h>
31#ifndef errno
32extern int errno;
33#endif
34
35#ifdef FULL_READ
36# include "safe-read.h"
37# define safe_rw safe_read
38# define full_rw full_read
39# undef const
40# define const /* empty */
41#else
42# include "safe-write.h"
43# define safe_rw safe_write
44# define full_rw full_write
45#endif
46
47#ifdef FULL_READ
48/* Set errno to zero upon EOF. */
49# define ZERO_BYTE_TRANSFER_ERRNO 0
50#else
51/* Some buggy drivers return 0 when one tries to write beyond
52 a device's end. (Example: Linux 1.2.13 on /dev/fd0.)
53 Set errno to ENOSPC so they get a sensible diagnostic. */
54# define ZERO_BYTE_TRANSFER_ERRNO ENOSPC
55#endif
56
57/* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if
58 interrupted or if a partial write(read) occurs. Return the number
59 of bytes transferred.
60 When writing, set errno if fewer than COUNT bytes are written.
61 When reading, if fewer than COUNT bytes are read, you must examine
62 errno to distinguish failure from EOF (errno == 0). */
63size_t
64full_rw (int fd, const void *buf, size_t count)
65{
66 size_t total = 0;
67 const char *ptr = buf;
68
69 while (count > 0)
70 {
71 size_t n_rw = safe_rw (fd, ptr, count);
72 if (n_rw == (size_t) -1)
73 break;
74 if (n_rw == 0)
75 {
76 errno = ZERO_BYTE_TRANSFER_ERRNO;
77 break;
78 }
79 total += n_rw;
80 ptr += n_rw;
81 count -= n_rw;
82 }
83
84 return total;
85}