Mercurial > hg > octave-nkf > gnulib-hg

annotate lib/areadlink.c @ 9268:a553c18c572d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Rename sys_time_.h to sys_time.in.h.
author Bruno Haible <bruno@clisp.org>
date Tue, 02 Oct 2007 00:37:40 +0200
parents 71cb1dd07dcd
children bbbbbf4cd1c5
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
9217
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
1 /* areadlink.c -- readlink wrapper to return the link name in malloc'd storage
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
2 Unlike xreadlink and xreadlink_with_size, don't ever call exit.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
3
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
4 Copyright (C) 2001, 2003-2007 Free Software Foundation, Inc.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
5
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
6 This program is free software; you can redistribute it and/or modify
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
7 it under the terms of the GNU General Public License as published by
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
8 the Free Software Foundation; either version 2, or (at your option)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
9 any later version.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
10
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
11 This program is distributed in the hope that it will be useful,
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
14 GNU General Public License for more details.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
15
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
16 You should have received a copy of the GNU General Public License
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
17 along with this program; see the file COPYING.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
18 If not, write to the Free Software Foundation,
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
19 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
20
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
21 /* Written by Jim Meyering <jim@meyering.net>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
22 and Bruno Haible <bruno@clisp.org>. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
23
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
24 #include <config.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
25
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
26 /* Specification. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
27 #include "areadlink.h"
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
28
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
29 #include <string.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
30 #include <errno.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
31 #include <limits.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
32 #include <sys/types.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
33 #include <stdlib.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
34 #include <unistd.h>
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
35
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
36 #ifndef SIZE_MAX
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
37 # define SIZE_MAX ((size_t) -1)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
38 #endif
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
39 #ifndef SSIZE_MAX
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
40 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
41 #endif
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
42
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
43 /* Call readlink to get the symbolic link value of FILENAME.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
44 Return a pointer to that NUL-terminated string in malloc'd storage.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
45 If readlink fails, return NULL and set errno.
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
46 If realloc fails, or if the link value is longer than SIZE_MAX :-),
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
47 return NULL and set errno to ENOMEM. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
48
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
49 char *
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
50 areadlink (char const *filename)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
51 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
52 /* The initial buffer size for the link value. A power of 2
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
53 detects arithmetic overflow earlier, but is not required. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
54 #define INITIAL_BUF_SIZE 1024
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
55
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
56 /* Allocate the initial buffer on the stack. This way, in the common
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
57 case of a symlink of small size, we get away with a single small malloc()
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
58 instead of a big malloc() followed by a shrinking realloc(). */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
59 char initial_buf[INITIAL_BUF_SIZE];
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
60
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
61 char *buffer = initial_buf;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
62 size_t buf_size = sizeof (initial_buf);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
63
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
64 while (1)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
65 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
66 /* Attempt to read the link into the current buffer. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
67 ssize_t link_length = readlink (filename, buffer, buf_size);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
68
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
69 /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
70 with errno == ERANGE if the buffer is too small. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
71 if (link_length < 0 && errno != ERANGE)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
72 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
73 if (buffer != initial_buf)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
74 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
75 int saved_errno = errno;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
76 free (buffer);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
77 errno = saved_errno;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
78 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
79 return NULL;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
80 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
81
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
82 if ((size_t) link_length < buf_size)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
83 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
84 buffer[link_length++] = '\0';
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
85
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
86 /* Return it in a chunk of memory as small as possible. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
87 if (buffer == initial_buf)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
88 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
89 buffer = (char *) malloc (link_length);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
90 if (buffer == NULL)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
91 /* errno is ENOMEM. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
92 return NULL;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
93 memcpy (buffer, initial_buf, link_length);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
94 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
95 else
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
96 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
97 /* Shrink buffer before returning it. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
98 if ((size_t) link_length < buf_size)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
99 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
100 char *smaller_buffer = (char *) realloc (buffer, link_length);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
101
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
102 if (smaller_buffer != NULL)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
103 buffer = smaller_buffer;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
104 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
105 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
106 return buffer;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
107 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
108
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
109 if (buffer != initial_buf)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
110 free (buffer);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
111 buf_size *= 2;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
112 if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
113 {
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
114 errno = ENOMEM;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
115 return NULL;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
116 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
117 buffer = (char *) malloc (buf_size);
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
118 if (buffer == NULL)
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
119 /* errno is ENOMEM. */
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
120 return NULL;
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
121 }
71cb1dd07dcd New module 'areadlink'. File based on lib/xreadlink.c.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
122 }