/[path-sandbox]/tags/sandbox_1_2_13/canonicalize.c
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Contents of /tags/sandbox_1_2_13/canonicalize.c

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Revision 2 - (show annotations) (download) (as text)
Fri Nov 19 22:03:42 2004 UTC (9 years, 10 months ago) by ferringb
Original Path: trunk/canonicalize.c
File MIME type: text/x-csrc
File size: 4718 byte(s)
Initial revision

1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
19
20 /*
21 * $Header$
22 */
23
24 #include <stdlib.h>
25 #include <string.h>
26 #include <unistd.h>
27 #include <limits.h>
28 #include <sys/param.h>
29 #include <sys/stat.h>
30 #include <errno.h>
31 #include <stddef.h>
32
33 #ifndef __set_errno
34 # define __set_errno(val) errno = (val)
35 #endif
36
37 /* Return the canonical absolute name of file NAME. A canonical name
38 does not contain any `.', `..' components nor any repeated path
39 separators ('/') or symlinks. All path components must exist. If
40 RESOLVED is null, the result is malloc'd; otherwise, if the
41 canonical name is SB_PATH_MAX chars or more, returns null with `errno'
42 set to ENAMETOOLONG; if the name fits in fewer than SB_PATH_MAX chars,
43 returns the name in RESOLVED. If the name cannot be resolved and
44 RESOLVED is non-NULL, it contains the path of the first component
45 that cannot be resolved. If the path can be resolved, RESOLVED
46 holds the same value as the value returned. */
47
48 /* Modified: 19 Aug 2002; Martin Schlemmer <azarah@gentoo.org>
49 *
50 * Cleaned up unneeded stuff, and change so that it will not
51 * resolve symlinks. Also prepended a 'e' to functions that
52 * I did not rip out.
53 *
54 */
55
56 char *
57 erealpath(const char *name, char *resolved)
58 {
59 char *rpath, *dest;
60 const char *start, *end, *rpath_limit;
61 long int path_max;
62
63 if (name == NULL) {
64 /* As per Single Unix Specification V2 we must return an error if
65 either parameter is a null pointer. We extend this to allow
66 the RESOLVED parameter to be NULL in case the we are expected to
67 allocate the room for the return value. */
68 __set_errno(EINVAL);
69 return NULL;
70 }
71
72 if (name[0] == '\0') {
73 /* As per Single Unix Specification V2 we must return an error if
74 the name argument points to an empty string. */
75 __set_errno(ENOENT);
76 return NULL;
77 }
78 #ifdef SB_PATH_MAX
79 path_max = SB_PATH_MAX;
80 #else
81 path_max = pathconf(name, _PC_PATH_MAX);
82 if (path_max <= 0)
83 path_max = 1024;
84 #endif
85
86 if (resolved == NULL) {
87 rpath = malloc(path_max);
88 if (rpath == NULL)
89 return NULL;
90 } else
91 rpath = resolved;
92 rpath_limit = rpath + path_max;
93
94 if (name[0] != '/') {
95 if (!egetcwd(rpath, path_max)) {
96 rpath[0] = '\0';
97 goto error;
98 }
99 dest = strchr(rpath, '\0');
100 } else {
101 rpath[0] = '/';
102 dest = rpath + 1;
103 }
104
105 for (start = end = name; *start; start = end) {
106 /* Skip sequence of multiple path-separators. */
107 while (*start == '/')
108 ++start;
109
110 /* Find end of path component. */
111 for (end = start; *end && *end != '/'; ++end)
112 /* Nothing. */ ;
113
114 if (end - start == 0)
115 break;
116 else if (end - start == 1 && start[0] == '.')
117 /* nothing */ ;
118 else if (end - start == 2 && start[0] == '.' && start[1] == '.') {
119 /* Back up to previous component, ignore if at root already. */
120 if (dest > rpath + 1)
121 while ((--dest)[-1] != '/') ;
122 } else {
123 size_t new_size;
124
125 if (dest[-1] != '/')
126 *dest++ = '/';
127
128 if (dest + (end - start) >= rpath_limit) {
129 ptrdiff_t dest_offset = dest - rpath;
130 char *new_rpath;
131
132 if (resolved) {
133 __set_errno(ENAMETOOLONG);
134 if (dest > rpath + 1)
135 dest--;
136 *dest = '\0';
137 goto error;
138 }
139 new_size = rpath_limit - rpath;
140 if (end - start + 1 > path_max)
141 new_size += end - start + 1;
142 else
143 new_size += path_max;
144 new_rpath = (char *) realloc(rpath, new_size);
145 if (new_rpath == NULL)
146 goto error;
147 rpath = new_rpath;
148 rpath_limit = rpath + new_size;
149
150 dest = rpath + dest_offset;
151 }
152
153 dest = __mempcpy(dest, start, end - start);
154 *dest = '\0';
155 }
156 }
157 #if 1
158 if (dest > rpath + 1 && dest[-1] == '/')
159 --dest;
160 #endif
161 *dest = '\0';
162
163 return resolved ? memcpy(resolved, rpath, dest - rpath + 1) : rpath;
164
165 error:
166 if (resolved)
167 strcpy(resolved, rpath);
168 else
169 free(rpath);
170 return NULL;
171 }
172
173 // vim:expandtab noai:cindent ai

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