|
0
|
1 /*
|
|
|
2 * realpath.c -- canonicalize pathname by removing symlinks
|
|
|
3 * Copyright (C) 1993 Rick Sladkey <jrs@world.std.com>
|
|
|
4 *
|
|
|
5
|
|
|
6 This file is part of XEmacs.
|
|
|
7
|
|
|
8 XEmacs is free software; you can redistribute it and/or modify it
|
|
|
9 under the terms of the GNU General Public License as published by the
|
|
|
10 Free Software Foundation; either version 2, or (at your option) any
|
|
|
11 later version.
|
|
|
12
|
|
|
13 XEmacs is distributed in the hope that it will be useful, but WITHOUT
|
|
|
14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
|
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
|
16 for more details.
|
|
|
17
|
|
|
18 You should have received a copy of the GNU General Public License
|
|
|
19 along with XEmacs; see the file COPYING. If not, write to
|
|
|
20 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
|
21 Boston, MA 02111-1307, USA. */
|
|
|
22
|
|
|
23 /* Synched up with: Not in FSF. */
|
|
|
24
|
|
|
25 #ifdef HAVE_CONFIG_H
|
|
|
26 #include <config.h>
|
|
|
27 #endif
|
|
|
28
|
|
|
29 #include <sys/types.h>
|
|
|
30 #if defined(HAVE_UNISTD_H) || defined(STDC_HEADERS)
|
|
|
31 #include <unistd.h>
|
|
|
32 #endif
|
|
|
33 #include <stdio.h>
|
|
|
34 #include <string.h>
|
|
|
35 #ifdef _POSIX_VERSION
|
|
|
36 #include <limits.h> /* for PATH_MAX */
|
|
|
37 #else
|
|
|
38 #include <sys/param.h> /* for MAXPATHLEN */
|
|
|
39 #endif
|
|
|
40 #include <errno.h>
|
|
|
41 #ifndef STDC_HEADERS
|
|
|
42 extern int errno;
|
|
|
43 #endif
|
|
|
44
|
|
|
45 #include <sys/stat.h> /* for S_IFLNK */
|
|
|
46
|
|
|
47 #ifndef PATH_MAX
|
|
|
48 #ifdef _POSIX_VERSION
|
|
|
49 #define PATH_MAX _POSIX_PATH_MAX
|
|
|
50 #else
|
|
|
51 #ifdef MAXPATHLEN
|
|
|
52 #define PATH_MAX MAXPATHLEN
|
|
|
53 #else
|
|
|
54 #define PATH_MAX 1024
|
|
|
55 #endif
|
|
|
56 #endif
|
|
|
57 #endif
|
|
|
58
|
|
|
59 #define MAX_READLINKS 32
|
|
|
60
|
|
|
61 #ifdef __STDC__
|
|
|
62 char *realpath(const char *path, char resolved_path [])
|
|
|
63 #else
|
|
|
64 char *realpath(path, resolved_path)
|
|
|
65 const char *path;
|
|
|
66 char resolved_path [];
|
|
|
67 #endif
|
|
|
68 {
|
|
|
69 char copy_path[PATH_MAX];
|
|
|
70 char link_path[PATH_MAX];
|
|
|
71 char *new_path = resolved_path;
|
|
|
72 char *max_path;
|
|
|
73 int readlinks = 0;
|
|
|
74 int n;
|
|
|
75
|
|
|
76 /* Make a copy of the source path since we may need to modify it. */
|
|
|
77 strcpy(copy_path, path);
|
|
|
78 path = copy_path;
|
|
|
79 max_path = copy_path + PATH_MAX - 2;
|
|
|
80 /* If it's a relative pathname use getwd for starters. */
|
|
|
81 if (*path != '/')
|
|
|
82 {
|
|
|
83 #ifdef HAVE_GETCWD
|
|
|
84 getcwd(new_path, PATH_MAX - 1);
|
|
|
85 #else
|
|
|
86 getwd(new_path);
|
|
|
87 #endif
|
|
|
88 new_path += strlen(new_path);
|
|
|
89 if (new_path[-1] != '/')
|
|
|
90 *new_path++ = '/';
|
|
|
91 }
|
|
|
92 else
|
|
|
93 {
|
|
|
94 *new_path++ = '/';
|
|
|
95 path++;
|
|
|
96 }
|
|
|
97
|
|
|
98 /* Expand each slash-separated pathname component. */
|
|
|
99 while (*path != '\0')
|
|
|
100 {
|
|
|
101 /* Ignore stray "/". */
|
|
|
102 if (*path == '/')
|
|
|
103 {
|
|
|
104 path++;
|
|
|
105 continue;
|
|
|
106 }
|
|
|
107
|
|
|
108 if (*path == '.')
|
|
|
109 {
|
|
|
110 /* Ignore ".". */
|
|
|
111 if (path[1] == '\0' || path[1] == '/')
|
|
|
112 {
|
|
|
113 path++;
|
|
|
114 continue;
|
|
|
115 }
|
|
|
116
|
|
|
117 if (path[1] == '.')
|
|
|
118 {
|
|
|
119 if (path[2] == '\0' || path[2] == '/')
|
|
|
120 {
|
|
|
121 path += 2;
|
|
|
122
|
|
|
123 /* Ignore ".." at root. */
|
|
|
124 if (new_path == resolved_path + 1)
|
|
|
125 continue;
|
|
|
126
|
|
|
127 /* Handle ".." by backing up. */
|
|
|
128 while ((--new_path)[-1] != '/')
|
|
|
129 ;
|
|
|
130 continue;
|
|
|
131 }
|
|
|
132 }
|
|
|
133 }
|
|
|
134
|
|
|
135 /* Safely copy the next pathname component. */
|
|
|
136 while (*path != '\0' && *path != '/')
|
|
|
137 {
|
|
|
138 if (path > max_path)
|
|
|
139 {
|
|
|
140 errno = ENAMETOOLONG;
|
|
|
141 return NULL;
|
|
|
142 }
|
|
|
143 *new_path++ = *path++;
|
|
|
144 }
|
|
|
145
|
|
|
146 #ifdef S_IFLNK
|
|
|
147 /* See if latest pathname component is a symlink. */
|
|
|
148 *new_path = '\0';
|
|
|
149 n = readlink(resolved_path, link_path, PATH_MAX - 1);
|
|
|
150
|
|
|
151 if (n < 0)
|
|
|
152 {
|
|
|
153 /* EINVAL means the file exists but isn't a symlink. */
|
|
|
154 if (errno != EINVAL)
|
|
|
155 return NULL;
|
|
|
156 }
|
|
|
157 else
|
|
|
158 {
|
|
|
159 /* Protect against infinite loops. */
|
|
|
160 if (readlinks++ > MAX_READLINKS)
|
|
|
161 {
|
|
|
162 errno = ELOOP;
|
|
|
163 return NULL;
|
|
|
164 }
|
|
|
165
|
|
|
166 /* Note: readlink doesn't add the null byte. */
|
|
|
167 link_path[n] = '\0';
|
|
|
168
|
|
|
169 if (*link_path == '/')
|
|
|
170 /* Start over for an absolute symlink. */
|
|
|
171 new_path = resolved_path;
|
|
|
172 else
|
|
|
173 /* Otherwise back up over this component. */
|
|
|
174 while (*(--new_path) != '/')
|
|
|
175 ;
|
|
|
176
|
|
|
177 /* Safe sex check. */
|
|
|
178 if (strlen(path) + n >= PATH_MAX)
|
|
|
179 {
|
|
|
180 errno = ENAMETOOLONG;
|
|
|
181 return NULL;
|
|
|
182 }
|
|
|
183
|
|
|
184 /* Insert symlink contents into path. */
|
|
|
185 strcat(link_path, path);
|
|
|
186 strcpy(copy_path, link_path);
|
|
|
187 path = copy_path;
|
|
|
188 }
|
|
|
189 #endif /* S_IFLNK */
|
|
|
190 *new_path++ = '/';
|
|
|
191 }
|
|
|
192
|
|
|
193 /* Delete trailing slash but don't whomp a lone slash. */
|
|
|
194 if (new_path != resolved_path + 1 && new_path[-1] == '/')
|
|
|
195 new_path--;
|
|
|
196
|
|
|
197 /* Make sure it's null terminated. */
|
|
|
198 *new_path = '\0';
|
|
|
199 return resolved_path;
|
|
|
200 }
|
