1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
/* $OpenBSD: realpath.c,v 1.18 2014/10/19 03:56:28 doug Exp $ */
/*
* Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* A slightly modified copy of this file exists in libexec/ld.so */
/*
* char *realpath(const char *path, char resolved[PATH_MAX]);
*
* Find the real name of path, by removing all ".", ".." and symlink
* components. Returns (resolved) on success, or (NULL) on failure,
* in which case the path which caused trouble is left in (resolved).
*/
char *
realpath(const char *path, char *resolved)
{
struct stat sb;
char *p, *q, *s;
size_t left_len, resolved_len;
unsigned symlinks;
int serrno, slen, mem_allocated;
char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
if (path[0] == '\0') {
errno = ENOENT;
return (NULL);
}
serrno = errno;
if (resolved == NULL) {
resolved = malloc(PATH_MAX);
if (resolved == NULL)
return (NULL);
mem_allocated = 1;
} else
mem_allocated = 0;
symlinks = 0;
if (path[0] == '/') {
resolved[0] = '/';
resolved[1] = '\0';
if (path[1] == '\0')
return (resolved);
resolved_len = 1;
left_len = strlcpy(left, path + 1, sizeof(left));
} else {
if (getcwd(resolved, PATH_MAX) == NULL) {
if (mem_allocated)
free(resolved);
else
strlcpy(resolved, ".", PATH_MAX);
return (NULL);
}
resolved_len = strlen(resolved);
left_len = strlcpy(left, path, sizeof(left));
}
if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
errno = ENAMETOOLONG;
goto err;
}
/*
* Iterate over path components in `left'.
*/
while (left_len != 0) {
/*
* Extract the next path component and adjust `left'
* and its length.
*/
p = strchr(left, '/');
s = p ? p : left + left_len;
if (s - left >= sizeof(next_token)) {
errno = ENAMETOOLONG;
goto err;
}
memcpy(next_token, left, s - left);
next_token[s - left] = '\0';
left_len -= s - left;
if (p != NULL)
memmove(left, s + 1, left_len + 1);
if (resolved[resolved_len - 1] != '/') {
if (resolved_len + 1 >= PATH_MAX) {
errno = ENAMETOOLONG;
goto err;
}
resolved[resolved_len++] = '/';
resolved[resolved_len] = '\0';
}
if (next_token[0] == '\0')
continue;
else if (strcmp(next_token, ".") == 0)
continue;
else if (strcmp(next_token, "..") == 0) {
/*
* Strip the last path component except when we have
* single "/"
*/
if (resolved_len > 1) {
resolved[resolved_len - 1] = '\0';
q = strrchr(resolved, '/') + 1;
*q = '\0';
resolved_len = q - resolved;
}
continue;
}
/*
* Append the next path component and lstat() it. If
* lstat() fails we still can return successfully if
* there are no more path components left.
*/
resolved_len = strlcat(resolved, next_token, PATH_MAX);
if (resolved_len >= PATH_MAX) {
errno = ENAMETOOLONG;
goto err;
}
if (lstat(resolved, &sb) != 0) {
if (errno == ENOENT && p == NULL) {
errno = serrno;
return (resolved);
}
goto err;
}
if (S_ISLNK(sb.st_mode)) {
if (symlinks++ > MAXSYMLINKS) {
errno = ELOOP;
goto err;
}
slen = readlink(resolved, symlink, sizeof(symlink) - 1);
if (slen < 0)
goto err;
symlink[slen] = '\0';
if (symlink[0] == '/') {
resolved[1] = 0;
resolved_len = 1;
} else if (resolved_len > 1) {
/* Strip the last path component. */
resolved[resolved_len - 1] = '\0';
q = strrchr(resolved, '/') + 1;
*q = '\0';
resolved_len = q - resolved;
}
/*
* If there are any path components left, then
* append them to symlink. The result is placed
* in `left'.
*/
if (p != NULL) {
if (symlink[slen - 1] != '/') {
if (slen + 1 >= sizeof(symlink)) {
errno = ENAMETOOLONG;
goto err;
}
symlink[slen] = '/';
symlink[slen + 1] = 0;
}
left_len = strlcat(symlink, left, sizeof(symlink));
if (left_len >= sizeof(left)) {
errno = ENAMETOOLONG;
goto err;
}
}
left_len = strlcpy(left, symlink, sizeof(left));
}
}
/*
* Remove trailing slash except when the resolved pathname
* is a single "/".
*/
if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
resolved[resolved_len - 1] = '\0';
return (resolved);
err:
if (mem_allocated)
free(resolved);
return (NULL);
}
|
