1 /*
2 * Copyright (c) 2009 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/types.h>
36 #include <sys/stat.h>
37
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42 #include <errno.h>
43 #include <paths.h>
44 #include <limits.h>
45 #include <fstab.h>
46
47 static void finddevlabel(char **pathp, const char *devname);
48 static int xlatedevpath(char **pathp, struct stat *st);
49 static char *dodequote(char *base);
50
51 /*
52 * Acquire device path.
53 *
54 */
55 char *
getdevpath(const char * devname,int flags)56 getdevpath(const char *devname, int flags)
57 {
58 struct stat st;
59 char *path = NULL;
60 int stgood = 0;
61
62 if (devname[0] == '/' || devname[0] == '.') {
63 asprintf(&path, "%s", devname);
64 } else {
65 asprintf(&path, "/dev/%s", devname);
66 if (lstat(path, &st) < 0) {
67 free(path);
68 path = NULL;
69 finddevlabel(&path, devname);
70 if (path == NULL)
71 asprintf(&path, "%s", devname);
72 } else {
73 stgood = 1;
74 }
75 }
76
77 /*
78 * Translate softlinks if requested. If the lstat() of the
79 * pre-translated path fails NULL is expected to be returned.
80 * lstat() is not called on the post-translated path.
81 */
82 if ((flags & GETDEVPATH_RAWDEV) && path) {
83 if (stgood == 0 && lstat(path, &st) == 0)
84 stgood = 1;
85 if (stgood)
86 stgood = xlatedevpath(&path, &st);
87 if (stgood == 0) {
88 free(path);
89 path = NULL;
90 }
91
92 }
93 if (path == NULL)
94 errno = ENOENT;
95 return(path);
96 }
97
98 static void
finddevlabel(char ** pathp,const char * devname)99 finddevlabel(char **pathp, const char *devname)
100 {
101 const char *prefix = _PATH_DEVTAB_PATHS;
102 const char *ptr1;
103 const char *trailer;
104 char *label;
105 char *ptr2;
106 char *ptr3;
107 char *dtpath;
108 char *bufp;
109 char buf[256];
110 FILE *fp;
111 size_t len; /* directory prefix length */
112 size_t tlen; /* devname length without trailer */
113
114 if ((trailer = strrchr(devname, '.')) != NULL)
115 tlen = trailer - devname;
116 else
117 tlen = 0;
118
119 while (*prefix && *pathp == NULL) {
120 /*
121 * Directory search path
122 */
123 ptr1 = strchr(prefix, ':');
124 len = (ptr1) ? (size_t)(ptr1 - prefix) : strlen(prefix);
125 asprintf(&dtpath, "%*.*s/devtab", (int)len, (int)len, prefix);
126
127 /*
128 * Each devtab file
129 */
130 if ((fp = fopen(dtpath, "r")) != NULL) {
131 while (fgets(buf, sizeof(buf), fp) != NULL) {
132 /*
133 * Extract label field, check degenerate
134 * cases.
135 */
136 label = strtok_r(buf, " \t\r\n", &bufp);
137 if (label == NULL || *label == 0 ||
138 *label == '#') {
139 continue;
140 }
141
142 /*
143 * Match label, with or without the
144 * trailer (aka ".s1a"). The trailer
145 * is tacked on if the match is without
146 * the trailer.
147 */
148 if (strcmp(devname, label) == 0) {
149 trailer = "";
150 } else if (tlen && strlen(label) == tlen &&
151 strncmp(devname, label, tlen) == 0) {
152 trailer = devname + tlen;
153 } else {
154 continue;
155 }
156
157 /*
158 * Match, extract and process remaining fields.
159 */
160 ptr2 = strtok_r(NULL, " \t\r\n", &bufp);
161 ptr3 = strtok_r(NULL, " \t\r\n", &bufp);
162 if (ptr2 == NULL || ptr3 == NULL)
163 continue;
164 if (*ptr2 == 0 || *ptr3 == 0)
165 continue;
166 ptr3 = dodequote(ptr3);
167 if (strcmp(ptr2, "path") == 0) {
168 asprintf(pathp, "%s%s", ptr3, trailer);
169 } else {
170 asprintf(pathp, "/dev/%s/%s%s",
171 ptr2, ptr3, trailer);
172 }
173 break;
174 }
175 fclose(fp);
176 }
177 free(dtpath);
178 prefix += len;
179 if (*prefix == ':')
180 ++prefix;
181 }
182 }
183
184 static int
xlatedevpath(char ** pathp,struct stat * st)185 xlatedevpath(char **pathp, struct stat *st)
186 {
187 char *path;
188 int n;
189 int len;
190
191 /*
192 * If not a softlink return unchanged.
193 */
194 if (!S_ISLNK(st->st_mode))
195 return(1);
196
197 /*
198 * If the softlink isn't reasonable return bad (0)
199 */
200 len = (int)st->st_size;
201 if (len < 0 || len > PATH_MAX)
202 return(0);
203
204 /*
205 * Read the link, return if the result is not what we expected.
206 */
207 path = malloc(len + 1);
208 n = readlink(*pathp, path, len);
209 if (n < 0 || n > len) {
210 free(path);
211 return(0);
212 }
213
214 /*
215 * Success, replace (*pathp).
216 */
217 path[n] = 0;
218 free(*pathp);
219 *pathp = path;
220 return(1);
221 }
222
223 static char *
dodequote(char * base)224 dodequote(char *base)
225 {
226 int len = strlen(base);
227
228 if (len && base[0] == '\"' && base[len-1] == '\"') {
229 base[len - 1] = 0;
230 ++base;
231 }
232 return(base);
233 }
234