cdac23e0d04bb6c707d9ca873085936a9749c54
[project/fstools.git] / libfstools / overlay.c
1 /*
2 * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License version 2.1
6 * as published by the Free Software Foundation
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14 #include <sys/stat.h>
15 #include <sys/types.h>
16 #include <sys/mount.h>
17
18 #include <asm/byteorder.h>
19
20 #include <errno.h>
21 #include <string.h>
22 #include <stdio.h>
23 #include <unistd.h>
24 #include <stdlib.h>
25 #include <glob.h>
26 #include <errno.h>
27 #include <dirent.h>
28 #include <fcntl.h>
29
30 #include "libfstools.h"
31 #include "volume.h"
32
33 #define SWITCH_JFFS2 "/tmp/.switch_jffs2"
34
35 static bool keep_sysupgrade;
36
37 static int
38 handle_rmdir(const char *dir)
39 {
40 struct dirent *dt;
41 struct stat st;
42 DIR *d;
43 int fd;
44
45 d = opendir(dir);
46 if (!d)
47 return -1;
48
49 fd = dirfd(d);
50
51 while ((dt = readdir(d)) != NULL) {
52 if (fstatat(fd, dt->d_name, &st, AT_SYMLINK_NOFOLLOW) || S_ISDIR(st.st_mode))
53 continue;
54
55 if (keep_sysupgrade && !strcmp(dt->d_name, "sysupgrade.tgz"))
56 continue;
57
58 unlinkat(fd, dt->d_name, 0);
59 }
60
61 closedir(d);
62 rmdir(dir);
63
64 return 0;
65 }
66
67 void
68 foreachdir(const char *dir, int (*cb)(const char*))
69 {
70 struct stat s = { 0 };
71 char globdir[256];
72 glob_t gl;
73 int j;
74
75 if (dir[strlen(dir) - 1] == '/')
76 snprintf(globdir, 256, "%s*", dir);
77 else
78 snprintf(globdir, 256, "%s/*", dir); /**/
79
80 if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
81 for (j = 0; j < gl.gl_pathc; j++) {
82 char *dir = gl.gl_pathv[j];
83 int len = strlen(gl.gl_pathv[j]);
84
85 if (len > 1 && dir[len - 1] == '/')
86 dir[len - 1] = '\0';
87
88 if (!lstat(gl.gl_pathv[j], &s) && !S_ISLNK(s.st_mode))
89 foreachdir(gl.gl_pathv[j], cb);
90 }
91 cb(dir);
92 }
93
94 void
95 overlay_delete(const char *dir, bool _keep_sysupgrade)
96 {
97 keep_sysupgrade = _keep_sysupgrade;
98 foreachdir(dir, handle_rmdir);
99 }
100
101 static int
102 overlay_mount(struct volume *v, char *fs)
103 {
104 if (mkdir("/tmp/overlay", 0755)) {
105 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
106 return -1;
107 }
108
109 if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
110 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
111 return -1;
112 }
113
114 return volume_init(v);
115 }
116
117 static int
118 switch2jffs(struct volume *v)
119 {
120 struct stat s;
121 int ret;
122
123 if (!stat(SWITCH_JFFS2, &s)) {
124 ULOG_ERR("jffs2 switch already running\n");
125 return -1;
126 }
127
128 creat("/tmp/.switch_jffs2", 0600);
129 ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
130 unlink("/tmp/.switch_jffs2");
131 if (ret) {
132 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
133 return -1;
134 }
135
136 if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
137 ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
138 return -1;
139 }
140
141 if (system("cp -a /tmp/root/* /rom/overlay")) {
142 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
143 return -1;
144 }
145
146 if (pivot("/rom", "/mnt")) {
147 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
148 return -1;
149 }
150
151 if (mount_move("/mnt", "/tmp/root", "")) {
152 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
153 return -1;
154 }
155
156 return fopivot("/overlay", "/rom");
157 }
158
159 int
160 handle_whiteout(const char *dir)
161 {
162 struct stat s;
163 char link[256];
164 ssize_t sz;
165 struct dirent **namelist;
166 int n;
167
168 n = scandir(dir, &namelist, NULL, NULL);
169
170 if (n < 1)
171 return -1;
172
173 while (n--) {
174 char file[256];
175
176 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
177 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
178 sz = readlink(file, link, sizeof(link) - 1);
179 if (sz > 0) {
180 char *orig;
181
182 link[sz] = '\0';
183 orig = strstr(&file[1], "/");
184 if (orig && !strcmp(link, "(overlay-whiteout)"))
185 unlink(orig);
186 }
187 }
188 free(namelist[n]);
189 }
190 free(namelist);
191
192 return 0;
193 }
194
195 int
196 jffs2_switch(struct volume *v)
197 {
198 char *mp;
199 int ret = -1;
200
201 if (find_overlay_mount("overlayfs:/tmp/root"))
202 return -1;
203
204 if (find_filesystem("overlay")) {
205 ULOG_ERR("overlayfs not supported by kernel\n");
206 return ret;
207 }
208
209 mp = find_mount_point(v->blk, 0);
210 if (mp) {
211 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
212 return -1;
213 }
214
215 switch (volume_identify(v)) {
216 case FS_NONE:
217 ULOG_ERR("no jffs2 marker found\n");
218 /* fall through */
219
220 case FS_DEADCODE:
221 ret = switch2jffs(v);
222 if (!ret) {
223 ULOG_INFO("performing overlay whiteout\n");
224 umount2("/tmp/root", MNT_DETACH);
225 foreachdir("/overlay/", handle_whiteout);
226 }
227 break;
228
229 case FS_JFFS2:
230 ret = overlay_mount(v, "jffs2");
231 if (ret)
232 break;
233 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
234 ULOG_ERR("switching to jffs2 failed\n");
235 ret = -1;
236 }
237 break;
238
239 case FS_UBIFS:
240 ret = overlay_mount(v, "ubifs");
241 if (ret)
242 break;
243 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
244 ULOG_ERR("switching to ubifs failed\n");
245 ret = -1;
246 }
247 break;
248 }
249
250 if (ret)
251 return ret;
252
253 sync();
254 fs_state_set("/overlay", FS_STATE_READY);
255 return 0;
256 }
257
258 static int overlay_mount_fs(struct volume *v)
259 {
260 char *fstype;
261
262 if (mkdir("/tmp/overlay", 0755)) {
263 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
264 return -1;
265 }
266
267 fstype = "jffs2";
268
269 switch (volume_identify(v)) {
270 case FS_UBIFS:
271 fstype = "ubifs";
272 break;
273 }
274
275 volume_init(v);
276
277 if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
278 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
279 fstype, v->blk, strerror(errno));
280 return -1;
281 }
282
283 return -1;
284 }
285
286 enum fs_state fs_state_get(const char *dir)
287 {
288 char *path;
289 char valstr[16];
290 uint32_t val;
291 ssize_t len;
292
293 path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
294 sprintf(path, "%s/.fs_state", dir);
295 len = readlink(path, valstr, sizeof(valstr) - 1);
296 if (len < 0)
297 return FS_STATE_UNKNOWN;
298
299 valstr[len] = 0;
300 val = atoi(valstr);
301
302 if (val > __FS_STATE_LAST)
303 return FS_STATE_UNKNOWN;
304
305 return val;
306 }
307
308
309 int fs_state_set(const char *dir, enum fs_state state)
310 {
311 char valstr[16];
312 char *path;
313
314 if (fs_state_get(dir) == state)
315 return 0;
316
317 path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
318 sprintf(path, "%s/.fs_state", dir);
319 unlink(path);
320 snprintf(valstr, sizeof(valstr), "%d", state);
321
322 return symlink(valstr, path);
323 }
324
325
326 int mount_overlay(struct volume *v)
327 {
328 char *mp;
329
330 if (!v)
331 return -1;
332
333 mp = find_mount_point(v->blk, 0);
334 if (mp) {
335 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
336 return -1;
337 }
338
339 overlay_mount_fs(v);
340
341 extroot_prefix = "/tmp/overlay";
342 if (!mount_extroot()) {
343 ULOG_INFO("switched to extroot\n");
344 return 0;
345 }
346
347 switch(fs_state_get("/tmp/overlay")) {
348 case FS_STATE_UNKNOWN:
349 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
350 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
351 ULOG_ERR("unable to set filesystem state\n");
352 break;
353 }
354 case FS_STATE_PENDING:
355 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
356 overlay_delete("/tmp/overlay", true);
357 break;
358 case FS_STATE_READY:
359 break;
360 }
361
362 ULOG_INFO("switching to jffs2 overlay\n");
363 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
364 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
365 return ramoverlay();
366 }
367
368 return -1;
369 }