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         char globdir[256];
  71         glob_t gl;
  72         int j;
  73
  74         if (dir[strlen(dir) - 1] == '/')
  75                 snprintf(globdir, 256, "%s*", dir);
  76         else
  77                 snprintf(globdir, 256, "%s/*", dir); /**/
  78
  79         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  80                 for (j = 0; j < gl.gl_pathc; j++)
  81                         foreachdir(gl.gl_pathv[j], cb);
  82
  83         cb(dir);
  84 }
  85
  86 void
  87 overlay_delete(const char *dir, bool _keep_sysupgrade)
  88 {
  89         keep_sysupgrade = _keep_sysupgrade;
  90         foreachdir(dir, handle_rmdir);
  91 }
  92
  93 static int
  94 overlay_mount(struct volume *v, char *fs)
  95 {
  96         if (mkdir("/tmp/overlay", 0755)) {
  97                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
  98                 return -1;
  99         }
 100
 101         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 102                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
 103                 return -1;
 104         }
 105
 106         return volume_init(v);
 107 }
 108
 109 static int
 110 switch2jffs(struct volume *v)
 111 {
 112         struct stat s;
 113         int ret;
 114
 115         if (!stat(SWITCH_JFFS2, &s)) {
 116                 ULOG_ERR("jffs2 switch already running\n");
 117                 return -1;
 118         }
 119
 120         creat("/tmp/.switch_jffs2", 0600);
 121         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 122         unlink("/tmp/.switch_jffs2");
 123         if (ret) {
 124                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
 125                 return -1;
 126         }
 127
 128         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 129                 ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
 130                 return -1;
 131         }
 132
 133         if (system("cp -a /tmp/root/* /rom/overlay")) {
 134                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
 135                 return -1;
 136         }
 137
 138         if (pivot("/rom", "/mnt")) {
 139                 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
 140                 return -1;
 141         }
 142
 143         if (mount_move("/mnt", "/tmp/root", "")) {
 144                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 145                 return -1;
 146         }
 147
 148         return fopivot("/overlay", "/rom");
 149 }
 150
 151 int
 152 handle_whiteout(const char *dir)
 153 {
 154         struct stat s;
 155         char link[256];
 156         ssize_t sz;
 157         struct dirent **namelist;
 158         int n;
 159
 160         n = scandir(dir, &namelist, NULL, NULL);
 161
 162         if (n < 1)
 163                 return -1;
 164
 165         while (n--) {
 166                 char file[256];
 167
 168                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 169                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 170                         sz = readlink(file, link, sizeof(link) - 1);
 171                         if (sz > 0) {
 172                                 char *orig;
 173
 174                                 link[sz] = '\0';
 175                                 orig = strstr(&file[1], "/");
 176                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 177                                         unlink(orig);
 178                         }
 179                 }
 180                 free(namelist[n]);
 181         }
 182         free(namelist);
 183
 184         return 0;
 185 }
 186
 187 int
 188 jffs2_switch(struct volume *v)
 189 {
 190         char *mp;
 191         int ret = -1;
 192
 193         if (find_overlay_mount("overlayfs:/tmp/root"))
 194                 return -1;
 195
 196         if (find_filesystem("overlay")) {
 197                 ULOG_ERR("overlayfs not supported by kernel\n");
 198                 return ret;
 199         }
 200
 201         mp = find_mount_point(v->blk, 0);
 202         if (mp) {
 203                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 204                 return -1;
 205         }
 206
 207         switch (volume_identify(v)) {
 208         case FS_NONE:
 209                 ULOG_ERR("no jffs2 marker found\n");
 210                 /* fall through */
 211
 212         case FS_DEADCODE:
 213                 ret = switch2jffs(v);
 214                 if (!ret) {
 215                         ULOG_INFO("performing overlay whiteout\n");
 216                         umount2("/tmp/root", MNT_DETACH);
 217                         foreachdir("/overlay/", handle_whiteout);
 218                 }
 219                 break;
 220
 221         case FS_JFFS2:
 222                 ret = overlay_mount(v, "jffs2");
 223                 if (ret)
 224                         break;
 225                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 226                         ULOG_ERR("switching to jffs2 failed\n");
 227                         ret = -1;
 228                 }
 229                 break;
 230
 231         case FS_UBIFS:
 232                 ret = overlay_mount(v, "ubifs");
 233                 if (ret)
 234                         break;
 235                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 236                         ULOG_ERR("switching to ubifs failed\n");
 237                         ret = -1;
 238                 }
 239                 break;
 240         }
 241
 242         if (ret)
 243                 return ret;
 244
 245         sync();
 246         fs_state_set("/overlay", FS_STATE_READY);
 247         return 0;
 248 }
 249
 250 static int overlay_mount_fs(struct volume *v)
 251 {
 252         char *fstype;
 253
 254         if (mkdir("/tmp/overlay", 0755)) {
 255                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 256                 return -1;
 257         }
 258
 259         fstype = "jffs2";
 260
 261         switch (volume_identify(v)) {
 262         case FS_UBIFS:
 263                 fstype = "ubifs";
 264                 break;
 265         }
 266
 267         volume_init(v);
 268
 269         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 270                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 271                          fstype, v->blk, strerror(errno));
 272                 return -1;
 273         }
 274
 275         return -1;
 276 }
 277
 278 enum fs_state fs_state_get(const char *dir)
 279 {
 280         char *path;
 281         char valstr[16];
 282         uint32_t val;
 283         ssize_t len;
 284
 285         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 286         sprintf(path, "%s/.fs_state", dir);
 287         len = readlink(path, valstr, sizeof(valstr) - 1);
 288         if (len < 0)
 289                 return FS_STATE_UNKNOWN;
 290
 291         valstr[len] = 0;
 292         val = atoi(valstr);
 293
 294         if (val > __FS_STATE_LAST)
 295                 return FS_STATE_UNKNOWN;
 296
 297         return val;
 298 }
 299
 300
 301 int fs_state_set(const char *dir, enum fs_state state)
 302 {
 303         char valstr[16];
 304         char *path;
 305
 306         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 307         sprintf(path, "%s/.fs_state", dir);
 308         unlink(path);
 309         snprintf(valstr, sizeof(valstr), "%d", state);
 310
 311         return symlink(valstr, path);
 312 }
 313
 314
 315 int mount_overlay(struct volume *v)
 316 {
 317         char *mp;
 318
 319         if (!v)
 320                 return -1;
 321
 322         mp = find_mount_point(v->blk, 0);
 323         if (mp) {
 324                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 325                 return -1;
 326         }
 327
 328         overlay_mount_fs(v);
 329
 330         extroot_prefix = "/tmp/overlay";
 331         if (!mount_extroot()) {
 332                 ULOG_INFO("switched to extroot\n");
 333                 return 0;
 334         }
 335
 336         switch(fs_state_get("/tmp/overlay")) {
 337         case FS_STATE_UNKNOWN:
 338                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 339                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 340                         ULOG_ERR("unable to set filesystem state\n");
 341                         break;
 342                 }
 343         case FS_STATE_PENDING:
 344                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 345                 overlay_delete("/tmp/overlay", true);
 346                 break;
 347         case FS_STATE_READY:
 348                 break;
 349         }
 350
 351         ULOG_INFO("switching to jffs2 overlay\n");
 352         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 353                 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
 354                 return ramoverlay();
 355         }
 356
 357         return -1;
 358 }