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         static char *globdir = NULL;
  71         static size_t globdirlen = 0;
  72         struct stat s = { 0 };
  73         size_t dirlen = strlen(dir);
  74         glob_t gl;
  75         int j;
  76
  77         if (dirlen + sizeof("/*") > globdirlen) {
  78                 /* Alloc extra 256 B to avoid too many reallocs */
  79                 size_t len = dirlen + sizeof("/*") + 256;
  80                 char *tmp;
  81
  82                 tmp = realloc(globdir, len);
  83                 if (!tmp)
  84                         return;
  85                 globdir = tmp;
  86                 globdirlen = len;
  87         }
  88
  89         sprintf(globdir, "%s/*", dir);
  90
  91         /* Include GLOB_MARK as callbacks expect a trailing slash */
  92         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  93                 for (j = 0; j < gl.gl_pathc; j++) {
  94                         char *dir = gl.gl_pathv[j];
  95                         int len = strlen(gl.gl_pathv[j]);
  96                         int err;
  97
  98                         /* Quick way of skipping files */
  99                         if (dir[len - 1] != '/')
 100                                 continue;
 101
 102                         /* lstat needs path without a trailing slash */
 103                         if (len > 1)
 104                                 dir[len - 1] = '\0';
 105                         err = lstat(gl.gl_pathv[j], &s);
 106                         if (len > 1)
 107                                 dir[len - 1] = '/';
 108
 109                         if (!err && !S_ISLNK(s.st_mode))
 110                                 foreachdir(gl.gl_pathv[j], cb);
 111         }
 112         cb(dir);
 113 }
 114
 115 void
 116 overlay_delete(const char *dir, bool _keep_sysupgrade)
 117 {
 118         keep_sysupgrade = _keep_sysupgrade;
 119         foreachdir(dir, handle_rmdir);
 120 }
 121
 122 static int
 123 overlay_mount(struct volume *v, char *fs)
 124 {
 125         if (mkdir("/tmp/overlay", 0755)) {
 126                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 127                 return -1;
 128         }
 129
 130         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 131                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n", fs, v->blk);
 132                 return -1;
 133         }
 134
 135         return 0;
 136 }
 137
 138 static int
 139 switch2jffs(struct volume *v)
 140 {
 141         struct stat s;
 142         int ret;
 143
 144         if (!stat(SWITCH_JFFS2, &s)) {
 145                 ULOG_ERR("jffs2 switch already running\n");
 146                 return -1;
 147         }
 148
 149         creat("/tmp/.switch_jffs2", 0600);
 150         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 151         unlink("/tmp/.switch_jffs2");
 152         if (ret) {
 153                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %m\n", v->blk);
 154                 return -1;
 155         }
 156
 157         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 158                 ULOG_ERR("failed - mount -o remount,ro none: %m\n");
 159                 return -1;
 160         }
 161
 162         if (system("cp -a /tmp/root/* /rom/overlay")) {
 163                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %m\n");
 164                 return -1;
 165         }
 166
 167         if (pivot("/rom", "/mnt")) {
 168                 ULOG_ERR("failed - pivot /rom /mnt: %m\n");
 169                 return -1;
 170         }
 171
 172         if (mount_move("/mnt", "/tmp/root", "")) {
 173                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %m\n");
 174                 return -1;
 175         }
 176
 177         return fopivot("/overlay", "/rom");
 178 }
 179
 180 int
 181 handle_whiteout(const char *dir)
 182 {
 183         struct stat s;
 184         char link[256];
 185         ssize_t sz;
 186         struct dirent **namelist;
 187         int n;
 188
 189         n = scandir(dir, &namelist, NULL, NULL);
 190
 191         if (n < 1)
 192                 return -1;
 193
 194         while (n--) {
 195                 char file[256];
 196
 197                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 198                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 199                         sz = readlink(file, link, sizeof(link) - 1);
 200                         if (sz > 0) {
 201                                 char *orig;
 202
 203                                 link[sz] = '\0';
 204                                 orig = strstr(&file[1], "/");
 205                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 206                                         unlink(orig);
 207                         }
 208                 }
 209                 free(namelist[n]);
 210         }
 211         free(namelist);
 212
 213         return 0;
 214 }
 215
 216 static char *overlay_fs_name(int type)
 217 {
 218         switch (type) {
 219                 case FS_EXT4:
 220                         return "ext4";
 221                 case FS_F2FS:
 222                         return "f2fs";
 223                 case FS_UBIFS:
 224                         return "ubifs";
 225                 case FS_JFFS2:
 226                 default:
 227                         return "jffs2";
 228         }
 229 }
 230
 231 int
 232 jffs2_switch(struct volume *v)
 233 {
 234         char *mp, *fs_name;
 235         int type;
 236
 237         if (find_overlay_mount("overlayfs:/tmp/root"))
 238                 return -1;
 239
 240         if (find_filesystem("overlay")) {
 241                 ULOG_ERR("overlayfs not supported by kernel\n");
 242                 return -1;
 243         }
 244
 245         volume_init(v);
 246         mp = find_mount_point(v->blk, 0);
 247         if (mp) {
 248                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 249                 return -1;
 250         }
 251
 252         type = volume_identify(v);
 253         fs_name = overlay_fs_name(type);
 254
 255         switch (type) {
 256         case FS_NONE:
 257                 ULOG_ERR("no jffs2 marker found\n");
 258                 /* fall through */
 259
 260         case FS_DEADCODE:
 261                 if (switch2jffs(v))
 262                         return -1;
 263
 264                 ULOG_INFO("performing overlay whiteout\n");
 265                 umount2("/tmp/root", MNT_DETACH);
 266                 foreachdir("/overlay/", handle_whiteout);
 267
 268                 /* try hard to be in sync */
 269                 ULOG_INFO("syncronizing overlay\n");
 270                 if (system("cp -a /tmp/root/upper/* / 2>/dev/null"))
 271                         ULOG_ERR("failed to sync jffs2 overlay\n");
 272                 break;
 273
 274         case FS_EXT4:
 275         case FS_F2FS:
 276         case FS_UBIFS:
 277                 if (overlay_mount(v, fs_name))
 278                         return -1;
 279                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 280                         ULOG_ERR("switching to %s failed\n", fs_name);
 281                         return -1;
 282                 }
 283                 break;
 284         }
 285
 286         sync();
 287         fs_state_set("/overlay", FS_STATE_READY);
 288         return 0;
 289 }
 290
 291 static int overlay_mount_fs(struct volume *v)
 292 {
 293         char *fstype = overlay_fs_name(volume_identify(v));
 294
 295         if (mkdir("/tmp/overlay", 0755)) {
 296                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 297                 return -1;
 298         }
 299
 300         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 301                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n",
 302                          fstype, v->blk);
 303                 return -1;
 304         }
 305
 306         return 0;
 307 }
 308
 309 enum fs_state fs_state_get(const char *dir)
 310 {
 311         char *path;
 312         char valstr[16];
 313         uint32_t val;
 314         ssize_t len;
 315
 316         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 317         sprintf(path, "%s/.fs_state", dir);
 318         len = readlink(path, valstr, sizeof(valstr) - 1);
 319         if (len < 0)
 320                 return FS_STATE_UNKNOWN;
 321
 322         valstr[len] = 0;
 323         val = atoi(valstr);
 324
 325         if (val > __FS_STATE_LAST)
 326                 return FS_STATE_UNKNOWN;
 327
 328         return val;
 329 }
 330
 331
 332 int fs_state_set(const char *dir, enum fs_state state)
 333 {
 334         char valstr[16];
 335         char *path;
 336
 337         if (fs_state_get(dir) == state)
 338                 return 0;
 339
 340         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 341         sprintf(path, "%s/.fs_state", dir);
 342         unlink(path);
 343         snprintf(valstr, sizeof(valstr), "%d", state);
 344
 345         return symlink(valstr, path);
 346 }
 347
 348
 349 int mount_overlay(struct volume *v)
 350 {
 351         char *mp, *fs_name;
 352
 353         if (!v)
 354                 return -1;
 355
 356         mp = find_mount_point(v->blk, 0);
 357         if (mp) {
 358                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 359                 return -1;
 360         }
 361
 362         overlay_mount_fs(v);
 363
 364         extroot_prefix = "/tmp/overlay";
 365         if (!mount_extroot()) {
 366                 ULOG_INFO("switched to extroot\n");
 367                 return 0;
 368         }
 369
 370         switch(fs_state_get("/tmp/overlay")) {
 371         case FS_STATE_UNKNOWN:
 372                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 373                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 374                         ULOG_ERR("unable to set filesystem state\n");
 375                         break;
 376                 }
 377         case FS_STATE_PENDING:
 378                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 379                 overlay_delete("/tmp/overlay", true);
 380                 break;
 381         case FS_STATE_READY:
 382                 break;
 383         }
 384
 385         fs_name = overlay_fs_name(volume_identify(v));
 386         ULOG_INFO("switching to %s overlay\n", fs_name);
 387         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 388                 ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
 389                 return ramoverlay();
 390         }
 391
 392         return -1;
 393 }