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         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  92                 for (j = 0; j < gl.gl_pathc; j++) {
  93                         char *dir = gl.gl_pathv[j];
  94                         int len = strlen(gl.gl_pathv[j]);
  95
  96                         if (len > 1 && dir[len - 1] == '/')
  97                                 dir[len - 1] = '\0';
  98
  99                         if (!lstat(gl.gl_pathv[j], &s) && !S_ISLNK(s.st_mode))
 100                                 foreachdir(gl.gl_pathv[j], cb);
 101         }
 102         cb(dir);
 103 }
 104
 105 void
 106 overlay_delete(const char *dir, bool _keep_sysupgrade)
 107 {
 108         keep_sysupgrade = _keep_sysupgrade;
 109         foreachdir(dir, handle_rmdir);
 110 }
 111
 112 static int
 113 overlay_mount(struct volume *v, char *fs)
 114 {
 115         if (mkdir("/tmp/overlay", 0755)) {
 116                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 117                 return -1;
 118         }
 119
 120         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 121                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n", fs, v->blk);
 122                 return -1;
 123         }
 124
 125         return 0;
 126 }
 127
 128 static int
 129 switch2jffs(struct volume *v)
 130 {
 131         struct stat s;
 132         int ret;
 133
 134         if (!stat(SWITCH_JFFS2, &s)) {
 135                 ULOG_ERR("jffs2 switch already running\n");
 136                 return -1;
 137         }
 138
 139         creat("/tmp/.switch_jffs2", 0600);
 140         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 141         unlink("/tmp/.switch_jffs2");
 142         if (ret) {
 143                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %m\n", v->blk);
 144                 return -1;
 145         }
 146
 147         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 148                 ULOG_ERR("failed - mount -o remount,ro none: %m\n");
 149                 return -1;
 150         }
 151
 152         if (system("cp -a /tmp/root/* /rom/overlay")) {
 153                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %m\n");
 154                 return -1;
 155         }
 156
 157         if (pivot("/rom", "/mnt")) {
 158                 ULOG_ERR("failed - pivot /rom /mnt: %m\n");
 159                 return -1;
 160         }
 161
 162         if (mount_move("/mnt", "/tmp/root", "")) {
 163                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %m\n");
 164                 return -1;
 165         }
 166
 167         return fopivot("/overlay", "/rom");
 168 }
 169
 170 int
 171 handle_whiteout(const char *dir)
 172 {
 173         struct stat s;
 174         char link[256];
 175         ssize_t sz;
 176         struct dirent **namelist;
 177         int n;
 178
 179         n = scandir(dir, &namelist, NULL, NULL);
 180
 181         if (n < 1)
 182                 return -1;
 183
 184         while (n--) {
 185                 char file[256];
 186
 187                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 188                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 189                         sz = readlink(file, link, sizeof(link) - 1);
 190                         if (sz > 0) {
 191                                 char *orig;
 192
 193                                 link[sz] = '\0';
 194                                 orig = strstr(&file[1], "/");
 195                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 196                                         unlink(orig);
 197                         }
 198                 }
 199                 free(namelist[n]);
 200         }
 201         free(namelist);
 202
 203         return 0;
 204 }
 205
 206 static char *overlay_fs_name(int type)
 207 {
 208         switch (type) {
 209                 case FS_EXT4:
 210                         return "ext4";
 211                 case FS_F2FS:
 212                         return "f2fs";
 213                 case FS_UBIFS:
 214                         return "ubifs";
 215                 case FS_JFFS2:
 216                 default:
 217                         return "jffs2";
 218         }
 219 }
 220
 221 int
 222 jffs2_switch(struct volume *v)
 223 {
 224         char *mp, *fs_name;
 225         int type;
 226
 227         if (find_overlay_mount("overlayfs:/tmp/root"))
 228                 return -1;
 229
 230         if (find_filesystem("overlay")) {
 231                 ULOG_ERR("overlayfs not supported by kernel\n");
 232                 return -1;
 233         }
 234
 235         volume_init(v);
 236         mp = find_mount_point(v->blk, 0);
 237         if (mp) {
 238                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 239                 return -1;
 240         }
 241
 242         type = volume_identify(v);
 243         fs_name = overlay_fs_name(type);
 244
 245         switch (type) {
 246         case FS_NONE:
 247                 ULOG_ERR("no jffs2 marker found\n");
 248                 /* fall through */
 249
 250         case FS_DEADCODE:
 251                 if (switch2jffs(v))
 252                         return -1;
 253
 254                 ULOG_INFO("performing overlay whiteout\n");
 255                 umount2("/tmp/root", MNT_DETACH);
 256                 foreachdir("/overlay/", handle_whiteout);
 257
 258                 /* try hard to be in sync */
 259                 ULOG_INFO("syncronizing overlay\n");
 260                 if (system("cp -a /tmp/root/upper/* / 2>/dev/null"))
 261                         ULOG_ERR("failed to sync jffs2 overlay\n");
 262                 break;
 263
 264         case FS_EXT4:
 265         case FS_F2FS:
 266         case FS_UBIFS:
 267                 if (overlay_mount(v, fs_name))
 268                         return -1;
 269                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 270                         ULOG_ERR("switching to %s failed\n", fs_name);
 271                         return -1;
 272                 }
 273                 break;
 274         }
 275
 276         sync();
 277         fs_state_set("/overlay", FS_STATE_READY);
 278         return 0;
 279 }
 280
 281 static int overlay_mount_fs(struct volume *v)
 282 {
 283         char *fstype = overlay_fs_name(volume_identify(v));
 284
 285         if (mkdir("/tmp/overlay", 0755)) {
 286                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 287                 return -1;
 288         }
 289
 290         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 291                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n",
 292                          fstype, v->blk);
 293                 return -1;
 294         }
 295
 296         return 0;
 297 }
 298
 299 enum fs_state fs_state_get(const char *dir)
 300 {
 301         char *path;
 302         char valstr[16];
 303         uint32_t val;
 304         ssize_t len;
 305
 306         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 307         sprintf(path, "%s/.fs_state", dir);
 308         len = readlink(path, valstr, sizeof(valstr) - 1);
 309         if (len < 0)
 310                 return FS_STATE_UNKNOWN;
 311
 312         valstr[len] = 0;
 313         val = atoi(valstr);
 314
 315         if (val > __FS_STATE_LAST)
 316                 return FS_STATE_UNKNOWN;
 317
 318         return val;
 319 }
 320
 321
 322 int fs_state_set(const char *dir, enum fs_state state)
 323 {
 324         char valstr[16];
 325         char *path;
 326
 327         if (fs_state_get(dir) == state)
 328                 return 0;
 329
 330         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 331         sprintf(path, "%s/.fs_state", dir);
 332         unlink(path);
 333         snprintf(valstr, sizeof(valstr), "%d", state);
 334
 335         return symlink(valstr, path);
 336 }
 337
 338
 339 int mount_overlay(struct volume *v)
 340 {
 341         char *mp, *fs_name;
 342
 343         if (!v)
 344                 return -1;
 345
 346         mp = find_mount_point(v->blk, 0);
 347         if (mp) {
 348                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 349                 return -1;
 350         }
 351
 352         overlay_mount_fs(v);
 353
 354         extroot_prefix = "/tmp/overlay";
 355         if (!mount_extroot()) {
 356                 ULOG_INFO("switched to extroot\n");
 357                 return 0;
 358         }
 359
 360         switch(fs_state_get("/tmp/overlay")) {
 361         case FS_STATE_UNKNOWN:
 362                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 363                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 364                         ULOG_ERR("unable to set filesystem state\n");
 365                         break;
 366                 }
 367         case FS_STATE_PENDING:
 368                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 369                 overlay_delete("/tmp/overlay", true);
 370                 break;
 371         case FS_STATE_READY:
 372                 break;
 373         }
 374
 375         fs_name = overlay_fs_name(volume_identify(v));
 376         ULOG_INFO("switching to %s overlay\n", fs_name);
 377         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 378                 ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
 379                 return ramoverlay();
 380         }
 381
 382         return -1;
 383 }