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         if (dir[dirlen - 1] == '/')
  90                 sprintf(globdir, "%s*", dir);
  91         else
  92                 sprintf(globdir, "%s/*", dir);
  93
  94         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  95                 for (j = 0; j < gl.gl_pathc; j++) {
  96                         char *dir = gl.gl_pathv[j];
  97                         int len = strlen(gl.gl_pathv[j]);
  98
  99                         if (len > 1 && dir[len - 1] == '/')
 100                                 dir[len - 1] = '\0';
 101
 102                         if (!lstat(gl.gl_pathv[j], &s) && !S_ISLNK(s.st_mode))
 103                                 foreachdir(gl.gl_pathv[j], cb);
 104         }
 105         cb(dir);
 106 }
 107
 108 void
 109 overlay_delete(const char *dir, bool _keep_sysupgrade)
 110 {
 111         keep_sysupgrade = _keep_sysupgrade;
 112         foreachdir(dir, handle_rmdir);
 113 }
 114
 115 static int
 116 overlay_mount(struct volume *v, char *fs)
 117 {
 118         if (mkdir("/tmp/overlay", 0755)) {
 119                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 120                 return -1;
 121         }
 122
 123         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 124                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n", fs, v->blk);
 125                 return -1;
 126         }
 127
 128         return 0;
 129 }
 130
 131 static int
 132 switch2jffs(struct volume *v)
 133 {
 134         struct stat s;
 135         int ret;
 136
 137         if (!stat(SWITCH_JFFS2, &s)) {
 138                 ULOG_ERR("jffs2 switch already running\n");
 139                 return -1;
 140         }
 141
 142         creat("/tmp/.switch_jffs2", 0600);
 143         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 144         unlink("/tmp/.switch_jffs2");
 145         if (ret) {
 146                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %m\n", v->blk);
 147                 return -1;
 148         }
 149
 150         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 151                 ULOG_ERR("failed - mount -o remount,ro none: %m\n");
 152                 return -1;
 153         }
 154
 155         if (system("cp -a /tmp/root/* /rom/overlay")) {
 156                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %m\n");
 157                 return -1;
 158         }
 159
 160         if (pivot("/rom", "/mnt")) {
 161                 ULOG_ERR("failed - pivot /rom /mnt: %m\n");
 162                 return -1;
 163         }
 164
 165         if (mount_move("/mnt", "/tmp/root", "")) {
 166                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %m\n");
 167                 return -1;
 168         }
 169
 170         return fopivot("/overlay", "/rom");
 171 }
 172
 173 int
 174 handle_whiteout(const char *dir)
 175 {
 176         struct stat s;
 177         char link[256];
 178         ssize_t sz;
 179         struct dirent **namelist;
 180         int n;
 181
 182         n = scandir(dir, &namelist, NULL, NULL);
 183
 184         if (n < 1)
 185                 return -1;
 186
 187         while (n--) {
 188                 char file[256];
 189
 190                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 191                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 192                         sz = readlink(file, link, sizeof(link) - 1);
 193                         if (sz > 0) {
 194                                 char *orig;
 195
 196                                 link[sz] = '\0';
 197                                 orig = strstr(&file[1], "/");
 198                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 199                                         unlink(orig);
 200                         }
 201                 }
 202                 free(namelist[n]);
 203         }
 204         free(namelist);
 205
 206         return 0;
 207 }
 208
 209 static char *overlay_fs_name(int type)
 210 {
 211         switch (type) {
 212                 case FS_EXT4:
 213                         return "ext4";
 214                 case FS_F2FS:
 215                         return "f2fs";
 216                 case FS_UBIFS:
 217                         return "ubifs";
 218                 case FS_JFFS2:
 219                 default:
 220                         return "jffs2";
 221         }
 222 }
 223
 224 int
 225 jffs2_switch(struct volume *v)
 226 {
 227         char *mp, *fs_name;
 228         int type;
 229
 230         if (find_overlay_mount("overlayfs:/tmp/root"))
 231                 return -1;
 232
 233         if (find_filesystem("overlay")) {
 234                 ULOG_ERR("overlayfs not supported by kernel\n");
 235                 return -1;
 236         }
 237
 238         volume_init(v);
 239         mp = find_mount_point(v->blk, 0);
 240         if (mp) {
 241                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 242                 return -1;
 243         }
 244
 245         type = volume_identify(v);
 246         fs_name = overlay_fs_name(type);
 247
 248         switch (type) {
 249         case FS_NONE:
 250                 ULOG_ERR("no jffs2 marker found\n");
 251                 /* fall through */
 252
 253         case FS_DEADCODE:
 254                 if (switch2jffs(v))
 255                         return -1;
 256
 257                 ULOG_INFO("performing overlay whiteout\n");
 258                 umount2("/tmp/root", MNT_DETACH);
 259                 foreachdir("/overlay/", handle_whiteout);
 260
 261                 /* try hard to be in sync */
 262                 ULOG_INFO("syncronizing overlay\n");
 263                 system("cp -a /tmp/root/upper/* / 2>/dev/null");
 264                 break;
 265
 266         case FS_EXT4:
 267         case FS_F2FS:
 268         case FS_UBIFS:
 269                 if (overlay_mount(v, fs_name))
 270                         return -1;
 271                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 272                         ULOG_ERR("switching to %s failed\n", fs_name);
 273                         return -1;
 274                 }
 275                 break;
 276         }
 277
 278         sync();
 279         fs_state_set("/overlay", FS_STATE_READY);
 280         return 0;
 281 }
 282
 283 static int overlay_mount_fs(struct volume *v)
 284 {
 285         char *fstype = overlay_fs_name(volume_identify(v));
 286
 287         if (mkdir("/tmp/overlay", 0755)) {
 288                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 289                 return -1;
 290         }
 291
 292         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 293                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n",
 294                          fstype, v->blk);
 295                 return -1;
 296         }
 297
 298         return 0;
 299 }
 300
 301 enum fs_state fs_state_get(const char *dir)
 302 {
 303         char *path;
 304         char valstr[16];
 305         uint32_t val;
 306         ssize_t len;
 307
 308         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 309         sprintf(path, "%s/.fs_state", dir);
 310         len = readlink(path, valstr, sizeof(valstr) - 1);
 311         if (len < 0)
 312                 return FS_STATE_UNKNOWN;
 313
 314         valstr[len] = 0;
 315         val = atoi(valstr);
 316
 317         if (val > __FS_STATE_LAST)
 318                 return FS_STATE_UNKNOWN;
 319
 320         return val;
 321 }
 322
 323
 324 int fs_state_set(const char *dir, enum fs_state state)
 325 {
 326         char valstr[16];
 327         char *path;
 328
 329         if (fs_state_get(dir) == state)
 330                 return 0;
 331
 332         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 333         sprintf(path, "%s/.fs_state", dir);
 334         unlink(path);
 335         snprintf(valstr, sizeof(valstr), "%d", state);
 336
 337         return symlink(valstr, path);
 338 }
 339
 340
 341 int mount_overlay(struct volume *v)
 342 {
 343         char *mp, *fs_name;
 344
 345         if (!v)
 346                 return -1;
 347
 348         mp = find_mount_point(v->blk, 0);
 349         if (mp) {
 350                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 351                 return -1;
 352         }
 353
 354         overlay_mount_fs(v);
 355
 356         extroot_prefix = "/tmp/overlay";
 357         if (!mount_extroot()) {
 358                 ULOG_INFO("switched to extroot\n");
 359                 return 0;
 360         }
 361
 362         switch(fs_state_get("/tmp/overlay")) {
 363         case FS_STATE_UNKNOWN:
 364                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 365                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 366                         ULOG_ERR("unable to set filesystem state\n");
 367                         break;
 368                 }
 369         case FS_STATE_PENDING:
 370                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 371                 overlay_delete("/tmp/overlay", true);
 372                 break;
 373         case FS_STATE_READY:
 374                 break;
 375         }
 376
 377         fs_name = overlay_fs_name(volume_identify(v));
 378         ULOG_INFO("switching to %s overlay\n", fs_name);
 379         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 380                 ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
 381                 return ramoverlay();
 382         }
 383
 384         return -1;
 385 }