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                         if (!stat(gl.gl_pathv[j], &s) && !S_ISLNK(s.st_mode))
  83                                 foreachdir(gl.gl_pathv[j], cb);
  84
  85         cb(dir);
  86 }
  87
  88 void
  89 overlay_delete(const char *dir, bool _keep_sysupgrade)
  90 {
  91         keep_sysupgrade = _keep_sysupgrade;
  92         foreachdir(dir, handle_rmdir);
  93 }
  94
  95 static int
  96 overlay_mount(struct volume *v, char *fs)
  97 {
  98         if (mkdir("/tmp/overlay", 0755)) {
  99                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 100                 return -1;
 101         }
 102
 103         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 104                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
 105                 return -1;
 106         }
 107
 108         return volume_init(v);
 109 }
 110
 111 static int
 112 switch2jffs(struct volume *v)
 113 {
 114         struct stat s;
 115         int ret;
 116
 117         if (!stat(SWITCH_JFFS2, &s)) {
 118                 ULOG_ERR("jffs2 switch already running\n");
 119                 return -1;
 120         }
 121
 122         creat("/tmp/.switch_jffs2", 0600);
 123         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 124         unlink("/tmp/.switch_jffs2");
 125         if (ret) {
 126                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
 127                 return -1;
 128         }
 129
 130         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 131                 ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
 132                 return -1;
 133         }
 134
 135         if (system("cp -a /tmp/root/* /rom/overlay")) {
 136                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
 137                 return -1;
 138         }
 139
 140         if (pivot("/rom", "/mnt")) {
 141                 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
 142                 return -1;
 143         }
 144
 145         if (mount_move("/mnt", "/tmp/root", "")) {
 146                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 147                 return -1;
 148         }
 149
 150         return fopivot("/overlay", "/rom");
 151 }
 152
 153 int
 154 handle_whiteout(const char *dir)
 155 {
 156         struct stat s;
 157         char link[256];
 158         ssize_t sz;
 159         struct dirent **namelist;
 160         int n;
 161
 162         n = scandir(dir, &namelist, NULL, NULL);
 163
 164         if (n < 1)
 165                 return -1;
 166
 167         while (n--) {
 168                 char file[256];
 169
 170                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 171                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 172                         sz = readlink(file, link, sizeof(link) - 1);
 173                         if (sz > 0) {
 174                                 char *orig;
 175
 176                                 link[sz] = '\0';
 177                                 orig = strstr(&file[1], "/");
 178                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 179                                         unlink(orig);
 180                         }
 181                 }
 182                 free(namelist[n]);
 183         }
 184         free(namelist);
 185
 186         return 0;
 187 }
 188
 189 int
 190 jffs2_switch(struct volume *v)
 191 {
 192         char *mp;
 193         int ret = -1;
 194
 195         if (find_overlay_mount("overlayfs:/tmp/root"))
 196                 return -1;
 197
 198         if (find_filesystem("overlay")) {
 199                 ULOG_ERR("overlayfs not supported by kernel\n");
 200                 return ret;
 201         }
 202
 203         mp = find_mount_point(v->blk, 0);
 204         if (mp) {
 205                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 206                 return -1;
 207         }
 208
 209         switch (volume_identify(v)) {
 210         case FS_NONE:
 211                 ULOG_ERR("no jffs2 marker found\n");
 212                 /* fall through */
 213
 214         case FS_DEADCODE:
 215                 ret = switch2jffs(v);
 216                 if (!ret) {
 217                         ULOG_INFO("performing overlay whiteout\n");
 218                         umount2("/tmp/root", MNT_DETACH);
 219                         foreachdir("/overlay/", handle_whiteout);
 220                 }
 221                 break;
 222
 223         case FS_JFFS2:
 224                 ret = overlay_mount(v, "jffs2");
 225                 if (ret)
 226                         break;
 227                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 228                         ULOG_ERR("switching to jffs2 failed\n");
 229                         ret = -1;
 230                 }
 231                 break;
 232
 233         case FS_UBIFS:
 234                 ret = overlay_mount(v, "ubifs");
 235                 if (ret)
 236                         break;
 237                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 238                         ULOG_ERR("switching to ubifs failed\n");
 239                         ret = -1;
 240                 }
 241                 break;
 242         }
 243
 244         if (ret)
 245                 return ret;
 246
 247         sync();
 248         fs_state_set("/overlay", FS_STATE_READY);
 249         return 0;
 250 }
 251
 252 static int overlay_mount_fs(struct volume *v)
 253 {
 254         char *fstype;
 255
 256         if (mkdir("/tmp/overlay", 0755)) {
 257                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 258                 return -1;
 259         }
 260
 261         fstype = "jffs2";
 262
 263         switch (volume_identify(v)) {
 264         case FS_UBIFS:
 265                 fstype = "ubifs";
 266                 break;
 267         }
 268
 269         volume_init(v);
 270
 271         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 272                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 273                          fstype, v->blk, strerror(errno));
 274                 return -1;
 275         }
 276
 277         return -1;
 278 }
 279
 280 enum fs_state fs_state_get(const char *dir)
 281 {
 282         char *path;
 283         char valstr[16];
 284         uint32_t val;
 285         ssize_t len;
 286
 287         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 288         sprintf(path, "%s/.fs_state", dir);
 289         len = readlink(path, valstr, sizeof(valstr) - 1);
 290         if (len < 0)
 291                 return FS_STATE_UNKNOWN;
 292
 293         valstr[len] = 0;
 294         val = atoi(valstr);
 295
 296         if (val > __FS_STATE_LAST)
 297                 return FS_STATE_UNKNOWN;
 298
 299         return val;
 300 }
 301
 302
 303 int fs_state_set(const char *dir, enum fs_state state)
 304 {
 305         char valstr[16];
 306         char *path;
 307
 308         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 309         sprintf(path, "%s/.fs_state", dir);
 310         unlink(path);
 311         snprintf(valstr, sizeof(valstr), "%d", state);
 312
 313         return symlink(valstr, path);
 314 }
 315
 316
 317 int mount_overlay(struct volume *v)
 318 {
 319         char *mp;
 320
 321         if (!v)
 322                 return -1;
 323
 324         mp = find_mount_point(v->blk, 0);
 325         if (mp) {
 326                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 327                 return -1;
 328         }
 329
 330         overlay_mount_fs(v);
 331
 332         extroot_prefix = "/tmp/overlay";
 333         if (!mount_extroot()) {
 334                 ULOG_INFO("switched to extroot\n");
 335                 return 0;
 336         }
 337
 338         switch(fs_state_get("/tmp/overlay")) {
 339         case FS_STATE_UNKNOWN:
 340                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 341                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 342                         ULOG_ERR("unable to set filesystem state\n");
 343                         break;
 344                 }
 345         case FS_STATE_PENDING:
 346                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 347                 overlay_delete("/tmp/overlay", true);
 348                 break;
 349         case FS_STATE_READY:
 350                 break;
 351         }
 352
 353         ULOG_INFO("switching to jffs2 overlay\n");
 354         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 355                 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
 356                 return ramoverlay();
 357         }
 358
 359         return -1;
 360 }