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                         char *dir = gl.gl_pathv[j];
  83                         int len = strlen(gl.gl_pathv[j]);
  84
  85                         if (len > 1 && dir[len - 1] == '/')
  86                                 dir[len - 1] = '\0';
  87
  88                         if (!lstat(gl.gl_pathv[j], &s) && !S_ISLNK(s.st_mode))
  89                                 foreachdir(gl.gl_pathv[j], cb);
  90         }
  91         cb(dir);
  92 }
  93
  94 void
  95 overlay_delete(const char *dir, bool _keep_sysupgrade)
  96 {
  97         keep_sysupgrade = _keep_sysupgrade;
  98         foreachdir(dir, handle_rmdir);
  99 }
 100
 101 static int
 102 overlay_mount(struct volume *v, char *fs)
 103 {
 104         if (mkdir("/tmp/overlay", 0755)) {
 105                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 106                 return -1;
 107         }
 108
 109         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 110                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
 111                 return -1;
 112         }
 113
 114         return volume_init(v);
 115 }
 116
 117 static int
 118 switch2jffs(struct volume *v)
 119 {
 120         struct stat s;
 121         int ret;
 122
 123         if (!stat(SWITCH_JFFS2, &s)) {
 124                 ULOG_ERR("jffs2 switch already running\n");
 125                 return -1;
 126         }
 127
 128         creat("/tmp/.switch_jffs2", 0600);
 129         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 130         unlink("/tmp/.switch_jffs2");
 131         if (ret) {
 132                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
 133                 return -1;
 134         }
 135
 136         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 137                 ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
 138                 return -1;
 139         }
 140
 141         if (system("cp -a /tmp/root/* /rom/overlay")) {
 142                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
 143                 return -1;
 144         }
 145
 146         if (pivot("/rom", "/mnt")) {
 147                 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
 148                 return -1;
 149         }
 150
 151         if (mount_move("/mnt", "/tmp/root", "")) {
 152                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 153                 return -1;
 154         }
 155
 156         return fopivot("/overlay", "/rom");
 157 }
 158
 159 int
 160 handle_whiteout(const char *dir)
 161 {
 162         struct stat s;
 163         char link[256];
 164         ssize_t sz;
 165         struct dirent **namelist;
 166         int n;
 167
 168         n = scandir(dir, &namelist, NULL, NULL);
 169
 170         if (n < 1)
 171                 return -1;
 172
 173         while (n--) {
 174                 char file[256];
 175
 176                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 177                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 178                         sz = readlink(file, link, sizeof(link) - 1);
 179                         if (sz > 0) {
 180                                 char *orig;
 181
 182                                 link[sz] = '\0';
 183                                 orig = strstr(&file[1], "/");
 184                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 185                                         unlink(orig);
 186                         }
 187                 }
 188                 free(namelist[n]);
 189         }
 190         free(namelist);
 191
 192         return 0;
 193 }
 194
 195 int
 196 jffs2_switch(struct volume *v)
 197 {
 198         char *mp;
 199         int ret = -1;
 200
 201         if (find_overlay_mount("overlayfs:/tmp/root"))
 202                 return -1;
 203
 204         if (find_filesystem("overlay")) {
 205                 ULOG_ERR("overlayfs not supported by kernel\n");
 206                 return ret;
 207         }
 208
 209         mp = find_mount_point(v->blk, 0);
 210         if (mp) {
 211                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 212                 return -1;
 213         }
 214
 215         switch (volume_identify(v)) {
 216         case FS_NONE:
 217                 ULOG_ERR("no jffs2 marker found\n");
 218                 /* fall through */
 219
 220         case FS_DEADCODE:
 221                 ret = switch2jffs(v);
 222                 if (!ret) {
 223                         ULOG_INFO("performing overlay whiteout\n");
 224                         umount2("/tmp/root", MNT_DETACH);
 225                         foreachdir("/overlay/", handle_whiteout);
 226                 }
 227                 break;
 228
 229         case FS_JFFS2:
 230                 ret = overlay_mount(v, "jffs2");
 231                 if (ret)
 232                         break;
 233                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 234                         ULOG_ERR("switching to jffs2 failed\n");
 235                         ret = -1;
 236                 }
 237                 break;
 238
 239         case FS_UBIFS:
 240                 ret = overlay_mount(v, "ubifs");
 241                 if (ret)
 242                         break;
 243                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 244                         ULOG_ERR("switching to ubifs failed\n");
 245                         ret = -1;
 246                 }
 247                 break;
 248         }
 249
 250         if (ret)
 251                 return ret;
 252
 253         sync();
 254         fs_state_set("/overlay", FS_STATE_READY);
 255         return 0;
 256 }
 257
 258 static int overlay_mount_fs(struct volume *v)
 259 {
 260         char *fstype;
 261
 262         if (mkdir("/tmp/overlay", 0755)) {
 263                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 264                 return -1;
 265         }
 266
 267         fstype = "jffs2";
 268
 269         switch (volume_identify(v)) {
 270         case FS_UBIFS:
 271                 fstype = "ubifs";
 272                 break;
 273         }
 274
 275         volume_init(v);
 276
 277         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 278                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 279                          fstype, v->blk, strerror(errno));
 280                 return -1;
 281         }
 282
 283         return -1;
 284 }
 285
 286 enum fs_state fs_state_get(const char *dir)
 287 {
 288         char *path;
 289         char valstr[16];
 290         uint32_t val;
 291         ssize_t len;
 292
 293         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 294         sprintf(path, "%s/.fs_state", dir);
 295         len = readlink(path, valstr, sizeof(valstr) - 1);
 296         if (len < 0)
 297                 return FS_STATE_UNKNOWN;
 298
 299         valstr[len] = 0;
 300         val = atoi(valstr);
 301
 302         if (val > __FS_STATE_LAST)
 303                 return FS_STATE_UNKNOWN;
 304
 305         return val;
 306 }
 307
 308
 309 int fs_state_set(const char *dir, enum fs_state state)
 310 {
 311         char valstr[16];
 312         char *path;
 313
 314         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 315         sprintf(path, "%s/.fs_state", dir);
 316         unlink(path);
 317         snprintf(valstr, sizeof(valstr), "%d", state);
 318
 319         return symlink(valstr, path);
 320 }
 321
 322
 323 int mount_overlay(struct volume *v)
 324 {
 325         char *mp;
 326
 327         if (!v)
 328                 return -1;
 329
 330         mp = find_mount_point(v->blk, 0);
 331         if (mp) {
 332                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 333                 return -1;
 334         }
 335
 336         overlay_mount_fs(v);
 337
 338         extroot_prefix = "/tmp/overlay";
 339         if (!mount_extroot()) {
 340                 ULOG_INFO("switched to extroot\n");
 341                 return 0;
 342         }
 343
 344         switch(fs_state_get("/tmp/overlay")) {
 345         case FS_STATE_UNKNOWN:
 346                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 347                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 348                         ULOG_ERR("unable to set filesystem state\n");
 349                         break;
 350                 }
 351         case FS_STATE_PENDING:
 352                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 353                 overlay_delete("/tmp/overlay", true);
 354                 break;
 355         case FS_STATE_READY:
 356                 break;
 357         }
 358
 359         ULOG_INFO("switching to jffs2 overlay\n");
 360         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 361                 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
 362                 return ramoverlay();
 363         }
 364
 365         return -1;
 366 }