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 0;
 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 static char *overlay_fs_name(int type)
 196 {
 197         switch (type) {
 198                 case FS_EXT4:
 199                         return "ext4";
 200                 case FS_F2FS:
 201                         return "f2fs";
 202                 case FS_UBIFS:
 203                         return "ubifs";
 204                 case FS_JFFS2:
 205                 default:
 206                         return "jffs2";
 207         }
 208 }
 209
 210 int
 211 jffs2_switch(struct volume *v)
 212 {
 213         char *mp;
 214         int type;
 215
 216         if (find_overlay_mount("overlayfs:/tmp/root"))
 217                 return -1;
 218
 219         if (find_filesystem("overlay")) {
 220                 ULOG_ERR("overlayfs not supported by kernel\n");
 221                 return -1;
 222         }
 223
 224         volume_init(v);
 225         mp = find_mount_point(v->blk, 0);
 226         if (mp) {
 227                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 228                 return -1;
 229         }
 230
 231         type = volume_identify(v);
 232         switch (type) {
 233         case FS_NONE:
 234                 ULOG_ERR("no jffs2 marker found\n");
 235                 /* fall through */
 236
 237         case FS_DEADCODE:
 238                 if (switch2jffs(v))
 239                         return -1;
 240
 241                 ULOG_INFO("performing overlay whiteout\n");
 242                 umount2("/tmp/root", MNT_DETACH);
 243                 foreachdir("/overlay/", handle_whiteout);
 244                 break;
 245
 246         case FS_EXT4:
 247         case FS_F2FS:
 248         case FS_UBIFS:
 249                 if (overlay_mount(v, overlay_fs_name(type)))
 250                         return -1;
 251                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 252                         ULOG_ERR("switching to jffs2 failed\n");
 253                         return -1;
 254                 }
 255                 break;
 256         }
 257
 258         sync();
 259         fs_state_set("/overlay", FS_STATE_READY);
 260         return 0;
 261 }
 262
 263 static int overlay_mount_fs(struct volume *v)
 264 {
 265         char *fstype = overlay_fs_name(volume_identify(v));
 266
 267         if (mkdir("/tmp/overlay", 0755)) {
 268                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 269                 return -1;
 270         }
 271
 272         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 273                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 274                          fstype, v->blk, strerror(errno));
 275                 return -1;
 276         }
 277
 278         return 0;
 279 }
 280
 281 enum fs_state fs_state_get(const char *dir)
 282 {
 283         char *path;
 284         char valstr[16];
 285         uint32_t val;
 286         ssize_t len;
 287
 288         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 289         sprintf(path, "%s/.fs_state", dir);
 290         len = readlink(path, valstr, sizeof(valstr) - 1);
 291         if (len < 0)
 292                 return FS_STATE_UNKNOWN;
 293
 294         valstr[len] = 0;
 295         val = atoi(valstr);
 296
 297         if (val > __FS_STATE_LAST)
 298                 return FS_STATE_UNKNOWN;
 299
 300         return val;
 301 }
 302
 303
 304 int fs_state_set(const char *dir, enum fs_state state)
 305 {
 306         char valstr[16];
 307         char *path;
 308
 309         if (fs_state_get(dir) == state)
 310                 return 0;
 311
 312         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 313         sprintf(path, "%s/.fs_state", dir);
 314         unlink(path);
 315         snprintf(valstr, sizeof(valstr), "%d", state);
 316
 317         return symlink(valstr, path);
 318 }
 319
 320
 321 int mount_overlay(struct volume *v)
 322 {
 323         char *mp;
 324
 325         if (!v)
 326                 return -1;
 327
 328         mp = find_mount_point(v->blk, 0);
 329         if (mp) {
 330                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 331                 return -1;
 332         }
 333
 334         overlay_mount_fs(v);
 335
 336         extroot_prefix = "/tmp/overlay";
 337         if (!mount_extroot()) {
 338                 ULOG_INFO("switched to extroot\n");
 339                 return 0;
 340         }
 341
 342         switch(fs_state_get("/tmp/overlay")) {
 343         case FS_STATE_UNKNOWN:
 344                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 345                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 346                         ULOG_ERR("unable to set filesystem state\n");
 347                         break;
 348                 }
 349         case FS_STATE_PENDING:
 350                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 351                 overlay_delete("/tmp/overlay", true);
 352                 break;
 353         case FS_STATE_READY:
 354                 break;
 355         }
 356
 357         ULOG_INFO("switching to jffs2 overlay\n");
 358         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 359                 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
 360                 return ramoverlay();
 361         }
 362
 363         return -1;
 364 }