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 void
  36 foreachdir(const char *dir, int (*cb)(const char*))
  37 {
  38         char globdir[256];
  39         glob_t gl;
  40         int j;
  41
  42         if (dir[strlen(dir) - 1] == '/')
  43                 snprintf(globdir, 256, "%s*", dir);
  44         else
  45                 snprintf(globdir, 256, "%s/*", dir);
  46
  47         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  48                 for (j = 0; j < gl.gl_pathc; j++)
  49                         foreachdir(gl.gl_pathv[j], cb);
  50
  51         cb(dir);
  52 }
  53
  54 static int
  55 overlay_mount(struct volume *v, char *fs)
  56 {
  57         if (mkdir("/tmp/overlay", 0755)) {
  58                 fprintf(stderr, "failed to mkdir /tmp/overlay: %s\n", strerror(errno));
  59                 return -1;
  60         }
  61
  62         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
  63                 fprintf(stderr, "failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
  64                 return -1;
  65         }
  66
  67         return volume_init(v);
  68 }
  69
  70 static int
  71 switch2jffs(struct volume *v)
  72 {
  73         struct stat s;
  74         int ret;
  75
  76         if (!stat(SWITCH_JFFS2, &s)) {
  77                 fprintf(stderr, "jffs2 switch already running\n");
  78                 return -1;
  79         }
  80
  81         creat("/tmp/.switch_jffs2", 0600);
  82         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
  83         unlink("/tmp/.switch_jffs2");
  84         if (ret) {
  85                 fprintf(stderr, "failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
  86                 return -1;
  87         }
  88
  89         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
  90                 fprintf(stderr, "failed - mount -o remount,ro none: %s\n", strerror(errno));
  91                 return -1;
  92         }
  93
  94         system("cp -a /tmp/root/* /rom/overlay");
  95
  96         if (pivot("/rom", "/mnt")) {
  97                 fprintf(stderr, "failed - pivot /rom /mnt: %s\n", strerror(errno));
  98                 return -1;
  99         }
 100
 101         if (mount_move("/mnt", "/tmp/root", "")) {
 102                 fprintf(stderr, "failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 103                 return -1;
 104         }
 105
 106         return fopivot("/overlay", "/rom");
 107 }
 108
 109 int
 110 handle_whiteout(const char *dir)
 111 {
 112         struct stat s;
 113         char link[256];
 114         ssize_t sz;
 115         struct dirent **namelist;
 116         int n;
 117
 118         n = scandir(dir, &namelist, NULL, NULL);
 119
 120         if (n < 1)
 121                 return -1;
 122
 123         while (n--) {
 124                 char file[256];
 125
 126                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 127                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 128                         sz = readlink(file, link, sizeof(link) - 1);
 129                         if (sz > 0) {
 130                                 char *orig;
 131
 132                                 link[sz] = '\0';
 133                                 orig = strstr(&file[1], "/");
 134                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 135                                         unlink(orig);
 136                         }
 137                 }
 138                 free(namelist[n]);
 139         }
 140         free(namelist);
 141
 142         return 0;
 143 }
 144
 145 int
 146 jffs2_switch(struct volume *v)
 147 {
 148         char *mp;
 149         int ret = -1;
 150
 151         if (find_overlay_mount("overlayfs:/tmp/root"))
 152                 return -1;
 153
 154         if (find_filesystem("overlay")) {
 155                 fprintf(stderr, "overlayfs not found\n");
 156                 return ret;
 157         }
 158
 159         mp = find_mount_point(v->blk, 0);
 160         if (mp) {
 161                 fprintf(stderr, "rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 162                 return -1;
 163         }
 164
 165         switch (volume_identify(v)) {
 166         case FS_NONE:
 167                 fprintf(stderr, "no jffs2 marker found\n");
 168                 /* fall through */
 169
 170         case FS_DEADCODE:
 171                 ret = switch2jffs(v);
 172                 if (!ret) {
 173                         fprintf(stderr, "doing fo cleanup\n");
 174                         umount2("/tmp/root", MNT_DETACH);
 175                         foreachdir("/overlay/", handle_whiteout);
 176                 }
 177                 break;
 178
 179         case FS_JFFS2:
 180                 ret = overlay_mount(v, "jffs2");
 181                 if (ret)
 182                         break;
 183                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 184                         fprintf(stderr, "switching to jffs2 failed\n");
 185                         ret = -1;
 186                 }
 187                 break;
 188
 189         case FS_UBIFS:
 190                 ret = overlay_mount(v, "ubifs");
 191                 if (ret)
 192                         break;
 193                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 194                         fprintf(stderr, "switching to ubifs failed\n");
 195                         ret = -1;
 196                 }
 197                 break;
 198         }
 199         return ret;
 200 }
 201
 202 static int overlay_mount_fs(struct volume *v)
 203 {
 204         char *fstype;
 205
 206         if (mkdir("/tmp/overlay", 0755)) {
 207                 fprintf(stderr, "failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 208                 return -1;
 209         }
 210
 211         fstype = "jffs2";
 212
 213         switch (volume_identify(v)) {
 214         case FS_UBIFS:
 215                 fstype = "ubifs";
 216                 break;
 217         }
 218
 219         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 220                 fprintf(stderr, "failed to mount -t %s %s /tmp/overlay: %s\n",
 221                                 fstype, v->blk, strerror(errno));
 222                 return -1;
 223         }
 224
 225         volume_init(v);
 226
 227         return -1;
 228 }
 229
 230 int mount_overlay(struct volume *v)
 231 {
 232         char *mp;
 233
 234         if (!v)
 235                 return -1;
 236
 237         mp = find_mount_point(v->blk, 0);
 238         if (mp) {
 239                 fprintf(stderr, "rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 240                 return -1;
 241         }
 242
 243         overlay_mount_fs(v);
 244
 245         extroot_prefix = "/tmp/overlay";
 246         if (!mount_extroot()) {
 247                 fprintf(stderr, "switched to extroot\n");
 248                 return 0;
 249         }
 250
 251         fprintf(stderr, "switching to overlay\n");
 252         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 253                 fprintf(stderr, "switching to jffs2 failed - fallback to ramoverlay\n");
 254                 return ramoverlay();
 255         }
 256
 257         return -1;
 258 }