src/machine/image.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2013 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/statfs.h>
  23
  24 #include "strv.h"
  25 #include "utf8.h"
  26 #include "btrfs-util.h"
  27 #include "path-util.h"
  28 #include "image.h"
  29
  30 static const char image_search_path[] =
  31         "/var/lib/machines\0"
  32         "/var/lib/container\0"
  33         "/usr/local/lib/machines\0"
  34         "/usr/lib/machines\0";
  35
  36 Image *image_unref(Image *i) {
  37         if (!i)
  38                 return NULL;
  39
  40         free(i->name);
  41         free(i->path);
  42         free(i);
  43         return NULL;
  44 }
  45
  46 static int image_new(
  47                 ImageType t,
  48                 const char *name,
  49                 const char *path,
  50                 bool read_only,
  51                 usec_t crtime,
  52                 usec_t mtime,
  53                 Image **ret) {
  54
  55         _cleanup_(image_unrefp) Image *i = NULL;
  56
  57         assert(t >= 0);
  58         assert(t < _IMAGE_TYPE_MAX);
  59         assert(name);
  60         assert(ret);
  61
  62         i = new0(Image, 1);
  63         if (!i)
  64                 return -ENOMEM;
  65
  66         i->type = t;
  67         i->read_only = read_only;
  68         i->crtime = crtime;
  69         i->mtime = mtime;
  70
  71         i->name = strdup(name);
  72         if (!i->name)
  73                 return -ENOMEM;
  74
  75         if (path) {
  76                 i->path = strjoin(path, "/", name, NULL);
  77                 if (!i->path)
  78                         return -ENOMEM;
  79
  80                 path_kill_slashes(i->path);
  81         }
  82
  83         *ret = i;
  84         i = NULL;
  85
  86         return 0;
  87 }
  88
  89 static int image_make(int dfd, const char *name, const char *path, Image **ret) {
  90         struct stat st;
  91         bool writable;
  92         int r;
  93
  94         assert(dfd >= 0);
  95         assert(name);
  96
  97         /* We explicitly *do* follow symlinks here, since we want to
  98          * allow symlinking trees into /var/lib/container/, and treat
  99          * them normally. */
 100
 101         if (fstatat(dfd, name, &st, 0) < 0)
 102                 return -errno;
 103
 104         writable = faccessat(dfd, name, W_OK, AT_EACCESS) >= 0;
 105
 106         if (S_ISDIR(st.st_mode)) {
 107
 108                 if (!ret)
 109                         return 1;
 110
 111                 /* btrfs subvolumes have inode 256 */
 112                 if (st.st_ino == 256) {
 113                         _cleanup_close_ int fd = -1;
 114                         struct statfs sfs;
 115
 116                         fd = openat(dfd, name, O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
 117                         if (fd < 0)
 118                                 return -errno;
 119
 120                         if (fstatfs(fd, &sfs) < 0)
 121                                 return -errno;
 122
 123                         if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)) {
 124                                 BtrfsSubvolInfo info;
 125
 126                                 /* It's a btrfs subvolume */
 127
 128                                 r = btrfs_subvol_get_info_fd(fd, &info);
 129                                 if (r < 0)
 130                                         return r;
 131
 132                                 r = image_new(IMAGE_SUBVOLUME,
 133                                               name,
 134                                               path,
 135                                               info.read_only || !writable,
 136                                               info.otime,
 137                                               0,
 138                                               ret);
 139                                 if (r < 0)
 140                                         return r;
 141
 142                                 return 1;
 143                         }
 144                 }
 145
 146                 /* It's just a normal directory. */
 147
 148                 r = image_new(IMAGE_DIRECTORY,
 149                               name,
 150                               path,
 151                               !writable,
 152                               0,
 153                               0,
 154                               ret);
 155                 if (r < 0)
 156                         return r;
 157
 158                 return 1;
 159
 160         } else if (S_ISREG(st.st_mode) && endswith(name, ".gpt")) {
 161                 const char *truncated;
 162                 usec_t crtime = 0;
 163
 164                 /* It's a GPT block device */
 165
 166                 if (!ret)
 167                         return 1;
 168
 169                 fd_getcrtime_at(dfd, name, &crtime, 0);
 170
 171                 truncated = strndupa(name, strlen(name) - 4);
 172
 173                 r = image_new(IMAGE_GPT,
 174                               truncated,
 175                               path,
 176                               !(st.st_mode & 0222) || !writable,
 177                               crtime,
 178                               timespec_load(&st.st_mtim),
 179                               ret);
 180                 if (r < 0)
 181                         return r;
 182
 183                 return 1;
 184         }
 185
 186         return 0;
 187 }
 188
 189 int image_find(const char *name, Image **ret) {
 190         const char *path;
 191         int r;
 192
 193         assert(name);
 194
 195         /* There are no images with invalid names */
 196         if (!image_name_is_valid(name))
 197                 return 0;
 198
 199         NULSTR_FOREACH(path, image_search_path) {
 200                 _cleanup_closedir_ DIR *d = NULL;
 201
 202                 d = opendir(path);
 203                 if (!d) {
 204                         if (errno == ENOENT)
 205                                 continue;
 206
 207                         return -errno;
 208                 }
 209
 210                 r = image_make(dirfd(d), name, path, ret);
 211                 if (r == 0 || r == -ENOENT)
 212                         continue;
 213                 if (r < 0)
 214                         return r;
 215
 216                 return 1;
 217         }
 218
 219         return 0;
 220 };
 221
 222 int image_discover(Hashmap *h) {
 223         const char *path;
 224         int r;
 225
 226         assert(h);
 227
 228         NULSTR_FOREACH(path, image_search_path) {
 229                 _cleanup_closedir_ DIR *d = NULL;
 230                 struct dirent *de;
 231
 232                 d = opendir(path);
 233                 if (!d) {
 234                         if (errno == ENOENT)
 235                                 continue;
 236
 237                         return -errno;
 238                 }
 239
 240                 FOREACH_DIRENT_ALL(de, d, return -errno) {
 241                         _cleanup_(image_unrefp) Image *image = NULL;
 242
 243                         if (!image_name_is_valid(de->d_name))
 244                                 continue;
 245
 246                         if (hashmap_contains(h, de->d_name))
 247                                 continue;
 248
 249                         r = image_make(dirfd(d), de->d_name, path, &image);
 250                         if (r == 0 || r == -ENOENT)
 251                                 continue;
 252                         if (r < 0)
 253                                 return r;
 254
 255                         r = hashmap_put(h, image->name, image);
 256                         if (r < 0)
 257                                 return r;
 258
 259                         image = NULL;
 260                 }
 261         }
 262
 263         return 0;
 264 }
 265
 266 void image_hashmap_free(Hashmap *map) {
 267         Image *i;
 268
 269         while ((i = hashmap_steal_first(map)))
 270                 image_unref(i);
 271
 272         hashmap_free(map);
 273 }
 274
 275 static const char* const image_type_table[_IMAGE_TYPE_MAX] = {
 276         [IMAGE_DIRECTORY] = "directory",
 277         [IMAGE_SUBVOLUME] = "subvolume",
 278         [IMAGE_GPT] = "gpt",
 279 };
 280
 281 DEFINE_STRING_TABLE_LOOKUP(image_type, ImageType);