send-utils.c

   1 /*
   2  * Copyright (C) 2012 Alexander Block.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 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 GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <unistd.h>
  20 #include <fcntl.h>
  21 #include <sys/ioctl.h>
  22 #include <uuid/uuid.h>
  23
  24 #include "ctree.h"
  25 #include "send-utils.h"
  26 #include "ioctl.h"
  27 #include "btrfs-list.h"
  28
  29 static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
  30                                       u64 subvol_id);
  31
  32 static int btrfs_get_root_id_by_sub_path(int mnt_fd, const char *sub_path,
  33                                          u64 *root_id)
  34 {
  35         int ret;
  36         int subvol_fd;
  37
  38         subvol_fd = openat(mnt_fd, sub_path, O_RDONLY);
  39         if (subvol_fd < 0) {
  40                 ret = -errno;
  41                 fprintf(stderr, "ERROR: open %s failed. %s\n", sub_path,
  42                         strerror(-ret));
  43                 return ret;
  44         }
  45
  46         ret = btrfs_list_get_path_rootid(subvol_fd, root_id);
  47         close(subvol_fd);
  48         return ret;
  49 }
  50
  51 static int btrfs_read_root_item_raw(int mnt_fd, u64 root_id, size_t buf_len,
  52                                     u32 *read_len, void *buf)
  53 {
  54         int ret;
  55         struct btrfs_ioctl_search_args args;
  56         struct btrfs_ioctl_search_key *sk = &args.key;
  57         struct btrfs_ioctl_search_header *sh;
  58         unsigned long off = 0;
  59         int found = 0;
  60         int i;
  61
  62         *read_len = 0;
  63         memset(&args, 0, sizeof(args));
  64
  65         sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
  66
  67         /*
  68          * there may be more than one ROOT_ITEM key if there are
  69          * snapshots pending deletion, we have to loop through
  70          * them.
  71          */
  72         sk->min_objectid = root_id;
  73         sk->max_objectid = root_id;
  74         sk->max_type = BTRFS_ROOT_ITEM_KEY;
  75         sk->min_type = BTRFS_ROOT_ITEM_KEY;
  76         sk->max_offset = (u64)-1;
  77         sk->max_transid = (u64)-1;
  78         sk->nr_items = 4096;
  79
  80         while (1) {
  81                 ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
  82                 if (ret < 0) {
  83                         fprintf(stderr,
  84                                 "ERROR: can't perform the search - %s\n",
  85                                 strerror(errno));
  86                         return 0;
  87                 }
  88                 /* the ioctl returns the number of item it found in nr_items */
  89                 if (sk->nr_items == 0)
  90                         break;
  91
  92                 off = 0;
  93                 for (i = 0; i < sk->nr_items; i++) {
  94                         struct btrfs_root_item *item;
  95                         sh = (struct btrfs_ioctl_search_header *)(args.buf +
  96                                                                   off);
  97
  98                         off += sizeof(*sh);
  99                         item = (struct btrfs_root_item *)(args.buf + off);
 100                         off += sh->len;
 101
 102                         sk->min_objectid = sh->objectid;
 103                         sk->min_type = sh->type;
 104                         sk->min_offset = sh->offset;
 105
 106                         if (sh->objectid > root_id)
 107                                 break;
 108
 109                         if (sh->objectid == root_id &&
 110                             sh->type == BTRFS_ROOT_ITEM_KEY) {
 111                                 if (sh->len > buf_len) {
 112                                         /* btrfs-progs is too old for kernel */
 113                                         fprintf(stderr,
 114                                                 "ERROR: buf for read_root_item_raw() is too small, get newer btrfs tools!\n");
 115                                         return -EOVERFLOW;
 116                                 }
 117                                 memcpy(buf, item, sh->len);
 118                                 *read_len = sh->len;
 119                                 found = 1;
 120                         }
 121                 }
 122                 if (sk->min_offset < (u64)-1)
 123                         sk->min_offset++;
 124                 else
 125                         break;
 126
 127                 if (sk->min_type != BTRFS_ROOT_ITEM_KEY ||
 128                     sk->min_objectid != root_id)
 129                         break;
 130         }
 131
 132         return found ? 0 : -ENOENT;
 133 }
 134
 135 /*
 136  * Read a root item from the tree. In case we detect a root item smaller then
 137  * sizeof(root_item), we know it's an old version of the root structure and
 138  * initialize all new fields to zero. The same happens if we detect mismatching
 139  * generation numbers as then we know the root was once mounted with an older
 140  * kernel that was not aware of the root item structure change.
 141  */
 142 static int btrfs_read_root_item(int mnt_fd, u64 root_id,
 143                                 struct btrfs_root_item *item)
 144 {
 145         int ret;
 146         u32 read_len;
 147
 148         ret = btrfs_read_root_item_raw(mnt_fd, root_id, sizeof(*item),
 149                                        &read_len, item);
 150         if (ret)
 151                 return ret;
 152
 153         if (read_len < sizeof(*item) ||
 154             btrfs_root_generation(item) != btrfs_root_generation_v2(item))
 155                 memset(&item->generation_v2, 0,
 156                         sizeof(*item) - offsetof(struct btrfs_root_item,
 157                                                  generation_v2));
 158
 159         return 0;
 160 }
 161
 162 int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id)
 163 {
 164         if (path_len < 1)
 165                 return -EOVERFLOW;
 166         path[0] = '\0';
 167         path_len--;
 168         path[path_len] = '\0';
 169         return btrfs_subvolid_resolve_sub(fd, path, &path_len, subvol_id);
 170 }
 171
 172 static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
 173                                       u64 subvol_id)
 174 {
 175         int ret;
 176         struct btrfs_ioctl_search_args search_arg;
 177         struct btrfs_ioctl_ino_lookup_args ino_lookup_arg;
 178         struct btrfs_ioctl_search_header *search_header;
 179         struct btrfs_root_ref *backref_item;
 180
 181         if (subvol_id == BTRFS_FS_TREE_OBJECTID) {
 182                 if (*path_len < 1)
 183                         return -EOVERFLOW;
 184                 *path = '\0';
 185                 (*path_len)--;
 186                 return 0;
 187         }
 188
 189         memset(&search_arg, 0, sizeof(search_arg));
 190         search_arg.key.tree_id = BTRFS_ROOT_TREE_OBJECTID;
 191         search_arg.key.min_objectid = subvol_id;
 192         search_arg.key.max_objectid = subvol_id;
 193         search_arg.key.min_type = BTRFS_ROOT_BACKREF_KEY;
 194         search_arg.key.max_type = BTRFS_ROOT_BACKREF_KEY;
 195         search_arg.key.max_offset = (u64)-1;
 196         search_arg.key.max_transid = (u64)-1;
 197         search_arg.key.nr_items = 1;
 198         ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
 199         if (ret) {
 200                 fprintf(stderr,
 201                         "ioctl(BTRFS_IOC_TREE_SEARCH, subvol_id %llu) ret=%d, error: %s\n",
 202                         (unsigned long long)subvol_id, ret, strerror(errno));
 203                 return ret;
 204         }
 205
 206         if (search_arg.key.nr_items < 1) {
 207                 fprintf(stderr,
 208                         "failed to lookup subvol_id %llu!\n",
 209                         (unsigned long long)subvol_id);
 210                 return -ENOENT;
 211         }
 212         search_header = (struct btrfs_ioctl_search_header *)search_arg.buf;
 213         backref_item = (struct btrfs_root_ref *)(search_header + 1);
 214         if (search_header->offset != BTRFS_FS_TREE_OBJECTID) {
 215                 int sub_ret;
 216
 217                 sub_ret = btrfs_subvolid_resolve_sub(fd, path, path_len,
 218                                                      search_header->offset);
 219                 if (sub_ret)
 220                         return sub_ret;
 221                 if (*path_len < 1)
 222                         return -EOVERFLOW;
 223                 strcat(path, "/");
 224                 (*path_len)--;
 225         }
 226
 227         if (btrfs_stack_root_ref_dirid(backref_item) !=
 228             BTRFS_FIRST_FREE_OBJECTID) {
 229                 int len;
 230
 231                 memset(&ino_lookup_arg, 0, sizeof(ino_lookup_arg));
 232                 ino_lookup_arg.treeid = search_header->offset;
 233                 ino_lookup_arg.objectid =
 234                         btrfs_stack_root_ref_dirid(backref_item);
 235                 ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_lookup_arg);
 236                 if (ret) {
 237                         fprintf(stderr,
 238                                 "ioctl(BTRFS_IOC_INO_LOOKUP) ret=%d, error: %s\n",
 239                                 ret, strerror(errno));
 240                         return ret;
 241                 }
 242
 243                 len = strlen(ino_lookup_arg.name);
 244                 if (*path_len < len)
 245                         return -EOVERFLOW;
 246                 strcat(path, ino_lookup_arg.name);
 247                 (*path_len) -= len;
 248         }
 249
 250         if (*path_len < btrfs_stack_root_ref_name_len(backref_item))
 251                 return -EOVERFLOW;
 252         strncat(path, (char *)(backref_item + 1),
 253                 btrfs_stack_root_ref_name_len(backref_item));
 254         (*path_len) -= btrfs_stack_root_ref_name_len(backref_item);
 255         return 0;
 256 }
 257
 258 void subvol_uuid_search_add(struct subvol_uuid_search *s,
 259                             struct subvol_info *si)
 260 {
 261         if (si) {
 262                 free(si->path);
 263                 free(si);
 264         }
 265 }
 266
 267 struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
 268                                        u64 root_id, const u8 *uuid, u64 transid,
 269                                        const char *path,
 270                                        enum subvol_search_type type)
 271 {
 272         int ret = 0;
 273         struct btrfs_root_item root_item;
 274         struct subvol_info *info = NULL;
 275
 276         switch (type) {
 277         case subvol_search_by_received_uuid:
 278                 ret = btrfs_lookup_uuid_received_subvol_item(s->mnt_fd, uuid,
 279                                                              &root_id);
 280                 break;
 281         case subvol_search_by_uuid:
 282                 ret = btrfs_lookup_uuid_subvol_item(s->mnt_fd, uuid, &root_id);
 283                 break;
 284         case subvol_search_by_root_id:
 285                 break;
 286         case subvol_search_by_path:
 287                 ret = btrfs_get_root_id_by_sub_path(s->mnt_fd, path, &root_id);
 288                 break;
 289         default:
 290                 ret = -EINVAL;
 291                 break;
 292         }
 293
 294         if (ret)
 295                 goto out;
 296
 297         ret = btrfs_read_root_item(s->mnt_fd, root_id, &root_item);
 298         if (ret)
 299                 goto out;
 300
 301         info = calloc(1, sizeof(*info));
 302         info->root_id = root_id;
 303         memcpy(info->uuid, root_item.uuid, BTRFS_UUID_SIZE);
 304         memcpy(info->received_uuid, root_item.received_uuid, BTRFS_UUID_SIZE);
 305         memcpy(info->parent_uuid, root_item.parent_uuid, BTRFS_UUID_SIZE);
 306         info->ctransid = btrfs_root_ctransid(&root_item);
 307         info->otransid = btrfs_root_otransid(&root_item);
 308         info->stransid = btrfs_root_stransid(&root_item);
 309         info->rtransid = btrfs_root_rtransid(&root_item);
 310         if (type == subvol_search_by_path) {
 311                 info->path = strdup(path);
 312         } else {
 313                 info->path = malloc(BTRFS_PATH_NAME_MAX);
 314                 ret = btrfs_subvolid_resolve(s->mnt_fd, info->path,
 315                                              BTRFS_PATH_NAME_MAX, root_id);
 316         }
 317
 318 out:
 319         if (ret && info) {
 320                 free(info->path);
 321                 free(info);
 322                 info = NULL;
 323         }
 324
 325         return info;
 326 }
 327
 328 int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
 329 {
 330         s->mnt_fd = mnt_fd;
 331
 332         return 0;
 333 }
 334
 335 void subvol_uuid_search_finit(struct subvol_uuid_search *s)
 336 {
 337 }
 338
 339 char *path_cat(const char *p1, const char *p2)
 340 {
 341         int p1_len = strlen(p1);
 342         int p2_len = strlen(p2);
 343         char *new = malloc(p1_len + p2_len + 2);
 344
 345         if (p1_len && p1[p1_len - 1] == '/')
 346                 p1_len--;
 347         if (p2_len && p2[p2_len - 1] == '/')
 348                 p2_len--;
 349         sprintf(new, "%.*s/%.*s", p1_len, p1, p2_len, p2);
 350         return new;
 351 }
 352
 353 char *path_cat3(const char *p1, const char *p2, const char *p3)
 354 {
 355         int p1_len = strlen(p1);
 356         int p2_len = strlen(p2);
 357         int p3_len = strlen(p3);
 358         char *new = malloc(p1_len + p2_len + p3_len + 3);
 359
 360         if (p1_len && p1[p1_len - 1] == '/')
 361                 p1_len--;
 362         if (p2_len && p2[p2_len - 1] == '/')
 363                 p2_len--;
 364         if (p3_len && p3[p3_len - 1] == '/')
 365                 p3_len--;
 366         sprintf(new, "%.*s/%.*s/%.*s", p1_len, p1, p2_len, p2, p3_len, p3);
 367         return new;
 368 }