lib/loopdev.c

   1
   2 /*
   3  * No copyright is claimed.  This code is in the public domain; do with
   4  * it what you wish.
   5  *
   6  * Written by Karel Zak <kzak@redhat.com>
   7  *
   8  * -- based on mount/losetup.c
   9  *
  10  * Simple library for work with loop devices.
  11  *
  12  *  - requires kernel 2.6.x
  13  *  - reads info from /sys/block/loop<N>/loop/<attr> (new kernels)
  14  *  - reads info by ioctl
  15  *  - supports *unlimited* number of loop devices
  16  *  - supports /dev/loop<N> as well as /dev/loop/<N>
  17  *  - minimize overhead (fd, loopinfo, ... are shared for all operations)
  18  *  - setup (associate device and backing file)
  19  *  - delete (dis-associate file)
  20  *  - old LOOP_{SET,GET}_STATUS (32bit) ioctls are unsupported
  21  *  - extendible
  22  */
  23 #include <stdio.h>
  24 #include <stdint.h>
  25 #include <string.h>
  26 #include <ctype.h>
  27 #include <fcntl.h>
  28 #include <stdlib.h>
  29 #include <unistd.h>
  30 #include <sys/ioctl.h>
  31 #include <sys/stat.h>
  32 #include <sys/mman.h>
  33 #include <inttypes.h>
  34 #include <dirent.h>
  35
  36 #include "linux_version.h"
  37 #include "c.h"
  38 #include "sysfs.h"
  39 #include "pathnames.h"
  40 #include "loopdev.h"
  41 #include "canonicalize.h"
  42 #include "blkdev.h"
  43 #include "debug.h"
  44
  45 /*
  46  * Debug stuff (based on include/debug.h)
  47  */
  48 static UL_DEBUG_DEFINE_MASK(loopdev);
  49 UL_DEBUG_DEFINE_MASKNAMES(loopdev) = UL_DEBUG_EMPTY_MASKNAMES;
  50
  51 #define LOOPDEV_DEBUG_INIT      (1 << 1)
  52 #define LOOPDEV_DEBUG_CXT       (1 << 2)
  53 #define LOOPDEV_DEBUG_ITER      (1 << 3)
  54 #define LOOPDEV_DEBUG_SETUP     (1 << 4)
  55
  56 #define DBG(m, x)       __UL_DBG(loopdev, LOOPDEV_DEBUG_, m, x)
  57 #define ON_DBG(m, x)    __UL_DBG_CALL(loopdev, LOOPDEV_DEBUG_, m, x)
  58
  59 #define UL_DEBUG_CURRENT_MASK   UL_DEBUG_MASK(loopdev)
  60 #include "debugobj.h"
  61
  62 static void loopdev_init_debug(void)
  63 {
  64         if (loopdev_debug_mask)
  65                 return;
  66         __UL_INIT_DEBUG_FROM_ENV(loopdev, LOOPDEV_DEBUG_, 0, LOOPDEV_DEBUG);
  67 }
  68
  69 /*
  70  * see loopcxt_init()
  71  */
  72 #define loopcxt_ioctl_enabled(_lc)      (!((_lc)->flags & LOOPDEV_FL_NOIOCTL))
  73 #define loopcxt_sysfs_available(_lc)    (!((_lc)->flags & LOOPDEV_FL_NOSYSFS)) \
  74                                          && !loopcxt_ioctl_enabled(_lc)
  75
  76 /*
  77  * @lc: context
  78  * @device: device name, absolute device path or NULL to reset the current setting
  79  *
  80  * Sets device, absolute paths (e.g. "/dev/loop<N>") are unchanged, device
  81  * names ("loop<N>") are converted to the path (/dev/loop<N> or to
  82  * /dev/loop/<N>)
  83  *
  84  * This sets the device name, but does not check if the device exists!
  85  *
  86  * Returns: <0 on error, 0 on success
  87  */
  88 int loopcxt_set_device(struct loopdev_cxt *lc, const char *device)
  89 {
  90         if (!lc)
  91                 return -EINVAL;
  92
  93         if (lc->fd >= 0) {
  94                 close(lc->fd);
  95                 DBG(CXT, ul_debugobj(lc, "closing old open fd"));
  96         }
  97         lc->fd = -1;
  98         lc->mode = 0;
  99         lc->blocksize = 0;
 100         lc->has_info = 0;
 101         lc->info_failed = 0;
 102         *lc->device = '\0';
 103         memset(&lc->info, 0, sizeof(lc->info));
 104
 105         /* set new */
 106         if (device) {
 107                 if (*device != '/') {
 108                         const char *dir = _PATH_DEV;
 109
 110                         /* compose device name for /dev/loop<n> or /dev/loop/<n> */
 111                         if (lc->flags & LOOPDEV_FL_DEVSUBDIR) {
 112                                 if (strlen(device) < 5)
 113                                         return -1;
 114                                 device += 4;
 115                                 dir = _PATH_DEV_LOOP "/";       /* _PATH_DEV uses tailing slash */
 116                         }
 117                         snprintf(lc->device, sizeof(lc->device), "%s%s",
 118                                 dir, device);
 119                 } else {
 120                         strncpy(lc->device, device, sizeof(lc->device));
 121                         lc->device[sizeof(lc->device) - 1] = '\0';
 122                 }
 123                 DBG(CXT, ul_debugobj(lc, "%s name assigned", device));
 124         }
 125
 126         ul_unref_path(lc->sysfs);
 127         lc->sysfs = NULL;
 128         return 0;
 129 }
 130
 131 inline int loopcxt_has_device(struct loopdev_cxt *lc)
 132 {
 133         return lc && *lc->device;
 134 }
 135
 136 /*
 137  * @lc: context
 138  * @flags: LOOPDEV_FL_* flags
 139  *
 140  * Initialize loop handler.
 141  *
 142  * We have two sets of the flags:
 143  *
 144  *      * LOOPDEV_FL_* flags control loopcxt_* API behavior
 145  *
 146  *      * LO_FLAGS_* are kernel flags used for LOOP_{SET,GET}_STAT64 ioctls
 147  *
 148  * Note about LOOPDEV_FL_{RDONLY,RDWR} flags. These flags are used for open(2)
 149  * syscall to open loop device. By default is the device open read-only.
 150  *
 151  * The exception is loopcxt_setup_device(), where the device is open read-write
 152  * if LO_FLAGS_READ_ONLY flags is not set (see loopcxt_set_flags()).
 153  *
 154  * Returns: <0 on error, 0 on success.
 155  */
 156 int loopcxt_init(struct loopdev_cxt *lc, int flags)
 157 {
 158         int rc;
 159         struct stat st;
 160         struct loopdev_cxt dummy = UL_LOOPDEVCXT_EMPTY;
 161
 162         if (!lc)
 163                 return -EINVAL;
 164
 165         loopdev_init_debug();
 166         DBG(CXT, ul_debugobj(lc, "initialize context"));
 167
 168         memcpy(lc, &dummy, sizeof(dummy));
 169         lc->flags = flags;
 170
 171         rc = loopcxt_set_device(lc, NULL);
 172         if (rc)
 173                 return rc;
 174
 175         if (stat(_PATH_SYS_BLOCK, &st) || !S_ISDIR(st.st_mode)) {
 176                 lc->flags |= LOOPDEV_FL_NOSYSFS;
 177                 lc->flags &= ~LOOPDEV_FL_NOIOCTL;
 178                 DBG(CXT, ul_debugobj(lc, "init: disable /sys usage"));
 179         }
 180
 181         if (!(lc->flags & LOOPDEV_FL_NOSYSFS) &&
 182             get_linux_version() >= KERNEL_VERSION(2,6,37)) {
 183                 /*
 184                  * Use only sysfs for basic information about loop devices
 185                  */
 186                 lc->flags |= LOOPDEV_FL_NOIOCTL;
 187                 DBG(CXT, ul_debugobj(lc, "init: ignore ioctls"));
 188         }
 189
 190         if (!(lc->flags & LOOPDEV_FL_CONTROL) && !stat(_PATH_DEV_LOOPCTL, &st)) {
 191                 lc->flags |= LOOPDEV_FL_CONTROL;
 192                 DBG(CXT, ul_debugobj(lc, "init: loop-control detected "));
 193         }
 194
 195         return 0;
 196 }
 197
 198 /*
 199  * @lc: context
 200  *
 201  * Deinitialize loop context
 202  */
 203 void loopcxt_deinit(struct loopdev_cxt *lc)
 204 {
 205         int errsv = errno;
 206
 207         if (!lc)
 208                 return;
 209
 210         DBG(CXT, ul_debugobj(lc, "de-initialize"));
 211
 212         free(lc->filename);
 213         lc->filename = NULL;
 214
 215         ignore_result( loopcxt_set_device(lc, NULL) );
 216         loopcxt_deinit_iterator(lc);
 217
 218         errno = errsv;
 219 }
 220
 221 /*
 222  * @lc: context
 223  *
 224  * Returns newly allocated device path.
 225  */
 226 char *loopcxt_strdup_device(struct loopdev_cxt *lc)
 227 {
 228         if (!lc || !*lc->device)
 229                 return NULL;
 230         return strdup(lc->device);
 231 }
 232
 233 /*
 234  * @lc: context
 235  *
 236  * Returns pointer device name in the @lc struct.
 237  */
 238 const char *loopcxt_get_device(struct loopdev_cxt *lc)
 239 {
 240         return lc && *lc->device ? lc->device : NULL;
 241 }
 242
 243 /*
 244  * @lc: context
 245  *
 246  * Returns pointer to the sysfs context (see lib/sysfs.c)
 247  */
 248 static struct path_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc)
 249 {
 250         if (!lc || !*lc->device || (lc->flags & LOOPDEV_FL_NOSYSFS))
 251                 return NULL;
 252
 253         if (!lc->sysfs) {
 254                 dev_t devno = sysfs_devname_to_devno(lc->device);
 255                 if (!devno) {
 256                         DBG(CXT, ul_debugobj(lc, "sysfs: failed devname to devno"));
 257                         return NULL;
 258                 }
 259
 260                 lc->sysfs = ul_new_sysfs_path(devno, NULL, NULL);
 261                 if (!lc->sysfs)
 262                         DBG(CXT, ul_debugobj(lc, "sysfs: init failed"));
 263         }
 264
 265         return lc->sysfs;
 266 }
 267
 268 /*
 269  * @lc: context
 270  *
 271  * Returns: file descriptor to the open loop device or <0 on error. The mode
 272  *          depends on LOOPDEV_FL_{RDWR,RDONLY} context flags. Default is
 273  *          read-only.
 274  */
 275 int loopcxt_get_fd(struct loopdev_cxt *lc)
 276 {
 277         if (!lc || !*lc->device)
 278                 return -EINVAL;
 279
 280         if (lc->fd < 0) {
 281                 lc->mode = lc->flags & LOOPDEV_FL_RDWR ? O_RDWR : O_RDONLY;
 282                 lc->fd = open(lc->device, lc->mode | O_CLOEXEC);
 283                 DBG(CXT, ul_debugobj(lc, "open %s [%s]: %m", lc->device,
 284                                 lc->flags & LOOPDEV_FL_RDWR ? "rw" : "ro"));
 285         }
 286         return lc->fd;
 287 }
 288
 289 int loopcxt_set_fd(struct loopdev_cxt *lc, int fd, int mode)
 290 {
 291         if (!lc)
 292                 return -EINVAL;
 293
 294         lc->fd = fd;
 295         lc->mode = mode;
 296         return 0;
 297 }
 298
 299 /*
 300  * @lc: context
 301  * @flags: LOOPITER_FL_* flags
 302  *
 303  * Iterator allows to scan list of the free or used loop devices.
 304  *
 305  * Returns: <0 on error, 0 on success
 306  */
 307 int loopcxt_init_iterator(struct loopdev_cxt *lc, int flags)
 308 {
 309         struct loopdev_iter *iter;
 310         struct stat st;
 311
 312         if (!lc)
 313                 return -EINVAL;
 314
 315
 316         iter = &lc->iter;
 317         DBG(ITER, ul_debugobj(iter, "initialize"));
 318
 319         /* always zeroize
 320          */
 321         memset(iter, 0, sizeof(*iter));
 322         iter->ncur = -1;
 323         iter->flags = flags;
 324         iter->default_check = 1;
 325
 326         if (!lc->extra_check) {
 327                 /*
 328                  * Check for /dev/loop/<N> subdirectory
 329                  */
 330                 if (!(lc->flags & LOOPDEV_FL_DEVSUBDIR) &&
 331                     stat(_PATH_DEV_LOOP, &st) == 0 && S_ISDIR(st.st_mode))
 332                         lc->flags |= LOOPDEV_FL_DEVSUBDIR;
 333
 334                 lc->extra_check = 1;
 335         }
 336         return 0;
 337 }
 338
 339 /*
 340  * @lc: context
 341  *
 342  * Returns: <0 on error, 0 on success
 343  */
 344 int loopcxt_deinit_iterator(struct loopdev_cxt *lc)
 345 {
 346         struct loopdev_iter *iter;
 347
 348         if (!lc)
 349                 return -EINVAL;
 350
 351         iter = &lc->iter;
 352         DBG(ITER, ul_debugobj(iter, "de-initialize"));
 353
 354         free(iter->minors);
 355         if (iter->proc)
 356                 fclose(iter->proc);
 357         if (iter->sysblock)
 358                 closedir(iter->sysblock);
 359
 360         memset(iter, 0, sizeof(*iter));
 361         return 0;
 362 }
 363
 364 /*
 365  * Same as loopcxt_set_device, but also checks if the device is
 366  * associated with any file.
 367  *
 368  * Returns: <0 on error, 0 on success, 1 device does not match with
 369  *         LOOPITER_FL_{USED,FREE} flags.
 370  */
 371 static int loopiter_set_device(struct loopdev_cxt *lc, const char *device)
 372 {
 373         int rc = loopcxt_set_device(lc, device);
 374         int used;
 375
 376         if (rc)
 377                 return rc;
 378
 379         if (!(lc->iter.flags & LOOPITER_FL_USED) &&
 380             !(lc->iter.flags & LOOPITER_FL_FREE))
 381                 return 0;       /* caller does not care about device status */
 382
 383         if (!is_loopdev(lc->device)) {
 384                 DBG(ITER, ul_debugobj(&lc->iter, "%s does not exist", lc->device));
 385                 return -errno;
 386         }
 387
 388         DBG(ITER, ul_debugobj(&lc->iter, "%s exist", lc->device));
 389
 390         used = loopcxt_get_offset(lc, NULL) == 0;
 391
 392         if ((lc->iter.flags & LOOPITER_FL_USED) && used)
 393                 return 0;
 394
 395         if ((lc->iter.flags & LOOPITER_FL_FREE) && !used)
 396                 return 0;
 397
 398         DBG(ITER, ul_debugobj(&lc->iter, "failed to use %s device", lc->device));
 399
 400         ignore_result( loopcxt_set_device(lc, NULL) );
 401         return 1;
 402 }
 403
 404 static int cmpnum(const void *p1, const void *p2)
 405 {
 406         return (((* (const int *) p1) > (* (const int *) p2)) -
 407                         ((* (const int *) p1) < (* (const int *) p2)));
 408 }
 409
 410 /*
 411  * The classic scandir() is more expensive and less portable.
 412  * We needn't full loop device names -- loop numbers (loop<N>)
 413  * are enough.
 414  */
 415 static int loop_scandir(const char *dirname, int **ary, int hasprefix)
 416 {
 417         DIR *dir;
 418         struct dirent *d;
 419         unsigned int n, count = 0, arylen = 0;
 420
 421         if (!dirname || !ary)
 422                 return 0;
 423
 424         DBG(ITER, ul_debug("scan dir: %s", dirname));
 425
 426         dir = opendir(dirname);
 427         if (!dir)
 428                 return 0;
 429         free(*ary);
 430         *ary = NULL;
 431
 432         while((d = readdir(dir))) {
 433 #ifdef _DIRENT_HAVE_D_TYPE
 434                 if (d->d_type != DT_BLK && d->d_type != DT_UNKNOWN &&
 435                     d->d_type != DT_LNK)
 436                         continue;
 437 #endif
 438                 if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
 439                         continue;
 440
 441                 if (hasprefix) {
 442                         /* /dev/loop<N> */
 443                         if (sscanf(d->d_name, "loop%u", &n) != 1)
 444                                 continue;
 445                 } else {
 446                         /* /dev/loop/<N> */
 447                         char *end = NULL;
 448
 449                         errno = 0;
 450                         n = strtol(d->d_name, &end, 10);
 451                         if (d->d_name == end || (end && *end) || errno)
 452                                 continue;
 453                 }
 454                 if (n < LOOPDEV_DEFAULT_NNODES)
 455                         continue;                       /* ignore loop<0..7> */
 456
 457                 if (count + 1 > arylen) {
 458                         int *tmp;
 459
 460                         arylen += 1;
 461
 462                         tmp = realloc(*ary, arylen * sizeof(int));
 463                         if (!tmp) {
 464                                 free(*ary);
 465                                 *ary = NULL;
 466                                 closedir(dir);
 467                                 return -1;
 468                         }
 469                         *ary = tmp;
 470                 }
 471                 if (*ary)
 472                         (*ary)[count++] = n;
 473         }
 474         if (count && *ary)
 475                 qsort(*ary, count, sizeof(int), cmpnum);
 476
 477         closedir(dir);
 478         return count;
 479 }
 480
 481 /*
 482  * Set the next *used* loop device according to /proc/partitions.
 483  *
 484  * Loop devices smaller than 512 bytes are invisible for this function.
 485  */
 486 static int loopcxt_next_from_proc(struct loopdev_cxt *lc)
 487 {
 488         struct loopdev_iter *iter = &lc->iter;
 489         char buf[BUFSIZ];
 490
 491         DBG(ITER, ul_debugobj(iter, "scan /proc/partitions"));
 492
 493         if (!iter->proc)
 494                 iter->proc = fopen(_PATH_PROC_PARTITIONS, "r" UL_CLOEXECSTR);
 495         if (!iter->proc)
 496                 return 1;
 497
 498         while (fgets(buf, sizeof(buf), iter->proc)) {
 499                 unsigned int m;
 500                 char name[128 + 1];
 501
 502
 503                 if (sscanf(buf, " %u %*s %*s %128[^\n ]",
 504                            &m, name) != 2 || m != LOOPDEV_MAJOR)
 505                         continue;
 506
 507                 DBG(ITER, ul_debugobj(iter, "checking %s", name));
 508
 509                 if (loopiter_set_device(lc, name) == 0)
 510                         return 0;
 511         }
 512
 513         return 1;
 514 }
 515
 516 /*
 517  * Set the next *used* loop device according to
 518  * /sys/block/loopN/loop/backing_file (kernel >= 2.6.37 is required).
 519  *
 520  * This is preferred method.
 521  */
 522 static int loopcxt_next_from_sysfs(struct loopdev_cxt *lc)
 523 {
 524         struct loopdev_iter *iter = &lc->iter;
 525         struct dirent *d;
 526         int fd;
 527
 528         DBG(ITER, ul_debugobj(iter, "scanning /sys/block"));
 529
 530         if (!iter->sysblock)
 531                 iter->sysblock = opendir(_PATH_SYS_BLOCK);
 532
 533         if (!iter->sysblock)
 534                 return 1;
 535
 536         fd = dirfd(iter->sysblock);
 537
 538         while ((d = readdir(iter->sysblock))) {
 539                 char name[NAME_MAX + 18 + 1];
 540                 struct stat st;
 541
 542                 DBG(ITER, ul_debugobj(iter, "check %s", d->d_name));
 543
 544                 if (strcmp(d->d_name, ".") == 0
 545                     || strcmp(d->d_name, "..") == 0
 546                     || strncmp(d->d_name, "loop", 4) != 0)
 547                         continue;
 548
 549                 snprintf(name, sizeof(name), "%s/loop/backing_file", d->d_name);
 550                 if (fstatat(fd, name, &st, 0) != 0)
 551                         continue;
 552
 553                 if (loopiter_set_device(lc, d->d_name) == 0)
 554                         return 0;
 555         }
 556
 557         return 1;
 558 }
 559
 560 /*
 561  * @lc: context, has to initialized by loopcxt_init_iterator()
 562  *
 563  * Returns: 0 on success, -1 on error, 1 at the end of scanning. The details
 564  *          about the current loop device are available by
 565  *          loopcxt_get_{fd,backing_file,device,offset, ...} functions.
 566  */
 567 int loopcxt_next(struct loopdev_cxt *lc)
 568 {
 569         struct loopdev_iter *iter;
 570
 571         if (!lc)
 572                 return -EINVAL;
 573
 574
 575         iter = &lc->iter;
 576         if (iter->done)
 577                 return 1;
 578
 579         DBG(ITER, ul_debugobj(iter, "next"));
 580
 581         /* A) Look for used loop devices in /proc/partitions ("losetup -a" only)
 582          */
 583         if (iter->flags & LOOPITER_FL_USED) {
 584                 int rc;
 585
 586                 if (loopcxt_sysfs_available(lc))
 587                         rc = loopcxt_next_from_sysfs(lc);
 588                 else
 589                         rc = loopcxt_next_from_proc(lc);
 590                 if (rc == 0)
 591                         return 0;
 592                 goto done;
 593         }
 594
 595         /* B) Classic way, try first eight loop devices (default number
 596          *    of loop devices). This is enough for 99% of all cases.
 597          */
 598         if (iter->default_check) {
 599                 DBG(ITER, ul_debugobj(iter, "next: default check"));
 600                 for (++iter->ncur; iter->ncur < LOOPDEV_DEFAULT_NNODES;
 601                                                         iter->ncur++) {
 602                         char name[16];
 603                         snprintf(name, sizeof(name), "loop%d", iter->ncur);
 604
 605                         if (loopiter_set_device(lc, name) == 0)
 606                                 return 0;
 607                 }
 608                 iter->default_check = 0;
 609         }
 610
 611         /* C) the worst possibility, scan whole /dev or /dev/loop/<N>
 612          */
 613         if (!iter->minors) {
 614                 DBG(ITER, ul_debugobj(iter, "next: scanning /dev"));
 615                 iter->nminors = (lc->flags & LOOPDEV_FL_DEVSUBDIR) ?
 616                         loop_scandir(_PATH_DEV_LOOP, &iter->minors, 0) :
 617                         loop_scandir(_PATH_DEV, &iter->minors, 1);
 618                 iter->ncur = -1;
 619         }
 620         for (++iter->ncur; iter->ncur < iter->nminors; iter->ncur++) {
 621                 char name[16];
 622                 snprintf(name, sizeof(name), "loop%d", iter->minors[iter->ncur]);
 623
 624                 if (loopiter_set_device(lc, name) == 0)
 625                         return 0;
 626         }
 627 done:
 628         loopcxt_deinit_iterator(lc);
 629         return 1;
 630 }
 631
 632 /*
 633  * @device: path to device
 634  */
 635 int is_loopdev(const char *device)
 636 {
 637         struct stat st;
 638
 639         if (device && stat(device, &st) == 0 &&
 640                 S_ISBLK(st.st_mode) &&
 641                 major(st.st_rdev) == LOOPDEV_MAJOR)
 642                 return 1;
 643
 644         errno = ENODEV;
 645         return 0;
 646 }
 647
 648 /*
 649  * @lc: context
 650  *
 651  * Returns result from LOOP_GET_STAT64 ioctl or NULL on error.
 652  */
 653 struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc)
 654 {
 655         int fd;
 656
 657         if (!lc || lc->info_failed) {
 658                 errno = EINVAL;
 659                 return NULL;
 660         }
 661         errno = 0;
 662         if (lc->has_info)
 663                 return &lc->info;
 664
 665         fd = loopcxt_get_fd(lc);
 666         if (fd < 0)
 667                 return NULL;
 668
 669         if (ioctl(fd, LOOP_GET_STATUS64, &lc->info) == 0) {
 670                 lc->has_info = 1;
 671                 lc->info_failed = 0;
 672                 DBG(CXT, ul_debugobj(lc, "reading loop_info64 OK"));
 673                 return &lc->info;
 674         }
 675
 676         lc->info_failed = 1;
 677         DBG(CXT, ul_debugobj(lc, "reading loop_info64 FAILED"));
 678
 679         return NULL;
 680 }
 681
 682 /*
 683  * @lc: context
 684  *
 685  * Returns (allocated) string with path to the file assicieted
 686  * with the current loop device.
 687  */
 688 char *loopcxt_get_backing_file(struct loopdev_cxt *lc)
 689 {
 690         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 691         char *res = NULL;
 692
 693         if (sysfs)
 694                 /*
 695                  * This is always preferred, the loop_info64
 696                  * has too small buffer for the filename.
 697                  */
 698                 ul_path_read_string(sysfs, &res, "loop/backing_file");
 699
 700         if (!res && loopcxt_ioctl_enabled(lc)) {
 701                 struct loop_info64 *lo = loopcxt_get_info(lc);
 702
 703                 if (lo) {
 704                         lo->lo_file_name[LO_NAME_SIZE - 2] = '*';
 705                         lo->lo_file_name[LO_NAME_SIZE - 1] = '\0';
 706                         res = strdup((char *) lo->lo_file_name);
 707                 }
 708         }
 709
 710         DBG(CXT, ul_debugobj(lc, "get_backing_file [%s]", res));
 711         return res;
 712 }
 713
 714 /*
 715  * @lc: context
 716  * @offset: returns offset number for the given device
 717  *
 718  * Returns: <0 on error, 0 on success
 719  */
 720 int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset)
 721 {
 722         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 723         int rc = -EINVAL;
 724
 725         if (sysfs)
 726                 rc = ul_path_read_u64(sysfs, offset, "loop/offset");
 727
 728         if (rc && loopcxt_ioctl_enabled(lc)) {
 729                 struct loop_info64 *lo = loopcxt_get_info(lc);
 730                 if (lo) {
 731                         if (offset)
 732                                 *offset = lo->lo_offset;
 733                         rc = 0;
 734                 } else
 735                         rc = -errno;
 736         }
 737
 738         DBG(CXT, ul_debugobj(lc, "get_offset [rc=%d]", rc));
 739         return rc;
 740 }
 741
 742 /*
 743  * @lc: context
 744  * @blocksize: returns logical blocksize for the given device
 745  *
 746  * Returns: <0 on error, 0 on success
 747  */
 748 int loopcxt_get_blocksize(struct loopdev_cxt *lc, uint64_t *blocksize)
 749 {
 750         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 751         int rc = -EINVAL;
 752
 753         if (sysfs)
 754                 rc = ul_path_read_u64(sysfs, blocksize, "queue/logical_block_size");
 755
 756         /* Fallback based on BLKSSZGET ioctl */
 757         if (rc) {
 758                 int fd = loopcxt_get_fd(lc);
 759                 int sz = 0;
 760
 761                 if (fd < 0)
 762                         return -EINVAL;
 763                 rc = blkdev_get_sector_size(fd, &sz);
 764                 if (rc)
 765                         return rc;
 766
 767                 *blocksize = sz;
 768         }
 769
 770         DBG(CXT, ul_debugobj(lc, "get_blocksize [rc=%d]", rc));
 771         return rc;
 772 }
 773
 774 /*
 775  * @lc: context
 776  * @sizelimit: returns size limit for the given device
 777  *
 778  * Returns: <0 on error, 0 on success
 779  */
 780 int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size)
 781 {
 782         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 783         int rc = -EINVAL;
 784
 785         if (sysfs)
 786                 rc = ul_path_read_u64(sysfs, size, "loop/sizelimit");
 787
 788         if (rc && loopcxt_ioctl_enabled(lc)) {
 789                 struct loop_info64 *lo = loopcxt_get_info(lc);
 790                 if (lo) {
 791                         if (size)
 792                                 *size = lo->lo_sizelimit;
 793                         rc = 0;
 794                 } else
 795                         rc = -errno;
 796         }
 797
 798         DBG(CXT, ul_debugobj(lc, "get_sizelimit [rc=%d]", rc));
 799         return rc;
 800 }
 801
 802 /*
 803  * @lc: context
 804  * @devno: returns encryption type
 805  *
 806  * Cryptoloop is DEPRECATED!
 807  *
 808  * Returns: <0 on error, 0 on success
 809  */
 810 int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type)
 811 {
 812         struct loop_info64 *lo = loopcxt_get_info(lc);
 813         int rc;
 814
 815         /* not provided by sysfs */
 816         if (lo) {
 817                 if (type)
 818                         *type = lo->lo_encrypt_type;
 819                 rc = 0;
 820         } else
 821                 rc = -errno;
 822
 823         DBG(CXT, ul_debugobj(lc, "get_encrypt_type [rc=%d]", rc));
 824         return rc;
 825 }
 826
 827 /*
 828  * @lc: context
 829  * @devno: returns crypt name
 830  *
 831  * Cryptoloop is DEPRECATED!
 832  *
 833  * Returns: <0 on error, 0 on success
 834  */
 835 const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc)
 836 {
 837         struct loop_info64 *lo = loopcxt_get_info(lc);
 838
 839         if (lo)
 840                 return (char *) lo->lo_crypt_name;
 841
 842         DBG(CXT, ul_debugobj(lc, "get_crypt_name failed"));
 843         return NULL;
 844 }
 845
 846 /*
 847  * @lc: context
 848  * @devno: returns backing file devno
 849  *
 850  * Returns: <0 on error, 0 on success
 851  */
 852 int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno)
 853 {
 854         struct loop_info64 *lo = loopcxt_get_info(lc);
 855         int rc;
 856
 857         if (lo) {
 858                 if (devno)
 859                         *devno = lo->lo_device;
 860                 rc = 0;
 861         } else
 862                 rc = -errno;
 863
 864         DBG(CXT, ul_debugobj(lc, "get_backing_devno [rc=%d]", rc));
 865         return rc;
 866 }
 867
 868 /*
 869  * @lc: context
 870  * @ino: returns backing file inode
 871  *
 872  * Returns: <0 on error, 0 on success
 873  */
 874 int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino)
 875 {
 876         struct loop_info64 *lo = loopcxt_get_info(lc);
 877         int rc;
 878
 879         if (lo) {
 880                 if (ino)
 881                         *ino = lo->lo_inode;
 882                 rc = 0;
 883         } else
 884                 rc = -errno;
 885
 886         DBG(CXT, ul_debugobj(lc, "get_backing_inode [rc=%d]", rc));
 887         return rc;
 888 }
 889
 890 /*
 891  * Check if the kernel supports partitioned loop devices.
 892  *
 893  * Notes:
 894  *   - kernels < 3.2 support partitioned loop devices and PT scanning
 895  *     only if max_part= module parameter is non-zero
 896  *
 897  *   - kernels >= 3.2 always support partitioned loop devices
 898  *
 899  *   - kernels >= 3.2 always support BLKPG_{ADD,DEL}_PARTITION ioctls
 900  *
 901  *   - kernels >= 3.2 enable PT scanner only if max_part= is non-zero or if the
 902  *     LO_FLAGS_PARTSCAN flag is set for the device. The PT scanner is disabled
 903  *     by default.
 904  *
 905  *  See kernel commit e03c8dd14915fabc101aa495828d58598dc5af98.
 906  */
 907 int loopmod_supports_partscan(void)
 908 {
 909         int rc, ret = 0;
 910         FILE *f;
 911
 912         if (get_linux_version() >= KERNEL_VERSION(3,2,0))
 913                 return 1;
 914
 915         f = fopen("/sys/module/loop/parameters/max_part", "r" UL_CLOEXECSTR);
 916         if (!f)
 917                 return 0;
 918         rc = fscanf(f, "%d", &ret);
 919         fclose(f);
 920         return rc == 1 ? ret : 0;
 921 }
 922
 923 /*
 924  * @lc: context
 925  *
 926  * Returns: 1 if the partscan flags is set *or* (for old kernels) partitions
 927  * scanning is enabled for all loop devices.
 928  */
 929 int loopcxt_is_partscan(struct loopdev_cxt *lc)
 930 {
 931         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 932
 933         if (sysfs) {
 934                 /* kernel >= 3.2 */
 935                 int fl;
 936                 if (ul_path_read_s32(sysfs, &fl, "loop/partscan") == 0)
 937                         return fl;
 938         }
 939
 940         /* old kernels (including kernels without loopN/loop/<flags> directory */
 941         return loopmod_supports_partscan();
 942 }
 943
 944 /*
 945  * @lc: context
 946  *
 947  * Returns: 1 if the autoclear flags is set.
 948  */
 949 int loopcxt_is_autoclear(struct loopdev_cxt *lc)
 950 {
 951         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 952
 953         if (sysfs) {
 954                 int fl;
 955                 if (ul_path_read_s32(sysfs, &fl, "loop/autoclear") == 0)
 956                         return fl;
 957         }
 958
 959         if (loopcxt_ioctl_enabled(lc)) {
 960                 struct loop_info64 *lo = loopcxt_get_info(lc);
 961                 if (lo)
 962                         return lo->lo_flags & LO_FLAGS_AUTOCLEAR;
 963         }
 964         return 0;
 965 }
 966
 967 /*
 968  * @lc: context
 969  *
 970  * Returns: 1 if the readonly flags is set.
 971  */
 972 int loopcxt_is_readonly(struct loopdev_cxt *lc)
 973 {
 974         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 975
 976         if (sysfs) {
 977                 int fl;
 978                 if (ul_path_read_s32(sysfs, &fl, "ro") == 0)
 979                         return fl;
 980         }
 981
 982         if (loopcxt_ioctl_enabled(lc)) {
 983                 struct loop_info64 *lo = loopcxt_get_info(lc);
 984                 if (lo)
 985                         return lo->lo_flags & LO_FLAGS_READ_ONLY;
 986         }
 987         return 0;
 988 }
 989
 990 /*
 991  * @lc: context
 992  *
 993  * Returns: 1 if the dio flags is set.
 994  */
 995 int loopcxt_is_dio(struct loopdev_cxt *lc)
 996 {
 997         struct path_cxt *sysfs = loopcxt_get_sysfs(lc);
 998
 999         if (sysfs) {
1000                 int fl;
1001                 if (ul_path_read_s32(sysfs, &fl, "loop/dio") == 0)
1002                         return fl;
1003         }
1004         if (loopcxt_ioctl_enabled(lc)) {
1005                 struct loop_info64 *lo = loopcxt_get_info(lc);
1006                 if (lo)
1007                         return lo->lo_flags & LO_FLAGS_DIRECT_IO;
1008         }
1009         return 0;
1010 }
1011
1012 /*
1013  * @lc: context
1014  * @st: backing file stat or NULL
1015  * @backing_file: filename
1016  * @offset: offset (use LOOPDEV_FL_OFFSET if specified)
1017  * @sizelimit: size limit (use LOOPDEV_FL_SIZELIMIT if specified)
1018  * @flags: LOOPDEV_FL_{OFFSET,SIZELIMIT}
1019  *
1020  * Returns 1 if the current @lc loopdev is associated with the given backing
1021  * file. Note that the preferred way is to use devno and inode number rather
1022  * than filename. The @backing_file filename is poor solution usable in case
1023  * that you don't have rights to call stat().
1024  *
1025  * LOOPDEV_FL_SIZELIMIT requires LOOPDEV_FL_OFFSET being set as well.
1026  *
1027  * Don't forget that old kernels provide very restricted (in size) backing
1028  * filename by LOOP_GET_STAT64 ioctl only.
1029  */
1030 int loopcxt_is_used(struct loopdev_cxt *lc,
1031                     struct stat *st,
1032                     const char *backing_file,
1033                     uint64_t offset,
1034                     uint64_t sizelimit,
1035                     int flags)
1036 {
1037         ino_t ino;
1038         dev_t dev;
1039
1040         if (!lc)
1041                 return 0;
1042
1043         DBG(CXT, ul_debugobj(lc, "checking %s vs. %s",
1044                                 loopcxt_get_device(lc),
1045                                 backing_file));
1046
1047         if (st && loopcxt_get_backing_inode(lc, &ino) == 0 &&
1048                   loopcxt_get_backing_devno(lc, &dev) == 0) {
1049
1050                 if (ino == st->st_ino && dev == st->st_dev)
1051                         goto found;
1052
1053                 /* don't use filename if we have devno and inode */
1054                 return 0;
1055         }
1056
1057         /* poor man's solution */
1058         if (backing_file) {
1059                 char *name = loopcxt_get_backing_file(lc);
1060                 int rc = name && strcmp(name, backing_file) == 0;
1061
1062                 free(name);
1063                 if (rc)
1064                         goto found;
1065         }
1066
1067         return 0;
1068 found:
1069         if (flags & LOOPDEV_FL_OFFSET) {
1070                 uint64_t off;
1071
1072                 int rc = loopcxt_get_offset(lc, &off) == 0 && off == offset;
1073
1074                 if (rc && flags & LOOPDEV_FL_SIZELIMIT) {
1075                         uint64_t sz;
1076
1077                         return loopcxt_get_sizelimit(lc, &sz) == 0 && sz == sizelimit;
1078                 } else
1079                         return rc;
1080         }
1081         return 1;
1082 }
1083
1084 /*
1085  * The setting is removed by loopcxt_set_device() loopcxt_next()!
1086  */
1087 int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset)
1088 {
1089         if (!lc)
1090                 return -EINVAL;
1091         lc->info.lo_offset = offset;
1092
1093         DBG(CXT, ul_debugobj(lc, "set offset=%jd", offset));
1094         return 0;
1095 }
1096
1097 /*
1098  * The setting is removed by loopcxt_set_device() loopcxt_next()!
1099  */
1100 int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit)
1101 {
1102         if (!lc)
1103                 return -EINVAL;
1104         lc->info.lo_sizelimit = sizelimit;
1105
1106         DBG(CXT, ul_debugobj(lc, "set sizelimit=%jd", sizelimit));
1107         return 0;
1108 }
1109
1110 /*
1111  * The blocksize will be used by loopcxt_set_device(). For already exiting
1112  * devices use  loopcxt_ioctl_blocksize().
1113  *
1114  * The setting is removed by loopcxt_set_device() loopcxt_next()!
1115  */
1116 int loopcxt_set_blocksize(struct loopdev_cxt *lc, uint64_t blocksize)
1117 {
1118         if (!lc)
1119                 return -EINVAL;
1120         lc->blocksize = blocksize;
1121
1122         DBG(CXT, ul_debugobj(lc, "set blocksize=%jd", blocksize));
1123         return 0;
1124 }
1125
1126 /*
1127  * @lc: context
1128  * @flags: kernel LO_FLAGS_{READ_ONLY,USE_AOPS,AUTOCLEAR} flags
1129  *
1130  * The setting is removed by loopcxt_set_device() loopcxt_next()!
1131  *
1132  * Returns: 0 on success, <0 on error.
1133  */
1134 int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags)
1135 {
1136         if (!lc)
1137                 return -EINVAL;
1138         lc->info.lo_flags = flags;
1139
1140         DBG(CXT, ul_debugobj(lc, "set flags=%u", (unsigned) flags));
1141         return 0;
1142 }
1143
1144 /*
1145  * @lc: context
1146  * @filename: backing file path (the path will be canonicalized)
1147  *
1148  * The setting is removed by loopcxt_set_device() loopcxt_next()!
1149  *
1150  * Returns: 0 on success, <0 on error.
1151  */
1152 int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename)
1153 {
1154         if (!lc)
1155                 return -EINVAL;
1156
1157         lc->filename = canonicalize_path(filename);
1158         if (!lc->filename)
1159                 return -errno;
1160
1161         strncpy((char *)lc->info.lo_file_name, lc->filename, LO_NAME_SIZE);
1162         lc->info.lo_file_name[LO_NAME_SIZE- 1] = '\0';
1163
1164         DBG(CXT, ul_debugobj(lc, "set backing file=%s", lc->info.lo_file_name));
1165         return 0;
1166 }
1167
1168 /*
1169  * In kernels prior to v3.9, if the offset or sizelimit options
1170  * are used, the block device's size won't be synced automatically.
1171  * blockdev --getsize64 and filesystems will use the backing
1172  * file size until the block device has been re-opened or the
1173  * LOOP_SET_CAPACITY ioctl is called to sync the sizes.
1174  *
1175  * Since mount -oloop uses the LO_FLAGS_AUTOCLEAR option and passes
1176  * the open file descriptor to the mount system call, we need to use
1177  * the ioctl. Calling losetup directly doesn't have this problem since
1178  * it closes the device when it exits and whatever consumes the device
1179  * next will re-open it, causing the resync.
1180  */
1181 static int loopcxt_check_size(struct loopdev_cxt *lc, int file_fd)
1182 {
1183         uint64_t size, expected_size;
1184         int dev_fd;
1185         struct stat st;
1186
1187         if (!lc->info.lo_offset && !lc->info.lo_sizelimit)
1188                 return 0;
1189
1190         if (fstat(file_fd, &st)) {
1191                 DBG(CXT, ul_debugobj(lc, "failed to fstat backing file"));
1192                 return -errno;
1193         }
1194         if (S_ISBLK(st.st_mode)) {
1195                 if (blkdev_get_size(file_fd,
1196                                 (unsigned long long *) &expected_size)) {
1197                         DBG(CXT, ul_debugobj(lc, "failed to determine device size"));
1198                         return -errno;
1199                 }
1200         } else
1201                 expected_size = st.st_size;
1202
1203         if (expected_size == 0 || expected_size <= lc->info.lo_offset) {
1204                 DBG(CXT, ul_debugobj(lc, "failed to determine expected size"));
1205                 return 0;       /* ignore this error */
1206         }
1207
1208         if (lc->info.lo_offset > 0)
1209                 expected_size -= lc->info.lo_offset;
1210
1211         if (lc->info.lo_sizelimit > 0 && lc->info.lo_sizelimit < expected_size)
1212                 expected_size = lc->info.lo_sizelimit;
1213
1214         dev_fd = loopcxt_get_fd(lc);
1215         if (dev_fd < 0) {
1216                 DBG(CXT, ul_debugobj(lc, "failed to get loop FD"));
1217                 return -errno;
1218         }
1219
1220         if (blkdev_get_size(dev_fd, (unsigned long long *) &size)) {
1221                 DBG(CXT, ul_debugobj(lc, "failed to determine loopdev size"));
1222                 return -errno;
1223         }
1224
1225         /* It's block device, so, align to 512-byte sectors */
1226         if (expected_size % 512) {
1227                 DBG(CXT, ul_debugobj(lc, "expected size misaligned to 512-byte sectors"));
1228                 expected_size = (expected_size >> 9) << 9;
1229         }
1230
1231         if (expected_size != size) {
1232                 DBG(CXT, ul_debugobj(lc, "warning: loopdev and expected "
1233                                       "size mismatch (%ju/%ju)",
1234                                       size, expected_size));
1235
1236                 if (loopcxt_ioctl_capacity(lc)) {
1237                         /* ioctl not available */
1238                         if (errno == ENOTTY || errno == EINVAL)
1239                                 errno = ERANGE;
1240                         return -errno;
1241                 }
1242
1243                 if (blkdev_get_size(dev_fd, (unsigned long long *) &size))
1244                         return -errno;
1245
1246                 if (expected_size != size) {
1247                         errno = ERANGE;
1248                         DBG(CXT, ul_debugobj(lc, "failed to set loopdev size, "
1249                                         "size: %ju, expected: %ju",
1250                                         size, expected_size));
1251                         return -errno;
1252                 }
1253         }
1254
1255         return 0;
1256 }
1257
1258 /*
1259  * @lc: context
1260  *
1261  * Associate the current device (see loopcxt_{set,get}_device()) with
1262  * a file (see loopcxt_set_backing_file()).
1263  *
1264  * The device is initialized read-write by default. If you want read-only
1265  * device then set LO_FLAGS_READ_ONLY by loopcxt_set_flags(). The LOOPDEV_FL_*
1266  * flags are ignored and modified according to LO_FLAGS_*.
1267  *
1268  * If the device is already open by loopcxt_get_fd() then this setup device
1269  * function will re-open the device to fix read/write mode.
1270  *
1271  * The device is also initialized read-only if the backing file is not
1272  * possible to open read-write (e.g. read-only FS).
1273  *
1274  * Returns: <0 on error, 0 on success.
1275  */
1276 int loopcxt_setup_device(struct loopdev_cxt *lc)
1277 {
1278         int file_fd, dev_fd, mode = O_RDWR, rc = -1, cnt = 0;
1279         int errsv = 0;
1280
1281         if (!lc || !*lc->device || !lc->filename)
1282                 return -EINVAL;
1283
1284         DBG(SETUP, ul_debugobj(lc, "device setup requested"));
1285
1286         /*
1287          * Open backing file and device
1288          */
1289         if (lc->info.lo_flags & LO_FLAGS_READ_ONLY)
1290                 mode = O_RDONLY;
1291
1292         if ((file_fd = open(lc->filename, mode | O_CLOEXEC)) < 0) {
1293                 if (mode != O_RDONLY && (errno == EROFS || errno == EACCES))
1294                         file_fd = open(lc->filename, mode = O_RDONLY);
1295
1296                 if (file_fd < 0) {
1297                         DBG(SETUP, ul_debugobj(lc, "open backing file failed: %m"));
1298                         return -errno;
1299                 }
1300         }
1301         DBG(SETUP, ul_debugobj(lc, "backing file open: OK"));
1302
1303         if (lc->fd != -1 && lc->mode != mode) {
1304                 DBG(SETUP, ul_debugobj(lc, "closing already open device (mode mismatch)"));
1305                 close(lc->fd);
1306                 lc->fd = -1;
1307                 lc->mode = 0;
1308         }
1309
1310         if (mode == O_RDONLY) {
1311                 lc->flags |= LOOPDEV_FL_RDONLY;                 /* open() mode */
1312                 lc->info.lo_flags |= LO_FLAGS_READ_ONLY;        /* kernel loopdev mode */
1313         } else {
1314                 lc->flags |= LOOPDEV_FL_RDWR;                   /* open() mode */
1315                 lc->info.lo_flags &= ~LO_FLAGS_READ_ONLY;
1316                 lc->flags &= ~LOOPDEV_FL_RDONLY;
1317         }
1318
1319         do {
1320                 errno = 0;
1321                 dev_fd = loopcxt_get_fd(lc);
1322                 if (dev_fd >= 0 || lc->control_ok == 0)
1323                         break;
1324                 if (errno != EACCES && errno != ENOENT)
1325                         break;
1326                 /* We have permissions to open /dev/loop-control, but open
1327                  * /dev/loopN failed with EACCES, it's probably because udevd
1328                  * does not applied chown yet. Let's wait a moment. */
1329                 xusleep(25000);
1330         } while (cnt++ < 16);
1331
1332         if (dev_fd < 0) {
1333                 rc = -errno;
1334                 goto err;
1335         }
1336
1337         DBG(SETUP, ul_debugobj(lc, "device open: OK"));
1338
1339         /*
1340          * Set FD
1341          */
1342         if (ioctl(dev_fd, LOOP_SET_FD, file_fd) < 0) {
1343                 rc = -errno;
1344                 errsv = errno;
1345                 DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD failed: %m"));
1346                 goto err;
1347         }
1348
1349         DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD: OK"));
1350
1351         if (lc->blocksize > 0
1352             && (rc = loopcxt_ioctl_blocksize(lc, lc->blocksize)) < 0) {
1353                 errsv = -rc;
1354                 goto err;
1355         }
1356
1357         if (ioctl(dev_fd, LOOP_SET_STATUS64, &lc->info)) {
1358                 rc = -errno;
1359                 errsv = errno;
1360                 DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m"));
1361                 goto err;
1362         }
1363
1364         DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64: OK"));
1365
1366         if ((rc = loopcxt_check_size(lc, file_fd)))
1367                 goto err;
1368
1369         close(file_fd);
1370
1371         memset(&lc->info, 0, sizeof(lc->info));
1372         lc->has_info = 0;
1373         lc->info_failed = 0;
1374
1375         DBG(SETUP, ul_debugobj(lc, "success [rc=0]"));
1376         return 0;
1377 err:
1378         if (file_fd >= 0)
1379                 close(file_fd);
1380         if (dev_fd >= 0 && rc != -EBUSY)
1381                 ioctl(dev_fd, LOOP_CLR_FD, 0);
1382         if (errsv)
1383                 errno = errsv;
1384
1385         DBG(SETUP, ul_debugobj(lc, "failed [rc=%d]", rc));
1386         return rc;
1387 }
1388
1389 /*
1390  * @lc: context
1391  *
1392  * Update status of the current device (see loopcxt_{set,get}_device()).
1393  *
1394  * Note that once initialized, kernel accepts only selected changes:
1395  * LO_FLAGS_AUTOCLEAR and LO_FLAGS_PARTSCAN
1396  * For more see linux/drivers/block/loop.c:loop_set_status()
1397  *
1398  * Returns: <0 on error, 0 on success.
1399  */
1400 int loopcxt_ioctl_status(struct loopdev_cxt *lc)
1401 {
1402         int dev_fd, rc = -1;
1403
1404         errno = 0;
1405         dev_fd = loopcxt_get_fd(lc);
1406
1407         if (dev_fd < 0) {
1408                 rc = -errno;
1409                 return rc;
1410         }
1411         DBG(SETUP, ul_debugobj(lc, "device open: OK"));
1412
1413         if (ioctl(dev_fd, LOOP_SET_STATUS64, &lc->info)) {
1414                 rc = -errno;
1415                 DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m"));
1416                 return rc;
1417         }
1418
1419         DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64: OK"));
1420         return 0;
1421 }
1422
1423 int loopcxt_ioctl_capacity(struct loopdev_cxt *lc)
1424 {
1425         int fd = loopcxt_get_fd(lc);
1426
1427         if (fd < 0)
1428                 return -EINVAL;
1429
1430         /* Kernels prior to v2.6.30 don't support this ioctl */
1431         if (ioctl(fd, LOOP_SET_CAPACITY, 0) < 0) {
1432                 int rc = -errno;
1433                 DBG(CXT, ul_debugobj(lc, "LOOP_SET_CAPACITY failed: %m"));
1434                 return rc;
1435         }
1436
1437         DBG(CXT, ul_debugobj(lc, "capacity set"));
1438         return 0;
1439 }
1440
1441 int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio)
1442 {
1443         int fd = loopcxt_get_fd(lc);
1444
1445         if (fd < 0)
1446                 return -EINVAL;
1447
1448         /* Kernels prior to v4.4 don't support this ioctl */
1449         if (ioctl(fd, LOOP_SET_DIRECT_IO, use_dio) < 0) {
1450                 int rc = -errno;
1451                 DBG(CXT, ul_debugobj(lc, "LOOP_SET_DIRECT_IO failed: %m"));
1452                 return rc;
1453         }
1454
1455         DBG(CXT, ul_debugobj(lc, "direct io set"));
1456         return 0;
1457 }
1458
1459 /*
1460  * Kernel uses "unsigned long" as ioctl arg, but we use u64 for all sizes to
1461  * keep loopdev internal API simple.
1462  */
1463 int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize)
1464 {
1465         int fd = loopcxt_get_fd(lc);
1466
1467         if (fd < 0)
1468                 return -EINVAL;
1469
1470         /* Kernels prior to v4.14 don't support this ioctl */
1471         if (ioctl(fd, LOOP_SET_BLOCK_SIZE, (unsigned long) blocksize) < 0) {
1472                 int rc = -errno;
1473                 DBG(CXT, ul_debugobj(lc, "LOOP_SET_BLOCK_SIZE failed: %m"));
1474                 return rc;
1475         }
1476
1477         DBG(CXT, ul_debugobj(lc, "logical block size set"));
1478         return 0;
1479 }
1480
1481 int loopcxt_delete_device(struct loopdev_cxt *lc)
1482 {
1483         int fd = loopcxt_get_fd(lc);
1484
1485         if (fd < 0)
1486                 return -EINVAL;
1487
1488         if (ioctl(fd, LOOP_CLR_FD, 0) < 0) {
1489                 DBG(CXT, ul_debugobj(lc, "LOOP_CLR_FD failed: %m"));
1490                 return -errno;
1491         }
1492
1493         DBG(CXT, ul_debugobj(lc, "device removed"));
1494         return 0;
1495 }
1496
1497 int loopcxt_add_device(struct loopdev_cxt *lc)
1498 {
1499         int rc = -EINVAL;
1500         int ctl, nr = -1;
1501         const char *p, *dev = loopcxt_get_device(lc);
1502
1503         if (!dev)
1504                 goto done;
1505
1506         if (!(lc->flags & LOOPDEV_FL_CONTROL)) {
1507                 rc = -ENOSYS;
1508                 goto done;
1509         }
1510
1511         p = strrchr(dev, '/');
1512         if (!p || (sscanf(p, "/loop%d", &nr) != 1 && sscanf(p, "/%d", &nr) != 1)
1513                || nr < 0)
1514                 goto done;
1515
1516         ctl = open(_PATH_DEV_LOOPCTL, O_RDWR|O_CLOEXEC);
1517         if (ctl >= 0) {
1518                 DBG(CXT, ul_debugobj(lc, "add_device %d", nr));
1519                 rc = ioctl(ctl, LOOP_CTL_ADD, nr);
1520                 close(ctl);
1521         }
1522         lc->control_ok = rc >= 0 ? 1 : 0;
1523 done:
1524         DBG(CXT, ul_debugobj(lc, "add_device done [rc=%d]", rc));
1525         return rc;
1526 }
1527
1528 /*
1529  * Note that LOOP_CTL_GET_FREE ioctl is supported since kernel 3.1. In older
1530  * kernels we have to check all loop devices to found unused one.
1531  *
1532  * See kernel commit 770fe30a46a12b6fb6b63fbe1737654d28e8484.
1533  */
1534 int loopcxt_find_unused(struct loopdev_cxt *lc)
1535 {
1536         int rc = -1;
1537
1538         DBG(CXT, ul_debugobj(lc, "find_unused requested"));
1539
1540         if (lc->flags & LOOPDEV_FL_CONTROL) {
1541                 int ctl;
1542
1543                 DBG(CXT, ul_debugobj(lc, "using loop-control"));
1544
1545                 ctl = open(_PATH_DEV_LOOPCTL, O_RDWR|O_CLOEXEC);
1546                 if (ctl >= 0)
1547                         rc = ioctl(ctl, LOOP_CTL_GET_FREE);
1548                 if (rc >= 0) {
1549                         char name[16];
1550                         snprintf(name, sizeof(name), "loop%d", rc);
1551
1552                         rc = loopiter_set_device(lc, name);
1553                 }
1554                 lc->control_ok = ctl >= 0 && rc == 0 ? 1 : 0;
1555                 if (ctl >= 0)
1556                         close(ctl);
1557                 DBG(CXT, ul_debugobj(lc, "find_unused by loop-control [rc=%d]", rc));
1558         }
1559
1560         if (rc < 0) {
1561                 DBG(CXT, ul_debugobj(lc, "using loop scan"));
1562                 rc = loopcxt_init_iterator(lc, LOOPITER_FL_FREE);
1563                 if (rc)
1564                         return rc;
1565
1566                 rc = loopcxt_next(lc);
1567                 loopcxt_deinit_iterator(lc);
1568                 DBG(CXT, ul_debugobj(lc, "find_unused by scan [rc=%d]", rc));
1569         }
1570         return rc;
1571 }
1572
1573
1574
1575 /*
1576  * Return: TRUE/FALSE
1577  */
1578 int loopdev_is_autoclear(const char *device)
1579 {
1580         struct loopdev_cxt lc;
1581         int rc;
1582
1583         if (!device)
1584                 return 0;
1585
1586         rc = loopcxt_init(&lc, 0);
1587         if (!rc)
1588                 rc = loopcxt_set_device(&lc, device);
1589         if (!rc)
1590                 rc = loopcxt_is_autoclear(&lc);
1591
1592         loopcxt_deinit(&lc);
1593         return rc;
1594 }
1595
1596 char *loopdev_get_backing_file(const char *device)
1597 {
1598         struct loopdev_cxt lc;
1599         char *res = NULL;
1600
1601         if (!device)
1602                 return NULL;
1603         if (loopcxt_init(&lc, 0))
1604                 return NULL;
1605         if (loopcxt_set_device(&lc, device) == 0)
1606                 res = loopcxt_get_backing_file(&lc);
1607
1608         loopcxt_deinit(&lc);
1609         return res;
1610 }
1611
1612 /*
1613  * Returns: TRUE/FALSE
1614  */
1615 int loopdev_is_used(const char *device, const char *filename,
1616                     uint64_t offset, uint64_t sizelimit, int flags)
1617 {
1618         struct loopdev_cxt lc;
1619         struct stat st;
1620         int rc = 0;
1621
1622         if (!device || !filename)
1623                 return 0;
1624
1625         rc = loopcxt_init(&lc, 0);
1626         if (!rc)
1627                 rc = loopcxt_set_device(&lc, device);
1628         if (rc)
1629                 return rc;
1630
1631         rc = !stat(filename, &st);
1632         rc = loopcxt_is_used(&lc, rc ? &st : NULL, filename, offset, sizelimit, flags);
1633
1634         loopcxt_deinit(&lc);
1635         return rc;
1636 }
1637
1638 int loopdev_delete(const char *device)
1639 {
1640         struct loopdev_cxt lc;
1641         int rc;
1642
1643         if (!device)
1644                 return -EINVAL;
1645
1646         rc = loopcxt_init(&lc, 0);
1647         if (!rc)
1648                 rc = loopcxt_set_device(&lc, device);
1649         if (!rc)
1650                 rc = loopcxt_delete_device(&lc);
1651         loopcxt_deinit(&lc);
1652         return rc;
1653 }
1654
1655 /*
1656  * Returns: 0 = success, < 0 error, 1 not found
1657  */
1658 int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename,
1659                                  uint64_t offset, uint64_t sizelimit, int flags)
1660 {
1661         int rc, hasst;
1662         struct stat st;
1663
1664         if (!filename)
1665                 return -EINVAL;
1666
1667         hasst = !stat(filename, &st);
1668
1669         rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED);
1670         if (rc)
1671                 return rc;
1672
1673         while ((rc = loopcxt_next(lc)) == 0) {
1674
1675                 if (loopcxt_is_used(lc, hasst ? &st : NULL,
1676                                     filename, offset, sizelimit, flags))
1677                         break;
1678         }
1679
1680         loopcxt_deinit_iterator(lc);
1681         return rc;
1682 }
1683
1684 /*
1685  * Returns: 0 = not found, < 0 error, 1 found, 2 found full size and offset match
1686  */
1687 int loopcxt_find_overlap(struct loopdev_cxt *lc, const char *filename,
1688                            uint64_t offset, uint64_t sizelimit)
1689 {
1690         int rc, hasst;
1691         struct stat st;
1692
1693         if (!filename)
1694                 return -EINVAL;
1695
1696         DBG(CXT, ul_debugobj(lc, "find_overlap requested"));
1697         hasst = !stat(filename, &st);
1698
1699         rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED);
1700         if (rc)
1701                 return rc;
1702
1703         while ((rc = loopcxt_next(lc)) == 0) {
1704                 uint64_t lc_sizelimit, lc_offset;
1705
1706                 rc = loopcxt_is_used(lc, hasst ? &st : NULL,
1707                                      filename, offset, sizelimit, 0);
1708                 if (!rc)
1709                         continue;       /* unused */
1710                 if (rc < 0)
1711                         break;          /* error */
1712
1713                 DBG(CXT, ul_debugobj(lc, "found %s backed by %s",
1714                         loopcxt_get_device(lc), filename));
1715
1716                 rc = loopcxt_get_offset(lc, &lc_offset);
1717                 if (rc) {
1718                         DBG(CXT, ul_debugobj(lc, "failed to get offset for device %s",
1719                                 loopcxt_get_device(lc)));
1720                         break;
1721                 }
1722                 rc = loopcxt_get_sizelimit(lc, &lc_sizelimit);
1723                 if (rc) {
1724                         DBG(CXT, ul_debugobj(lc, "failed to get sizelimit for device %s",
1725                                 loopcxt_get_device(lc)));
1726                         break;
1727                 }
1728
1729                 /* full match */
1730                 if (lc_sizelimit == sizelimit && lc_offset == offset) {
1731                         DBG(CXT, ul_debugobj(lc, "overlapping loop device %s (full match)",
1732                                                 loopcxt_get_device(lc)));
1733                         rc = 2;
1734                         goto found;
1735                 }
1736
1737                 /* overlap */
1738                 if (lc_sizelimit != 0 && offset >= lc_offset + lc_sizelimit)
1739                         continue;
1740                 if (sizelimit != 0 && offset + sizelimit <= lc_offset)
1741                         continue;
1742
1743                 DBG(CXT, ul_debugobj(lc, "overlapping loop device %s",
1744                         loopcxt_get_device(lc)));
1745                         rc = 1;
1746                         goto found;
1747         }
1748
1749         if (rc == 1)
1750                 rc = 0; /* not found */
1751 found:
1752         loopcxt_deinit_iterator(lc);
1753         DBG(CXT, ul_debugobj(lc, "find_overlap done [rc=%d]", rc));
1754         return rc;
1755 }
1756
1757 /*
1758  * Returns allocated string with device name
1759  */
1760 char *loopdev_find_by_backing_file(const char *filename, uint64_t offset, uint64_t sizelimit, int flags)
1761 {
1762         struct loopdev_cxt lc;
1763         char *res = NULL;
1764
1765         if (!filename)
1766                 return NULL;
1767
1768         if (loopcxt_init(&lc, 0))
1769                 return NULL;
1770         if (loopcxt_find_by_backing_file(&lc, filename, offset, sizelimit, flags) == 0)
1771                 res = loopcxt_strdup_device(&lc);
1772         loopcxt_deinit(&lc);
1773
1774         return res;
1775 }
1776
1777 /*
1778  * Returns number of loop devices associated with @file, if only one loop
1779  * device is associated with the given @filename and @loopdev is not NULL then
1780  * @loopdev returns name of the device.
1781  */
1782 int loopdev_count_by_backing_file(const char *filename, char **loopdev)
1783 {
1784         struct loopdev_cxt lc;
1785         int count = 0, rc;
1786
1787         if (!filename)
1788                 return -1;
1789
1790         rc = loopcxt_init(&lc, 0);
1791         if (rc)
1792                 return rc;
1793         if (loopcxt_init_iterator(&lc, LOOPITER_FL_USED))
1794                 return -1;
1795
1796         while(loopcxt_next(&lc) == 0) {
1797                 char *backing = loopcxt_get_backing_file(&lc);
1798
1799                 if (!backing || strcmp(backing, filename)) {
1800                         free(backing);
1801                         continue;
1802                 }
1803
1804                 free(backing);
1805                 if (loopdev && count == 0)
1806                         *loopdev = loopcxt_strdup_device(&lc);
1807                 count++;
1808         }
1809
1810         loopcxt_deinit(&lc);
1811
1812         if (loopdev && count > 1) {
1813                 free(*loopdev);
1814                 *loopdev = NULL;
1815         }
1816         return count;
1817 }
1818