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Diffstat (limited to '')
| -rw-r--r-- | lib/loopdev.c | 1924 |
1 files changed, 1924 insertions, 0 deletions
diff --git a/lib/loopdev.c b/lib/loopdev.c new file mode 100644 index 0000000..05376dd --- /dev/null +++ b/lib/loopdev.c @@ -0,0 +1,1924 @@ + +/* + * No copyright is claimed. This code is in the public domain; do with + * it what you wish. + * + * Written by Karel Zak <kzak@redhat.com> + * + * -- based on mount/losetup.c + * + * Simple library for work with loop devices. + * + * - requires kernel 2.6.x + * - reads info from /sys/block/loop<N>/loop/<attr> (new kernels) + * - reads info by ioctl + * - supports *unlimited* number of loop devices + * - supports /dev/loop<N> as well as /dev/loop/<N> + * - minimize overhead (fd, loopinfo, ... are shared for all operations) + * - setup (associate device and backing file) + * - delete (dis-associate file) + * - old LOOP_{SET,GET}_STATUS (32bit) ioctls are unsupported + * - extendible + */ +#include <stdio.h> +#include <stdint.h> +#include <string.h> +#include <ctype.h> +#include <fcntl.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <inttypes.h> +#include <dirent.h> + +#include "linux_version.h" +#include "c.h" +#include "sysfs.h" +#include "pathnames.h" +#include "loopdev.h" +#include "canonicalize.h" +#include "blkdev.h" +#include "debug.h" +#include "fileutils.h" + + +#define LOOPDEV_MAX_TRIES 10 + +/* + * Debug stuff (based on include/debug.h) + */ +static UL_DEBUG_DEFINE_MASK(loopdev); +UL_DEBUG_DEFINE_MASKNAMES(loopdev) = UL_DEBUG_EMPTY_MASKNAMES; + +#define LOOPDEV_DEBUG_INIT (1 << 1) +#define LOOPDEV_DEBUG_CXT (1 << 2) +#define LOOPDEV_DEBUG_ITER (1 << 3) +#define LOOPDEV_DEBUG_SETUP (1 << 4) + +#define DBG(m, x) __UL_DBG(loopdev, LOOPDEV_DEBUG_, m, x) +#define ON_DBG(m, x) __UL_DBG_CALL(loopdev, LOOPDEV_DEBUG_, m, x) + +#define UL_DEBUG_CURRENT_MASK UL_DEBUG_MASK(loopdev) +#include "debugobj.h" + +static void loopdev_init_debug(void) +{ + if (loopdev_debug_mask) + return; + __UL_INIT_DEBUG_FROM_ENV(loopdev, LOOPDEV_DEBUG_, 0, LOOPDEV_DEBUG); +} + +/* + * see loopcxt_init() + */ +#define loopcxt_ioctl_enabled(_lc) (!((_lc)->flags & LOOPDEV_FL_NOIOCTL)) +#define loopcxt_sysfs_available(_lc) (!((_lc)->flags & LOOPDEV_FL_NOSYSFS)) \ + && !loopcxt_ioctl_enabled(_lc) + +/* + * @lc: context + * @device: device name, absolute device path or NULL to reset the current setting + * + * Sets device, absolute paths (e.g. "/dev/loop<N>") are unchanged, device + * names ("loop<N>") are converted to the path (/dev/loop<N> or to + * /dev/loop/<N>) + * + * This sets the device name, but does not check if the device exists! + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_set_device(struct loopdev_cxt *lc, const char *device) +{ + if (!lc) + return -EINVAL; + + if (lc->fd >= 0) { + close(lc->fd); + DBG(CXT, ul_debugobj(lc, "closing old open fd")); + } + lc->fd = -1; + lc->mode = 0; + lc->blocksize = 0; + lc->has_info = 0; + lc->info_failed = 0; + *lc->device = '\0'; + memset(&lc->config, 0, sizeof(lc->config)); + + /* set new */ + if (device) { + if (*device != '/') { + const char *dir = _PATH_DEV; + + /* compose device name for /dev/loop<n> or /dev/loop/<n> */ + if (lc->flags & LOOPDEV_FL_DEVSUBDIR) { + if (strlen(device) < 5) + return -1; + device += 4; + dir = _PATH_DEV_LOOP "/"; /* _PATH_DEV uses tailing slash */ + } + snprintf(lc->device, sizeof(lc->device), "%s%s", + dir, device); + } else + xstrncpy(lc->device, device, sizeof(lc->device)); + + DBG(CXT, ul_debugobj(lc, "%s name assigned", device)); + } + + ul_unref_path(lc->sysfs); + lc->sysfs = NULL; + return 0; +} + +int loopcxt_has_device(struct loopdev_cxt *lc) +{ + return lc && *lc->device; +} + +/* + * @lc: context + * @flags: LOOPDEV_FL_* flags + * + * Initialize loop handler. + * + * We have two sets of the flags: + * + * * LOOPDEV_FL_* flags control loopcxt_* API behavior + * + * * LO_FLAGS_* are kernel flags used for LOOP_{SET,GET}_STAT64 ioctls + * + * Note about LOOPDEV_FL_{RDONLY,RDWR} flags. These flags are used for open(2) + * syscall to open loop device. By default is the device open read-only. + * + * The exception is loopcxt_setup_device(), where the device is open read-write + * if LO_FLAGS_READ_ONLY flags is not set (see loopcxt_set_flags()). + * + * Returns: <0 on error, 0 on success. + */ +int loopcxt_init(struct loopdev_cxt *lc, int flags) +{ + int rc; + struct stat st; + struct loopdev_cxt dummy = UL_LOOPDEVCXT_EMPTY; + + if (!lc) + return -EINVAL; + + loopdev_init_debug(); + DBG(CXT, ul_debugobj(lc, "initialize context")); + + memcpy(lc, &dummy, sizeof(dummy)); + lc->flags = flags; + + rc = loopcxt_set_device(lc, NULL); + if (rc) + return rc; + + if (stat(_PATH_SYS_BLOCK, &st) || !S_ISDIR(st.st_mode)) { + lc->flags |= LOOPDEV_FL_NOSYSFS; + lc->flags &= ~LOOPDEV_FL_NOIOCTL; + DBG(CXT, ul_debugobj(lc, "init: disable /sys usage")); + } + + if (!(lc->flags & LOOPDEV_FL_NOSYSFS) && + get_linux_version() >= KERNEL_VERSION(2,6,37)) { + /* + * Use only sysfs for basic information about loop devices + */ + lc->flags |= LOOPDEV_FL_NOIOCTL; + DBG(CXT, ul_debugobj(lc, "init: ignore ioctls")); + } + + if (!(lc->flags & LOOPDEV_FL_CONTROL) && !stat(_PATH_DEV_LOOPCTL, &st)) { + lc->flags |= LOOPDEV_FL_CONTROL; + DBG(CXT, ul_debugobj(lc, "init: loop-control detected ")); + } + + return 0; +} + +/* + * @lc: context + * + * Deinitialize loop context + */ +void loopcxt_deinit(struct loopdev_cxt *lc) +{ + int errsv = errno; + + if (!lc) + return; + + DBG(CXT, ul_debugobj(lc, "de-initialize")); + + free(lc->filename); + lc->filename = NULL; + + ignore_result( loopcxt_set_device(lc, NULL) ); + loopcxt_deinit_iterator(lc); + + errno = errsv; +} + +/* + * @lc: context + * + * Returns newly allocated device path. + */ +char *loopcxt_strdup_device(struct loopdev_cxt *lc) +{ + if (!lc || !*lc->device) + return NULL; + return strdup(lc->device); +} + +/* + * @lc: context + * + * Returns pointer device name in the @lc struct. + */ +const char *loopcxt_get_device(struct loopdev_cxt *lc) +{ + return lc && *lc->device ? lc->device : NULL; +} + +/* + * @lc: context + * + * Returns pointer to the sysfs context (see lib/sysfs.c) + */ +static struct path_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc) +{ + if (!lc || !*lc->device || (lc->flags & LOOPDEV_FL_NOSYSFS)) + return NULL; + + if (!lc->sysfs) { + dev_t devno = sysfs_devname_to_devno(lc->device); + if (!devno) { + DBG(CXT, ul_debugobj(lc, "sysfs: failed devname to devno")); + return NULL; + } + + lc->sysfs = ul_new_sysfs_path(devno, NULL, NULL); + if (!lc->sysfs) + DBG(CXT, ul_debugobj(lc, "sysfs: init failed")); + } + + return lc->sysfs; +} + +/* + * @lc: context + * + * Returns: file descriptor to the open loop device or <0 on error. The mode + * depends on LOOPDEV_FL_{RDWR,RDONLY} context flags. Default is + * read-only. + */ +int loopcxt_get_fd(struct loopdev_cxt *lc) +{ + if (!lc || !*lc->device) + return -EINVAL; + + if (lc->fd < 0) { + lc->mode = lc->flags & LOOPDEV_FL_RDWR ? O_RDWR : O_RDONLY; + lc->fd = open(lc->device, lc->mode | O_CLOEXEC); + DBG(CXT, ul_debugobj(lc, "open %s [%s]: %m", lc->device, + lc->flags & LOOPDEV_FL_RDWR ? "rw" : "ro")); + } + return lc->fd; +} + +int loopcxt_set_fd(struct loopdev_cxt *lc, int fd, int mode) +{ + if (!lc) + return -EINVAL; + + lc->fd = fd; + lc->mode = mode; + return 0; +} + +/* + * @lc: context + * @flags: LOOPITER_FL_* flags + * + * Iterator can be used to scan list of the free or used loop devices. + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_init_iterator(struct loopdev_cxt *lc, int flags) +{ + struct loopdev_iter *iter; + struct stat st; + + if (!lc) + return -EINVAL; + + + iter = &lc->iter; + DBG(ITER, ul_debugobj(iter, "initialize")); + + /* always zeroize + */ + memset(iter, 0, sizeof(*iter)); + iter->ncur = -1; + iter->flags = flags; + iter->default_check = 1; + + if (!lc->extra_check) { + /* + * Check for /dev/loop/<N> subdirectory + */ + if (!(lc->flags & LOOPDEV_FL_DEVSUBDIR) && + stat(_PATH_DEV_LOOP, &st) == 0 && S_ISDIR(st.st_mode)) + lc->flags |= LOOPDEV_FL_DEVSUBDIR; + + lc->extra_check = 1; + } + return 0; +} + +/* + * @lc: context + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_deinit_iterator(struct loopdev_cxt *lc) +{ + struct loopdev_iter *iter; + + if (!lc) + return -EINVAL; + + iter = &lc->iter; + DBG(ITER, ul_debugobj(iter, "de-initialize")); + + free(iter->minors); + if (iter->proc) + fclose(iter->proc); + if (iter->sysblock) + closedir(iter->sysblock); + + memset(iter, 0, sizeof(*iter)); + return 0; +} + +/* + * Same as loopcxt_set_device, but also checks if the device is + * associated with any file. + * + * Returns: <0 on error, 0 on success, 1 device does not match with + * LOOPITER_FL_{USED,FREE} flags. + */ +static int loopiter_set_device(struct loopdev_cxt *lc, const char *device) +{ + int rc = loopcxt_set_device(lc, device); + int used; + + if (rc) + return rc; + + if (!(lc->iter.flags & LOOPITER_FL_USED) && + !(lc->iter.flags & LOOPITER_FL_FREE)) + return 0; /* caller does not care about device status */ + + if (!is_loopdev(lc->device)) { + DBG(ITER, ul_debugobj(&lc->iter, "%s does not exist", lc->device)); + return -errno; + } + + DBG(ITER, ul_debugobj(&lc->iter, "%s exist", lc->device)); + + used = loopcxt_get_offset(lc, NULL) == 0; + + if ((lc->iter.flags & LOOPITER_FL_USED) && used) + return 0; + + if ((lc->iter.flags & LOOPITER_FL_FREE) && !used) + return 0; + + DBG(ITER, ul_debugobj(&lc->iter, "failed to use %s device", lc->device)); + + ignore_result( loopcxt_set_device(lc, NULL) ); + return 1; +} + +static int cmpnum(const void *p1, const void *p2) +{ + return (((* (const int *) p1) > (* (const int *) p2)) - + ((* (const int *) p1) < (* (const int *) p2))); +} + +/* + * The classic scandir() is more expensive and less portable. + * We needn't full loop device names -- loop numbers (loop<N>) + * are enough. + */ +static int loop_scandir(const char *dirname, int **ary, int hasprefix) +{ + DIR *dir; + struct dirent *d; + unsigned int n, count = 0, arylen = 0; + + if (!dirname || !ary) + return 0; + + DBG(ITER, ul_debug("scan dir: %s", dirname)); + + dir = opendir(dirname); + if (!dir) + return 0; + free(*ary); + *ary = NULL; + + while((d = readdir(dir))) { +#ifdef _DIRENT_HAVE_D_TYPE + if (d->d_type != DT_BLK && d->d_type != DT_UNKNOWN && + d->d_type != DT_LNK) + continue; +#endif + if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, "..")) + continue; + + if (hasprefix) { + /* /dev/loop<N> */ + if (sscanf(d->d_name, "loop%u", &n) != 1) + continue; + } else { + /* /dev/loop/<N> */ + char *end = NULL; + + errno = 0; + n = strtol(d->d_name, &end, 10); + if (d->d_name == end || (end && *end) || errno) + continue; + } + if (n < LOOPDEV_DEFAULT_NNODES) + continue; /* ignore loop<0..7> */ + + if (count + 1 > arylen) { + int *tmp; + + arylen += 1; + + tmp = realloc(*ary, arylen * sizeof(int)); + if (!tmp) { + free(*ary); + *ary = NULL; + closedir(dir); + return -1; + } + *ary = tmp; + } + if (*ary) + (*ary)[count++] = n; + } + if (count && *ary) + qsort(*ary, count, sizeof(int), cmpnum); + + closedir(dir); + return count; +} + +/* + * Set the next *used* loop device according to /proc/partitions. + * + * Loop devices smaller than 512 bytes are invisible for this function. + */ +static int loopcxt_next_from_proc(struct loopdev_cxt *lc) +{ + struct loopdev_iter *iter = &lc->iter; + char buf[BUFSIZ]; + + DBG(ITER, ul_debugobj(iter, "scan /proc/partitions")); + + if (!iter->proc) + iter->proc = fopen(_PATH_PROC_PARTITIONS, "r" UL_CLOEXECSTR); + if (!iter->proc) + return 1; + + while (fgets(buf, sizeof(buf), iter->proc)) { + unsigned int m; + char name[128 + 1]; + + + if (sscanf(buf, " %u %*s %*s %128[^\n ]", + &m, name) != 2 || m != LOOPDEV_MAJOR) + continue; + + DBG(ITER, ul_debugobj(iter, "checking %s", name)); + + if (loopiter_set_device(lc, name) == 0) + return 0; + } + + return 1; +} + +/* + * Set the next *used* loop device according to + * /sys/block/loopN/loop/backing_file (kernel >= 2.6.37 is required). + * + * This is preferred method. + */ +static int loopcxt_next_from_sysfs(struct loopdev_cxt *lc) +{ + struct loopdev_iter *iter = &lc->iter; + struct dirent *d; + int fd; + + DBG(ITER, ul_debugobj(iter, "scanning /sys/block")); + + if (!iter->sysblock) + iter->sysblock = opendir(_PATH_SYS_BLOCK); + + if (!iter->sysblock) + return 1; + + fd = dirfd(iter->sysblock); + + while ((d = readdir(iter->sysblock))) { + char name[NAME_MAX + 18 + 1]; + struct stat st; + + DBG(ITER, ul_debugobj(iter, "check %s", d->d_name)); + + if (strcmp(d->d_name, ".") == 0 + || strcmp(d->d_name, "..") == 0 + || strncmp(d->d_name, "loop", 4) != 0) + continue; + + snprintf(name, sizeof(name), "%s/loop/backing_file", d->d_name); + if (fstatat(fd, name, &st, 0) != 0) + continue; + + if (loopiter_set_device(lc, d->d_name) == 0) + return 0; + } + + return 1; +} + +/* + * @lc: context, has to initialized by loopcxt_init_iterator() + * + * Returns: 0 on success, -1 on error, 1 at the end of scanning. The details + * about the current loop device are available by + * loopcxt_get_{fd,backing_file,device,offset, ...} functions. + */ +int loopcxt_next(struct loopdev_cxt *lc) +{ + struct loopdev_iter *iter; + + if (!lc) + return -EINVAL; + + + iter = &lc->iter; + if (iter->done) + return 1; + + DBG(ITER, ul_debugobj(iter, "next")); + + /* A) Look for used loop devices in /proc/partitions ("losetup -a" only) + */ + if (iter->flags & LOOPITER_FL_USED) { + int rc; + + if (loopcxt_sysfs_available(lc)) + rc = loopcxt_next_from_sysfs(lc); + else + rc = loopcxt_next_from_proc(lc); + if (rc == 0) + return 0; + goto done; + } + + /* B) Classic way, try first eight loop devices (default number + * of loop devices). This is enough for 99% of all cases. + */ + if (iter->default_check) { + DBG(ITER, ul_debugobj(iter, "next: default check")); + for (++iter->ncur; iter->ncur < LOOPDEV_DEFAULT_NNODES; + iter->ncur++) { + char name[16]; + snprintf(name, sizeof(name), "loop%d", iter->ncur); + + if (loopiter_set_device(lc, name) == 0) + return 0; + } + iter->default_check = 0; + } + + /* C) the worst possibility, scan whole /dev or /dev/loop/<N> + */ + if (!iter->minors) { + DBG(ITER, ul_debugobj(iter, "next: scanning /dev")); + iter->nminors = (lc->flags & LOOPDEV_FL_DEVSUBDIR) ? + loop_scandir(_PATH_DEV_LOOP, &iter->minors, 0) : + loop_scandir(_PATH_DEV, &iter->minors, 1); + iter->ncur = -1; + } + for (++iter->ncur; iter->ncur < iter->nminors; iter->ncur++) { + char name[16]; + snprintf(name, sizeof(name), "loop%d", iter->minors[iter->ncur]); + + if (loopiter_set_device(lc, name) == 0) + return 0; + } +done: + loopcxt_deinit_iterator(lc); + return 1; +} + +/* + * @device: path to device + */ +int is_loopdev(const char *device) +{ + struct stat st; + int rc = 0; + + if (!device || stat(device, &st) != 0 || !S_ISBLK(st.st_mode)) + rc = 0; + else if (major(st.st_rdev) == LOOPDEV_MAJOR) + rc = 1; + else if (sysfs_devno_is_wholedisk(st.st_rdev)) { + /* It's possible that kernel creates a device with a different + * major number ... check by /sys it's really loop device. + */ + char name[PATH_MAX], *cn, *p = NULL; + + snprintf(name, sizeof(name), _PATH_SYS_DEVBLOCK "/%d:%d", + major(st.st_rdev), minor(st.st_rdev)); + cn = canonicalize_path(name); + if (cn) + p = stripoff_last_component(cn); + rc = p && startswith(p, "loop"); + free(cn); + } + + if (rc == 0) + errno = ENODEV; + return rc; +} + +/* + * @lc: context + * + * Returns result from LOOP_GET_STAT64 ioctl or NULL on error. + */ +struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc) +{ + int fd; + + if (!lc || lc->info_failed) { + errno = EINVAL; + return NULL; + } + errno = 0; + if (lc->has_info) + return &lc->config.info; + + fd = loopcxt_get_fd(lc); + if (fd < 0) + return NULL; + + if (ioctl(fd, LOOP_GET_STATUS64, &lc->config.info) == 0) { + lc->has_info = 1; + lc->info_failed = 0; + DBG(CXT, ul_debugobj(lc, "reading loop_info64 OK")); + return &lc->config.info; + } + + lc->info_failed = 1; + DBG(CXT, ul_debugobj(lc, "reading loop_info64 FAILED")); + + return NULL; +} + +/* + * @lc: context + * + * Returns (allocated) string with path to the file associated + * with the current loop device. + */ +char *loopcxt_get_backing_file(struct loopdev_cxt *lc) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + char *res = NULL; + + if (sysfs) + /* + * This is always preferred, the loop_info64 + * has too small buffer for the filename. + */ + ul_path_read_string(sysfs, &res, "loop/backing_file"); + + if (!res && loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + + if (lo) { + lo->lo_file_name[LO_NAME_SIZE - 2] = '*'; + lo->lo_file_name[LO_NAME_SIZE - 1] = '\0'; + res = strdup((char *) lo->lo_file_name); + } + } + + DBG(CXT, ul_debugobj(lc, "get_backing_file [%s]", res)); + return res; +} + +/* + * @lc: context + * @offset: returns offset number for the given device + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + int rc = -EINVAL; + + if (sysfs) + if (ul_path_read_u64(sysfs, offset, "loop/offset") == 0) + rc = 0; + + if (rc && loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) { + if (offset) + *offset = lo->lo_offset; + rc = 0; + } else + rc = -errno; + } + + DBG(CXT, ul_debugobj(lc, "get_offset [rc=%d]", rc)); + return rc; +} + +/* + * @lc: context + * @blocksize: returns logical blocksize for the given device + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_get_blocksize(struct loopdev_cxt *lc, uint64_t *blocksize) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + int rc = -EINVAL; + + if (sysfs) + if (ul_path_read_u64(sysfs, blocksize, "queue/logical_block_size") == 0) + rc = 0; + + /* Fallback based on BLKSSZGET ioctl */ + if (rc) { + int fd = loopcxt_get_fd(lc); + int sz = 0; + + if (fd < 0) + return -EINVAL; + rc = blkdev_get_sector_size(fd, &sz); + if (rc) + return rc; + + *blocksize = sz; + } + + DBG(CXT, ul_debugobj(lc, "get_blocksize [rc=%d]", rc)); + return rc; +} + +/* + * @lc: context + * @sizelimit: returns size limit for the given device + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + int rc = -EINVAL; + + if (sysfs) + if (ul_path_read_u64(sysfs, size, "loop/sizelimit") == 0) + rc = 0; + + if (rc && loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) { + if (size) + *size = lo->lo_sizelimit; + rc = 0; + } else + rc = -errno; + } + + DBG(CXT, ul_debugobj(lc, "get_sizelimit [rc=%d]", rc)); + return rc; +} + +/* + * @lc: context + * @devno: returns encryption type + * + * Cryptoloop is DEPRECATED! + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type) +{ + struct loop_info64 *lo = loopcxt_get_info(lc); + int rc; + + /* not provided by sysfs */ + if (lo) { + if (type) + *type = lo->lo_encrypt_type; + rc = 0; + } else + rc = -errno; + + DBG(CXT, ul_debugobj(lc, "get_encrypt_type [rc=%d]", rc)); + return rc; +} + +/* + * @lc: context + * @devno: returns crypt name + * + * Cryptoloop is DEPRECATED! + * + * Returns: <0 on error, 0 on success + */ +const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc) +{ + struct loop_info64 *lo = loopcxt_get_info(lc); + + if (lo) + return (char *) lo->lo_crypt_name; + + DBG(CXT, ul_debugobj(lc, "get_crypt_name failed")); + return NULL; +} + +/* + * @lc: context + * @devno: returns backing file devno + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno) +{ + struct loop_info64 *lo = loopcxt_get_info(lc); + int rc; + + if (lo) { + if (devno) + *devno = lo->lo_device; + rc = 0; + } else + rc = -errno; + + DBG(CXT, ul_debugobj(lc, "get_backing_devno [rc=%d]", rc)); + return rc; +} + +/* + * @lc: context + * @ino: returns backing file inode + * + * Returns: <0 on error, 0 on success + */ +int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino) +{ + struct loop_info64 *lo = loopcxt_get_info(lc); + int rc; + + if (lo) { + if (ino) + *ino = lo->lo_inode; + rc = 0; + } else + rc = -errno; + + DBG(CXT, ul_debugobj(lc, "get_backing_inode [rc=%d]", rc)); + return rc; +} + +/* + * Check if the kernel supports partitioned loop devices. + * + * Notes: + * - kernels < 3.2 support partitioned loop devices and PT scanning + * only if max_part= module parameter is non-zero + * + * - kernels >= 3.2 always support partitioned loop devices + * + * - kernels >= 3.2 always support BLKPG_{ADD,DEL}_PARTITION ioctls + * + * - kernels >= 3.2 enable PT scanner only if max_part= is non-zero or if the + * LO_FLAGS_PARTSCAN flag is set for the device. The PT scanner is disabled + * by default. + * + * See kernel commit e03c8dd14915fabc101aa495828d58598dc5af98. + */ +int loopmod_supports_partscan(void) +{ + int rc, ret = 0; + FILE *f; + + if (get_linux_version() >= KERNEL_VERSION(3,2,0)) + return 1; + + f = fopen("/sys/module/loop/parameters/max_part", "r" UL_CLOEXECSTR); + if (!f) + return 0; + rc = fscanf(f, "%d", &ret); + fclose(f); + return rc == 1 ? ret : 0; +} + +/* + * @lc: context + * + * Returns: 1 if the partscan flags is set *or* (for old kernels) partitions + * scanning is enabled for all loop devices. + */ +int loopcxt_is_partscan(struct loopdev_cxt *lc) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + /* kernel >= 3.2 */ + int fl; + if (ul_path_read_s32(sysfs, &fl, "loop/partscan") == 0) + return fl; + } + + /* old kernels (including kernels without loopN/loop/<flags> directory */ + return loopmod_supports_partscan(); +} + +/* + * @lc: context + * + * Returns: 1 if the autoclear flags is set. + */ +int loopcxt_is_autoclear(struct loopdev_cxt *lc) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + int fl; + if (ul_path_read_s32(sysfs, &fl, "loop/autoclear") == 0) + return fl; + } + + if (loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) + return lo->lo_flags & LO_FLAGS_AUTOCLEAR; + } + return 0; +} + +/* + * @lc: context + * + * Returns: 1 if the readonly flags is set. + */ +int loopcxt_is_readonly(struct loopdev_cxt *lc) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + int fl; + if (ul_path_read_s32(sysfs, &fl, "ro") == 0) + return fl; + } + + if (loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) + return lo->lo_flags & LO_FLAGS_READ_ONLY; + } + return 0; +} + +/* + * @lc: context + * + * Returns: 1 if the dio flags is set. + */ +int loopcxt_is_dio(struct loopdev_cxt *lc) +{ + struct path_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + int fl; + if (ul_path_read_s32(sysfs, &fl, "loop/dio") == 0) + return fl; + } + if (loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) + return lo->lo_flags & LO_FLAGS_DIRECT_IO; + } + return 0; +} + +/* + * @lc: context + * @st: backing file stat or NULL + * @backing_file: filename + * @offset: offset (use LOOPDEV_FL_OFFSET if specified) + * @sizelimit: size limit (use LOOPDEV_FL_SIZELIMIT if specified) + * @flags: LOOPDEV_FL_{OFFSET,SIZELIMIT} + * + * Returns 1 if the current @lc loopdev is associated with the given backing + * file. Note that the preferred way is to use devno and inode number rather + * than filename. The @backing_file filename is poor solution usable in case + * that you don't have rights to call stat(). + * + * LOOPDEV_FL_SIZELIMIT requires LOOPDEV_FL_OFFSET being set as well. + * + * Don't forget that old kernels provide very restricted (in size) backing + * filename by LOOP_GET_STAT64 ioctl only. + */ +int loopcxt_is_used(struct loopdev_cxt *lc, + struct stat *st, + const char *backing_file, + uint64_t offset, + uint64_t sizelimit, + int flags) +{ + ino_t ino = 0; + dev_t dev = 0; + + if (!lc) + return 0; + + DBG(CXT, ul_debugobj(lc, "checking %s vs. %s", + loopcxt_get_device(lc), + backing_file)); + + if (st && loopcxt_get_backing_inode(lc, &ino) == 0 && + loopcxt_get_backing_devno(lc, &dev) == 0) { + + if (ino == st->st_ino && dev == st->st_dev) + goto found; + + /* don't use filename if we have devno and inode */ + return 0; + } + + /* poor man's solution */ + if (backing_file) { + char *name = loopcxt_get_backing_file(lc); + int rc = name && strcmp(name, backing_file) == 0; + + free(name); + if (rc) + goto found; + } + + return 0; +found: + if (flags & LOOPDEV_FL_OFFSET) { + uint64_t off = 0; + + int rc = loopcxt_get_offset(lc, &off) == 0 && off == offset; + + if (rc && flags & LOOPDEV_FL_SIZELIMIT) { + uint64_t sz = 0; + + return loopcxt_get_sizelimit(lc, &sz) == 0 && sz == sizelimit; + } + return rc; + } + return 1; +} + +/* + * The setting is removed by loopcxt_set_device() loopcxt_next()! + */ +int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset) +{ + if (!lc) + return -EINVAL; + lc->config.info.lo_offset = offset; + + DBG(CXT, ul_debugobj(lc, "set offset=%jd", offset)); + return 0; +} + +/* + * The setting is removed by loopcxt_set_device() loopcxt_next()! + */ +int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit) +{ + if (!lc) + return -EINVAL; + lc->config.info.lo_sizelimit = sizelimit; + + DBG(CXT, ul_debugobj(lc, "set sizelimit=%jd", sizelimit)); + return 0; +} + +/* + * The blocksize will be used by loopcxt_set_device(). For already exiting + * devices use loopcxt_ioctl_blocksize(). + * + * The setting is removed by loopcxt_set_device() loopcxt_next()! + */ +int loopcxt_set_blocksize(struct loopdev_cxt *lc, uint64_t blocksize) +{ + if (!lc) + return -EINVAL; + lc->blocksize = blocksize; + + DBG(CXT, ul_debugobj(lc, "set blocksize=%jd", blocksize)); + return 0; +} + +/* + * @lc: context + * @flags: kernel LO_FLAGS_{READ_ONLY,USE_AOPS,AUTOCLEAR} flags + * + * The setting is removed by loopcxt_set_device() loopcxt_next()! + * + * Returns: 0 on success, <0 on error. + */ +int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags) +{ + if (!lc) + return -EINVAL; + lc->config.info.lo_flags = flags; + + DBG(CXT, ul_debugobj(lc, "set flags=%u", (unsigned) flags)); + return 0; +} + +/* + * @lc: context + * @filename: backing file path (the path will be canonicalized) + * + * The setting is removed by loopcxt_set_device() loopcxt_next()! + * + * Returns: 0 on success, <0 on error. + */ +int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename) +{ + if (!lc) + return -EINVAL; + + lc->filename = canonicalize_path(filename); + if (!lc->filename) + return -errno; + + xstrncpy((char *)lc->config.info.lo_file_name, lc->filename, LO_NAME_SIZE); + + DBG(CXT, ul_debugobj(lc, "set backing file=%s", lc->config.info.lo_file_name)); + return 0; +} + +/* + * In kernels prior to v3.9, if the offset or sizelimit options + * are used, the block device's size won't be synced automatically. + * blockdev --getsize64 and filesystems will use the backing + * file size until the block device has been re-opened or the + * LOOP_SET_CAPACITY ioctl is called to sync the sizes. + * + * Since mount -oloop uses the LO_FLAGS_AUTOCLEAR option and passes + * the open file descriptor to the mount system call, we need to use + * the ioctl. Calling losetup directly doesn't have this problem since + * it closes the device when it exits and whatever consumes the device + * next will re-open it, causing the resync. + */ +static int loopcxt_check_size(struct loopdev_cxt *lc, int file_fd) +{ + uint64_t size, expected_size; + int dev_fd; + struct stat st; + + if (!lc->config.info.lo_offset && !lc->config.info.lo_sizelimit) + return 0; + + if (fstat(file_fd, &st)) { + DBG(CXT, ul_debugobj(lc, "failed to fstat backing file")); + return -errno; + } + if (S_ISBLK(st.st_mode)) { + if (blkdev_get_size(file_fd, + (unsigned long long *) &expected_size)) { + DBG(CXT, ul_debugobj(lc, "failed to determine device size")); + return -errno; + } + } else + expected_size = st.st_size; + + if (expected_size == 0 || expected_size <= lc->config.info.lo_offset) { + DBG(CXT, ul_debugobj(lc, "failed to determine expected size")); + return 0; /* ignore this error */ + } + + if (lc->config.info.lo_offset > 0) + expected_size -= lc->config.info.lo_offset; + + if (lc->config.info.lo_sizelimit > 0 && lc->config.info.lo_sizelimit < expected_size) + expected_size = lc->config.info.lo_sizelimit; + + dev_fd = loopcxt_get_fd(lc); + if (dev_fd < 0) { + DBG(CXT, ul_debugobj(lc, "failed to get loop FD")); + return -errno; + } + + if (blkdev_get_size(dev_fd, (unsigned long long *) &size)) { + DBG(CXT, ul_debugobj(lc, "failed to determine loopdev size")); + return -errno; + } + + /* It's block device, so, align to 512-byte sectors */ + if (expected_size % 512) { + DBG(CXT, ul_debugobj(lc, "expected size misaligned to 512-byte sectors")); + expected_size = (expected_size >> 9) << 9; + } + + if (expected_size != size) { + DBG(CXT, ul_debugobj(lc, "warning: loopdev and expected " + "size mismatch (%ju/%ju)", + size, expected_size)); + + if (loopcxt_ioctl_capacity(lc)) { + /* ioctl not available */ + if (errno == ENOTTY || errno == EINVAL) + errno = ERANGE; + return -errno; + } + + if (blkdev_get_size(dev_fd, (unsigned long long *) &size)) + return -errno; + + if (expected_size != size) { + errno = ERANGE; + DBG(CXT, ul_debugobj(lc, "failed to set loopdev size, " + "size: %ju, expected: %ju", + size, expected_size)); + return -errno; + } + } + + return 0; +} + +/* + * @lc: context + * + * Associate the current device (see loopcxt_{set,get}_device()) with + * a file (see loopcxt_set_backing_file()). + * + * The device is initialized read-write by default. If you want read-only + * device then set LO_FLAGS_READ_ONLY by loopcxt_set_flags(). The LOOPDEV_FL_* + * flags are ignored and modified according to LO_FLAGS_*. + * + * If the device is already open by loopcxt_get_fd() then this setup device + * function will re-open the device to fix read/write mode. + * + * The device is also initialized read-only if the backing file is not + * possible to open read-write (e.g. read-only FS). + * + * Returns: <0 on error, 0 on success. + */ +int loopcxt_setup_device(struct loopdev_cxt *lc) +{ + int file_fd, dev_fd, mode = O_RDWR, flags = O_CLOEXEC; + int rc = -1, cnt = 0, err, again; + int errsv = 0; + int fallback = 0; + + if (!lc || !*lc->device || !lc->filename) + return -EINVAL; + + DBG(SETUP, ul_debugobj(lc, "device setup requested")); + + /* + * Open backing file and device + */ + if (lc->config.info.lo_flags & LO_FLAGS_READ_ONLY) + mode = O_RDONLY; + + if (lc->config.info.lo_flags & LO_FLAGS_DIRECT_IO) + flags |= O_DIRECT; + + if ((file_fd = open(lc->filename, mode | flags)) < 0) { + if (mode != O_RDONLY && (errno == EROFS || errno == EACCES)) + file_fd = open(lc->filename, (mode = O_RDONLY) | flags); + + if (file_fd < 0) { + DBG(SETUP, ul_debugobj(lc, "open backing file failed: %m")); + return -errno; + } + } + DBG(SETUP, ul_debugobj(lc, "backing file open: OK")); + + if (lc->fd != -1 && lc->mode != mode) { + DBG(SETUP, ul_debugobj(lc, "closing already open device (mode mismatch)")); + close(lc->fd); + lc->fd = -1; + lc->mode = 0; + } + + if (mode == O_RDONLY) { + lc->flags |= LOOPDEV_FL_RDONLY; /* open() mode */ + lc->config.info.lo_flags |= LO_FLAGS_READ_ONLY; /* kernel loopdev mode */ + } else { + lc->flags |= LOOPDEV_FL_RDWR; /* open() mode */ + lc->config.info.lo_flags &= ~LO_FLAGS_READ_ONLY; + lc->flags &= ~LOOPDEV_FL_RDONLY; + } + + do { + errno = 0; + dev_fd = loopcxt_get_fd(lc); + if (dev_fd >= 0 || lc->control_ok == 0) + break; + if (errno != EACCES && errno != ENOENT) + break; + /* We have permissions to open /dev/loop-control, but open + * /dev/loopN failed with EACCES, it's probably because udevd + * does not applied chown yet. Let's wait a moment. */ + xusleep(25000); + } while (cnt++ < 16); + + if (dev_fd < 0) { + rc = -errno; + goto err; + } + + DBG(SETUP, ul_debugobj(lc, "device open: OK")); + + /* + * Atomic way to configure all by one ioctl call + * -- since Linux v5.8-rc1, commit 3448914e8cc550ba792d4ccc74471d1ca4293aae + */ + lc->config.fd = file_fd; + if (lc->blocksize > 0) + lc->config.block_size = lc->blocksize; + + if (ioctl(dev_fd, LOOP_CONFIGURE, &lc->config) < 0) { + rc = -errno; + errsv = errno; + if (errno != EINVAL && errno != ENOTTY && errno != ENOSYS) { + DBG(SETUP, ul_debugobj(lc, "LOOP_CONFIGURE failed: %m")); + goto err; + } + fallback = 1; + } else { + DBG(SETUP, ul_debugobj(lc, "LOOP_CONFIGURE: OK")); + } + + /* + * Old deprecated way; first assign backing file FD and then in the + * second step set loop device properties. + */ + if (fallback) { + if (ioctl(dev_fd, LOOP_SET_FD, file_fd) < 0) { + rc = -errno; + errsv = errno; + DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD failed: %m")); + goto err; + } + + DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD: OK")); + + if (lc->blocksize > 0 + && (rc = loopcxt_ioctl_blocksize(lc, lc->blocksize)) < 0) { + errsv = -rc; + goto err; + } + + do { + err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->config.info); + again = err && errno == EAGAIN; + if (again) + xusleep(250000); + } while (again); + + if (err) { + rc = -errno; + errsv = errno; + DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m")); + goto err; + } + + DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64: OK")); + } + + if ((rc = loopcxt_check_size(lc, file_fd))) + goto err; + + close(file_fd); + + memset(&lc->config, 0, sizeof(lc->config)); + lc->has_info = 0; + lc->info_failed = 0; + + DBG(SETUP, ul_debugobj(lc, "success [rc=0]")); + return 0; +err: + if (file_fd >= 0) + close(file_fd); + if (dev_fd >= 0 && rc != -EBUSY) + ioctl(dev_fd, LOOP_CLR_FD, 0); + if (errsv) + errno = errsv; + + DBG(SETUP, ul_debugobj(lc, "failed [rc=%d]", rc)); + return rc; +} + +/* + * @lc: context + * + * Update status of the current device (see loopcxt_{set,get}_device()). + * + * Note that once initialized, kernel accepts only selected changes: + * LO_FLAGS_AUTOCLEAR and LO_FLAGS_PARTSCAN + * For more see linux/drivers/block/loop.c:loop_set_status() + * + * Returns: <0 on error, 0 on success. + */ +int loopcxt_ioctl_status(struct loopdev_cxt *lc) +{ + int dev_fd, rc = -1, err, again, tries = 0; + + errno = 0; + dev_fd = loopcxt_get_fd(lc); + + if (dev_fd < 0) { + rc = -errno; + return rc; + } + DBG(SETUP, ul_debugobj(lc, "device open: OK")); + + do { + err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->config.info); + again = err && errno == EAGAIN; + if (again) { + xusleep(250000); + tries++; + } + } while (again && tries <= LOOPDEV_MAX_TRIES); + + if (err) { + rc = -errno; + DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m")); + return rc; + } + + DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64: OK")); + return 0; +} + +int loopcxt_ioctl_capacity(struct loopdev_cxt *lc) +{ + int fd = loopcxt_get_fd(lc); + + if (fd < 0) + return -EINVAL; + + /* Kernels prior to v2.6.30 don't support this ioctl */ + if (ioctl(fd, LOOP_SET_CAPACITY, 0) < 0) { + int rc = -errno; + DBG(CXT, ul_debugobj(lc, "LOOP_SET_CAPACITY failed: %m")); + return rc; + } + + DBG(CXT, ul_debugobj(lc, "capacity set")); + return 0; +} + +int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio) +{ + int fd = loopcxt_get_fd(lc); + + if (fd < 0) + return -EINVAL; + + /* Kernels prior to v4.4 don't support this ioctl */ + if (ioctl(fd, LOOP_SET_DIRECT_IO, use_dio) < 0) { + int rc = -errno; + DBG(CXT, ul_debugobj(lc, "LOOP_SET_DIRECT_IO failed: %m")); + return rc; + } + + DBG(CXT, ul_debugobj(lc, "direct io set")); + return 0; +} + +/* + * Kernel uses "unsigned long" as ioctl arg, but we use u64 for all sizes to + * keep loopdev internal API simple. + */ +int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize) +{ + int fd = loopcxt_get_fd(lc); + int err, again, tries = 0; + + if (fd < 0) + return -EINVAL; + + do { + /* Kernels prior to v4.14 don't support this ioctl */ + err = ioctl(fd, LOOP_SET_BLOCK_SIZE, (unsigned long) blocksize); + again = err && errno == EAGAIN; + if (again) { + xusleep(250000); + tries++; + } else if (err) { + int rc = -errno; + DBG(CXT, ul_debugobj(lc, "LOOP_SET_BLOCK_SIZE failed: %m")); + return rc; + } + } while (again && tries <= LOOPDEV_MAX_TRIES); + + DBG(CXT, ul_debugobj(lc, "logical block size set")); + return 0; +} + +int loopcxt_delete_device(struct loopdev_cxt *lc) +{ + int fd = loopcxt_get_fd(lc); + + if (fd < 0) + return -EINVAL; + + if (ioctl(fd, LOOP_CLR_FD, 0) < 0) { + DBG(CXT, ul_debugobj(lc, "LOOP_CLR_FD failed: %m")); + return -errno; + } + + DBG(CXT, ul_debugobj(lc, "device removed")); + return 0; +} + +int loopcxt_add_device(struct loopdev_cxt *lc) +{ + int rc = -EINVAL; + int ctl, nr = -1; + const char *p, *dev = loopcxt_get_device(lc); + + if (!dev) + goto done; + + if (!(lc->flags & LOOPDEV_FL_CONTROL)) { + rc = -ENOSYS; + goto done; + } + + p = strrchr(dev, '/'); + if (!p || (sscanf(p, "/loop%d", &nr) != 1 && sscanf(p, "/%d", &nr) != 1) + || nr < 0) + goto done; + + ctl = open(_PATH_DEV_LOOPCTL, O_RDWR|O_CLOEXEC); + if (ctl >= 0) { + DBG(CXT, ul_debugobj(lc, "add_device %d", nr)); + rc = ioctl(ctl, LOOP_CTL_ADD, nr); + close(ctl); + } + lc->control_ok = rc >= 0 ? 1 : 0; +done: + DBG(CXT, ul_debugobj(lc, "add_device done [rc=%d]", rc)); + return rc; +} + +/* + * Note that LOOP_CTL_GET_FREE ioctl is supported since kernel 3.1. In older + * kernels we have to check all loop devices to found unused one. + * + * See kernel commit 770fe30a46a12b6fb6b63fbe1737654d28e8484. + */ +int loopcxt_find_unused(struct loopdev_cxt *lc) +{ + int rc = -1; + + DBG(CXT, ul_debugobj(lc, "find_unused requested")); + + if (lc->flags & LOOPDEV_FL_CONTROL) { + int ctl; + + DBG(CXT, ul_debugobj(lc, "using loop-control")); + + ctl = open(_PATH_DEV_LOOPCTL, O_RDWR|O_CLOEXEC); + if (ctl >= 0) + rc = ioctl(ctl, LOOP_CTL_GET_FREE); + if (rc >= 0) { + char name[16]; + snprintf(name, sizeof(name), "loop%d", rc); + + rc = loopiter_set_device(lc, name); + } + lc->control_ok = ctl >= 0 && rc == 0 ? 1 : 0; + if (ctl >= 0) + close(ctl); + DBG(CXT, ul_debugobj(lc, "find_unused by loop-control [rc=%d]", rc)); + } + + if (rc < 0) { + DBG(CXT, ul_debugobj(lc, "using loop scan")); + rc = loopcxt_init_iterator(lc, LOOPITER_FL_FREE); + if (rc) + return rc; + + rc = loopcxt_next(lc); + loopcxt_deinit_iterator(lc); + DBG(CXT, ul_debugobj(lc, "find_unused by scan [rc=%d]", rc)); + } + return rc; +} + + + +/* + * Return: TRUE/FALSE + */ +int loopdev_is_autoclear(const char *device) +{ + struct loopdev_cxt lc; + int rc; + + if (!device) + return 0; + + rc = loopcxt_init(&lc, 0); + if (!rc) + rc = loopcxt_set_device(&lc, device); + if (!rc) + rc = loopcxt_is_autoclear(&lc); + + loopcxt_deinit(&lc); + return rc; +} + +char *loopdev_get_backing_file(const char *device) +{ + struct loopdev_cxt lc; + char *res = NULL; + + if (!device) + return NULL; + if (loopcxt_init(&lc, 0)) + return NULL; + if (loopcxt_set_device(&lc, device) == 0) + res = loopcxt_get_backing_file(&lc); + + loopcxt_deinit(&lc); + return res; +} + +int loopdev_has_backing_file(const char *device) +{ + char *tmp = loopdev_get_backing_file(device); + + if (tmp) { + free(tmp); + return 1; + } + return 0; +} + +/* + * Returns: TRUE/FALSE + */ +int loopdev_is_used(const char *device, const char *filename, + uint64_t offset, uint64_t sizelimit, int flags) +{ + struct loopdev_cxt lc; + struct stat st; + int rc = 0; + + if (!device || !filename) + return 0; + + rc = loopcxt_init(&lc, 0); + if (!rc) + rc = loopcxt_set_device(&lc, device); + if (rc) + return rc; + + rc = !stat(filename, &st); + rc = loopcxt_is_used(&lc, rc ? &st : NULL, filename, offset, sizelimit, flags); + + loopcxt_deinit(&lc); + return rc; +} + +int loopdev_delete(const char *device) +{ + struct loopdev_cxt lc; + int rc; + + if (!device) + return -EINVAL; + + rc = loopcxt_init(&lc, 0); + if (!rc) + rc = loopcxt_set_device(&lc, device); + if (!rc) + rc = loopcxt_delete_device(&lc); + loopcxt_deinit(&lc); + return rc; +} + +/* + * Returns: 0 = success, < 0 error, 1 not found + */ +int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename, + uint64_t offset, uint64_t sizelimit, int flags) +{ + int rc, hasst; + struct stat st; + + if (!filename) + return -EINVAL; + + hasst = !stat(filename, &st); + + rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED); + if (rc) + return rc; + + while ((rc = loopcxt_next(lc)) == 0) { + + if (loopcxt_is_used(lc, hasst ? &st : NULL, + filename, offset, sizelimit, flags)) + break; + } + + loopcxt_deinit_iterator(lc); + return rc; +} + +/* + * Returns: 0 = not found, < 0 error, 1 found, 2 found full size and offset match + */ +int loopcxt_find_overlap(struct loopdev_cxt *lc, const char *filename, + uint64_t offset, uint64_t sizelimit) +{ + int rc, hasst; + struct stat st; + + if (!filename) + return -EINVAL; + + DBG(CXT, ul_debugobj(lc, "find_overlap requested")); + hasst = !stat(filename, &st); + + rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED); + if (rc) + return rc; + + while ((rc = loopcxt_next(lc)) == 0) { + uint64_t lc_sizelimit, lc_offset; + + rc = loopcxt_is_used(lc, hasst ? &st : NULL, + filename, offset, sizelimit, 0); + /* + * Either the loopdev is unused or we've got an error which can + * happen when we are racing with device autoclear. Just ignore + * this loopdev... + */ + if (rc <= 0) + continue; + + DBG(CXT, ul_debugobj(lc, "found %s backed by %s", + loopcxt_get_device(lc), filename)); + + rc = loopcxt_get_offset(lc, &lc_offset); + if (rc) { + DBG(CXT, ul_debugobj(lc, "failed to get offset for device %s", + loopcxt_get_device(lc))); + continue; + } + rc = loopcxt_get_sizelimit(lc, &lc_sizelimit); + if (rc) { + DBG(CXT, ul_debugobj(lc, "failed to get sizelimit for device %s", + loopcxt_get_device(lc))); + continue; + } + + /* full match */ + if (lc_sizelimit == sizelimit && lc_offset == offset) { + DBG(CXT, ul_debugobj(lc, "overlapping loop device %s (full match)", + loopcxt_get_device(lc))); + rc = 2; + goto found; + } + + /* overlap */ + if (lc_sizelimit != 0 && offset >= lc_offset + lc_sizelimit) + continue; + if (sizelimit != 0 && offset + sizelimit <= lc_offset) + continue; + + DBG(CXT, ul_debugobj(lc, "overlapping loop device %s", + loopcxt_get_device(lc))); + rc = 1; + goto found; + } + + if (rc == 1) + rc = 0; /* not found */ +found: + loopcxt_deinit_iterator(lc); + DBG(CXT, ul_debugobj(lc, "find_overlap done [rc=%d]", rc)); + return rc; +} + +/* + * Returns allocated string with device name + */ +char *loopdev_find_by_backing_file(const char *filename, uint64_t offset, uint64_t sizelimit, int flags) +{ + struct loopdev_cxt lc; + char *res = NULL; + + if (!filename) + return NULL; + + if (loopcxt_init(&lc, 0)) + return NULL; + if (loopcxt_find_by_backing_file(&lc, filename, offset, sizelimit, flags) == 0) + res = loopcxt_strdup_device(&lc); + loopcxt_deinit(&lc); + + return res; +} + +/* + * Returns number of loop devices associated with @file, if only one loop + * device is associated with the given @filename and @loopdev is not NULL then + * @loopdev returns name of the device. + */ +int loopdev_count_by_backing_file(const char *filename, char **loopdev) +{ + struct loopdev_cxt lc; + int count = 0, rc; + + if (!filename) + return -1; + + rc = loopcxt_init(&lc, 0); + if (rc) + return rc; + if (loopcxt_init_iterator(&lc, LOOPITER_FL_USED)) + return -1; + + while(loopcxt_next(&lc) == 0) { + char *backing = loopcxt_get_backing_file(&lc); + + if (!backing || strcmp(backing, filename) != 0) { + free(backing); + continue; + } + + free(backing); + if (loopdev && count == 0) + *loopdev = loopcxt_strdup_device(&lc); + count++; + } + + loopcxt_deinit(&lc); + + if (loopdev && count > 1) { + free(*loopdev); + *loopdev = NULL; + } + return count; +} + +#ifdef TEST_PROGRAM_LOOPDEV +int main(int argc, char *argv[]) +{ + if (argc < 2) + goto usage; + + if (strcmp(argv[1], "--is-loopdev") == 0 && argc == 3) + printf("%s: %s\n", argv[2], is_loopdev(argv[2]) ? "OK" : "FAIL"); + else + goto usage; + + return EXIT_SUCCESS; +usage: + fprintf(stderr, "usage: %1$s --is-loopdev <dev>\n", + program_invocation_short_name); + return EXIT_FAILURE; +} +#endif + |