diff options
Diffstat (limited to 'libblkid/loopdev.c')
| -rw-r--r-- | libblkid/loopdev.c | 1559 |
1 files changed, 1559 insertions, 0 deletions
diff --git a/libblkid/loopdev.c b/libblkid/loopdev.c new file mode 100644 index 000000000..a25a2fae4 --- /dev/null +++ b/libblkid/loopdev.c @@ -0,0 +1,1559 @@ +/* + * 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 <sys/sysmacros.h> +#include <inttypes.h> +#include <dirent.h> +#include <linux/posix_types.h> + +#include "linux_version.h" +#include "c.h" +#include "sysfs.h" +#include "pathnames.h" +#include "loopdev.h" +#include "canonicalize.h" +#include "at.h" + +#define CONFIG_LOOPDEV_DEBUG + +#ifdef CONFIG_LOOPDEV_DEBUG +# include <stdarg.h> + +# define DBG(l,x) do { \ + if ((l)->debug) {\ + fprintf(stderr, "loopdev: [%p]: ", (l)); \ + x; \ + } \ + } while(0) + +static inline void __attribute__ ((__format__ (__printf__, 1, 2))) +loopdev_debug(const char *mesg, ...) +{ + va_list ap; + va_start(ap, mesg); + vfprintf(stderr, mesg, ap); + va_end(ap); + fputc('\n', stderr); +} + +#else /* !CONFIG_LOOPDEV_DEBUG */ +# define DBG(m,x) do { ; } while(0) +#endif + +/* + * 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>) + * + * 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(lc, loopdev_debug("closing old open fd")); + } + lc->fd = -1; + lc->mode = 0; + lc->has_info = 0; + lc->info_failed = 0; + *lc->device = '\0'; + memset(&lc->info, 0, sizeof(lc->info)); + + /* 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 { + strncpy(lc->device, device, sizeof(lc->device)); + lc->device[sizeof(lc->device) - 1] = '\0'; + } + DBG(lc, loopdev_debug("%s successfully assigned", device)); + } + + sysfs_deinit(&lc->sysfs); + return 0; +} + +int loopcxt_has_device(struct loopdev_cxt *lc) +{ + return lc && *lc->device; +} + +/* + * @lc: context + * @flags: LOOPDEV_FL_* flags + * + * Initilize 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 expection 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; + + memcpy(lc, &dummy, sizeof(dummy)); + lc->flags = flags; + + if (getenv("LOOPDEV_DEBUG")) + loopcxt_enable_debug(lc, TRUE); + + 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(lc, loopdev_debug("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(lc, loopdev_debug("init: ignore ioctls")); + } + + if (!(lc->flags & LOOPDEV_FL_CONTROL) && !stat(_PATH_DEV_LOOPCTL, &st)) { + lc->flags |= LOOPDEV_FL_CONTROL; + DBG(lc, loopdev_debug("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(lc, loopdev_debug("de-initialize")); + + free(lc->filename); + lc->filename = NULL; + + ignore_result( loopcxt_set_device(lc, NULL) ); + loopcxt_deinit_iterator(lc); + + errno = errsv; +} + +/* + * @lc: context + * @enable: TRUE/FALSE + * + * Enabled/disables debug messages + */ +void loopcxt_enable_debug(struct loopdev_cxt *lc, int enable) +{ + if (lc) + lc->debug = enable ? 1 : 0; +} + +/* + * @lc: context + * + * Returns newly allocated device path. + */ +char *loopcxt_strdup_device(struct loopdev_cxt *lc) +{ + if (!lc || !lc->device || !*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 ? lc->device : NULL; +} + +/* + * @lc: context + * + * Returns pointer to the sysfs context (see lib/sysfs.c) + */ +struct sysfs_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc) +{ + if (!lc || !*lc->device || (lc->flags & LOOPDEV_FL_NOSYSFS)) + return NULL; + + if (!lc->sysfs.devno) { + dev_t devno = sysfs_devname_to_devno(lc->device, NULL); + if (!devno) { + DBG(lc, loopdev_debug("sysfs: failed devname to devno")); + return NULL; + } + if (sysfs_init(&lc->sysfs, devno, NULL)) { + DBG(lc, loopdev_debug("sysfs: init failed")); + return NULL; + } + } + + 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); + DBG(lc, loopdev_debug("open %s [%s]: %s", lc->device, + lc->flags & LOOPDEV_FL_RDWR ? "rw" : "ro", + lc->fd < 0 ? "failed" : "ok")); + } + 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 allows 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; + + DBG(lc, loopdev_debug("iter: initialize")); + + iter = &lc->iter; + + /* 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; + + DBG(lc, loopdev_debug("iter: de-initialize")); + + iter = &lc->iter; + + free(iter->minors); + if (iter->proc) + fclose(iter->proc); + if (iter->sysblock) + closedir(iter->sysblock); + iter->minors = NULL; + iter->proc = NULL; + iter->sysblock = NULL; + iter->done = 1; + return 0; +} + +/* + * Same as loopcxt_set_device, but also checks if the device is + * associeted 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 */ + + 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(lc, loopdev_debug("iter: unset device")); + ignore_result( loopcxt_set_device(lc, NULL) ); + return 1; +} + +static int cmpnum(const void *p1, const void *p2) +{ + return (((* (int *) p1) > (* (int *) p2)) - + ((* (int *) p1) < (* (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; + 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; + + 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); + 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(lc, loopdev_debug("iter: scan /proc/partitions")); + + if (!iter->proc) + iter->proc = fopen(_PATH_PROC_PARTITIONS, "r"); + 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(lc, loopdev_debug("iter: check %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(lc, loopdev_debug("iter: scan /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[256]; + struct stat st; + + DBG(lc, loopdev_debug("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 (fstat_at(fd, _PATH_SYS_BLOCK, 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; + + DBG(lc, loopdev_debug("iter: next")); + + iter = &lc->iter; + if (iter->done) + return 1; + + /* 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(lc, loopdev_debug("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(lc, loopdev_debug("iter: next: scan /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; + + if (!device) + return 0; + + return (stat(device, &st) == 0 && + S_ISBLK(st.st_mode) && + major(st.st_rdev) == LOOPDEV_MAJOR); +} + +/* + * @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) + return NULL; + if (lc->has_info) + return &lc->info; + + fd = loopcxt_get_fd(lc); + if (fd < 0) + return NULL; + + if (ioctl(fd, LOOP_GET_STATUS64, &lc->info) == 0) { + lc->has_info = 1; + lc->info_failed = 0; + DBG(lc, loopdev_debug("reading loop_info64 OK")); + return &lc->info; + } else { + lc->info_failed = 1; + DBG(lc, loopdev_debug("reading loop_info64 FAILED")); + } + + return NULL; +} + +/* + * @lc: context + * + * Returns (allocated) string with path to the file assicieted + * with the current loop device. + */ +char *loopcxt_get_backing_file(struct loopdev_cxt *lc) +{ + struct sysfs_cxt *sysfs = loopcxt_get_sysfs(lc); + char *res = NULL; + + if (sysfs) + /* + * This is always preffered, the loop_info64 + * has too small buffer for the filename. + */ + res = sysfs_strdup(sysfs, "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(lc, loopdev_debug("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 sysfs_cxt *sysfs = loopcxt_get_sysfs(lc); + int rc = -EINVAL; + + if (sysfs) + rc = sysfs_read_u64(sysfs, "loop/offset", offset); + + if (rc && loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) { + if (offset) + *offset = lo->lo_offset; + rc = 0; + } + } + + DBG(lc, loopdev_debug("get_offset [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 sysfs_cxt *sysfs = loopcxt_get_sysfs(lc); + int rc = -EINVAL; + + if (sysfs) + rc = sysfs_read_u64(sysfs, "loop/sizelimit", size); + + if (rc && loopcxt_ioctl_enabled(lc)) { + struct loop_info64 *lo = loopcxt_get_info(lc); + if (lo) { + if (size) + *size = lo->lo_sizelimit; + rc = 0; + } + } + + DBG(lc, loopdev_debug("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 = -EINVAL; + + if (lo) { + if (type) + *type = lo->lo_encrypt_type; + rc = 0; + } + DBG(lc, loopdev_debug("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(lc, loopdev_debug("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 = -EINVAL; + + if (lo) { + if (devno) + *devno = lo->lo_device; + rc = 0; + } + DBG(lc, loopdev_debug("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 = -EINVAL; + + if (lo) { + if (ino) + *ino = lo->lo_inode; + rc = 0; + } + DBG(lc, loopdev_debug("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 paremeter 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"); + 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 + * scannig is enabled for all loop devices. + */ +int loopcxt_is_partscan(struct loopdev_cxt *lc) +{ + struct sysfs_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + /* kernel >= 3.2 */ + int fl; + if (sysfs_read_int(sysfs, "loop/partscan", &fl) == 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 sysfs_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + int fl; + if (sysfs_read_int(sysfs, "loop/autoclear", &fl) == 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 sysfs_cxt *sysfs = loopcxt_get_sysfs(lc); + + if (sysfs) { + int fl; + if (sysfs_read_int(sysfs, "ro", &fl) == 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 + * @st: backing file stat or NULL + * @backing_file: filename + * @offset: offset + * @flags: LOOPDEV_FL_OFFSET if @offset should not be ignored + * + * 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(). + * + * 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, + int flags) +{ + ino_t ino; + dev_t dev; + + if (!lc) + return 0; + + DBG(lc, loopdev_debug("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; + + return loopcxt_get_offset(lc, &off) == 0 && off == offset; + } + 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->info.lo_offset = offset; + + DBG(lc, loopdev_debug("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->info.lo_sizelimit = sizelimit; + + DBG(lc, loopdev_debug("set sizelimit=%jd", sizelimit)); + 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->info.lo_flags = flags; + + DBG(lc, loopdev_debug("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; + + strncpy((char *)lc->info.lo_file_name, lc->filename, LO_NAME_SIZE); + lc->info.lo_file_name[LO_NAME_SIZE- 1] = '\0'; + + DBG(lc, loopdev_debug("set backing file=%s", lc->info.lo_file_name)); + return 0; +} + +/* + * @cl: 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, rc = -1; + + if (!lc || !*lc->device || !lc->filename) + return -EINVAL; + + DBG(lc, loopdev_debug("device setup requested")); + + /* + * Open backing file and device + */ + if (lc->info.lo_flags & LO_FLAGS_READ_ONLY) + mode = O_RDONLY; + + if ((file_fd = open(lc->filename, mode)) < 0) { + if (mode != O_RDONLY && (errno == EROFS || errno == EACCES)) + file_fd = open(lc->filename, mode = O_RDONLY); + + if (file_fd < 0) { + DBG(lc, loopdev_debug("open backing file failed: %m")); + return -errno; + } + } + DBG(lc, loopdev_debug("setup: backing file open: OK")); + + if (lc->fd != -1 && lc->mode != mode) { + DBG(lc, loopdev_debug("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->info.lo_flags |= LO_FLAGS_READ_ONLY; /* kernel loopdev mode */ + } else { + lc->flags |= LOOPDEV_FL_RDWR; /* open() mode */ + lc->info.lo_flags &= ~LO_FLAGS_READ_ONLY; + lc->flags &= ~LOOPDEV_FL_RDONLY; + } + + dev_fd = loopcxt_get_fd(lc); + if (dev_fd < 0) { + rc = -errno; + goto err; + } + + DBG(lc, loopdev_debug("setup: device open: OK")); + + /* + * Set FD + */ + if (ioctl(dev_fd, LOOP_SET_FD, file_fd) < 0) { + rc = -errno; + DBG(lc, loopdev_debug("LOOP_SET_FD failed: %m")); + goto err; + } + + DBG(lc, loopdev_debug("setup: LOOP_SET_FD: OK")); + + close(file_fd); + file_fd = -1; + + if (ioctl(dev_fd, LOOP_SET_STATUS64, &lc->info)) { + DBG(lc, loopdev_debug("LOOP_SET_STATUS64 failed: %m")); + goto err; + } + + DBG(lc, loopdev_debug("setup: LOOP_SET_STATUS64: OK")); + + memset(&lc->info, 0, sizeof(lc->info)); + lc->has_info = 0; + lc->info_failed = 0; + + DBG(lc, loopdev_debug("setup success [rc=0]")); + return 0; +err: + if (file_fd >= 0) + close(file_fd); + if (dev_fd >= 0) + ioctl(dev_fd, LOOP_CLR_FD, 0); + + DBG(lc, loopdev_debug("setup failed [rc=%d]", rc)); + return rc; +} + +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(lc, loopdev_debug("LOOP_CLR_FD failed: %m")); + return -errno; + } + + DBG(lc, loopdev_debug("device removed")); + return 0; +} + +/* + * 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(lc, loopdev_debug("find_unused requested")); + + if (lc->flags & LOOPDEV_FL_CONTROL) { + int ctl = open(_PATH_DEV_LOOPCTL, O_RDWR); + + 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); + } + if (ctl >= 0) + close(ctl); + DBG(lc, loopdev_debug("find_unused by loop-control [rc=%d]", rc)); + } + + if (rc < 0) { + rc = loopcxt_init_iterator(lc, LOOPITER_FL_FREE); + if (rc) + return rc; + + rc = loopcxt_next(lc); + loopcxt_deinit_iterator(lc); + DBG(lc, loopdev_debug("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; +} + +/* + * Returns: TRUE/FALSE + */ +int loopdev_is_used(const char *device, const char *filename, + uint64_t offset, 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, 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, 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, flags)) + break; + } + + loopcxt_deinit_iterator(lc); + return rc; +} + +/* + * Returns allocated string with device name + */ +char *loopdev_find_by_backing_file(const char *filename, uint64_t offset, 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, 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 associeted 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)) { + 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 +#include <errno.h> +#include <err.h> + +static void test_loop_info(const char *device, int flags, int debug) +{ + struct loopdev_cxt lc; + char *p; + uint64_t u64; + + if (loopcxt_init(&lc, flags)) + return; + loopcxt_enable_debug(&lc, debug); + + if (loopcxt_set_device(&lc, device)) + err(EXIT_FAILURE, "failed to set device"); + + p = loopcxt_get_backing_file(&lc); + printf("\tBACKING FILE: %s\n", p); + free(p); + + if (loopcxt_get_offset(&lc, &u64) == 0) + printf("\tOFFSET: %jd\n", u64); + + if (loopcxt_get_sizelimit(&lc, &u64) == 0) + printf("\tSIZE LIMIT: %jd\n", u64); + + printf("\tAUTOCLEAR: %s\n", loopcxt_is_autoclear(&lc) ? "YES" : "NOT"); + + loopcxt_deinit(&lc); +} + +static void test_loop_scan(int flags, int debug) +{ + struct loopdev_cxt lc; + int rc; + + if (loopcxt_init(&lc, 0)) + return; + loopcxt_enable_debug(&lc, debug); + + if (loopcxt_init_iterator(&lc, flags)) + err(EXIT_FAILURE, "iterator initlization failed"); + + while((rc = loopcxt_next(&lc)) == 0) { + const char *device = loopcxt_get_device(&lc); + + if (flags & LOOPITER_FL_USED) { + char *backing = loopcxt_get_backing_file(&lc); + printf("\t%s: %s\n", device, backing); + free(backing); + } else + printf("\t%s\n", device); + } + + if (rc < 0) + err(EXIT_FAILURE, "loopdevs scanning failed"); + + loopcxt_deinit(&lc); +} + +static int test_loop_setup(const char *filename, const char *device, int debug) +{ + struct loopdev_cxt lc; + int rc; + + rc = loopcxt_init(&lc, 0); + if (rc) + return rc; + loopcxt_enable_debug(&lc, debug); + + if (device) { + rc = loopcxt_set_device(&lc, device); + if (rc) + err(EXIT_FAILURE, "failed to set device: %s", device); + } + + do { + if (!device) { + rc = loopcxt_find_unused(&lc); + if (rc) + err(EXIT_FAILURE, "failed to find unused device"); + printf("Trying to use '%s'\n", loopcxt_get_device(&lc)); + } + + if (loopcxt_set_backing_file(&lc, filename)) + err(EXIT_FAILURE, "failed to set backing file"); + + rc = loopcxt_setup_device(&lc); + if (rc == 0) + break; /* success */ + + if (device || rc != -EBUSY) + err(EXIT_FAILURE, "failed to setup device for %s", + lc.filename); + + printf("device stolen...trying again\n"); + } while (1); + + loopcxt_deinit(&lc); + + return 0; +} + +int main(int argc, char *argv[]) +{ + int dbg; + + if (argc < 2) + goto usage; + + dbg = getenv("LOOPDEV_DEBUG") == NULL ? 0 : 1; + + if (argc == 3 && strcmp(argv[1], "--info") == 0) { + printf("---sysfs & ioctl:---\n"); + test_loop_info(argv[2], 0, dbg); + printf("---sysfs only:---\n"); + test_loop_info(argv[2], LOOPDEV_FL_NOIOCTL, dbg); + printf("---ioctl only:---\n"); + test_loop_info(argv[2], LOOPDEV_FL_NOSYSFS, dbg); + + } else if (argc == 2 && strcmp(argv[1], "--used") == 0) { + printf("---all used devices---\n"); + test_loop_scan(LOOPITER_FL_USED, dbg); + + } else if (argc == 2 && strcmp(argv[1], "--free") == 0) { + printf("---all free devices---\n"); + test_loop_scan(LOOPITER_FL_FREE, dbg); + + } else if (argc >= 3 && strcmp(argv[1], "--setup") == 0) { + test_loop_setup(argv[2], argv[3], dbg); + + } else if (argc == 3 && strcmp(argv[1], "--delete") == 0) { + if (loopdev_delete(argv[2])) + errx(EXIT_FAILURE, "failed to deinitialize device %s", argv[2]); + } else + goto usage; + + return EXIT_SUCCESS; + +usage: + errx(EXIT_FAILURE, "usage: \n" + " %1$s --info <device>\n" + " %1$s --free\n" + " %1$s --used\n" + " %1$s --setup <filename> [<device>]\n" + " %1$s --delete\n", + argv[0]); +} + +#endif /* TEST_PROGRAM */ |