/*
* 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 */
