2017-11-18 17:09:20 +01:00
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/* SPDX-License-Identifier: LGPL-2.1+ */
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2016-12-01 20:25:26 +01:00
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2018-01-11 00:39:12 +01:00
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#include <errno.h>
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2016-12-01 20:25:26 +01:00
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#include <fcntl.h>
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#include <linux/loop.h>
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#include <sys/ioctl.h>
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "loop-util.h"
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2018-02-19 18:01:05 +01:00
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#include "stat-util.h"
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2016-12-01 20:25:26 +01:00
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int loop_device_make(int fd, int open_flags, LoopDevice **ret) {
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const struct loop_info64 info = {
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.lo_flags = LO_FLAGS_AUTOCLEAR|LO_FLAGS_PARTSCAN|(open_flags == O_RDONLY ? LO_FLAGS_READ_ONLY : 0),
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};
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_cleanup_close_ int control = -1, loop = -1;
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_cleanup_free_ char *loopdev = NULL;
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2019-05-21 18:13:55 +02:00
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unsigned n_attempts = 0;
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2016-12-01 20:25:26 +01:00
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struct stat st;
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LoopDevice *d;
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2018-02-19 18:01:05 +01:00
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int nr, r;
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2016-12-01 20:25:26 +01:00
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assert(fd >= 0);
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assert(ret);
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assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
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if (fstat(fd, &st) < 0)
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return -errno;
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if (S_ISBLK(st.st_mode)) {
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int copy;
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/* If this is already a block device, store a copy of the fd as it is */
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copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
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if (copy < 0)
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return -errno;
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d = new0(LoopDevice, 1);
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if (!d)
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return -ENOMEM;
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*d = (LoopDevice) {
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.fd = copy,
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.nr = -1,
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2018-12-31 17:00:10 +01:00
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.relinquished = true, /* It's not allocated by us, don't destroy it when this object is freed */
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2016-12-01 20:25:26 +01:00
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};
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*ret = d;
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2018-12-31 17:00:10 +01:00
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return d->fd;
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2016-12-01 20:25:26 +01:00
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}
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2018-02-19 18:01:05 +01:00
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r = stat_verify_regular(&st);
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if (r < 0)
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return r;
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2016-12-01 20:25:26 +01:00
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control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
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if (control < 0)
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return -errno;
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2019-05-21 18:13:55 +02:00
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/* Loop around LOOP_CTL_GET_FREE, since at the moment we attempt to open the returned device it might
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* be gone already, taken by somebody else racing against us. */
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for (;;) {
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nr = ioctl(control, LOOP_CTL_GET_FREE);
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if (nr < 0)
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return -errno;
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2016-12-01 20:25:26 +01:00
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2019-05-21 18:13:55 +02:00
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if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
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return -ENOMEM;
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2016-12-01 20:25:26 +01:00
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2019-05-21 18:13:55 +02:00
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loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
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if (loop < 0)
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return -errno;
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if (ioctl(loop, LOOP_SET_FD, fd) < 0) {
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if (errno != EBUSY)
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return -errno;
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2016-12-01 20:25:26 +01:00
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2019-05-21 18:13:55 +02:00
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if (++n_attempts >= 64) /* Give up eventually */
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return -EBUSY;
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} else
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break;
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loopdev = mfree(loopdev);
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loop = safe_close(loop);
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}
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2016-12-01 20:25:26 +01:00
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if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0)
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return -errno;
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d = new(LoopDevice, 1);
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if (!d)
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return -ENOMEM;
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*d = (LoopDevice) {
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2018-04-05 07:26:26 +02:00
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.fd = TAKE_FD(loop),
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.node = TAKE_PTR(loopdev),
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2016-12-01 20:25:26 +01:00
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.nr = nr,
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};
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*ret = d;
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2018-12-31 16:56:06 +01:00
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return d->fd;
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2016-12-01 20:25:26 +01:00
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}
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int loop_device_make_by_path(const char *path, int open_flags, LoopDevice **ret) {
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_cleanup_close_ int fd = -1;
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assert(path);
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assert(ret);
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assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
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fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
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if (fd < 0)
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return -errno;
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return loop_device_make(fd, open_flags, ret);
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}
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LoopDevice* loop_device_unref(LoopDevice *d) {
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if (!d)
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return NULL;
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if (d->fd >= 0) {
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2016-12-02 19:32:09 +01:00
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if (d->nr >= 0 && !d->relinquished) {
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2016-12-01 20:25:26 +01:00
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if (ioctl(d->fd, LOOP_CLR_FD) < 0)
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log_debug_errno(errno, "Failed to clear loop device: %m");
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}
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safe_close(d->fd);
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}
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2016-12-02 19:32:09 +01:00
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if (d->nr >= 0 && !d->relinquished) {
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2016-12-01 20:25:26 +01:00
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_cleanup_close_ int control = -1;
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control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
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if (control < 0)
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log_debug_errno(errno, "Failed to open loop control device: %m");
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else {
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if (ioctl(control, LOOP_CTL_REMOVE, d->nr) < 0)
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log_debug_errno(errno, "Failed to remove loop device: %m");
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}
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}
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free(d->node);
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2017-11-24 11:31:49 +01:00
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return mfree(d);
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2016-12-01 20:25:26 +01:00
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}
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2016-12-02 19:32:09 +01:00
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void loop_device_relinquish(LoopDevice *d) {
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assert(d);
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/* Don't attempt to clean up the loop device anymore from this point on. Leave the clean-ing up to the kernel
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* itself, using the loop device "auto-clear" logic we already turned on when creating the device. */
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d->relinquished = true;
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}
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