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-rw-r--r--src/shared/loop-util.c722
1 files changed, 722 insertions, 0 deletions
diff --git a/src/shared/loop-util.c b/src/shared/loop-util.c
new file mode 100644
index 0000000..84f415a
--- /dev/null
+++ b/src/shared/loop-util.c
@@ -0,0 +1,722 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#if HAVE_VALGRIND_MEMCHECK_H
+#include <valgrind/memcheck.h>
+#endif
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/blkpg.h>
+#include <linux/fs.h>
+#include <linux/loop.h>
+#include <sys/file.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "blockdev-util.h"
+#include "device-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "loop-util.h"
+#include "missing_loop.h"
+#include "parse-util.h"
+#include "random-util.h"
+#include "stat-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "tmpfile-util.h"
+
+static void cleanup_clear_loop_close(int *fd) {
+ if (*fd < 0)
+ return;
+
+ (void) ioctl(*fd, LOOP_CLR_FD);
+ (void) safe_close(*fd);
+}
+
+static int loop_is_bound(int fd) {
+ struct loop_info64 info;
+
+ assert(fd >= 0);
+
+ if (ioctl(fd, LOOP_GET_STATUS64, &info) < 0) {
+ if (errno == ENXIO)
+ return false; /* not bound! */
+
+ return -errno;
+ }
+
+ return true; /* bound! */
+}
+
+static int device_has_block_children(sd_device *d) {
+ _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+ const char *main_sn, *main_ss;
+ sd_device *q;
+ int r;
+
+ assert(d);
+
+ /* Checks if the specified device currently has block device children (i.e. partition block
+ * devices). */
+
+ r = sd_device_get_sysname(d, &main_sn);
+ if (r < 0)
+ return r;
+
+ r = sd_device_get_subsystem(d, &main_ss);
+ if (r < 0)
+ return r;
+
+ if (!streq(main_ss, "block"))
+ return -EINVAL;
+
+ r = sd_device_enumerator_new(&e);
+ if (r < 0)
+ return r;
+
+ r = sd_device_enumerator_allow_uninitialized(e);
+ if (r < 0)
+ return r;
+
+ r = sd_device_enumerator_add_match_parent(e, d);
+ if (r < 0)
+ return r;
+
+ FOREACH_DEVICE(e, q) {
+ const char *ss, *sn;
+
+ r = sd_device_get_subsystem(q, &ss);
+ if (r < 0)
+ continue;
+
+ if (!streq(ss, "block"))
+ continue;
+
+ r = sd_device_get_sysname(q, &sn);
+ if (r < 0)
+ continue;
+
+ if (streq(sn, main_sn))
+ continue;
+
+ return 1; /* we have block device children */
+ }
+
+ return 0;
+}
+
+static int loop_configure(
+ int fd,
+ int nr,
+ const struct loop_config *c,
+ bool *try_loop_configure) {
+
+ _cleanup_(sd_device_unrefp) sd_device *d = NULL;
+ _cleanup_free_ char *sysname = NULL;
+ _cleanup_close_ int lock_fd = -1;
+ int r;
+
+ assert(fd >= 0);
+ assert(nr >= 0);
+ assert(c);
+ assert(try_loop_configure);
+
+ if (asprintf(&sysname, "loop%i", nr) < 0)
+ return -ENOMEM;
+
+ r = sd_device_new_from_subsystem_sysname(&d, "block", sysname);
+ if (r < 0)
+ return r;
+
+ /* Let's lock the device before we do anything. We take the BSD lock on a second, separately opened
+ * fd for the device. udev after all watches for close() events (specifically IN_CLOSE_WRITE) on
+ * block devices to reprobe them, hence by having a separate fd we will later close() we can ensure
+ * we trigger udev after everything is done. If we'd lock our own fd instead and keep it open for a
+ * long time udev would possibly never run on it again, even though the fd is unlocked, simply
+ * because we never close() it. It also has the nice benefit we can use the _cleanup_close_ logic to
+ * automatically release the lock, after we are done. */
+ lock_fd = fd_reopen(fd, O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+ if (lock_fd < 0)
+ return lock_fd;
+ if (flock(lock_fd, LOCK_EX) < 0)
+ return -errno;
+
+ /* Let's see if the device is really detached, i.e. currently has no associated partition block
+ * devices. On various kernels (such as 5.8) it is possible to have a loopback block device that
+ * superficially is detached but still has partition block devices associated for it. They only go
+ * away when the device is reattached. (Yes, LOOP_CLR_FD doesn't work then, because officially
+ * nothing is attached and LOOP_CTL_REMOVE doesn't either, since it doesn't care about partition
+ * block devices. */
+ r = device_has_block_children(d);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ r = loop_is_bound(fd);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return -EBUSY;
+
+ return -EUCLEAN; /* Bound but children? Tell caller to reattach something so that the
+ * partition block devices are gone too. */
+ }
+
+ if (*try_loop_configure) {
+ if (ioctl(fd, LOOP_CONFIGURE, c) < 0) {
+ /* Do fallback only if LOOP_CONFIGURE is not supported, propagate all other
+ * errors. Note that the kernel is weird: non-existing ioctls currently return EINVAL
+ * rather than ENOTTY on loopback block devices. They should fix that in the kernel,
+ * but in the meantime we accept both here. */
+ if (!ERRNO_IS_NOT_SUPPORTED(errno) && errno != EINVAL)
+ return -errno;
+
+ *try_loop_configure = false;
+ } else {
+ bool good = true;
+
+ if (c->info.lo_sizelimit != 0) {
+ /* Kernel 5.8 vanilla doesn't properly propagate the size limit into the
+ * block device. If it's used, let's immediately check if it had the desired
+ * effect hence. And if not use classic LOOP_SET_STATUS64. */
+ uint64_t z;
+
+ if (ioctl(fd, BLKGETSIZE64, &z) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ if (z != c->info.lo_sizelimit) {
+ log_debug("LOOP_CONFIGURE is broken, doesn't honour .lo_sizelimit. Falling back to LOOP_SET_STATUS64.");
+ good = false;
+ }
+ }
+
+ if (FLAGS_SET(c->info.lo_flags, LO_FLAGS_PARTSCAN)) {
+ /* Kernel 5.8 vanilla doesn't properly propagate the partition scanning flag
+ * into the block device. Let's hence verify if things work correctly here
+ * before returning. */
+
+ r = blockdev_partscan_enabled(fd);
+ if (r < 0)
+ goto fail;
+ if (r == 0) {
+ log_debug("LOOP_CONFIGURE is broken, doesn't honour LO_FLAGS_PARTSCAN. Falling back to LOOP_SET_STATUS64.");
+ good = false;
+ }
+ }
+
+ if (!good) {
+ /* LOOP_CONFIGURE doesn't work. Remember that. */
+ *try_loop_configure = false;
+
+ /* We return EBUSY here instead of retrying immediately with LOOP_SET_FD,
+ * because LOOP_CLR_FD is async: if the operation cannot be executed right
+ * away it just sets the autoclear flag on the device. This means there's a
+ * good chance we cannot actually reuse the loopback device right-away. Hence
+ * let's assume it's busy, avoid the trouble and let the calling loop call us
+ * again with a new, likely unused device. */
+ r = -EBUSY;
+ goto fail;
+ }
+
+ return 0;
+ }
+ }
+
+ /* Since kernel commit 5db470e229e22b7eda6e23b5566e532c96fb5bc3 (kernel v5.0) the LOOP_SET_STATUS64
+ * ioctl can return EAGAIN in case we change the lo_offset field, if someone else is accessing the
+ * block device while we try to reconfigure it. This is a pretty common case, since udev might
+ * instantly start probing the device as soon as we attach an fd to it. Hence handle it in two ways:
+ * first, let's take the BSD lock to ensure that udev will not step in between the point in
+ * time where we attach the fd and where we reconfigure the device. Secondly, let's wait 50ms on
+ * EAGAIN and retry. The former should be an efficient mechanism to avoid we have to wait 50ms
+ * needlessly if we are just racing against udev. The latter is protection against all other cases,
+ * i.e. peers that do not take the BSD lock. */
+
+ if (ioctl(fd, LOOP_SET_FD, c->fd) < 0)
+ return -errno;
+
+ for (unsigned n_attempts = 0;;) {
+ if (ioctl(fd, LOOP_SET_STATUS64, &c->info) >= 0)
+ break;
+ if (errno != EAGAIN || ++n_attempts >= 64) {
+ r = log_debug_errno(errno, "Failed to configure loopback device: %m");
+ goto fail;
+ }
+
+ /* Sleep some random time, but at least 10ms, at most 250ms. Increase the delay the more
+ * failed attempts we see */
+ (void) usleep(UINT64_C(10) * USEC_PER_MSEC +
+ random_u64() % (UINT64_C(240) * USEC_PER_MSEC * n_attempts/64));
+ }
+
+ return 0;
+
+fail:
+ (void) ioctl(fd, LOOP_CLR_FD);
+ return r;
+}
+
+static int attach_empty_file(int loop, int nr) {
+ _cleanup_close_ int fd = -1;
+
+ /* So here's the thing: on various kernels (5.8 at least) loop block devices might enter a state
+ * where they are detached but nonetheless have partitions, when used heavily. Accessing these
+ * partitions results in immediatey IO errors. There's no pretty way to get rid of them
+ * again. Neither LOOP_CLR_FD nor LOOP_CTL_REMOVE suffice (see above). What does work is to
+ * reassociate them with a new fd however. This is what we do here hence: we associate the devices
+ * with an empty file (i.e. an image that definitely has no partitions). We then immediately clear it
+ * again. This suffices to make the partitions go away. Ugly but appears to work. */
+
+ log_debug("Found unattached loopback block device /dev/loop%i with partitions. Attaching empty file to remove them.", nr);
+
+ fd = open_tmpfile_unlinkable(NULL, O_RDONLY);
+ if (fd < 0)
+ return fd;
+
+ if (flock(loop, LOCK_EX) < 0)
+ return -errno;
+
+ if (ioctl(loop, LOOP_SET_FD, fd) < 0)
+ return -errno;
+
+ if (ioctl(loop, LOOP_SET_STATUS64, &(struct loop_info64) {
+ .lo_flags = LO_FLAGS_READ_ONLY|
+ LO_FLAGS_AUTOCLEAR|
+ LO_FLAGS_PARTSCAN, /* enable partscan, so that the partitions really go away */
+ }) < 0)
+ return -errno;
+
+ if (ioctl(loop, LOOP_CLR_FD) < 0)
+ return -errno;
+
+ /* The caller is expected to immediately close the loopback device after this, so that the BSD lock
+ * is released, and udev sees the changes. */
+ return 0;
+}
+
+int loop_device_make(
+ int fd,
+ int open_flags,
+ uint64_t offset,
+ uint64_t size,
+ uint32_t loop_flags,
+ LoopDevice **ret) {
+
+ _cleanup_free_ char *loopdev = NULL;
+ bool try_loop_configure = true;
+ struct loop_config config;
+ LoopDevice *d = NULL;
+ struct stat st;
+ int nr = -1, r;
+
+ assert(fd >= 0);
+ assert(ret);
+ assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (S_ISBLK(st.st_mode)) {
+ if (ioctl(fd, LOOP_GET_STATUS64, &config.info) >= 0) {
+ /* Oh! This is a loopback device? That's interesting! */
+
+#if HAVE_VALGRIND_MEMCHECK_H
+ /* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
+ VALGRIND_MAKE_MEM_DEFINED(&config.info, sizeof(config.info));
+#endif
+ nr = config.info.lo_number;
+
+ if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
+ return -ENOMEM;
+ }
+
+ if (offset == 0 && IN_SET(size, 0, UINT64_MAX)) {
+ _cleanup_close_ int copy = -1;
+
+ /* If this is already a block device, store a copy of the fd as it is */
+
+ copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
+ if (copy < 0)
+ return -errno;
+
+ d = new(LoopDevice, 1);
+ if (!d)
+ return -ENOMEM;
+ *d = (LoopDevice) {
+ .fd = TAKE_FD(copy),
+ .nr = nr,
+ .node = TAKE_PTR(loopdev),
+ .relinquished = true, /* It's not allocated by us, don't destroy it when this object is freed */
+ };
+
+ *ret = d;
+ return d->fd;
+ }
+ } else {
+ r = stat_verify_regular(&st);
+ if (r < 0)
+ return r;
+ }
+
+ _cleanup_close_ int control = -1;
+ _cleanup_(cleanup_clear_loop_close) int loop_with_fd = -1;
+
+ control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+ if (control < 0)
+ return -errno;
+
+ config = (struct loop_config) {
+ .fd = fd,
+ .info = {
+ /* Use the specified flags, but configure the read-only flag from the open flags, and force autoclear */
+ .lo_flags = (loop_flags & ~LO_FLAGS_READ_ONLY) | ((open_flags & O_ACCMODE) == O_RDONLY ? LO_FLAGS_READ_ONLY : 0) | LO_FLAGS_AUTOCLEAR,
+ .lo_offset = offset,
+ .lo_sizelimit = size == UINT64_MAX ? 0 : size,
+ },
+ };
+
+ /* Loop around LOOP_CTL_GET_FREE, since at the moment we attempt to open the returned device it might
+ * be gone already, taken by somebody else racing against us. */
+ for (unsigned n_attempts = 0;;) {
+ _cleanup_close_ int loop = -1;
+
+ nr = ioctl(control, LOOP_CTL_GET_FREE);
+ if (nr < 0)
+ return -errno;
+
+ if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
+ return -ENOMEM;
+
+ loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
+ if (loop < 0) {
+ /* Somebody might've gotten the same number from the kernel, used the device,
+ * and called LOOP_CTL_REMOVE on it. Let's retry with a new number. */
+ if (!IN_SET(errno, ENOENT, ENXIO))
+ return -errno;
+ } else {
+ r = loop_configure(loop, nr, &config, &try_loop_configure);
+ if (r >= 0) {
+ loop_with_fd = TAKE_FD(loop);
+ break;
+ }
+ if (r == -EUCLEAN) {
+ /* Make left-over partition disappear hack (see above) */
+ r = attach_empty_file(loop, nr);
+ if (r < 0 && r != -EBUSY)
+ return r;
+ } else if (r != -EBUSY)
+ return r;
+ }
+
+ if (++n_attempts >= 64) /* Give up eventually */
+ return -EBUSY;
+
+ loopdev = mfree(loopdev);
+
+ /* Wait some random time, to make collision less likely. Let's pick a random time in the
+ * range 0ms…250ms, linearly scaled by the number of failed attempts. */
+ (void) usleep(random_u64() % (UINT64_C(10) * USEC_PER_MSEC +
+ UINT64_C(240) * USEC_PER_MSEC * n_attempts/64));
+ }
+
+ d = new(LoopDevice, 1);
+ if (!d)
+ return -ENOMEM;
+ *d = (LoopDevice) {
+ .fd = TAKE_FD(loop_with_fd),
+ .node = TAKE_PTR(loopdev),
+ .nr = nr,
+ };
+
+ *ret = d;
+ return 0;
+}
+
+int loop_device_make_by_path(const char *path, int open_flags, uint32_t loop_flags, LoopDevice **ret) {
+ _cleanup_close_ int fd = -1;
+ int r;
+
+ assert(path);
+ assert(ret);
+ assert(open_flags < 0 || IN_SET(open_flags, O_RDWR, O_RDONLY));
+
+ /* Passing < 0 as open_flags here means we'll try to open the device writable if we can, retrying
+ * read-only if we cannot. */
+
+ fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|(open_flags >= 0 ? open_flags : O_RDWR));
+ if (fd < 0) {
+ r = -errno;
+
+ /* Retry read-only? */
+ if (open_flags >= 0 || !(ERRNO_IS_PRIVILEGE(r) || r == -EROFS))
+ return r;
+
+ fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|O_RDONLY);
+ if (fd < 0)
+ return r; /* Propagate original error */
+
+ open_flags = O_RDONLY;
+ } else if (open_flags < 0)
+ open_flags = O_RDWR;
+
+ return loop_device_make(fd, open_flags, 0, 0, loop_flags, ret);
+}
+
+LoopDevice* loop_device_unref(LoopDevice *d) {
+ if (!d)
+ return NULL;
+
+ if (d->fd >= 0) {
+ /* Implicitly sync the device, since otherwise in-flight blocks might not get written */
+ if (fsync(d->fd) < 0)
+ log_debug_errno(errno, "Failed to sync loop block device, ignoring: %m");
+
+ if (d->nr >= 0 && !d->relinquished) {
+ if (ioctl(d->fd, LOOP_CLR_FD) < 0)
+ log_debug_errno(errno, "Failed to clear loop device: %m");
+
+ }
+
+ safe_close(d->fd);
+ }
+
+ if (d->nr >= 0 && !d->relinquished) {
+ _cleanup_close_ int control = -1;
+
+ control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+ if (control < 0)
+ log_warning_errno(errno,
+ "Failed to open loop control device, cannot remove loop device %s: %m",
+ strna(d->node));
+ else
+ for (unsigned n_attempts = 0;;) {
+ if (ioctl(control, LOOP_CTL_REMOVE, d->nr) >= 0)
+ break;
+ if (errno != EBUSY || ++n_attempts >= 64) {
+ log_warning_errno(errno, "Failed to remove device %s: %m", strna(d->node));
+ break;
+ }
+ (void) usleep(50 * USEC_PER_MSEC);
+ }
+ }
+
+ free(d->node);
+ return mfree(d);
+}
+
+void loop_device_relinquish(LoopDevice *d) {
+ assert(d);
+
+ /* Don't attempt to clean up the loop device anymore from this point on. Leave the clean-ing up to the kernel
+ * itself, using the loop device "auto-clear" logic we already turned on when creating the device. */
+
+ d->relinquished = true;
+}
+
+int loop_device_open(const char *loop_path, int open_flags, LoopDevice **ret) {
+ _cleanup_close_ int loop_fd = -1;
+ _cleanup_free_ char *p = NULL;
+ struct loop_info64 info;
+ struct stat st;
+ LoopDevice *d;
+ int nr;
+
+ assert(loop_path);
+ assert(ret);
+
+ loop_fd = open(loop_path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
+ if (loop_fd < 0)
+ return -errno;
+
+ if (fstat(loop_fd, &st) < 0)
+ return -errno;
+ if (!S_ISBLK(st.st_mode))
+ return -ENOTBLK;
+
+ if (ioctl(loop_fd, LOOP_GET_STATUS64, &info) >= 0) {
+#if HAVE_VALGRIND_MEMCHECK_H
+ /* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
+ VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
+#endif
+ nr = info.lo_number;
+ } else
+ nr = -1;
+
+ p = strdup(loop_path);
+ if (!p)
+ return -ENOMEM;
+
+ d = new(LoopDevice, 1);
+ if (!d)
+ return -ENOMEM;
+
+ *d = (LoopDevice) {
+ .fd = TAKE_FD(loop_fd),
+ .nr = nr,
+ .node = TAKE_PTR(p),
+ .relinquished = true, /* It's not ours, don't try to destroy it when this object is freed */
+ };
+
+ *ret = d;
+ return d->fd;
+}
+
+static int resize_partition(int partition_fd, uint64_t offset, uint64_t size) {
+ char sysfs[STRLEN("/sys/dev/block/:/partition") + 2*DECIMAL_STR_MAX(dev_t) + 1];
+ _cleanup_free_ char *whole = NULL, *buffer = NULL;
+ uint64_t current_offset, current_size, partno;
+ _cleanup_close_ int whole_fd = -1;
+ struct stat st;
+ dev_t devno;
+ int r;
+
+ assert(partition_fd >= 0);
+
+ /* Resizes the partition the loopback device refer to (assuming it refers to one instead of an actual
+ * loopback device), and changes the offset, if needed. This is a fancy wrapper around
+ * BLKPG_RESIZE_PARTITION. */
+
+ if (fstat(partition_fd, &st) < 0)
+ return -errno;
+
+ assert(S_ISBLK(st.st_mode));
+
+ xsprintf(sysfs, "/sys/dev/block/%u:%u/partition", major(st.st_rdev), minor(st.st_rdev));
+ r = read_one_line_file(sysfs, &buffer);
+ if (r == -ENOENT) /* not a partition, cannot resize */
+ return -ENOTTY;
+ if (r < 0)
+ return r;
+ r = safe_atou64(buffer, &partno);
+ if (r < 0)
+ return r;
+
+ xsprintf(sysfs, "/sys/dev/block/%u:%u/start", major(st.st_rdev), minor(st.st_rdev));
+
+ buffer = mfree(buffer);
+ r = read_one_line_file(sysfs, &buffer);
+ if (r < 0)
+ return r;
+ r = safe_atou64(buffer, &current_offset);
+ if (r < 0)
+ return r;
+ if (current_offset > UINT64_MAX/512U)
+ return -EINVAL;
+ current_offset *= 512U;
+
+ if (ioctl(partition_fd, BLKGETSIZE64, &current_size) < 0)
+ return -EINVAL;
+
+ if (size == UINT64_MAX && offset == UINT64_MAX)
+ return 0;
+ if (current_size == size && current_offset == offset)
+ return 0;
+
+ xsprintf(sysfs, "/sys/dev/block/%u:%u/../dev", major(st.st_rdev), minor(st.st_rdev));
+
+ buffer = mfree(buffer);
+ r = read_one_line_file(sysfs, &buffer);
+ if (r < 0)
+ return r;
+ r = parse_dev(buffer, &devno);
+ if (r < 0)
+ return r;
+
+ r = device_path_make_major_minor(S_IFBLK, devno, &whole);
+ if (r < 0)
+ return r;
+
+ whole_fd = open(whole, O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+ if (whole_fd < 0)
+ return -errno;
+
+ struct blkpg_partition bp = {
+ .pno = partno,
+ .start = offset == UINT64_MAX ? current_offset : offset,
+ .length = size == UINT64_MAX ? current_size : size,
+ };
+
+ struct blkpg_ioctl_arg ba = {
+ .op = BLKPG_RESIZE_PARTITION,
+ .data = &bp,
+ .datalen = sizeof(bp),
+ };
+
+ if (ioctl(whole_fd, BLKPG, &ba) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int loop_device_refresh_size(LoopDevice *d, uint64_t offset, uint64_t size) {
+ struct loop_info64 info;
+ assert(d);
+
+ /* Changes the offset/start of the loop device relative to the beginning of the underlying file or
+ * block device. If this loop device actually refers to a partition and not a loopback device, we'll
+ * try to adjust the partition offsets instead.
+ *
+ * If either offset or size is UINT64_MAX we won't change that parameter. */
+
+ if (d->fd < 0)
+ return -EBADF;
+
+ if (d->nr < 0) /* not a loopback device */
+ return resize_partition(d->fd, offset, size);
+
+ if (ioctl(d->fd, LOOP_GET_STATUS64, &info) < 0)
+ return -errno;
+
+#if HAVE_VALGRIND_MEMCHECK_H
+ /* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
+ VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
+#endif
+
+ if (size == UINT64_MAX && offset == UINT64_MAX)
+ return 0;
+ if (info.lo_sizelimit == size && info.lo_offset == offset)
+ return 0;
+
+ if (size != UINT64_MAX)
+ info.lo_sizelimit = size;
+ if (offset != UINT64_MAX)
+ info.lo_offset = offset;
+
+ if (ioctl(d->fd, LOOP_SET_STATUS64, &info) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int loop_device_flock(LoopDevice *d, int operation) {
+ assert(d);
+
+ if (d->fd < 0)
+ return -EBADF;
+
+ if (flock(d->fd, operation) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int loop_device_sync(LoopDevice *d) {
+ assert(d);
+
+ /* We also do this implicitly in loop_device_unref(). Doing this explicitly here has the benefit that
+ * we can check the return value though. */
+
+ if (d->fd < 0)
+ return -EBADF;
+
+ if (fsync(d->fd) < 0)
+ return -errno;
+
+ return 0;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-30 15:17:03 +0000