src/shared/loop-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <fcntl.h>
   5
   6 #include "sd-device.h"
   7
   8 #include "macro.h"
   9 #include "time-util.h"
  10
  11 typedef struct LoopDevice LoopDevice;
  12
  13 /* Some helpers for setting up loopback block devices */
  14
  15 struct LoopDevice {
  16         unsigned n_ref;
  17         int fd;
  18         int lock_fd;
  19         int nr;         /* The loopback device index (i.e. 4 for /dev/loop4); if this object encapsulates a non-loopback block device, set to -1 */
  20         dev_t devno;    /* The loopback device's own dev_t */
  21         char *node;
  22         sd_device *dev;
  23         char *backing_file;
  24         bool relinquished;
  25         dev_t backing_devno; /* The backing file's dev_t */
  26         ino_t backing_inode; /* The backing file's ino_t */
  27         uint64_t diskseq; /* Block device sequence number, monothonically incremented by the kernel on create/attach, or 0 if we don't know */
  28         uint64_t uevent_seqnum_not_before; /* uevent sequm right before we attached the loopback device, or UINT64_MAX if we don't know */
  29         usec_t timestamp_not_before; /* CLOCK_MONOTONIC timestamp taken immediately before attaching the loopback device, or USEC_INFINITY if we don't know */
  30         uint32_t sector_size;
  31 };
  32
  33 /* Returns true if LoopDevice object is not actually a loopback device but some other block device we just wrap */
  34 #define LOOP_DEVICE_IS_FOREIGN(d) ((d)->nr < 0)
  35
  36 int loop_device_make(int fd, int open_flags, uint64_t offset, uint64_t size, uint32_t sector_size, uint32_t loop_flags, int lock_op, LoopDevice **ret);
  37 int loop_device_make_by_path_at(int dir_fd, const char *path, int open_flags, uint32_t sector_size, uint32_t loop_flags, int lock_op, LoopDevice **ret);
  38 static inline int loop_device_make_by_path(const char *path, int open_flags, uint32_t sector_size, uint32_t loop_flags, int lock_op, LoopDevice **ret) {
  39         return loop_device_make_by_path_at(AT_FDCWD, path, open_flags, sector_size, loop_flags, lock_op, ret);
  40 }
  41 int loop_device_make_by_path_memory(const char *path, int open_flags, uint32_t sector_size, uint32_t loop_flags, int lock_op, LoopDevice **ret);
  42 int loop_device_open(sd_device *dev, int open_flags, int lock_op, LoopDevice **ret);
  43 int loop_device_open_from_fd(int fd, int open_flags, int lock_op, LoopDevice **ret);
  44 int loop_device_open_from_path(const char *path, int open_flags, int lock_op, LoopDevice **ret);
  45
  46 LoopDevice* loop_device_ref(LoopDevice *d);
  47 LoopDevice* loop_device_unref(LoopDevice *d);
  48 DEFINE_TRIVIAL_CLEANUP_FUNC(LoopDevice*, loop_device_unref);
  49
  50 void loop_device_relinquish(LoopDevice *d);
  51 void loop_device_unrelinquish(LoopDevice *d);
  52
  53 int loop_device_refresh_size(LoopDevice *d, uint64_t offset, uint64_t size);
  54
  55 int loop_device_flock(LoopDevice *d, int operation);
  56 int loop_device_sync(LoopDevice *d);
  57
  58 int loop_device_set_autoclear(LoopDevice *d, bool autoclear);
  59 int loop_device_set_filename(LoopDevice *d, const char *name);