include/loopdev.h

   1 /*
   2  * No copyright is claimed.  This code is in the public domain; do with
   3  * it what you wish.
   4  */
   5 #ifndef UTIL_LINUX_LOOPDEV_H
   6 #define UTIL_LINUX_LOOPDEV_H
   7
   8 #include "sysfs.h"
   9
  10 /*
  11  * loop_info.lo_encrypt_type
  12  */
  13 #define LO_CRYPT_NONE   0
  14 #define LO_CRYPT_XOR    1
  15 #define LO_CRYPT_DES    2
  16 #define LO_CRYPT_CRYPTOAPI 18
  17
  18 #define LOOP_SET_FD             0x4C00
  19 #define LOOP_CLR_FD             0x4C01
  20 /*
  21  * Obsolete (kernel < 2.6)
  22  *
  23  * #define LOOP_SET_STATUS      0x4C02
  24  * #define LOOP_GET_STATUS      0x4C03
  25  */
  26 #define LOOP_SET_STATUS64       0x4C04
  27 #define LOOP_GET_STATUS64       0x4C05
  28 /* #define LOOP_CHANGE_FD       0x4C06 */
  29 #define LOOP_SET_CAPACITY       0x4C07
  30 #define LOOP_SET_DIRECT_IO      0x4C08
  31 #define LOOP_SET_BLOCK_SIZE     0x4C09
  32
  33 /* /dev/loop-control interface */
  34 #ifndef LOOP_CTL_ADD
  35 # define LOOP_CTL_ADD           0x4C80
  36 # define LOOP_CTL_REMOVE        0x4C81
  37 # define LOOP_CTL_GET_FREE      0x4C82
  38 #endif
  39
  40 /*
  41  * loop_info.lo_flags
  42  */
  43 enum {
  44         LO_FLAGS_READ_ONLY  = 1,
  45         LO_FLAGS_USE_AOPS   = 2,
  46         LO_FLAGS_AUTOCLEAR  = 4,        /* kernel >= 2.6.25 */
  47         LO_FLAGS_PARTSCAN   = 8,        /* kernel >= 3.2 */
  48         LO_FLAGS_DIRECT_IO  = 16,       /* kernel >= 4.2 */
  49 };
  50
  51 #define LO_NAME_SIZE    64
  52 #define LO_KEY_SIZE     32
  53
  54 /*
  55  * Linux LOOP_{SET,GET}_STATUS64 ioctl struct
  56  */
  57 struct loop_info64 {
  58         uint64_t        lo_device;
  59         uint64_t        lo_inode;
  60         uint64_t        lo_rdevice;
  61         uint64_t        lo_offset;
  62         uint64_t        lo_sizelimit; /* bytes, 0 == max available */
  63         uint32_t        lo_number;
  64         uint32_t        lo_encrypt_type;
  65         uint32_t        lo_encrypt_key_size;
  66         uint32_t        lo_flags;
  67         uint8_t         lo_file_name[LO_NAME_SIZE];
  68         uint8_t         lo_crypt_name[LO_NAME_SIZE];
  69         uint8_t         lo_encrypt_key[LO_KEY_SIZE];
  70         uint64_t        lo_init[2];
  71 };
  72
  73 #ifndef LOOP_CONFIGURE
  74 /*
  75  * Since Linux v5.8-rc1 (commit 3448914e8cc550ba792d4ccc74471d1ca4293aae)
  76  */
  77 # define LOOP_CONFIGURE         0x4C0A
  78 struct loop_config {
  79   uint32_t fd;
  80   uint32_t block_size;
  81   struct loop_info64 info;
  82   uint64_t __reserved[8];
  83 };
  84 #endif
  85
  86 #define LOOPDEV_MAJOR           7       /* loop major number */
  87 #define LOOPDEV_DEFAULT_NNODES  8       /* default number of loop devices */
  88
  89 struct loopdev_iter {
  90         FILE            *proc;          /* /proc/partitions */
  91         DIR             *sysblock;      /* /sys/block */
  92         int             ncur;           /* current position */
  93         int             *minors;        /* ary of minor numbers (when scan whole /dev) */
  94         int             nminors;        /* number of items in *minors */
  95         int             ct_perm;        /* count permission problems */
  96         int             ct_succ;        /* count number of detected devices */
  97
  98         unsigned int    done:1;         /* scanning done */
  99         unsigned int    default_check:1;/* check first LOOPDEV_NLOOPS */
 100         int             flags;          /* LOOPITER_FL_* flags */
 101 };
 102
 103 enum {
 104         LOOPITER_FL_FREE        = (1 << 0),
 105         LOOPITER_FL_USED        = (1 << 1)
 106 };
 107
 108 /*
 109  * handler for work with loop devices
 110  */
 111 struct loopdev_cxt {
 112         char            device[128];    /* device path (e.g. /dev/loop<N>) */
 113         char            *filename;      /* backing file for loopcxt_set_... */
 114         int             fd;             /* open(/dev/looo<N>) */
 115         int             mode;           /* fd mode O_{RDONLY,RDWR} */
 116         uint64_t        blocksize;      /* used by loopcxt_setup_device() */
 117
 118         int             flags;          /* LOOPDEV_FL_* flags */
 119         unsigned int    has_info:1;     /* .info contains data */
 120         unsigned int    extra_check:1;  /* unusual stuff for iterator */
 121         unsigned int    info_failed:1;  /* LOOP_GET_STATUS ioctl failed */
 122         unsigned int    control_ok:1;   /* /dev/loop-control success */
 123
 124         struct path_cxt         *sysfs; /* pointer to /sys/dev/block/<maj:min>/ */
 125         struct loop_config      config; /* for GET/SET ioctl */
 126         struct loopdev_iter     iter;   /* scans /sys or /dev for used/free devices */
 127 };
 128
 129 #define UL_LOOPDEVCXT_EMPTY { .fd = -1  }
 130
 131 /*
 132  * loopdev_cxt.flags
 133  */
 134 enum {
 135         LOOPDEV_FL_RDONLY       = (1 << 0),     /* open(/dev/loop) mode; default */
 136         LOOPDEV_FL_RDWR         = (1 << 1),     /* necessary for loop setup only */
 137         LOOPDEV_FL_OFFSET       = (1 << 4),
 138         LOOPDEV_FL_NOSYSFS      = (1 << 5),
 139         LOOPDEV_FL_NOIOCTL      = (1 << 6),
 140         LOOPDEV_FL_DEVSUBDIR    = (1 << 7),
 141         LOOPDEV_FL_CONTROL      = (1 << 8),     /* system with /dev/loop-control */
 142         LOOPDEV_FL_SIZELIMIT    = (1 << 9)
 143 };
 144
 145 /*
 146  * High-level
 147  */
 148 extern int loopmod_supports_partscan(void);
 149
 150 extern int is_loopdev(const char *device);
 151 extern int loopdev_is_autoclear(const char *device);
 152
 153 extern char *loopdev_get_backing_file(const char *device);
 154 extern int loopdev_has_backing_file(const char *device);
 155 extern int loopdev_is_used(const char *device, const char *filename,
 156                            uint64_t offset, uint64_t sizelimit, int flags);
 157 extern char *loopdev_find_by_backing_file(const char *filename,
 158                                 uint64_t offset, uint64_t sizelimit, int flags);
 159 extern int loopcxt_find_unused(struct loopdev_cxt *lc);
 160 extern int loopdev_delete(const char *device);
 161 extern int loopdev_count_by_backing_file(const char *filename, char **loopdev);
 162
 163 /*
 164  * Low-level
 165  */
 166 extern int loopcxt_init(struct loopdev_cxt *lc, int flags)
 167                                 __attribute__ ((warn_unused_result));
 168 extern void loopcxt_deinit(struct loopdev_cxt *lc);
 169
 170 extern int loopcxt_set_device(struct loopdev_cxt *lc, const char *device)
 171                                 __attribute__ ((warn_unused_result));
 172 extern int loopcxt_has_device(struct loopdev_cxt *lc);
 173 extern int loopcxt_add_device(struct loopdev_cxt *lc);
 174 extern char *loopcxt_strdup_device(struct loopdev_cxt *lc);
 175 extern const char *loopcxt_get_device(struct loopdev_cxt *lc);
 176 extern struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc);
 177
 178 extern int loopcxt_get_fd(struct loopdev_cxt *lc);
 179 extern int loopcxt_set_fd(struct loopdev_cxt *lc, int fd, int mode);
 180
 181 extern int loopcxt_init_iterator(struct loopdev_cxt *lc, int flags);
 182 extern int loopcxt_deinit_iterator(struct loopdev_cxt *lc);
 183 extern int loopcxt_next(struct loopdev_cxt *lc);
 184
 185 extern int loopcxt_setup_device(struct loopdev_cxt *lc);
 186 extern int loopcxt_delete_device(struct loopdev_cxt *lc);
 187
 188 extern int loopcxt_ioctl_status(struct loopdev_cxt *lc);
 189 extern int loopcxt_ioctl_capacity(struct loopdev_cxt *lc);
 190 extern int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio);
 191 extern int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize);
 192
 193 int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset);
 194 int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit);
 195 int loopcxt_set_blocksize(struct loopdev_cxt *lc, uint64_t blocksize);
 196 int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags);
 197 int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename);
 198
 199 extern char *loopcxt_get_backing_file(struct loopdev_cxt *lc);
 200 extern int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno);
 201 extern int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino);
 202 extern int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset);
 203 extern int loopcxt_get_blocksize(struct loopdev_cxt *lc, uint64_t *blocksize);
 204 extern int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size);
 205 extern int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type);
 206 extern const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc);
 207 extern int loopcxt_is_autoclear(struct loopdev_cxt *lc);
 208 extern int loopcxt_is_readonly(struct loopdev_cxt *lc);
 209 extern int loopcxt_is_dio(struct loopdev_cxt *lc);
 210 extern int loopcxt_is_partscan(struct loopdev_cxt *lc);
 211 extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc,
 212                                 const char *filename,
 213                                 uint64_t offset, uint64_t sizelimit,
 214                                 int flags);
 215 extern int loopcxt_find_overlap(struct loopdev_cxt *lc,
 216                                 const char *filename,
 217                                 uint64_t offset, uint64_t sizelimit);
 218
 219 extern int loopcxt_is_used(struct loopdev_cxt *lc,
 220                     struct stat *st,
 221                     const char *backing_file,
 222                     uint64_t offset,
 223                     uint64_t sizelimit,
 224                     int flags);
 225
 226 #endif /* UTIL_LINUX_LOOPDEV_H */