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 <stdbool.h>
   9 #include "sysfs.h"
  10
  11 /*
  12  * loop_info.lo_encrypt_type
  13  */
  14 #define LO_CRYPT_NONE   0
  15 #define LO_CRYPT_XOR    1
  16 #define LO_CRYPT_DES    2
  17 #define LO_CRYPT_CRYPTOAPI 18
  18
  19 #define LOOP_SET_FD             0x4C00
  20 #define LOOP_CLR_FD             0x4C01
  21 /*
  22  * Obsolete (kernel < 2.6)
  23  *
  24  * #define LOOP_SET_STATUS      0x4C02
  25  * #define LOOP_GET_STATUS      0x4C03
  26  */
  27 #define LOOP_SET_STATUS64       0x4C04
  28 #define LOOP_GET_STATUS64       0x4C05
  29 /* #define LOOP_CHANGE_FD       0x4C06 */
  30 #define LOOP_SET_CAPACITY       0x4C07
  31 #define LOOP_SET_DIRECT_IO      0x4C08
  32 #define LOOP_SET_BLOCK_SIZE     0x4C09
  33
  34 /* /dev/loop-control interface */
  35 #ifndef LOOP_CTL_ADD
  36 # define LOOP_CTL_ADD           0x4C80
  37 # define LOOP_CTL_REMOVE        0x4C81
  38 # define LOOP_CTL_GET_FREE      0x4C82
  39 #endif
  40
  41 /*
  42  * loop_info.lo_flags
  43  */
  44 enum {
  45         LO_FLAGS_READ_ONLY  = 1,
  46         LO_FLAGS_USE_AOPS   = 2,
  47         LO_FLAGS_AUTOCLEAR  = 4,        /* kernel >= 2.6.25 */
  48         LO_FLAGS_PARTSCAN   = 8,        /* kernel >= 3.2 */
  49         LO_FLAGS_DIRECT_IO  = 16,       /* kernel >= 4.2 */
  50 };
  51
  52 #define LO_NAME_SIZE    64
  53 #define LO_KEY_SIZE     32
  54
  55 /*
  56  * Linux LOOP_{SET,GET}_STATUS64 ioctl struct
  57  */
  58 struct loop_info64 {
  59         uint64_t        lo_device;
  60         uint64_t        lo_inode;
  61         uint64_t        lo_rdevice;
  62         uint64_t        lo_offset;
  63         uint64_t        lo_sizelimit; /* bytes, 0 == max available */
  64         uint32_t        lo_number;
  65         uint32_t        lo_encrypt_type;
  66         uint32_t        lo_encrypt_key_size;
  67         uint32_t        lo_flags;
  68         uint8_t         lo_file_name[LO_NAME_SIZE];
  69         uint8_t         lo_crypt_name[LO_NAME_SIZE];
  70         uint8_t         lo_encrypt_key[LO_KEY_SIZE];
  71         uint64_t        lo_init[2];
  72 };
  73
  74 #ifndef LOOP_CONFIGURE
  75 /*
  76  * Since Linux v5.8-rc1 (commit 3448914e8cc550ba792d4ccc74471d1ca4293aae)
  77  */
  78 # define LOOP_CONFIGURE         0x4C0A
  79 struct loop_config {
  80   uint32_t fd;
  81   uint32_t block_size;
  82   struct loop_info64 info;
  83   uint64_t __reserved[8];
  84 };
  85 #endif
  86
  87 #define LOOPDEV_MAJOR           7       /* loop major number */
  88 #define LOOPDEV_DEFAULT_NNODES  8       /* default number of loop devices */
  89
  90 struct loopdev_iter {
  91         FILE            *proc;          /* /proc/partitions */
  92         DIR             *sysblock;      /* /sys/block */
  93         int             ncur;           /* current position */
  94         int             *minors;        /* ary of minor numbers (when scan whole /dev) */
  95         int             nminors;        /* number of items in *minors */
  96         int             ct_perm;        /* count permission problems */
  97         int             ct_succ;        /* count number of detected devices */
  98
  99         bool            done;           /* scanning done */
 100         bool            default_check;  /* check first LOOPDEV_NLOOPS */
 101         int             flags;          /* LOOPITER_FL_* flags */
 102 };
 103
 104 enum {
 105         LOOPITER_FL_FREE        = (1 << 0),
 106         LOOPITER_FL_USED        = (1 << 1)
 107 };
 108
 109 /*
 110  * handler for work with loop devices
 111  */
 112 struct loopdev_cxt {
 113         char            device[128];    /* device path (e.g. /dev/loop<N>) */
 114         char            *filename;      /* backing file for loopcxt_set_... */
 115         int             fd;             /* open(/dev/looo<N>) */
 116         dev_t           devno;          /* loop device devno from /sys */
 117         mode_t          mode;           /* fd mode O_{RDONLY,RDWR} */
 118         uint64_t        blocksize;      /* used by loopcxt_setup_device() */
 119
 120         int             flags;          /* LOOPDEV_FL_* flags */
 121         bool            has_info;       /* .info contains data */
 122         bool            extra_check;    /* unusual stuff for iterator */
 123         bool            info_failed;    /* LOOP_GET_STATUS ioctl failed */
 124         bool            control_ok;     /* /dev/loop-control success */
 125         bool            is_lost;        /* device in /sys, but missing in /dev */
 126
 127         struct path_cxt         *sysfs; /* pointer to /sys/dev/block/<maj:min>/ */
 128         struct loop_config      config; /* for GET/SET ioctl */
 129         struct loopdev_iter     iter;   /* scans /sys or /dev for used/free devices */
 130 };
 131
 132 #define UL_LOOPDEVCXT_EMPTY { .fd = -1  }
 133
 134 /*
 135  * loopdev_cxt.flags
 136  */
 137 enum {
 138         LOOPDEV_FL_OFFSET       = (1 << 4),
 139         LOOPDEV_FL_NOSYSFS      = (1 << 5),
 140         LOOPDEV_FL_NOIOCTL      = (1 << 6),
 141         LOOPDEV_FL_DEVSUBDIR    = (1 << 7),
 142         LOOPDEV_FL_CONTROL      = (1 << 8),     /* system with /dev/loop-control */
 143         LOOPDEV_FL_SIZELIMIT    = (1 << 9)
 144 };
 145
 146 /*
 147  * High-level
 148  */
 149 extern int loopmod_supports_partscan(void);
 150
 151 extern int is_loopdev(const char *device);
 152 extern int loopdev_is_autoclear(const char *device);
 153
 154 extern char *loopdev_get_backing_file(const char *device);
 155 extern dev_t loopcxt_get_devno(struct loopdev_cxt *lc);
 156 extern int loopdev_has_backing_file(const char *device);
 157 extern int loopcxt_is_lost(struct loopdev_cxt *lc);
 158 extern int loopdev_is_used(const char *device, const char *filename,
 159                            uint64_t offset, uint64_t sizelimit, int flags);
 160 extern char *loopdev_find_by_backing_file(const char *filename,
 161                                 uint64_t offset, uint64_t sizelimit, int flags);
 162 extern int loopcxt_find_unused(struct loopdev_cxt *lc);
 163 extern int loopdev_delete(const char *device);
 164 extern int loopdev_count_by_backing_file(const char *filename, char **loopdev);
 165
 166 /*
 167  * Low-level
 168  */
 169 extern int loopcxt_init(struct loopdev_cxt *lc, int flags)
 170                                 __attribute__ ((warn_unused_result));
 171 extern void loopcxt_deinit(struct loopdev_cxt *lc);
 172
 173 extern int loopcxt_set_device(struct loopdev_cxt *lc, const char *device)
 174                                 __attribute__ ((warn_unused_result));
 175 extern int loopcxt_has_device(struct loopdev_cxt *lc);
 176 extern int loopcxt_add_device(struct loopdev_cxt *lc);
 177 extern char *loopcxt_strdup_device(struct loopdev_cxt *lc);
 178 extern const char *loopcxt_get_device(struct loopdev_cxt *lc);
 179 extern struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc);
 180
 181 extern int loopcxt_get_fd(struct loopdev_cxt *lc);
 182
 183 extern int loopcxt_init_iterator(struct loopdev_cxt *lc, int flags);
 184 extern int loopcxt_deinit_iterator(struct loopdev_cxt *lc);
 185 extern int loopcxt_next(struct loopdev_cxt *lc);
 186
 187 extern int loopcxt_setup_device(struct loopdev_cxt *lc);
 188 extern int loopcxt_delete_device(struct loopdev_cxt *lc);
 189
 190 extern int loopcxt_ioctl_status(struct loopdev_cxt *lc);
 191 extern int loopcxt_ioctl_capacity(struct loopdev_cxt *lc);
 192 extern int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio);
 193 extern int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize);
 194
 195 int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset);
 196 int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit);
 197 int loopcxt_set_blocksize(struct loopdev_cxt *lc, uint64_t blocksize);
 198 int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags);
 199 int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename);
 200 int loopcxt_set_refname(struct loopdev_cxt *lc, const char *refname);
 201
 202 extern char *loopcxt_get_backing_file(struct loopdev_cxt *lc);
 203 extern char *loopcxt_get_refname(struct loopdev_cxt *lc);
 204 extern int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno);
 205 extern int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino);
 206 extern int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset);
 207 extern int loopcxt_get_blocksize(struct loopdev_cxt *lc, uint64_t *blocksize);
 208 extern int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size);
 209 extern int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type);
 210 extern const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc);
 211 extern int loopcxt_is_autoclear(struct loopdev_cxt *lc);
 212 extern int loopcxt_is_readonly(struct loopdev_cxt *lc);
 213 extern int loopcxt_is_dio(struct loopdev_cxt *lc);
 214 extern int loopcxt_is_partscan(struct loopdev_cxt *lc);
 215 extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc,
 216                                 const char *filename,
 217                                 uint64_t offset, uint64_t sizelimit,
 218                                 int flags);
 219 extern int loopcxt_find_overlap(struct loopdev_cxt *lc,
 220                                 const char *filename,
 221                                 uint64_t offset, uint64_t sizelimit);
 222
 223 extern int loopcxt_is_used(struct loopdev_cxt *lc,
 224                     struct stat *st,
 225                     const char *backing_file,
 226                     uint64_t offset,
 227                     uint64_t sizelimit,
 228                     int flags);
 229
 230 #endif /* UTIL_LINUX_LOOPDEV_H */