include/linux/loop.h

   1 #ifndef _LINUX_LOOP_H
   2 #define _LINUX_LOOP_H
   3
   4 #include <linux/kdev_t.h>
   5
   6 /*
   7  * include/linux/loop.h
   8  *
   9  * Written by Theodore Ts'o, 3/29/93.
  10  *
  11  * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
  12  * permitted under the GNU Public License.
  13  */
  14
  15 #define LO_NAME_SIZE    64
  16 #define LO_KEY_SIZE     32
  17
  18 #ifdef __KERNEL__
  19
  20 struct loop_device {
  21         int             lo_number;
  22         struct dentry   *lo_dentry;
  23         int             lo_refcnt;
  24         kdev_t          lo_device;
  25         int             lo_offset;
  26         int             lo_encrypt_type;
  27         int             lo_encrypt_key_size;
  28         int             lo_flags;
  29         int             (*transfer)(struct loop_device *, int cmd,
  30                                     char *raw_buf, char *loop_buf, int size,
  31                                     int real_block);
  32         char            lo_name[LO_NAME_SIZE];
  33         char            lo_encrypt_key[LO_KEY_SIZE];
  34         __u32           lo_init[2];
  35         uid_t           lo_key_owner;   /* Who set the key */
  36         int             (*ioctl)(struct loop_device *, int cmd,
  37                                  unsigned long arg);
  38
  39         struct file *   lo_backing_file;
  40         void            *key_data;
  41         char            key_reserved[48]; /* for use by the filter modules */
  42 };
  43
  44 typedef int (* transfer_proc_t)(struct loop_device *, int cmd,
  45                                 char *raw_buf, char *loop_buf, int size,
  46                                 int real_block);
  47
  48 #endif /* __KERNEL__ */
  49
  50 /*
  51  * Loop flags
  52  */
  53 #define LO_FLAGS_DO_BMAP        0x00000001
  54 #define LO_FLAGS_READ_ONLY      0x00000002
  55
  56 /*
  57  * Note that this structure gets the wrong offsets when directly used
  58  * from a glibc program, because glibc has a 32bit dev_t.
  59  * Prevent people from shooting in their own foot.
  60  */
  61 #if __GLIBC__ >= 2 && !defined(dev_t)
  62 #error "Wrong dev_t in loop.h"
  63 #endif
  64
  65 /*
  66  *      This uses kdev_t because glibc currently has no appropiate
  67  *      conversion version for the loop ioctls.
  68  *      The situation is very unpleasant
  69  */
  70
  71 struct loop_info {
  72         int             lo_number;      /* ioctl r/o */
  73         dev_t           lo_device;      /* ioctl r/o */
  74         unsigned long   lo_inode;       /* ioctl r/o */
  75         dev_t           lo_rdevice;     /* ioctl r/o */
  76         int             lo_offset;
  77         int             lo_encrypt_type;
  78         int             lo_encrypt_key_size;    /* ioctl w/o */
  79         int             lo_flags;       /* ioctl r/o */
  80         char            lo_name[LO_NAME_SIZE];
  81         unsigned char   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
  82         unsigned long   lo_init[2];
  83         char            reserved[4];
  84 };
  85
  86 /*
  87  * Loop filter types
  88  */
  89
  90 #define LO_CRYPT_NONE     0
  91 #define LO_CRYPT_XOR      1
  92 #define LO_CRYPT_DES      2
  93 #define LO_CRYPT_FISH2    3    /* Brand new Twofish encryption */
  94 #define LO_CRYPT_BLOW     4
  95 #define LO_CRYPT_CAST128  5
  96 #define LO_CRYPT_IDEA     6
  97 #define LO_CRYPT_DUMMY    9
  98 #define LO_CRYPT_SKIPJACK 10
  99 #define MAX_LO_CRYPT    20
 100
 101 #ifdef __KERNEL__
 102 /* Support for loadable transfer modules */
 103 struct loop_func_table {
 104         int number;     /* filter type */
 105         int (*transfer)(struct loop_device *lo, int cmd,
 106                         char *raw_buf, char *loop_buf, int size,
 107                         int real_block);
 108         int (*init)(struct loop_device *, struct loop_info *);
 109         /* release is called from loop_unregister_transfer or clr_fd */
 110         int (*release)(struct loop_device *);
 111         int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
 112         /* lock and unlock manage the module use counts */
 113         void (*lock)(struct loop_device *);
 114         void (*unlock)(struct loop_device *);
 115 };
 116
 117 int  loop_register_transfer(struct loop_func_table *funcs);
 118 int loop_unregister_transfer(int number);
 119
 120 #endif
 121 /*
 122  * IOCTL commands --- we will commandeer 0x4C ('L')
 123  */
 124
 125 #define LOOP_SET_FD     0x4C00
 126 #define LOOP_CLR_FD     0x4C01
 127 #define LOOP_SET_STATUS 0x4C02
 128 #define LOOP_GET_STATUS 0x4C03
 129
 130 #endif