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      1 /*
      2  * qcow2.h --- structures and function prototypes for qcow2.c to generate
      3  * qcow2 formatted disk images.  This format is used originally by QEMU
      4  * for virtual machines, and stores the filesystem data on disk in a
      5  * packed format to avoid creating sparse image files that need lots of
      6  * seeking to read and write.
      7  *
      8  * The qcow2 format supports zlib compression, but that is not yet
      9  * implemented.
     10  *
     11  * It is possible to directly mount a qcow2 image using qemu-nbd:
     12  *
     13  * [root]# modprobe nbd max_part=63
     14  * [root]# qemu-nbd -c /dev/nbd0 image.img
     15  * [root]# mount /dev/nbd0p1 /mnt/qemu
     16  *
     17  * Format details at http://people.gnome.org/~markmc/qcow-image-format.html
     18  *
     19  * Copyright (C) 2010 Red Hat, Inc., Lukas Czerner <lczerner (at) redhat.com>
     20  *
     21  * %Begin-Header%
     22  * This file may be redistributed under the terms of the GNU Public
     23  * License.
     24  * %End-Header%
     25  */
     26 
     27 /* Number of l2 tables in memory before writeback */
     28 #define L2_CACHE_PREALLOC	512
     29 
     30 
     31 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
     32 #define QCOW_VERSION		2
     33 #define QCOW_OFLAG_COPIED	(1LL << 63)
     34 #define QCOW_OFLAG_COMPRESSED	(1LL << 62)
     35 
     36 #define QCOW_COMPRESSED		1
     37 #define QCOW_ENCRYPTED		2
     38 
     39 struct ext2_qcow2_hdr {
     40 	__u32	magic;
     41 	__u32	version;
     42 
     43 	__u64	backing_file_offset;
     44 	__u32	backing_file_size;
     45 
     46 	__u32	cluster_bits;
     47 	__u64	size;
     48 	__u32	crypt_method;
     49 
     50 	__u32	l1_size;
     51 	__u64	l1_table_offset;
     52 
     53 	__u64	refcount_table_offset;
     54 	__u32	refcount_table_clusters;
     55 
     56 	__u32	nb_snapshots;
     57 	__u64	snapshots_offset;
     58 };
     59 
     60 typedef struct ext2_qcow2_l2_table L2_CACHE_HEAD;
     61 
     62 struct ext2_qcow2_l2_table {
     63 	__u32		l1_index;
     64 	__u64		offset;
     65 	__u64		*data;
     66 	L2_CACHE_HEAD	*next;
     67 };
     68 
     69 struct ext2_qcow2_l2_cache {
     70 	L2_CACHE_HEAD	*used_head;
     71 	L2_CACHE_HEAD	*used_tail;
     72 	L2_CACHE_HEAD	*free_head;
     73 	__u32		free;
     74 	__u32		count;
     75 	__u64		next_offset;
     76 };
     77 
     78 struct ext2_qcow2_refcount {
     79 	__u64	*refcount_table;
     80 	__u64	refcount_table_offset;
     81 	__u64	refcount_block_offset;
     82 
     83 	__u32	refcount_table_clusters;
     84 	__u32	refcount_table_index;
     85 	__u32	refcount_block_index;
     86 
     87 	__u16	*refcount_block;
     88 };
     89 
     90 struct ext2_qcow2_image {
     91 	int	fd;
     92 	struct	ext2_qcow2_hdr		*hdr;
     93 	struct	ext2_qcow2_l2_cache	*l2_cache;
     94 	struct	ext2_qcow2_refcount	refcount;
     95 	__u32	cluster_size;
     96 	__u32	cluster_bits;
     97 	__u32	l1_size;
     98 	__u32	l2_size;
     99 
    100 	__u64	*l1_table;
    101 	__u64	l2_offset;
    102 	__u64	l1_offset;
    103 	__u64	image_size;
    104 };
    105 
    106 /* Function prototypes */
    107 
    108 /* qcow2.c */
    109 
    110 /* Functions for converting qcow2 image into raw image */
    111 struct ext2_qcow2_hdr *qcow2_read_header(int);
    112 int qcow2_write_raw_image(int, int, struct ext2_qcow2_hdr *);
    113 
    114