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114 lines
2.5 KiB
C
114 lines
2.5 KiB
C
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/*
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* qcow2.h --- structures and function prototypes for qcow2.c to generate
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* qcow2 formatted disk images. This format is used originally by QEMU
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* for virtual machines, and stores the filesystem data on disk in a
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* packed format to avoid creating sparse image files that need lots of
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* seeking to read and write.
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*
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* The qcow2 format supports zlib compression, but that is not yet
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* implemented.
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*
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* It is possible to directly mount a qcow2 image using qemu-nbd:
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*
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* [root]# modprobe nbd max_part=63
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* [root]# qemu-nbd -c /dev/nbd0 image.img
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* [root]# mount /dev/nbd0p1 /mnt/qemu
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*
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* Format details at http://people.gnome.org/~markmc/qcow-image-format.html
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*
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* Copyright (C) 2010 Red Hat, Inc., Lukas Czerner <lczerner@redhat.com>
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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/* Number of l2 tables in memory before writeback */
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#define L2_CACHE_PREALLOC 512
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#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
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#define QCOW_VERSION 2
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#define QCOW_OFLAG_COPIED (1LL << 63)
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#define QCOW_OFLAG_COMPRESSED (1LL << 62)
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#define QCOW_COMPRESSED 1
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#define QCOW_ENCRYPTED 2
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struct ext2_qcow2_hdr {
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__u32 magic;
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__u32 version;
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__u64 backing_file_offset;
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__u32 backing_file_size;
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__u32 cluster_bits;
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__u64 size;
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__u32 crypt_method;
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__u32 l1_size;
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__u64 l1_table_offset;
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__u64 refcount_table_offset;
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__u32 refcount_table_clusters;
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__u32 nb_snapshots;
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__u64 snapshots_offset;
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};
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typedef struct ext2_qcow2_l2_table L2_CACHE_HEAD;
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struct ext2_qcow2_l2_table {
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__u32 l1_index;
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__u64 offset;
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__u64 *data;
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L2_CACHE_HEAD *next;
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};
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struct ext2_qcow2_l2_cache {
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L2_CACHE_HEAD *used_head;
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L2_CACHE_HEAD *used_tail;
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L2_CACHE_HEAD *free_head;
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__u32 free;
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__u32 count;
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__u64 next_offset;
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};
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struct ext2_qcow2_refcount {
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__u64 *refcount_table;
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__u64 refcount_table_offset;
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__u64 refcount_block_offset;
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__u32 refcount_table_clusters;
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__u32 refcount_table_index;
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__u32 refcount_block_index;
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__u16 *refcount_block;
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};
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struct ext2_qcow2_image {
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int fd;
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struct ext2_qcow2_hdr *hdr;
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struct ext2_qcow2_l2_cache *l2_cache;
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struct ext2_qcow2_refcount refcount;
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__u32 cluster_size;
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__u32 cluster_bits;
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__u32 l1_size;
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__u32 l2_size;
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__u64 *l1_table;
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__u64 l2_offset;
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__u64 l1_offset;
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__u64 image_size;
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};
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/* Function prototypes */
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/* qcow2.c */
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/* Functions for converting qcow2 image into raw image */
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struct ext2_qcow2_hdr *qcow2_read_header(int);
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int qcow2_write_raw_image(int, int, struct ext2_qcow2_hdr *);
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