/* * Block driver for the QCOW format * * Copyright (c) 2004-2006 Fabrice Bellard * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "qemu-common.h" #include "block.h" #include "block_int.h" #include #if 0 #include "aes.h" #endif /**************************************************************/ /* QEMU COW block driver with compression and encryption support */ #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb) #define QCOW_VERSION 1 #define QCOW_CRYPT_NONE 0 #define QCOW_CRYPT_AES 1 #define QCOW_OFLAG_COMPRESSED (1LL << 63) typedef struct QCowHeader { uint32_t magic; uint32_t version; uint64_t backing_file_offset; uint32_t backing_file_size; uint32_t mtime; uint64_t size; /* in bytes */ uint8_t cluster_bits; uint8_t l2_bits; uint32_t crypt_method; uint64_t l1_table_offset; } QCowHeader; #define L2_CACHE_SIZE 16 typedef struct BDRVQcowState { BlockDriverState *hd; int cluster_bits; int cluster_size; int cluster_sectors; int l2_bits; int l2_size; int l1_size; uint64_t cluster_offset_mask; uint64_t l1_table_offset; uint64_t *l1_table; uint64_t *l2_cache; uint64_t l2_cache_offsets[L2_CACHE_SIZE]; uint32_t l2_cache_counts[L2_CACHE_SIZE]; uint8_t *cluster_cache; uint8_t *cluster_data; uint64_t cluster_cache_offset; } BDRVQcowState; static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset); static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename) { const QCowHeader *cow_header = (const void *)buf; if (buf_size >= sizeof(QCowHeader) && be32_to_cpu(cow_header->magic) == QCOW_MAGIC && be32_to_cpu(cow_header->version) == QCOW_VERSION) return 100; else return 0; } static int qcow_open(BlockDriverState *bs, const char *filename, int flags) { BDRVQcowState *s = bs->opaque; int len, i, shift, ret; QCowHeader header; ret = bdrv_file_open(&s->hd, filename, flags); if (ret < 0) return ret; if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header)) goto fail; be32_to_cpus(&header.magic); be32_to_cpus(&header.version); be64_to_cpus(&header.backing_file_offset); be32_to_cpus(&header.backing_file_size); be32_to_cpus(&header.mtime); be64_to_cpus(&header.size); be32_to_cpus(&header.crypt_method); be64_to_cpus(&header.l1_table_offset); if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION) goto fail; if (header.size <= 1 || header.cluster_bits < 9) goto fail; if (header.crypt_method > QCOW_CRYPT_AES) goto fail; s->cluster_bits = header.cluster_bits; s->cluster_size = 1 << s->cluster_bits; s->cluster_sectors = 1 << (s->cluster_bits - 9); s->l2_bits = header.l2_bits; s->l2_size = 1 << s->l2_bits; bs->total_sectors = header.size / 512; s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1; /* read the level 1 table */ shift = s->cluster_bits + s->l2_bits; s->l1_size = (header.size + (1LL << shift) - 1) >> shift; s->l1_table_offset = header.l1_table_offset; s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t)); if (!s->l1_table) goto fail; if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) != s->l1_size * sizeof(uint64_t)) goto fail; for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } /* alloc L2 cache */ s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t)); if (!s->l2_cache) goto fail; s->cluster_cache = qemu_malloc(s->cluster_size); if (!s->cluster_cache) goto fail; s->cluster_data = qemu_malloc(s->cluster_size); if (!s->cluster_data) goto fail; s->cluster_cache_offset = -1; /* read the backing file name */ if (header.backing_file_offset != 0) { len = header.backing_file_size; if (len > 1023) len = 1023; if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len) goto fail; bs->backing_file[len] = '\0'; } return 0; fail: qemu_free(s->l1_table); qemu_free(s->l2_cache); qemu_free(s->cluster_cache); qemu_free(s->cluster_data); bdrv_delete(s->hd); return -1; } /* 'allocate' is: * * 0 to not allocate. * * 1 to allocate a normal cluster (for sector indexes 'n_start' to * 'n_end') * * 2 to allocate a compressed cluster of size * 'compressed_size'. 'compressed_size' must be > 0 and < * cluster_size * * return 0 if not allocated. */ static uint64_t get_cluster_offset(BlockDriverState *bs, uint64_t offset, int allocate, int compressed_size, int n_start, int n_end) { BDRVQcowState *s = bs->opaque; int min_index, i, j, l1_index, l2_index; uint64_t l2_offset, *l2_table, cluster_offset, tmp; uint32_t min_count; int new_l2_table; l1_index = offset >> (s->l2_bits + s->cluster_bits); l2_offset = s->l1_table[l1_index]; new_l2_table = 0; if (!l2_offset) { if (!allocate) return 0; /* allocate a new l2 entry */ l2_offset = bdrv_getlength(s->hd); /* round to cluster size */ l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1); /* update the L1 entry */ s->l1_table[l1_index] = l2_offset; tmp = cpu_to_be64(l2_offset); if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp)) return 0; new_l2_table = 1; } for(i = 0; i < L2_CACHE_SIZE; i++) { if (l2_offset == s->l2_cache_offsets[i]) { /* increment the hit count */ if (++s->l2_cache_counts[i] == 0xffffffff) { for(j = 0; j < L2_CACHE_SIZE; j++) { s->l2_cache_counts[j] >>= 1; } } l2_table = s->l2_cache + (i << s->l2_bits); goto found; } } /* not found: load a new entry in the least used one */ min_index = 0; min_count = 0xffffffff; for(i = 0; i < L2_CACHE_SIZE; i++) { if (s->l2_cache_counts[i] < min_count) { min_count = s->l2_cache_counts[i]; min_index = i; } } l2_table = s->l2_cache + (min_index << s->l2_bits); if (new_l2_table) { memset(l2_table, 0, s->l2_size * sizeof(uint64_t)); if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) != s->l2_size * sizeof(uint64_t)) return 0; } else { if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) != s->l2_size * sizeof(uint64_t)) return 0; } s->l2_cache_offsets[min_index] = l2_offset; s->l2_cache_counts[min_index] = 1; found: l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); cluster_offset = be64_to_cpu(l2_table[l2_index]); if (!cluster_offset || ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) { if (!allocate) return 0; /* allocate a new cluster */ if ((cluster_offset & QCOW_OFLAG_COMPRESSED) && (n_end - n_start) < s->cluster_sectors) { /* if the cluster is already compressed, we must decompress it in the case it is not completely overwritten */ if (decompress_cluster(s, cluster_offset) < 0) return 0; cluster_offset = bdrv_getlength(s->hd); cluster_offset = (cluster_offset + s->cluster_size - 1) & ~(s->cluster_size - 1); /* write the cluster content */ if (bdrv_pwrite(s->hd, cluster_offset, s->cluster_cache, s->cluster_size) != s->cluster_size) return -1; } else { cluster_offset = bdrv_getlength(s->hd); if (allocate == 1) { /* round to cluster size */ cluster_offset = (cluster_offset + s->cluster_size - 1) & ~(s->cluster_size - 1); bdrv_truncate(s->hd, cluster_offset + s->cluster_size); } else { cluster_offset |= QCOW_OFLAG_COMPRESSED | (uint64_t)compressed_size << (63 - s->cluster_bits); } } /* update L2 table */ tmp = cpu_to_be64(cluster_offset); l2_table[l2_index] = tmp; if (bdrv_pwrite(s->hd, l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp)) return 0; } return cluster_offset; } static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { BDRVQcowState *s = bs->opaque; int index_in_cluster, n; uint64_t cluster_offset; cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0); index_in_cluster = sector_num & (s->cluster_sectors - 1); n = s->cluster_sectors - index_in_cluster; if (n > nb_sectors) n = nb_sectors; *pnum = n; return (cluster_offset != 0); } static int decompress_buffer(uint8_t *out_buf, int out_buf_size, const uint8_t *buf, int buf_size) { z_stream strm1, *strm = &strm1; int ret, out_len; memset(strm, 0, sizeof(*strm)); strm->next_in = (uint8_t *)buf; strm->avail_in = buf_size; strm->next_out = out_buf; strm->avail_out = out_buf_size; ret = inflateInit2(strm, -12); if (ret != Z_OK) return -1; ret = inflate(strm, Z_FINISH); out_len = strm->next_out - out_buf; if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) || out_len != out_buf_size) { inflateEnd(strm); return -1; } inflateEnd(strm); return 0; } static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset) { int ret, csize; uint64_t coffset; coffset = cluster_offset & s->cluster_offset_mask; if (s->cluster_cache_offset != coffset) { csize = cluster_offset >> (63 - s->cluster_bits); csize &= (s->cluster_size - 1); ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize); if (ret != csize) return -1; if (decompress_buffer(s->cluster_cache, s->cluster_size, s->cluster_data, csize) < 0) { return -1; } s->cluster_cache_offset = coffset; } return 0; } static int qcow_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors) { BDRVQcowState *s = bs->opaque; int ret, index_in_cluster, n; uint64_t cluster_offset; while (nb_sectors > 0) { cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0); index_in_cluster = sector_num & (s->cluster_sectors - 1); n = s->cluster_sectors - index_in_cluster; if (n > nb_sectors) n = nb_sectors; if (!cluster_offset) { if (bs->backing_hd) { /* read from the base image */ ret = bdrv_read(bs->backing_hd, sector_num, buf, n); if (ret < 0) return -1; } else { memset(buf, 0, 512 * n); } } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) { if (decompress_cluster(s, cluster_offset) < 0) return -1; memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n); } else { ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512); if (ret != n * 512) return -1; } nb_sectors -= n; sector_num += n; buf += n * 512; } return 0; } static int qcow_write(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { BDRVQcowState *s = bs->opaque; int ret, index_in_cluster, n; uint64_t cluster_offset; while (nb_sectors > 0) { index_in_cluster = sector_num & (s->cluster_sectors - 1); n = s->cluster_sectors - index_in_cluster; if (n > nb_sectors) n = nb_sectors; cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0, index_in_cluster, index_in_cluster + n); if (!cluster_offset) return -1; { ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512); } if (ret != n * 512) return -1; nb_sectors -= n; sector_num += n; buf += n * 512; } s->cluster_cache_offset = -1; /* disable compressed cache */ return 0; } static void qcow_close(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; qemu_free(s->l1_table); qemu_free(s->l2_cache); qemu_free(s->cluster_cache); qemu_free(s->cluster_data); bdrv_delete(s->hd); } static int qcow_create(const char *filename, int64_t total_size, const char *backing_file, int flags) { int fd, header_size, backing_filename_len, l1_size, i, shift; QCowHeader header; uint64_t tmp; fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644); if (fd < 0) return -1; memset(&header, 0, sizeof(header)); header.magic = cpu_to_be32(QCOW_MAGIC); header.version = cpu_to_be32(QCOW_VERSION); header.size = cpu_to_be64(total_size * 512); header_size = sizeof(header); backing_filename_len = 0; if (backing_file) { header.backing_file_offset = cpu_to_be64(header_size); backing_filename_len = strlen(backing_file); header.backing_file_size = cpu_to_be32(backing_filename_len); header_size += backing_filename_len; header.mtime = cpu_to_be32(0); header.cluster_bits = 9; /* 512 byte cluster to avoid copying unmodifyed sectors */ header.l2_bits = 12; /* 32 KB L2 tables */ } else { header.cluster_bits = 12; /* 4 KB clusters */ header.l2_bits = 9; /* 4 KB L2 tables */ } header_size = (header_size + 7) & ~7; shift = header.cluster_bits + header.l2_bits; l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift; header.l1_table_offset = cpu_to_be64(header_size); if (flags) { header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES); } else { header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); } /* write all the data */ write(fd, &header, sizeof(header)); if (backing_file) { write(fd, backing_file, backing_filename_len); } lseek(fd, header_size, SEEK_SET); tmp = 0; for(i = 0;i < l1_size; i++) { write(fd, &tmp, sizeof(tmp)); } close(fd); return 0; } static int qcow_make_empty(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; uint32_t l1_length = s->l1_size * sizeof(uint64_t); int ret; memset(s->l1_table, 0, l1_length); if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0) return -1; ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length); if (ret < 0) return ret; memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t)); memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t)); memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t)); return 0; } /* XXX: put compressed sectors first, then all the cluster aligned tables to avoid losing bytes in alignment */ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { BDRVQcowState *s = bs->opaque; z_stream strm; int ret, out_len; uint8_t *out_buf; uint64_t cluster_offset; if (nb_sectors != s->cluster_sectors) return -EINVAL; out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); if (!out_buf) return -1; /* best compression, small window, no zlib header */ memset(&strm, 0, sizeof(strm)); ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -12, 9, Z_DEFAULT_STRATEGY); if (ret != 0) { qemu_free(out_buf); return -1; } strm.avail_in = s->cluster_size; strm.next_in = (uint8_t *)buf; strm.avail_out = s->cluster_size; strm.next_out = out_buf; ret = deflate(&strm, Z_FINISH); if (ret != Z_STREAM_END && ret != Z_OK) { qemu_free(out_buf); deflateEnd(&strm); return -1; } out_len = strm.next_out - out_buf; deflateEnd(&strm); if (ret != Z_STREAM_END || out_len >= s->cluster_size) { /* could not compress: write normal cluster */ qcow_write(bs, sector_num, buf, s->cluster_sectors); } else { cluster_offset = get_cluster_offset(bs, sector_num << 9, 2, out_len, 0, 0); cluster_offset &= s->cluster_offset_mask; if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) { qemu_free(out_buf); return -1; } } qemu_free(out_buf); return 0; } static void qcow_flush(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; bdrv_flush(s->hd); } static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) { BDRVQcowState *s = bs->opaque; bdi->cluster_size = s->cluster_size; return 0; } BlockDriver bdrv_qcow = { "qcow", sizeof(BDRVQcowState), qcow_probe, qcow_open, qcow_read, qcow_write, qcow_close, qcow_create, qcow_flush, qcow_is_allocated, NULL, qcow_make_empty, .bdrv_write_compressed = qcow_write_compressed, .bdrv_get_info = qcow_get_info, };