diff options
Diffstat (limited to 'src/import/qcow2-util.c')
| -rw-r--r-- | src/import/qcow2-util.c | 334 |
1 files changed, 334 insertions, 0 deletions
diff --git a/src/import/qcow2-util.c b/src/import/qcow2-util.c new file mode 100644 index 0000000..e927b60 --- /dev/null +++ b/src/import/qcow2-util.c @@ -0,0 +1,334 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include <zlib.h> + +#include "alloc-util.h" +#include "btrfs-util.h" +#include "qcow2-util.h" +#include "sparse-endian.h" +#include "util.h" + +#define QCOW2_MAGIC 0x514649fb + +#define QCOW2_COPIED (1ULL << 63) +#define QCOW2_COMPRESSED (1ULL << 62) +#define QCOW2_ZERO (1ULL << 0) + +typedef struct _packed_ Header { + be32_t magic; + be32_t version; + + be64_t backing_file_offset; + be32_t backing_file_size; + + be32_t cluster_bits; + be64_t size; + be32_t crypt_method; + + be32_t l1_size; + be64_t l1_table_offset; + + be64_t refcount_table_offset; + be32_t refcount_table_clusters; + + be32_t nb_snapshots; + be64_t snapshots_offset; + + /* The remainder is only present on QCOW3 */ + be64_t incompatible_features; + be64_t compatible_features; + be64_t autoclear_features; + + be32_t refcount_order; + be32_t header_length; +} Header; + +#define HEADER_MAGIC(header) be32toh((header)->magic) +#define HEADER_VERSION(header) be32toh((header)->version) +#define HEADER_CLUSTER_BITS(header) be32toh((header)->cluster_bits) +#define HEADER_CLUSTER_SIZE(header) (1ULL << HEADER_CLUSTER_BITS(header)) +#define HEADER_L2_BITS(header) (HEADER_CLUSTER_BITS(header) - 3) +#define HEADER_SIZE(header) be64toh((header)->size) +#define HEADER_CRYPT_METHOD(header) be32toh((header)->crypt_method) +#define HEADER_L1_SIZE(header) be32toh((header)->l1_size) +#define HEADER_L2_SIZE(header) (HEADER_CLUSTER_SIZE(header)/sizeof(uint64_t)) +#define HEADER_L1_TABLE_OFFSET(header) be64toh((header)->l1_table_offset) + +static uint32_t HEADER_HEADER_LENGTH(const Header *h) { + if (HEADER_VERSION(h) < 3) + return offsetof(Header, incompatible_features); + + return be32toh(h->header_length); +} + +static int copy_cluster( + int sfd, uint64_t soffset, + int dfd, uint64_t doffset, + uint64_t cluster_size, + void *buffer) { + + ssize_t l; + int r; + + r = btrfs_clone_range(sfd, soffset, dfd, doffset, cluster_size); + if (r >= 0) + return r; + + l = pread(sfd, buffer, cluster_size, soffset); + if (l < 0) + return -errno; + if ((uint64_t) l != cluster_size) + return -EIO; + + l = pwrite(dfd, buffer, cluster_size, doffset); + if (l < 0) + return -errno; + if ((uint64_t) l != cluster_size) + return -EIO; + + return 0; +} + +static int decompress_cluster( + int sfd, uint64_t soffset, + int dfd, uint64_t doffset, + uint64_t compressed_size, + uint64_t cluster_size, + void *buffer1, + void *buffer2) { + + _cleanup_free_ void *large_buffer = NULL; + z_stream s = {}; + uint64_t sz; + ssize_t l; + int r; + + if (compressed_size > cluster_size) { + /* The usual cluster buffer doesn't suffice, let's + * allocate a larger one, temporarily */ + + large_buffer = malloc(compressed_size); + if (!large_buffer) + return -ENOMEM; + + buffer1 = large_buffer; + } + + l = pread(sfd, buffer1, compressed_size, soffset); + if (l < 0) + return -errno; + if ((uint64_t) l != compressed_size) + return -EIO; + + s.next_in = buffer1; + s.avail_in = compressed_size; + s.next_out = buffer2; + s.avail_out = cluster_size; + + r = inflateInit2(&s, -12); + if (r != Z_OK) + return -EIO; + + r = inflate(&s, Z_FINISH); + sz = (uint8_t*) s.next_out - (uint8_t*) buffer2; + inflateEnd(&s); + if (r != Z_STREAM_END || sz != cluster_size) + return -EIO; + + l = pwrite(dfd, buffer2, cluster_size, doffset); + if (l < 0) + return -errno; + if ((uint64_t) l != cluster_size) + return -EIO; + + return 0; +} + +static int normalize_offset( + const Header *header, + uint64_t p, + uint64_t *ret, + bool *compressed, + uint64_t *compressed_size) { + + uint64_t q; + + q = be64toh(p); + + if (q & QCOW2_COMPRESSED) { + uint64_t sz, csize_shift, csize_mask; + + if (!compressed) + return -EOPNOTSUPP; + + csize_shift = 64 - 2 - (HEADER_CLUSTER_BITS(header) - 8); + csize_mask = (1ULL << (HEADER_CLUSTER_BITS(header) - 8)) - 1; + sz = (((q >> csize_shift) & csize_mask) + 1) * 512 - (q & 511); + q &= ((1ULL << csize_shift) - 1); + + if (compressed_size) + *compressed_size = sz; + + *compressed = true; + + } else { + if (compressed) { + *compressed = false; + *compressed_size = 0; + } + + if (q & QCOW2_ZERO) { + /* We make no distinction between zero blocks and holes */ + *ret = 0; + return 0; + } + + q &= ~QCOW2_COPIED; + } + + *ret = q; + return q > 0; /* returns positive if not a hole */ +} + +static int verify_header(const Header *header) { + assert(header); + + if (HEADER_MAGIC(header) != QCOW2_MAGIC) + return -EBADMSG; + + if (!IN_SET(HEADER_VERSION(header), 2, 3)) + return -EOPNOTSUPP; + + if (HEADER_CRYPT_METHOD(header) != 0) + return -EOPNOTSUPP; + + if (HEADER_CLUSTER_BITS(header) < 9) /* 512K */ + return -EBADMSG; + + if (HEADER_CLUSTER_BITS(header) > 21) /* 2MB */ + return -EBADMSG; + + if (HEADER_SIZE(header) % HEADER_CLUSTER_SIZE(header) != 0) + return -EBADMSG; + + if (HEADER_L1_SIZE(header) > 32*1024*1024) /* 32MB */ + return -EBADMSG; + + if (HEADER_VERSION(header) == 3) { + + if (header->incompatible_features != 0) + return -EOPNOTSUPP; + + if (HEADER_HEADER_LENGTH(header) < sizeof(Header)) + return -EBADMSG; + } + + return 0; +} + +int qcow2_convert(int qcow2_fd, int raw_fd) { + _cleanup_free_ void *buffer1 = NULL, *buffer2 = NULL; + _cleanup_free_ be64_t *l1_table = NULL, *l2_table = NULL; + uint64_t sz, i; + Header header; + ssize_t l; + int r; + + l = pread(qcow2_fd, &header, sizeof(header), 0); + if (l < 0) + return -errno; + if (l != sizeof(header)) + return -EIO; + + r = verify_header(&header); + if (r < 0) + return r; + + l1_table = new(be64_t, HEADER_L1_SIZE(&header)); + if (!l1_table) + return -ENOMEM; + + l2_table = malloc(HEADER_CLUSTER_SIZE(&header)); + if (!l2_table) + return -ENOMEM; + + buffer1 = malloc(HEADER_CLUSTER_SIZE(&header)); + if (!buffer1) + return -ENOMEM; + + buffer2 = malloc(HEADER_CLUSTER_SIZE(&header)); + if (!buffer2) + return -ENOMEM; + + /* Empty the file if it exists, we rely on zero bits */ + if (ftruncate(raw_fd, 0) < 0) + return -errno; + + if (ftruncate(raw_fd, HEADER_SIZE(&header)) < 0) + return -errno; + + sz = sizeof(uint64_t) * HEADER_L1_SIZE(&header); + l = pread(qcow2_fd, l1_table, sz, HEADER_L1_TABLE_OFFSET(&header)); + if (l < 0) + return -errno; + if ((uint64_t) l != sz) + return -EIO; + + for (i = 0; i < HEADER_L1_SIZE(&header); i ++) { + uint64_t l2_begin, j; + + r = normalize_offset(&header, l1_table[i], &l2_begin, NULL, NULL); + if (r < 0) + return r; + if (r == 0) + continue; + + l = pread(qcow2_fd, l2_table, HEADER_CLUSTER_SIZE(&header), l2_begin); + if (l < 0) + return -errno; + if ((uint64_t) l != HEADER_CLUSTER_SIZE(&header)) + return -EIO; + + for (j = 0; j < HEADER_L2_SIZE(&header); j++) { + uint64_t data_begin, p, compressed_size; + bool compressed; + + p = ((i << HEADER_L2_BITS(&header)) + j) << HEADER_CLUSTER_BITS(&header); + + r = normalize_offset(&header, l2_table[j], &data_begin, &compressed, &compressed_size); + if (r < 0) + return r; + if (r == 0) + continue; + + if (compressed) + r = decompress_cluster( + qcow2_fd, data_begin, + raw_fd, p, + compressed_size, HEADER_CLUSTER_SIZE(&header), + buffer1, buffer2); + else + r = copy_cluster( + qcow2_fd, data_begin, + raw_fd, p, + HEADER_CLUSTER_SIZE(&header), buffer1); + if (r < 0) + return r; + } + } + + return 0; +} + +int qcow2_detect(int fd) { + be32_t id; + ssize_t l; + + l = pread(fd, &id, sizeof(id), 0); + if (l < 0) + return -errno; + if (l != sizeof(id)) + return -EIO; + + return htobe32(QCOW2_MAGIC) == id; +} |