Add a new function qcow1_read_cluster() to read a qcow cluster size data at a time. The function qcow1_read_sector() is modified to use the function qcow1_read_cluster().
Signed-off-by: Prasad Joshi <[email protected]> --- tools/kvm/qcow.c | 123 ++++++++++++++++++++++++++++++++++-------------------- 1 files changed, 78 insertions(+), 45 deletions(-) diff --git a/tools/kvm/qcow.c b/tools/kvm/qcow.c index 9b9af86..e6d5897 100644 --- a/tools/kvm/qcow.c +++ b/tools/kvm/qcow.c @@ -36,68 +36,101 @@ static inline uint64_t get_cluster_offset(struct qcow *q, uint64_t offset) return offset & ((1 << header->cluster_bits)-1); } -static int qcow1_read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len) +static uint32_t qcow1_read_cluster(struct qcow *q, uint64_t offset, void *dst, uint32_t dst_len) { - struct qcow *q = self->priv; struct qcow1_header *header = q->header; - uint64_t l2_table_offset; - uint64_t l2_table_size; - uint64_t clust_offset; - uint64_t clust_start; - uint64_t *l2_table; - uint64_t l1_idx; - uint64_t l2_idx; - uint64_t offset; - - offset = sector << SECTOR_SHIFT; - if (offset >= header->size) - goto out_error; + struct qcow_table *table = &q->table; + uint32_t length; + + uint32_t l2_table_size; + u64 l2_table_offset; + u64 *l2_table; + u64 l2_idx; - l1_idx = get_l1_index(q, offset); + uint32_t clust_size; + u64 clust_offset; + u64 clust_start; - if (l1_idx >= q->table.table_size) - goto out_error; + u64 l1_idx; - l2_table_offset = q->table.l1_table[l1_idx]; - if (!l2_table_offset) - goto zero_sector; + clust_size = 1 << header->cluster_bits; + l2_table_size = 1 << header->l2_bits; - l2_table_size = 1 << header->l2_bits; + l1_idx = get_l1_index(q, offset); + if (l1_idx >= table->table_size) + goto error; - l2_table = calloc(l2_table_size, sizeof(uint64_t)); - if (!l2_table) - goto out_error; + l2_idx = get_l2_index(q, offset); + if (l2_idx >= l2_table_size) + goto error; - if (pread_in_full(q->fd, l2_table, sizeof(uint64_t) * l2_table_size, l2_table_offset) < 0) - goto out_error_free_l2; + clust_offset = get_cluster_offset(q, offset); + if (clust_offset >= clust_size) + goto error; - l2_idx = get_l2_index(q, offset); + length = clust_size - clust_offset; + if (length > dst_len) + length = dst_len; - if (l2_idx >= l2_table_size) - goto out_error_free_l2; + l2_table_offset = table->l1_table[l1_idx]; + if (!l2_table_offset) { + /* unallocated level 2 table: returned zeroed data */ + memset(dst, 0, length); + goto out; + } - clust_start = be64_to_cpu(l2_table[l2_idx]); + l2_table = calloc(l2_table_size, sizeof(u64)); + if (!l2_table) + goto error; - if (!clust_start) - goto zero_sector; + if (pread_in_full(q->fd, l2_table, sizeof(u64) * l2_table_size, + l2_table_offset) < 0) + goto free_l2; - clust_offset = get_cluster_offset(q, offset); + clust_start = be64_to_cpu(l2_table[l2_idx]); + if (!clust_start) { + /* unalloacted cluster return zeroed data */ + memset(dst, 0, length); + free(l2_table); + goto out; + } - if (pread_in_full(q->fd, dst, dst_len, clust_start + clust_offset) < 0) - goto out_error_free_l2; + if (pread_in_full(q->fd, dst, length, clust_start + clust_offset) < 0) + goto free_l2; +out: + return length; +free_l2: free(l2_table); - +error: return 0; +} -zero_sector: - memset(dst, 0, dst_len); +static int qcow1_read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len) +{ + struct qcow *q = self->priv; + struct qcow1_header *header = q->header; + uint32_t length = 0; + char *buf = dst; + uint64_t offset; + uint32_t nr; - return 0; + while (length < dst_len) { + offset = sector << SECTOR_SHIFT; + if (offset >= header->size) + goto error; -out_error_free_l2: - free(l2_table); -out_error: + nr = qcow1_read_cluster(q, offset, buf, dst_len - length); + if (!nr) + goto error; + + length += nr; + buf += nr; + sector += (nr >> SECTOR_SHIFT); + } + + return 0; +error: return -1; } -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
