return QcowHeaderExtension(magic, len(data), data)
-class QcowHeader:
+# Mapping from c types to python struct format
+ctypes = {
+ 'u8': 'B',
+ 'u16': 'H',
+ 'u32': 'I',
+ 'u64': 'Q'
+}
+
- uint32_t = 'I'
- uint64_t = 'Q'
+class QcowHeader:
fields = (
# Version 2 header fields
- (uint32_t, '{:#x}', 'magic'),
- (uint32_t, '{}', 'version'),
- (uint64_t, '{:#x}', 'backing_file_offset'),
- (uint32_t, '{:#x}', 'backing_file_size'),
- (uint32_t, '{}', 'cluster_bits'),
- (uint64_t, '{}', 'size'),
- (uint32_t, '{}', 'crypt_method'),
- (uint32_t, '{}', 'l1_size'),
- (uint64_t, '{:#x}', 'l1_table_offset'),
- (uint64_t, '{:#x}', 'refcount_table_offset'),
- (uint32_t, '{}', 'refcount_table_clusters'),
- (uint32_t, '{}', 'nb_snapshots'),
- (uint64_t, '{:#x}', 'snapshot_offset'),
+ ('u32', '{:#x}', 'magic'),
+ ('u32', '{}', 'version'),
+ ('u64', '{:#x}', 'backing_file_offset'),
+ ('u32', '{:#x}', 'backing_file_size'),
+ ('u32', '{}', 'cluster_bits'),
+ ('u64', '{}', 'size'),
+ ('u32', '{}', 'crypt_method'),
+ ('u32', '{}', 'l1_size'),
+ ('u64', '{:#x}', 'l1_table_offset'),
+ ('u64', '{:#x}', 'refcount_table_offset'),
+ ('u32', '{}', 'refcount_table_clusters'),
+ ('u32', '{}', 'nb_snapshots'),
+ ('u64', '{:#x}', 'snapshot_offset'),
# Version 3 header fields
- (uint64_t, 'mask', 'incompatible_features'),
- (uint64_t, 'mask', 'compatible_features'),
- (uint64_t, 'mask', 'autoclear_features'),
- (uint32_t, '{}', 'refcount_order'),
- (uint32_t, '{}', 'header_length'),
+ ('u64', 'mask', 'incompatible_features'),
+ ('u64', 'mask', 'compatible_features'),
+ ('u64', 'mask', 'autoclear_features'),
+ ('u32', '{}', 'refcount_order'),
+ ('u32', '{}', 'header_length'),
)
- fmt = '>' + ''.join(field[0] for field in fields)
+ fmt = '>' + ''.join(ctypes[f[0]] for f in fields)
def __init__(self, fd):