1from __future__ import absolute_import
2
3from ._snappy_cffi import ffi, lib
4
5try:
6    unicode        # Python 2
7except NameError:
8    unicode = str  # Python 3
9
10
11class UncompressError(Exception):
12    pass
13
14
15class SnappyBufferSmallError(Exception):
16    pass
17
18
19def prepare(data):
20    _out_data = None
21    _out_size = None
22
23    _out_data = ffi.from_buffer(data)
24    _out_size = ffi.cast('size_t', len(data))
25
26    return (_out_data, _out_size)
27
28
29def compress(data):
30    if isinstance(data, unicode):
31        data = data.encode('utf-8')
32
33    _input_data, _input_size = prepare(data)
34
35    max_compressed = lib.snappy_max_compressed_length(_input_size)
36
37    _out_data = ffi.new('char[]', max_compressed)
38    _out_size = ffi.new('size_t*', max_compressed)
39
40    rc = lib.snappy_compress(_input_data, _input_size, _out_data, _out_size)
41
42    if rc != lib.SNAPPY_OK:
43        raise SnappyBufferSmallError()
44
45    value = ffi.buffer(ffi.cast('char*', _out_data), _out_size[0])
46
47    return value[:]
48
49
50def uncompress(data):
51    _out_data, _out_size = prepare(data)
52
53    result = ffi.new('size_t*', 0)
54
55    rc = lib.snappy_validate_compressed_buffer(_out_data, _out_size)
56
57    if not rc == lib.SNAPPY_OK:
58        raise UncompressError()
59
60    rc = lib.snappy_uncompressed_length(_out_data,
61                                      _out_size,
62                                      result)
63
64    if not rc == lib.SNAPPY_OK:
65        raise UncompressError()
66
67    _uncompressed_data = ffi.new('char[]', result[0])
68
69    rc = lib.snappy_uncompress(_out_data, _out_size, _uncompressed_data, result)
70
71    if rc != lib.SNAPPY_OK:
72        raise UncompressError()
73
74    buf =  ffi.buffer(ffi.cast('char*', _uncompressed_data), result[0])
75
76    return buf[:]
77
78
79def isValidCompressed(data):
80    if isinstance(data, unicode):
81        data = data.encode('utf-8')
82
83    _out_data, _out_size= prepare(data)
84
85    rc = lib.snappy_validate_compressed_buffer(_out_data, _out_size)
86
87    return rc == lib.SNAPPY_OK
88
89decompress = uncompress
90
91def _crc32c(data):
92    c_data = ffi.from_buffer(data)
93    size = ffi.cast('int', len(data))
94    return int(lib._crc32c(c_data, size))
95