Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/unblob/handlers/archive/sevenzip.py: 71%

1"""7-zip handlers. 

2 

37-zip archive file format SHALL consist of three part. 7-zip archive 

4file SHALL start with signature header. The data block SHOULD placed 

5after the signature header. The data block is shown as Packed 

6Streams. A header database SHOULD be placed after the data block. 

7The data block MAY be empty when no archived contents exists. So 

8Packed Streams is optional. Since Header database CAN be encoded then 

9it SHOULD place after data block, that is Packed Streams for Headers. 

10When Header database is encoded, Header encode Information SHALL 

11placed instead of Header. 

12 

13[Signature Header] [Data] [Header Database] 

14 

15https://fastapi.metacpan.org/source/BJOERN/Compress-Deflate7-1.0/7zip/DOC/7zFormat.txt 

16"7z uses little endian encoding." 

17 

18https://py7zr.readthedocs.io/en/latest/archive_format.html 

19""" 

20 

21import binascii 

22from pathlib import Path 

23 

24from structlog import get_logger 

25 

26from unblob.extractors import Command 

27 

28from ...extractors.command import MultiFileCommand 

29from ...file_utils import Endian, InvalidInputFormat, StructParser 

30from ...models import ( 

31 DirectoryHandler, 

32 File, 

33 Glob, 

34 HandlerDoc, 

35 HandlerType, 

36 HexString, 

37 MultiFile, 

38 Reference, 

39 StructHandler, 

40 ValidChunk, 

41) 

42 

43logger = get_logger() 

44 

45C_DEFINITIONS = r""" 

46 typedef struct sevenzip_header { 

47 char magic[6]; 

48 uint8 version_maj; 

49 uint8 version_min; 

50 uint32 crc; 

51 uint64 next_header_offset; 

52 uint64 next_header_size; 

53 uint32 next_header_crc; 

54 } sevenzip_header_t; 

55""" 

56HEADER_STRUCT = "sevenzip_header_t" 

57HEADER_SIZE = 6 + 1 + 1 + 4 + 8 + 8 + 4 

58 

59HEADER_PARSER = StructParser(C_DEFINITIONS) 

60 

61# StartHeader (next_header_offset, next_header_size, next_header_crc) 

62START_HEADER_SIZE = 8 + 8 + 4 

63 

64 

65SEVENZIP_MAGIC = b"7z\xbc\xaf\x27\x1c" 

66 

67 

68def check_header_crc(header): 

69 # CRC includes the StartHeader (next_header_offset, next_header_size, next_header_crc) 

70 # CPP/7zip/Archive/7z/7zOut.cpp COutArchive::WriteStartHeader 

71 calculated_crc = binascii.crc32(header.dumps()[-START_HEADER_SIZE:]) 

72 if header.crc != calculated_crc: 

73 raise InvalidInputFormat("Invalid sevenzip header CRC") 

74 

75 

76def calculate_sevenzip_size(header) -> int: 

77 return len(header) + header.next_header_offset + header.next_header_size 

78 

79 

80class SevenZipHandler(StructHandler): 

81 NAME = "sevenzip" 

82 

83 PATTERNS = [ 

84 HexString( 

85 """ 

86 // '7', 'z', 0xBC, 0xAF, 0x27, 0x1C 

87 37 7A BC AF 27 1C 

88 """ 

89 ) 

90 ] 

91 C_DEFINITIONS = C_DEFINITIONS 

92 HEADER_STRUCT = HEADER_STRUCT 

93 EXTRACTOR = Command("7z", "x", "-p", "-y", "{inpath}", "-o{outdir}") 

94 

95 DOC = HandlerDoc( 

96 name="7-Zip", 

97 description="The 7-Zip file format is a compressed archive format with high compression ratios, supporting multiple algorithms, CRC checks, and multi-volume archives.", 

98 handler_type=HandlerType.ARCHIVE, 

99 vendor=None, 

100 references=[ 

101 Reference( 

102 title="7-Zip Technical Documentation", 

103 url="https://fastapi.metacpan.org/source/BJOERN/Compress-Deflate7-1.0/7zip/DOC/7zFormat.txt", 

104 ), 

105 ], 

106 limitations=[], 

107 ) 

108 

109 def calculate_chunk(self, file: File, start_offset: int) -> ValidChunk | None: 

110 header = self.parse_header(file) 

111 

112 check_header_crc(header) 

113 

114 size = calculate_sevenzip_size(header) 

115 

116 return ValidChunk(start_offset=start_offset, end_offset=start_offset + size) 

117 

118 

119class MultiVolumeSevenZipHandler(DirectoryHandler): 

120 NAME = "multi-sevenzip" 

121 EXTRACTOR = MultiFileCommand("7z", "x", "-p", "-y", "{inpath}", "-o{outdir}") 

122 

123 PATTERN = Glob("*.7z.001") 

124 

125 DOC = HandlerDoc( 

126 name=NAME, 

127 description="The 7-Zip file format is a compressed archive format with high compression ratios, supporting multiple algorithms, CRC checks, and multi-volume archives.", 

128 handler_type=HandlerType.ARCHIVE, 

129 vendor=None, 

130 references=[ 

131 Reference( 

132 title="7-Zip Technical Documentation", 

133 url="https://fastapi.metacpan.org/source/BJOERN/Compress-Deflate7-1.0/7zip/DOC/7zFormat.txt", 

134 ), 

135 ], 

136 limitations=[], 

137 ) 

138 

139 def calculate_multifile(self, file: Path) -> MultiFile | None: 

140 paths = sorted( 

141 [p for p in file.parent.glob(f"{file.stem}.*") if p.resolve().exists()] 

142 ) 

143 if not paths: 

144 return None 

145 

146 with file.open("rb") as f: 

147 header_data = f.read(HEADER_SIZE) 

148 

149 header = HEADER_PARSER.parse(HEADER_STRUCT, header_data, Endian.LITTLE) 

150 if header.magic != SEVENZIP_MAGIC: 

151 return None 

152 

153 check_header_crc(header) 

154 size = calculate_sevenzip_size(header) 

155 logger.debug("Sevenzip header", header=header, size=size, _verbosity=3) 

156 

157 files_size = sum(path.stat().st_size for path in paths) 

158 logger.debug( 

159 "Multi-volume files", paths=paths, files_size=files_size, _verbosity=2 

160 ) 

161 if files_size != size: 

162 return None 

163 

164 return MultiFile( 

165 name=file.stem, 

166 paths=paths, 

167 )