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 

23from typing import Optional 

24 

25from structlog import get_logger 

26 

27from unblob.extractors import Command 

28 

29from ...extractors.command import MultiFileCommand 

30from ...file_utils import Endian, InvalidInputFormat, StructParser 

31from ...models import ( 

32 DirectoryHandler, 

33 File, 

34 Glob, 

35 HandlerDoc, 

36 HandlerType, 

37 HexString, 

38 MultiFile, 

39 Reference, 

40 StructHandler, 

41 ValidChunk, 

42) 

43 

44logger = get_logger() 

45 

46C_DEFINITIONS = r""" 

47 typedef struct sevenzip_header { 

48 char magic[6]; 

49 uint8 version_maj; 

50 uint8 version_min; 

51 uint32 crc; 

52 uint64 next_header_offset; 

53 uint64 next_header_size; 

54 uint32 next_header_crc; 

55 } sevenzip_header_t; 

56""" 

57HEADER_STRUCT = "sevenzip_header_t" 

58HEADER_SIZE = 6 + 1 + 1 + 4 + 8 + 8 + 4 

59 

60HEADER_PARSER = StructParser(C_DEFINITIONS) 

61 

62# StartHeader (next_header_offset, next_header_size, next_header_crc) 

63START_HEADER_SIZE = 8 + 8 + 4 

64 

65 

66SEVENZIP_MAGIC = b"7z\xbc\xaf\x27\x1c" 

67 

68 

69def check_header_crc(header): 

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

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

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

73 if header.crc != calculated_crc: 

74 raise InvalidInputFormat("Invalid sevenzip header CRC") 

75 

76 

77def calculate_sevenzip_size(header) -> int: 

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

79 

80 

81class SevenZipHandler(StructHandler): 

82 NAME = "sevenzip" 

83 

84 PATTERNS = [ 

85 HexString( 

86 """ 

87 // '7', 'z', 0xBC, 0xAF, 0x27, 0x1C 

88 37 7A BC AF 27 1C 

89 """ 

90 ) 

91 ] 

92 C_DEFINITIONS = C_DEFINITIONS 

93 HEADER_STRUCT = HEADER_STRUCT 

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

95 

96 DOC = HandlerDoc( 

97 name="7-Zip", 

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

99 handler_type=HandlerType.ARCHIVE, 

100 vendor=None, 

101 references=[ 

102 Reference( 

103 title="7-Zip Technical Documentation", 

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

105 ), 

106 ], 

107 limitations=[], 

108 ) 

109 

110 def calculate_chunk(self, file: File, start_offset: int) -> Optional[ValidChunk]: 

111 header = self.parse_header(file) 

112 

113 check_header_crc(header) 

114 

115 size = calculate_sevenzip_size(header) 

116 

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

118 

119 

120class MultiVolumeSevenZipHandler(DirectoryHandler): 

121 NAME = "multi-sevenzip" 

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

123 

124 PATTERN = Glob("*.7z.001") 

125 

126 DOC = HandlerDoc( 

127 name=NAME, 

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

129 handler_type=HandlerType.ARCHIVE, 

130 vendor=None, 

131 references=[ 

132 Reference( 

133 title="7-Zip Technical Documentation", 

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

135 ), 

136 ], 

137 limitations=[], 

138 ) 

139 

140 def calculate_multifile(self, file: Path) -> Optional[MultiFile]: 

141 paths = sorted( 

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

143 ) 

144 if not paths: 

145 return None 

146 

147 with file.open("rb") as f: 

148 header_data = f.read(HEADER_SIZE) 

149 

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

151 if header.magic != SEVENZIP_MAGIC: 

152 return None 

153 

154 check_header_crc(header) 

155 size = calculate_sevenzip_size(header) 

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

157 

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

159 logger.debug( 

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

161 ) 

162 if files_size != size: 

163 return None 

164 

165 return MultiFile( 

166 name=file.stem, 

167 paths=paths, 

168 )