Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/dulwich/object_format.py: 56%

1# hash.py -- Object format abstraction layer for Git 

2# Copyright (C) 2024 The Dulwich contributors 

3# 

4# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 

5# Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU 

6# General Public License as published by the Free Software Foundation; version 2.0 

7# or (at your option) any later version. You can redistribute it and/or 

8# modify it under the terms of either of these two licenses. 

9# 

10# Unless required by applicable law or agreed to in writing, software 

11# distributed under the License is distributed on an "AS IS" BASIS, 

12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 

13# See the License for the specific language governing permissions and 

14# limitations under the License. 

15# 

16# You should have received a copy of the licenses; if not, see 

17# <http://www.gnu.org/licenses/> for a copy of the GNU General Public License 

18# and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache 

19# License, Version 2.0. 

20# 

21 

22"""Object format abstraction for Git objects. 

23 

24This module provides an abstraction layer for different object formats 

25used in Git repositories (SHA-1 and SHA-256). 

26""" 

27 

28from collections.abc import Callable 

29from hashlib import sha1, sha256 

30from typing import TYPE_CHECKING 

31 

32if TYPE_CHECKING: 

33 from _hashlib import HASH 

34 

35 

36class ObjectFormat: 

37 """Object format (hash algorithm) used in Git.""" 

38 

39 def __init__( 

40 self, 

41 name: str, 

42 type_num: int, 

43 oid_length: int, 

44 hex_length: int, 

45 hash_func: Callable[[], "HASH"], 

46 ) -> None: 

47 """Initialize an object format. 

48 

49 Args: 

50 name: Name of the format (e.g., "sha1", "sha256") 

51 type_num: Format type number used in Git 

52 oid_length: Length of the binary object ID in bytes 

53 hex_length: Length of the hexadecimal object ID in characters 

54 hash_func: Hash function from hashlib 

55 """ 

56 self.name = name 

57 self.type_num = type_num 

58 self.oid_length = oid_length 

59 self.hex_length = hex_length 

60 self.hash_func = hash_func 

61 

62 def __str__(self) -> str: 

63 """Return string representation.""" 

64 return self.name 

65 

66 def __repr__(self) -> str: 

67 """Return repr.""" 

68 return f"ObjectFormat({self.name!r})" 

69 

70 def new_hash(self) -> "HASH": 

71 """Create a new hash object.""" 

72 return self.hash_func() 

73 

74 def hash_object(self, data: bytes) -> bytes: 

75 """Hash data and return the digest. 

76 

77 Args: 

78 data: Data to hash 

79 

80 Returns: 

81 Binary digest 

82 """ 

83 h = self.new_hash() 

84 h.update(data) 

85 return h.digest() 

86 

87 def hash_object_hex(self, data: bytes) -> bytes: 

88 """Hash data and return the hexadecimal digest. 

89 

90 Args: 

91 data: Data to hash 

92 

93 Returns: 

94 Hexadecimal digest as bytes 

95 """ 

96 h = self.new_hash() 

97 h.update(data) 

98 return h.hexdigest().encode("ascii") 

99 

100 

101# Define the supported object formats 

102SHA1 = ObjectFormat("sha1", type_num=1, oid_length=20, hex_length=40, hash_func=sha1) 

103SHA256 = ObjectFormat( 

104 "sha256", type_num=20, oid_length=32, hex_length=64, hash_func=sha256 

105) 

106 

107# Map of format names to ObjectFormat instances 

108OBJECT_FORMATS = { 

109 "sha1": SHA1, 

110 "sha256": SHA256, 

111} 

112 

113# Map of format numbers to ObjectFormat instances 

114OBJECT_FORMAT_TYPE_NUMS = { 

115 1: SHA1, 

116 2: SHA256, 

117} 

118 

119# Default format for backward compatibility 

120DEFAULT_OBJECT_FORMAT = SHA1 

121 

122 

123def get_object_format(name: str | None = None) -> ObjectFormat: 

124 """Get an object format by name. 

125 

126 Args: 

127 name: Format name ("sha1" or "sha256"). If None, returns default. 

128 

129 Returns: 

130 ObjectFormat instance 

131 

132 Raises: 

133 ValueError: If the format name is not supported 

134 """ 

135 if name is None: 

136 return DEFAULT_OBJECT_FORMAT 

137 try: 

138 return OBJECT_FORMATS[name.lower()] 

139 except KeyError: 

140 raise ValueError(f"Unsupported object format: {name}") 

141 

142 

143def verify_same_object_format(*formats: ObjectFormat) -> ObjectFormat: 

144 """Verify that all provided object formats are the same. 

145 

146 Args: 

147 *formats: Object format instances to verify 

148 

149 Returns: 

150 The common object format 

151 

152 Raises: 

153 ValueError: If formats don't match or no formats provided 

154 """ 

155 if not formats: 

156 raise ValueError("At least one object format must be provided") 

157 

158 first = formats[0] 

159 for fmt in formats[1:]: 

160 if fmt != first: 

161 raise ValueError(f"Object format mismatch: {first.name} != {fmt.name}") 

162 

163 return first