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1 = Git bundle v2 format
2
3 The Git bundle format is a format that represents both refs and Git objects.
4
5 == Format
6
7 We will use ABNF notation to define the Git bundle format. See
8 protocol-common.txt for the details.
9
10 A v2 bundle looks like this:
11
12 ----
13 bundle = signature *prerequisite *reference LF pack
14 signature = "# v2 git bundle" LF
15
16 prerequisite = "-" obj-id SP comment LF
17 comment = *CHAR
18 reference = obj-id SP refname LF
19
20 pack = ... ; packfile
21 ----
22
23 A v3 bundle looks like this:
24
25 ----
26 bundle = signature *capability *prerequisite *reference LF pack
27 signature = "# v3 git bundle" LF
28
29 capability = "@" key ["=" value] LF
30 prerequisite = "-" obj-id SP comment LF
31 comment = *CHAR
32 reference = obj-id SP refname LF
33 key = 1*(ALPHA / DIGIT / "-")
34 value = *(%01-09 / %0b-FF)
35
36 pack = ... ; packfile
37 ----
38
39 == Semantics
40
41 A Git bundle consists of several parts.
42
43 * "Capabilities", which are only in the v3 format, indicate functionality that
44 the bundle requires to be read properly.
45
46 * "Prerequisites" lists the objects that are NOT included in the bundle and the
47 reader of the bundle MUST already have, in order to use the data in the
48 bundle. The objects stored in the bundle may refer to prerequisite objects and
49 anything reachable from them (e.g. a tree object in the bundle can reference
50 a blob that is reachable from a prerequisite) and/or expressed as a delta
51 against prerequisite objects.
52
53 * "References" record the tips of the history graph, iow, what the reader of the
54 bundle CAN "git fetch" from it.
55
56 * "Pack" is the pack data stream "git fetch" would send, if you fetch from a
57 repository that has the references recorded in the "References" above into a
58 repository that has references pointing at the objects listed in
59 "Prerequisites" above.
60
61 In the bundle format, there can be a comment following a prerequisite obj-id.
62 This is a comment and it has no specific meaning. The writer of the bundle MAY
63 put any string here. The reader of the bundle MUST ignore the comment.
64
65 === Note on the shallow clone and a Git bundle
66
67 Note that the prerequisites does not represent a shallow-clone boundary. The
68 semantics of the prerequisites and the shallow-clone boundaries are different,
69 and the Git bundle v2 format cannot represent a shallow clone repository.
70
71 == Capabilities
72
73 Because there is no opportunity for negotiation, unknown capabilities cause 'git
74 bundle' to abort.
75
76 * `object-format` specifies the hash algorithm in use, and can take the same
77 values as the `extensions.objectFormat` configuration value.
78
79 * `filter` specifies an object filter as in the `--filter` option in
80 linkgit:git-rev-list[1]. The resulting pack-file must be marked as a
81 `.promisor` pack-file after it is unbundled.