f4609b896f
This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because there is some breakage in the git build related to the netrc credentials helper which someone has taken care of in nixpkgs. The stable channel is not used for anything other than git, so this should be fine. Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb
76 lines
2.6 KiB
Text
76 lines
2.6 KiB
Text
= Git bundle v2 format
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The Git bundle format is a format that represents both refs and Git objects.
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== Format
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We will use ABNF notation to define the Git bundle format. See
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protocol-common.txt for the details.
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A v2 bundle looks like this:
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----
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bundle = signature *prerequisite *reference LF pack
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signature = "# v2 git bundle" LF
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prerequisite = "-" obj-id SP comment LF
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comment = *CHAR
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reference = obj-id SP refname LF
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pack = ... ; packfile
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----
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A v3 bundle looks like this:
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----
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bundle = signature *capability *prerequisite *reference LF pack
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signature = "# v3 git bundle" LF
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capability = "@" key ["=" value] LF
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prerequisite = "-" obj-id SP comment LF
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comment = *CHAR
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reference = obj-id SP refname LF
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key = 1*(ALPHA / DIGIT / "-")
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value = *(%01-09 / %0b-FF)
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pack = ... ; packfile
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----
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== Semantics
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A Git bundle consists of several parts.
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* "Capabilities", which are only in the v3 format, indicate functionality that
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the bundle requires to be read properly.
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* "Prerequisites" lists the objects that are NOT included in the bundle and the
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reader of the bundle MUST already have, in order to use the data in the
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bundle. The objects stored in the bundle may refer to prerequisite objects and
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anything reachable from them (e.g. a tree object in the bundle can reference
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a blob that is reachable from a prerequisite) and/or expressed as a delta
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against prerequisite objects.
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* "References" record the tips of the history graph, iow, what the reader of the
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bundle CAN "git fetch" from it.
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* "Pack" is the pack data stream "git fetch" would send, if you fetch from a
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repository that has the references recorded in the "References" above into a
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repository that has references pointing at the objects listed in
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"Prerequisites" above.
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In the bundle format, there can be a comment following a prerequisite obj-id.
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This is a comment and it has no specific meaning. The writer of the bundle MAY
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put any string here. The reader of the bundle MUST ignore the comment.
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=== Note on the shallow clone and a Git bundle
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Note that the prerequisites does not represent a shallow-clone boundary. The
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semantics of the prerequisites and the shallow-clone boundaries are different,
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and the Git bundle v2 format cannot represent a shallow clone repository.
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== Capabilities
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Because there is no opportunity for negotiation, unknown capabilities cause 'git
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bundle' to abort. The only known capability is `object-format`, which specifies
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the hash algorithm in use, and can take the same values as the
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`extensions.objectFormat` configuration value.
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