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author | Scott Chacon <schacon@gmail.com> | 2009-11-04 08:58:23 +0300 |
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committer | Junio C Hamano <gitster@pobox.com> | 2009-11-13 23:07:21 +0300 |
commit | b31222cfb7f2fcdc5b3d76ce5fcebf6ff1929826 (patch) | |
tree | ac2bec7c226d90cdcfeef5eac679a40a585d1acc /Documentation/technical/protocol-common.txt | |
parent | 78d553b7d7b269bb22ebd8b1198657c37484a3a0 (diff) |
Update packfile transfer protocol documentation
The current technical documentation for the packfile protocol is both
sparse and incorrect. This documents the fetch-pack/upload-pack and
send-pack/ receive-pack protocols much more fully.
Add documentation from Shawn's upcoming http-protocol docs that is
shared by the packfile protocol. protocol-common.txt describes ABNF
notation amendments, refname rules and the packet line format.
Add documentation on the various capabilities supported by the
upload-pack and receive-pack protocols. protocol-capabilities.txt
describes multi-ack, thin-pack, side-band[-64k], shallow, no-progress,
include-tag, ofs-delta, delete-refs and report-status.
Signed-off-by: Scott Chacon <schacon@gmail.com>
Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/technical/protocol-common.txt')
-rw-r--r-- | Documentation/technical/protocol-common.txt | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/Documentation/technical/protocol-common.txt b/Documentation/technical/protocol-common.txt new file mode 100644 index 0000000000..d30a1b9510 --- /dev/null +++ b/Documentation/technical/protocol-common.txt @@ -0,0 +1,96 @@ +Documentation Common to Pack and Http Protocols +=============================================== + +ABNF Notation +------------- + +ABNF notation as described by RFC 5234 is used within the protocol documents, +except the following replacement core rules are used: +---- + HEXDIG = DIGIT / "a" / "b" / "c" / "d" / "e" / "f" +---- + +We also define the following common rules: +---- + NUL = %x00 + zero-id = 40*"0" + obj-id = 40*(HEXDIGIT) + + refname = "HEAD" + refname /= "refs/" <see discussion below> +---- + +A refname is a hierarchical octet string beginning with "refs/" and +not violating the 'git-check-ref-format' command's validation rules. +More specifically, they: + +. They can include slash `/` for hierarchical (directory) + grouping, but no slash-separated component can begin with a + dot `.`. + +. They must contain at least one `/`. This enforces the presence of a + category like `heads/`, `tags/` etc. but the actual names are not + restricted. + +. They cannot have two consecutive dots `..` anywhere. + +. They cannot have ASCII control characters (i.e. bytes whose + values are lower than \040, or \177 `DEL`), space, tilde `~`, + caret `{caret}`, colon `:`, question-mark `?`, asterisk `*`, + or open bracket `[` anywhere. + +. They cannot end with a slash `/` nor a dot `.`. + +. They cannot end with the sequence `.lock`. + +. They cannot contain a sequence `@{`. + +. They cannot contain a `\\`. + + +pkt-line Format +--------------- + +Much (but not all) of the payload is described around pkt-lines. + +A pkt-line is a variable length binary string. The first four bytes +of the line, the pkt-len, indicates the total length of the line, +in hexadecimal. The pkt-len includes the 4 bytes used to contain +the length's hexadecimal representation. + +A pkt-line MAY contain binary data, so implementors MUST ensure +pkt-line parsing/formatting routines are 8-bit clean. + +A non-binary line SHOULD BE terminated by an LF, which if present +MUST be included in the total length. + +The maximum length of a pkt-line's data component is 65520 bytes. +Implementations MUST NOT send pkt-line whose length exceeds 65524 +(65520 bytes of payload + 4 bytes of length data). + +Implementations SHOULD NOT send an empty pkt-line ("0004"). + +A pkt-line with a length field of 0 ("0000"), called a flush-pkt, +is a special case and MUST be handled differently than an empty +pkt-line ("0004"). + +---- + pkt-line = data-pkt / flush-pkt + + data-pkt = pkt-len pkt-payload + pkt-len = 4*(HEXDIG) + pkt-payload = (pkt-len - 4)*(OCTET) + + flush-pkt = "0000" +---- + +Examples (as C-style strings): + +---- + pkt-line actual value + --------------------------------- + "0006a\n" "a\n" + "0005a" "a" + "000bfoobar\n" "foobar\n" + "0004" "" +---- |