NAME
gitprotocol-common - Things common to various protocols
SYNOPSIS
<over-the-wire-protocol>DESCRIPTION
This document defines things common to various over-the-wire protocols and file formats used in Git.
ABNF NOTATION
ABNF notation as described by RFC 5234 is used within the protocol documents, except the following replacement core rules are used:
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HEXDIG = DIGIT / "a" / "b" / "c" / "d" / "e" / "f"We also define the following common rules:
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NUL = %x00
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zero-id = 40*"0"
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obj-id = 40*(HEXDIGIT)
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refname = "HEAD"
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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:
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. Receivers MUST treat pkt-lines with non-binary data the same whether or not they contain the trailing LF (stripping the LF if present, and not complaining when it is missing).
The maximum length of a pkt-line’s data component is 65516 bytes. Implementations MUST NOT send pkt-line whose length exceeds 65520 (65516 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").
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pkt-line = data-pkt / flush-pkt
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data-pkt = pkt-len pkt-payload
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pkt-len = 4*(HEXDIG)
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pkt-payload = (pkt-len - 4)*(OCTET)
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flush-pkt = "0000"Examples (as C-style strings):
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pkt-line actual value
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"0006a\n" "a\n"
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"0005a" "a"
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"000bfoobar\n" "foobar\n"
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"0004" ""GIT
Part of the git(1) suite