1GITPROTOCOL-COMMON(5)             Git Manual             GITPROTOCOL-COMMON(5)
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NAME

6       gitprotocol-common - Things common to various protocols
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SYNOPSIS

9       <over-the-wire-protocol>
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DESCRIPTION

12       This document defines things common to various over-the-wire protocols
13       and file formats used in Git.
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ABNF NOTATION

16       ABNF notation as described by RFC 5234 is used within the protocol
17       documents, except the following replacement core rules are used:
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19             HEXDIG    =  DIGIT / "a" / "b" / "c" / "d" / "e" / "f"
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21       We also define the following common rules:
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23             NUL       =  %x00
24             zero-id   =  40*"0"
25             obj-id    =  40*(HEXDIGIT)
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27             refname  =  "HEAD"
28             refname /=  "refs/" <see discussion below>
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30       A refname is a hierarchical octet string beginning with "refs/" and not
31       violating the git-check-ref-format command’s validation rules. More
32       specifically, they:
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34        1. They can include slash / for hierarchical (directory) grouping, but
35           no slash-separated component can begin with a dot ..
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37        2. They must contain at least one /. This enforces the presence of a
38           category like heads/, tags/ etc. but the actual names are not
39           restricted.
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41        3. They cannot have two consecutive dots ..  anywhere.
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43        4. They cannot have ASCII control characters (i.e. bytes whose values
44           are lower than \040, or \177 DEL), space, tilde ~, caret ^, colon
45           :, question-mark ?, asterisk *, or open bracket [ anywhere.
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47        5. They cannot end with a slash / or a dot ..
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49        6. They cannot end with the sequence .lock.
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51        7. They cannot contain a sequence @{.
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53        8. They cannot contain a \\.
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PKT-LINE FORMAT

56       Much (but not all) of the payload is described around pkt-lines.
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58       A pkt-line is a variable length binary string. The first four bytes of
59       the line, the pkt-len, indicates the total length of the line, in
60       hexadecimal. The pkt-len includes the 4 bytes used to contain the
61       length’s hexadecimal representation.
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63       A pkt-line MAY contain binary data, so implementors MUST ensure
64       pkt-line parsing/formatting routines are 8-bit clean.
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66       A non-binary line SHOULD BE terminated by an LF, which if present MUST
67       be included in the total length. Receivers MUST treat pkt-lines with
68       non-binary data the same whether or not they contain the trailing LF
69       (stripping the LF if present, and not complaining when it is missing).
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71       The maximum length of a pkt-line’s data component is 65516 bytes.
72       Implementations MUST NOT send pkt-line whose length exceeds 65520
73       (65516 bytes of payload + 4 bytes of length data).
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75       Implementations SHOULD NOT send an empty pkt-line ("0004").
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77       A pkt-line with a length field of 0 ("0000"), called a flush-pkt, is a
78       special case and MUST be handled differently than an empty pkt-line
79       ("0004").
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81             pkt-line     =  data-pkt / flush-pkt
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83             data-pkt     =  pkt-len pkt-payload
84             pkt-len      =  4*(HEXDIG)
85             pkt-payload  =  (pkt-len - 4)*(OCTET)
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87             flush-pkt    = "0000"
88
89       Examples (as C-style strings):
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91             pkt-line          actual value
92             ---------------------------------
93             "0006a\n"         "a\n"
94             "0005a"           "a"
95             "000bfoobar\n"    "foobar\n"
96             "0004"            ""
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GIT

99       Part of the git(1) suite
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103Git 2.43.0                        11/20/2023             GITPROTOCOL-COMMON(5)