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gitprotocol-common(5)             Git Manual             gitprotocol-common(5)


       gitprotocol-common - Things common to various protocols




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


       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:

        1. They can include slash / for hierarchical (directory) grouping, but
           no slash-separated component can begin with a dot ..

        2. They must contain at least one /. This enforces the presence of a
           category like heads/, tags/ etc. but the actual names are not

        3. They cannot have two consecutive dots .. anywhere.

        4. They cannot have ASCII control characters (i.e. bytes whose values
           are lower than \040, or \177 DEL), space, tilde ~, caret ^, colon
           :, question-mark ?, asterisk *, or open bracket [ anywhere.

        5. They cannot end with a slash / or a dot ..

        6. They cannot end with the sequence .lock.

        7. They cannot contain a sequence @{.

        8. They cannot contain a \\.


       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

             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"            ""


       Part of the git(1) suite

Git 2.43.0                        2023-11-20             gitprotocol-common(5)

git 2.43.0 - Generated Sun Nov 26 15:54:47 CST 2023
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