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96 lines
2.7 KiB
96 lines
2.7 KiB
Documentation Common to Pack and Http Protocols |
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ABNF Notation |
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------------- |
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ABNF notation as described by RFC 5234 is used within the protocol documents, |
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except the following replacement core rules are used: |
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---- |
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HEXDIG = DIGIT / "a" / "b" / "c" / "d" / "e" / "f" |
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---- |
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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> |
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---- |
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A refname is a hierarchical octet string beginning with "refs/" and |
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not violating the 'git-check-ref-format' command's validation rules. |
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More specifically, they: |
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. They can include slash `/` for hierarchical (directory) |
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grouping, but no slash-separated component can begin with a |
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dot `.`. |
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. They must contain at least one `/`. This enforces the presence of a |
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category like `heads/`, `tags/` etc. but the actual names are not |
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restricted. |
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. They cannot have two consecutive dots `..` anywhere. |
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. They cannot have ASCII control characters (i.e. bytes whose |
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values are lower than \040, or \177 `DEL`), space, tilde `~`, |
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caret `{caret}`, colon `:`, question-mark `?`, asterisk `*`, |
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or open bracket `[` anywhere. |
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. They cannot end with a slash `/` nor a dot `.`. |
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. They cannot end with the sequence `.lock`. |
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. They cannot contain a sequence `@{`. |
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. They cannot contain a `\\`. |
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pkt-line Format |
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--------------- |
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Much (but not all) of the payload is described around pkt-lines. |
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A pkt-line is a variable length binary string. The first four bytes |
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of the line, the pkt-len, indicates the total length of the line, |
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in hexadecimal. The pkt-len includes the 4 bytes used to contain |
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the length's hexadecimal representation. |
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A pkt-line MAY contain binary data, so implementors MUST ensure |
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pkt-line parsing/formatting routines are 8-bit clean. |
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A non-binary line SHOULD BE terminated by an LF, which if present |
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MUST be included in the total length. |
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The maximum length of a pkt-line's data component is 65520 bytes. |
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Implementations MUST NOT send pkt-line whose length exceeds 65524 |
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(65520 bytes of payload + 4 bytes of length data). |
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Implementations SHOULD NOT send an empty pkt-line ("0004"). |
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A pkt-line with a length field of 0 ("0000"), called a flush-pkt, |
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is a special case and MUST be handled differently than an empty |
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pkt-line ("0004"). |
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---- |
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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" |
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---- |
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Examples (as C-style strings): |
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---- |
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pkt-line actual value |
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--------------------------------- |
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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" "" |
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----
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