projects / thirdparty / git.git / blame
| Commit | Line | Data |
|---|---|---|
| b31222cf SC |
1 | Documentation Common to Pack and Http Protocols |
| 2 | =============================================== | |
| 3 | ||
| 4 | ABNF Notation | |
| 5 | ------------- | |
| 6 | ||
| 7 | ABNF notation as described by RFC 5234 is used within the protocol documents, | |
| 8 | except the following replacement core rules are used: | |
| 9 | ---- | |
| 10 | HEXDIG = DIGIT / "a" / "b" / "c" / "d" / "e" / "f" | |
| 11 | ---- | |
| 12 | ||
| 13 | We also define the following common rules: | |
| 14 | ---- | |
| 15 | NUL = %x00 | |
| 16 | zero-id = 40*"0" | |
| 17 | obj-id = 40*(HEXDIGIT) | |
| 18 | ||
| 19 | refname = "HEAD" | |
| 20 | refname /= "refs/" <see discussion below> | |
| 21 | ---- | |
| 22 | ||
| 23 | A refname is a hierarchical octet string beginning with "refs/" and | |
| 24 | not violating the 'git-check-ref-format' command's validation rules. | |
| 25 | More specifically, they: | |
| 26 | ||
| 27 | . They can include slash `/` for hierarchical (directory) | |
| 28 | grouping, but no slash-separated component can begin with a | |
| 29 | dot `.`. | |
| 30 | ||
| 31 | . They must contain at least one `/`. This enforces the presence of a | |
| 32 | category like `heads/`, `tags/` etc. but the actual names are not | |
| 33 | restricted. | |
| 34 | ||
| 35 | . They cannot have two consecutive dots `..` anywhere. | |
| 36 | ||
| 37 | . They cannot have ASCII control characters (i.e. bytes whose | |
| 38 | values are lower than \040, or \177 `DEL`), space, tilde `~`, | |
| 6cf378f0 | 39 | caret `^`, colon `:`, question-mark `?`, asterisk `*`, |
| b31222cf SC |
40 | or open bracket `[` anywhere. |
| 41 | ||
| 42 | . They cannot end with a slash `/` nor a dot `.`. | |
| 43 | ||
| 44 | . They cannot end with the sequence `.lock`. | |
| 45 | ||
| 46 | . They cannot contain a sequence `@{`. | |
| 47 | ||
| 48 | . They cannot contain a `\\`. | |
| 49 | ||
| 50 | ||
| 51 | pkt-line Format | |
| 52 | --------------- | |
| 53 | ||
| 54 | Much (but not all) of the payload is described around pkt-lines. | |
| 55 | ||
| 56 | A pkt-line is a variable length binary string. The first four bytes | |
| 57 | of the line, the pkt-len, indicates the total length of the line, | |
| 58 | in hexadecimal. The pkt-len includes the 4 bytes used to contain | |
| 59 | the length's hexadecimal representation. | |
| 60 | ||
| 61 | A pkt-line MAY contain binary data, so implementors MUST ensure | |
| 62 | pkt-line parsing/formatting routines are 8-bit clean. | |
| 63 | ||
| 64 | A non-binary line SHOULD BE terminated by an LF, which if present | |
| 65 | MUST be included in the total length. | |
| 66 | ||
| 67 | The maximum length of a pkt-line's data component is 65520 bytes. | |
| 68 | Implementations MUST NOT send pkt-line whose length exceeds 65524 | |
| 69 | (65520 bytes of payload + 4 bytes of length data). | |
| 70 | ||
| 71 | Implementations SHOULD NOT send an empty pkt-line ("0004"). | |
| 72 | ||
| 73 | A pkt-line with a length field of 0 ("0000"), called a flush-pkt, | |
| 74 | is a special case and MUST be handled differently than an empty | |
| 75 | pkt-line ("0004"). | |
| 76 | ||
| 77 | ---- | |
| 78 | pkt-line = data-pkt / flush-pkt | |
| 79 | ||
| 80 | data-pkt = pkt-len pkt-payload | |
| 81 | pkt-len = 4*(HEXDIG) | |
| 82 | pkt-payload = (pkt-len - 4)*(OCTET) | |
| 83 | ||
| 84 | flush-pkt = "0000" | |
| 85 | ---- | |
| 86 | ||
| 87 | Examples (as C-style strings): | |
| 88 | ||
| 89 | ---- | |
| 90 | pkt-line actual value | |
| 91 | --------------------------------- | |
| 92 | "0006a\n" "a\n" | |
| 93 | "0005a" "a" | |
| 94 | "000bfoobar\n" "foobar\n" | |
| 95 | "0004" "" | |
| 96 | ---- |