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https://github.com/go-gitea/gitea
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08bf443016
* Inital routes to git refs api * Git refs API implementation * Update swagger * Fix copyright * Make swagger happy add basic test * Fix test * Fix test again :)
123 lines
3.0 KiB
Go
123 lines
3.0 KiB
Go
// Package pktline implements reading payloads form pkt-lines and encoding
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// pkt-lines from payloads.
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package pktline
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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)
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// An Encoder writes pkt-lines to an output stream.
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type Encoder struct {
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w io.Writer
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}
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const (
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// MaxPayloadSize is the maximum payload size of a pkt-line in bytes.
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MaxPayloadSize = 65516
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// For compatibility with canonical Git implementation, accept longer pkt-lines
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OversizePayloadMax = 65520
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)
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var (
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// FlushPkt are the contents of a flush-pkt pkt-line.
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FlushPkt = []byte{'0', '0', '0', '0'}
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// Flush is the payload to use with the Encode method to encode a flush-pkt.
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Flush = []byte{}
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// FlushString is the payload to use with the EncodeString method to encode a flush-pkt.
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FlushString = ""
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// ErrPayloadTooLong is returned by the Encode methods when any of the
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// provided payloads is bigger than MaxPayloadSize.
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ErrPayloadTooLong = errors.New("payload is too long")
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)
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// NewEncoder returns a new encoder that writes to w.
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func NewEncoder(w io.Writer) *Encoder {
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return &Encoder{
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w: w,
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}
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}
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// Flush encodes a flush-pkt to the output stream.
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func (e *Encoder) Flush() error {
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_, err := e.w.Write(FlushPkt)
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return err
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}
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// Encode encodes a pkt-line with the payload specified and write it to
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// the output stream. If several payloads are specified, each of them
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// will get streamed in their own pkt-lines.
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func (e *Encoder) Encode(payloads ...[]byte) error {
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for _, p := range payloads {
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if err := e.encodeLine(p); err != nil {
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return err
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}
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}
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return nil
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}
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func (e *Encoder) encodeLine(p []byte) error {
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if len(p) > MaxPayloadSize {
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return ErrPayloadTooLong
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}
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if bytes.Equal(p, Flush) {
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return e.Flush()
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}
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n := len(p) + 4
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if _, err := e.w.Write(asciiHex16(n)); err != nil {
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return err
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}
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_, err := e.w.Write(p)
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return err
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}
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// Returns the hexadecimal ascii representation of the 16 less
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// significant bits of n. The length of the returned slice will always
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// be 4. Example: if n is 1234 (0x4d2), the return value will be
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// []byte{'0', '4', 'd', '2'}.
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func asciiHex16(n int) []byte {
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var ret [4]byte
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ret[0] = byteToASCIIHex(byte(n & 0xf000 >> 12))
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ret[1] = byteToASCIIHex(byte(n & 0x0f00 >> 8))
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ret[2] = byteToASCIIHex(byte(n & 0x00f0 >> 4))
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ret[3] = byteToASCIIHex(byte(n & 0x000f))
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return ret[:]
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}
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// turns a byte into its hexadecimal ascii representation. Example:
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// from 11 (0xb) to 'b'.
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func byteToASCIIHex(n byte) byte {
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if n < 10 {
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return '0' + n
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}
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return 'a' - 10 + n
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}
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// EncodeString works similarly as Encode but payloads are specified as strings.
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func (e *Encoder) EncodeString(payloads ...string) error {
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for _, p := range payloads {
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if err := e.Encode([]byte(p)); err != nil {
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return err
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}
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}
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return nil
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}
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// Encodef encodes a single pkt-line with the payload formatted as
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// the format specifier. The rest of the arguments will be used in
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// the format string.
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func (e *Encoder) Encodef(format string, a ...interface{}) error {
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return e.EncodeString(
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fmt.Sprintf(format, a...),
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)
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}
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