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package packp
import (
"bytes"
"encoding/hex"
"fmt"
"io"
"strconv"
"time"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/format/pktline"
)
// Decode reads the next upload-request form its input and
// stores it in the UploadRequest.
func (req *UploadRequest) Decode(r io.Reader) error {
d := newUlReqDecoder(r)
return d.Decode(req)
}
type ulReqDecoder struct {
s *pktline.Scanner // a pkt-line scanner from the input stream
line []byte // current pkt-line contents, use parser.nextLine() to make it advance
nLine int // current pkt-line number for debugging, begins at 1
err error // sticky error, use the parser.error() method to fill this out
data *UploadRequest // parsed data is stored here
}
func newUlReqDecoder(r io.Reader) *ulReqDecoder {
return &ulReqDecoder{
s: pktline.NewScanner(r),
}
}
func (d *ulReqDecoder) Decode(v *UploadRequest) error {
d.data = v
for state := d.decodeFirstWant; state != nil; {
state = state()
}
return d.err
}
// fills out the parser sticky error
func (d *ulReqDecoder) error(format string, a ...interface{}) {
msg := fmt.Sprintf(
"pkt-line %d: %s", d.nLine,
fmt.Sprintf(format, a...),
)
d.err = NewErrUnexpectedData(msg, d.line)
}
// Reads a new pkt-line from the scanner, makes its payload available as
// p.line and increments p.nLine. A successful invocation returns true,
// otherwise, false is returned and the sticky error is filled out
// accordingly. Trims eols at the end of the payloads.
func (d *ulReqDecoder) nextLine() bool {
d.nLine++
if !d.s.Scan() {
if d.err = d.s.Err(); d.err != nil {
return false
}
d.error("EOF")
return false
}
d.line = d.s.Bytes()
d.line = bytes.TrimSuffix(d.line, eol)
return true
}
// Expected format: want <hash>[ capabilities]
func (d *ulReqDecoder) decodeFirstWant() stateFn {
if ok := d.nextLine(); !ok {
return nil
}
if !bytes.HasPrefix(d.line, want) {
d.error("missing 'want ' prefix")
return nil
}
d.line = bytes.TrimPrefix(d.line, want)
hash, ok := d.readHash()
if !ok {
return nil
}
d.data.Wants = append(d.data.Wants, hash)
return d.decodeCaps
}
func (d *ulReqDecoder) readHash() (plumbing.Hash, bool) {
if len(d.line) < hashSize {
d.err = fmt.Errorf("malformed hash: %v", d.line)
return plumbing.ZeroHash, false
}
var hash plumbing.Hash
if _, err := hex.Decode(hash[:], d.line[:hashSize]); err != nil {
d.error("invalid hash text: %s", err)
return plumbing.ZeroHash, false
}
d.line = d.line[hashSize:]
return hash, true
}
// Expected format: sp cap1 sp cap2 sp cap3...
func (d *ulReqDecoder) decodeCaps() stateFn {
d.line = bytes.TrimPrefix(d.line, sp)
if err := d.data.Capabilities.Decode(d.line); err != nil {
d.error("invalid capabilities: %s", err)
}
return d.decodeOtherWants
}
// Expected format: want <hash>
func (d *ulReqDecoder) decodeOtherWants() stateFn {
if ok := d.nextLine(); !ok {
return nil
}
if bytes.HasPrefix(d.line, shallow) {
return d.decodeShallow
}
if bytes.HasPrefix(d.line, deepen) {
return d.decodeDeepen
}
if len(d.line) == 0 {
return nil
}
if !bytes.HasPrefix(d.line, want) {
d.error("unexpected payload while expecting a want: %q", d.line)
return nil
}
d.line = bytes.TrimPrefix(d.line, want)
hash, ok := d.readHash()
if !ok {
return nil
}
d.data.Wants = append(d.data.Wants, hash)
return d.decodeOtherWants
}
// Expected format: shallow <hash>
func (d *ulReqDecoder) decodeShallow() stateFn {
if bytes.HasPrefix(d.line, deepen) {
return d.decodeDeepen
}
if len(d.line) == 0 {
return nil
}
if !bytes.HasPrefix(d.line, shallow) {
d.error("unexpected payload while expecting a shallow: %q", d.line)
return nil
}
d.line = bytes.TrimPrefix(d.line, shallow)
hash, ok := d.readHash()
if !ok {
return nil
}
d.data.Shallows = append(d.data.Shallows, hash)
if ok := d.nextLine(); !ok {
return nil
}
return d.decodeShallow
}
// Expected format: deepen <n> / deepen-since <ul> / deepen-not <ref>
func (d *ulReqDecoder) decodeDeepen() stateFn {
if bytes.HasPrefix(d.line, deepenCommits) {
return d.decodeDeepenCommits
}
if bytes.HasPrefix(d.line, deepenSince) {
return d.decodeDeepenSince
}
if bytes.HasPrefix(d.line, deepenReference) {
return d.decodeDeepenReference
}
if len(d.line) == 0 {
return nil
}
d.error("unexpected deepen specification: %q", d.line)
return nil
}
func (d *ulReqDecoder) decodeDeepenCommits() stateFn {
d.line = bytes.TrimPrefix(d.line, deepenCommits)
var n int
if n, d.err = strconv.Atoi(string(d.line)); d.err != nil {
return nil
}
if n < 0 {
d.err = fmt.Errorf("negative depth")
return nil
}
d.data.Depth = DepthCommits(n)
return d.decodeFlush
}
func (d *ulReqDecoder) decodeDeepenSince() stateFn {
d.line = bytes.TrimPrefix(d.line, deepenSince)
var secs int64
secs, d.err = strconv.ParseInt(string(d.line), 10, 64)
if d.err != nil {
return nil
}
t := time.Unix(secs, 0).UTC()
d.data.Depth = DepthSince(t)
return d.decodeFlush
}
func (d *ulReqDecoder) decodeDeepenReference() stateFn {
d.line = bytes.TrimPrefix(d.line, deepenReference)
d.data.Depth = DepthReference(string(d.line))
return d.decodeFlush
}
func (d *ulReqDecoder) decodeFlush() stateFn {
if ok := d.nextLine(); !ok {
return nil
}
if len(d.line) != 0 {
d.err = fmt.Errorf("unexpected payload while expecting a flush-pkt: %q", d.line)
}
return nil
}
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