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package catfile
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"strconv"
"strings"
"time"
"gitlab.com/gitlab-org/gitaly/v16/internal/git"
"gitlab.com/gitlab-org/gitaly/v16/proto/go/gitalypb"
"google.golang.org/protobuf/types/known/timestamppb"
)
// Parser parses Git objects into their gitalypb representations.
type Parser interface {
ParseCommit(object git.Object) (*Commit, error)
ParseTag(object git.Object) (*gitalypb.Tag, error)
}
type parser struct {
bufferedReader *bufio.Reader
}
// NewParser creates a new parser for Git objects.
func NewParser() Parser {
return newParser()
}
func newParser() *parser {
return &parser{
bufferedReader: bufio.NewReader(nil),
}
}
const maxUnixCommitDate = 1 << 53
// fallbackTimeValue is the value returned in case there is a parse error. It's the maximum
// time value possible in golang. See
// https://gitlab.com/gitlab-org/gitaly/issues/556#note_40289573
var fallbackTimeValue = time.Unix(1<<63-62135596801, 999999999)
func parseCommitAuthor(line string) *gitalypb.CommitAuthor {
author := &gitalypb.CommitAuthor{}
name, line, ok := strings.Cut(line, "<")
author.Name = []byte(strings.TrimSuffix(name, " "))
if !ok {
return author
}
email, line, ok := strings.Cut(line, ">")
if !ok {
return author
}
author.Email = []byte(email)
secSplit := strings.Fields(line)
if len(secSplit) < 1 {
return author
}
sec, err := strconv.ParseInt(secSplit[0], 10, 64)
if err != nil || sec > maxUnixCommitDate || sec < 0 {
sec = fallbackTimeValue.Unix()
}
author.Date = ×tamppb.Timestamp{Seconds: sec}
if len(secSplit) == 2 {
author.Timezone = []byte(secSplit[1])
}
return author
}
func subjectFromBody(body []byte) []byte {
subject, _, _ := bytes.Cut(body, []byte("\n"))
return bytes.TrimRight(subject, "\r\n")
}
func detectSignatureType(line string) gitalypb.SignatureType {
switch strings.TrimSuffix(line, "\n") {
case "-----BEGIN SIGNED MESSAGE-----":
return gitalypb.SignatureType_X509
case "-----BEGIN PGP MESSAGE-----":
return gitalypb.SignatureType_PGP
case "-----BEGIN PGP SIGNATURE-----":
return gitalypb.SignatureType_PGP
case "-----BEGIN SSH SIGNATURE-----":
return gitalypb.SignatureType_SSH
default:
return gitalypb.SignatureType_NONE
}
}
// ParseTag parses the given object, which is expected to refer to a Git tag. The tag's tagged
// commit is not populated. The given object ID shall refer to the tag itself such that the returned
// Tag structure has the correct OID.
func (p *parser) ParseTag(object git.Object) (*gitalypb.Tag, error) {
tag, _, err := p.parseTag(object, nil)
return tag, err
}
type taggedObject struct {
objectID string
objectType string
}
func (p *parser) parseTag(object git.Object, name []byte) (*gitalypb.Tag, taggedObject, error) {
p.bufferedReader.Reset(object)
tag := &gitalypb.Tag{
Id: object.ObjectID().String(),
Name: name,
}
var tagged taggedObject
var lastLine bool
bytesRemaining := object.ObjectSize()
for !lastLine {
line, err := p.bufferedReader.ReadString('\n')
if errors.Is(err, io.EOF) {
lastLine = true
} else if err != nil {
return nil, taggedObject{}, fmt.Errorf("reading tag header: %w", err)
}
bytesRemaining -= int64(len(line))
if len(line) == 0 {
continue
}
if line == "\n" {
break
}
if line[len(line)-1] == '\n' {
line = line[:len(line)-1]
}
key, value, ok := strings.Cut(line, " ")
if !ok {
continue
}
switch key {
case "object":
tagged.objectID = value
case "type":
tagged.objectType = value
case "tag":
if len(tag.Name) == 0 {
tag.Name = []byte(value)
}
case "tagger":
tag.Tagger = parseCommitAuthor(value)
}
}
// We only need to try reading the message if we haven't seen an EOF yet, but instead saw
// the "\n\n" separator.
if !lastLine {
message := make([]byte, bytesRemaining)
if _, err := io.ReadFull(p.bufferedReader, message); err != nil {
return nil, taggedObject{}, fmt.Errorf("reading tag message: %w", err)
}
// After we have copied the message, we must make sure that there really is no
// additional data. For once, this is to detect bugs in our implementation where we
// would accidentally have truncated the commit message. On the other hand, we also
// need to do this such that we observe the EOF, which we must observe in order to
// unblock reading the next object.
//
// This all feels a bit complicated, where it would be much easier to just read into
// a preallocated `bytes.Buffer`. But this complexity is indeed required to optimize
// allocations. So if you want to change this, please make sure to execute the
// `BenchmarkFindAllTags` benchmark.
if n, err := io.Copy(io.Discard, p.bufferedReader); err != nil {
return nil, taggedObject{}, fmt.Errorf("reading tag message: %w", err)
} else if n != 0 {
return nil, taggedObject{}, fmt.Errorf(
"tag message exceeds expected length %v by %v bytes",
object.ObjectSize(), n,
)
}
tag.Message = message
tag.MessageSize = int64(len(message))
if signature, _ := ExtractTagSignature(message); signature != nil {
length := bytes.Index(signature, []byte("\n"))
if length > 0 {
signature := string(signature[:length])
tag.SignatureType = detectSignatureType(signature)
}
}
}
return tag, tagged, nil
}
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