hook.go hinzugefügt

hook.go

@@ -0,0 +1,812 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cmd
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/private"
+	repo_module "code.gitea.io/gitea/modules/repository"
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/urfave/cli/v2"
+)
+
+const (
+	hookBatchSize = 30
+)
+
+var (
+	// CmdHook represents the available hooks sub-command.
+	CmdHook = &cli.Command{
+		Name:        "hook",
+		Usage:       "(internal) Should only be called by Git",
+		Description: "Delegate commands to corresponding Git hooks",
+		Before:      PrepareConsoleLoggerLevel(log.FATAL),
+		Subcommands: []*cli.Command{
+			subcmdHookPreReceive,
+			subcmdHookUpdate,
+			subcmdHookPostReceive,
+			subcmdHookProcReceive,
+		},
+	}
+
+	subcmdHookPreReceive = &cli.Command{
+		Name:        "pre-receive",
+		Usage:       "Delegate pre-receive Git hook",
+		Description: "This command should only be called by Git",
+		Action:      runHookPreReceive,
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name: "debug",
+			},
+		},
+	}
+	subcmdHookUpdate = &cli.Command{
+		Name:        "update",
+		Usage:       "Delegate update Git hook",
+		Description: "This command should only be called by Git",
+		Action:      runHookUpdate,
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name: "debug",
+			},
+		},
+	}
+	subcmdHookPostReceive = &cli.Command{
+		Name:        "post-receive",
+		Usage:       "Delegate post-receive Git hook",
+		Description: "This command should only be called by Git",
+		Action:      runHookPostReceive,
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name: "debug",
+			},
+		},
+	}
+	// Note: new hook since git 2.29
+	subcmdHookProcReceive = &cli.Command{
+		Name:        "proc-receive",
+		Usage:       "Delegate proc-receive Git hook",
+		Description: "This command should only be called by Git",
+		Action:      runHookProcReceive,
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name: "debug",
+			},
+		},
+	}
+)
+
+type delayWriter struct {
+	internal io.Writer
+	buf      *bytes.Buffer
+	timer    *time.Timer
+}
+
+func newDelayWriter(internal io.Writer, delay time.Duration) *delayWriter {
+	timer := time.NewTimer(delay)
+	return &delayWriter{
+		internal: internal,
+		buf:      &bytes.Buffer{},
+		timer:    timer,
+	}
+}
+
+func (d *delayWriter) Write(p []byte) (n int, err error) {
+	if d.buf != nil {
+		select {
+		case <-d.timer.C:
+			_, err := d.internal.Write(d.buf.Bytes())
+			if err != nil {
+				return 0, err
+			}
+			d.buf = nil
+			return d.internal.Write(p)
+		default:
+			return d.buf.Write(p)
+		}
+	}
+	return d.internal.Write(p)
+}
+
+func (d *delayWriter) WriteString(s string) (n int, err error) {
+	if d.buf != nil {
+		select {
+		case <-d.timer.C:
+			_, err := d.internal.Write(d.buf.Bytes())
+			if err != nil {
+				return 0, err
+			}
+			d.buf = nil
+			return d.internal.Write([]byte(s))
+		default:
+			return d.buf.WriteString(s)
+		}
+	}
+	return d.internal.Write([]byte(s))
+}
+
+func (d *delayWriter) Close() error {
+	if d == nil {
+		return nil
+	}
+	stopped := d.timer.Stop()
+	if stopped || d.buf == nil {
+		return nil
+	}
+	_, err := d.internal.Write(d.buf.Bytes())
+	d.buf = nil
+	return err
+}
+
+type nilWriter struct{}
+
+func (n *nilWriter) Write(p []byte) (int, error) {
+	return len(p), nil
+}
+
+func (n *nilWriter) WriteString(s string) (int, error) {
+	return len(s), nil
+}
+
+func runHookPreReceive(c *cli.Context) error {
+	if isInternal, _ := strconv.ParseBool(os.Getenv(repo_module.EnvIsInternal)); isInternal {
+		return nil
+	}
+	ctx, cancel := installSignals()
+	defer cancel()
+
+	setup(ctx, c.Bool("debug"))
+
+	if len(os.Getenv("SSH_ORIGINAL_COMMAND")) == 0 {
+		if setting.OnlyAllowPushIfGiteaEnvironmentSet {
+			return fail(ctx, `Rejecting changes as Forgejo environment not set.
+If you are pushing over SSH you must push with a key managed by
+Forgejo or set your environment appropriately.`, "")
+		}
+		return nil
+	}
+
+	// the environment is set by serv command
+	isWiki, _ := strconv.ParseBool(os.Getenv(repo_module.EnvRepoIsWiki))
+	username := os.Getenv(repo_module.EnvRepoUsername)
+	reponame := os.Getenv(repo_module.EnvRepoName)
+	userID, _ := strconv.ParseInt(os.Getenv(repo_module.EnvPusherID), 10, 64)
+	prID, _ := strconv.ParseInt(os.Getenv(repo_module.EnvPRID), 10, 64)
+	deployKeyID, _ := strconv.ParseInt(os.Getenv(repo_module.EnvDeployKeyID), 10, 64)
+	actionPerm, _ := strconv.ParseInt(os.Getenv(repo_module.EnvActionPerm), 10, 64)
+
+	hookOptions := private.HookOptions{
+		UserID:                          userID,
+		GitAlternativeObjectDirectories: os.Getenv(private.GitAlternativeObjectDirectories),
+		GitObjectDirectory:              os.Getenv(private.GitObjectDirectory),
+		GitQuarantinePath:               os.Getenv(private.GitQuarantinePath),
+		GitPushOptions:                  pushOptions(),
+		PullRequestID:                   prID,
+		DeployKeyID:                     deployKeyID,
+		ActionPerm:                      int(actionPerm),
+	}
+
+	scanner := bufio.NewScanner(os.Stdin)
+
+	oldCommitIDs := make([]string, hookBatchSize)
+	newCommitIDs := make([]string, hookBatchSize)
+	refFullNames := make([]git.RefName, hookBatchSize)
+	count := 0
+	total := 0
+	lastline := 0
+
+	var out io.Writer
+	out = &nilWriter{}
+	if setting.Git.VerbosePush {
+		if setting.Git.VerbosePushDelay > 0 {
+			dWriter := newDelayWriter(os.Stdout, setting.Git.VerbosePushDelay)
+			defer dWriter.Close()
+			out = dWriter
+		} else {
+			out = os.Stdout
+		}
+	}
+
+	supportProcReceive := false
+	if git.CheckGitVersionAtLeast("2.29") == nil {
+		supportProcReceive = true
+	}
+
+	for scanner.Scan() {
+		// TODO: support news feeds for wiki
+		if isWiki {
+			continue
+		}
+
+		fields := bytes.Fields(scanner.Bytes())
+		if len(fields) != 3 {
+			continue
+		}
+
+		oldCommitID := string(fields[0])
+		newCommitID := string(fields[1])
+		refFullName := git.RefName(fields[2])
+		total++
+		lastline++
+
+		// If the ref is a branch or tag, check if it's protected
+		// if supportProcReceive all ref should be checked because
+		// permission check was delayed
+		if supportProcReceive || refFullName.IsBranch() || refFullName.IsTag() {
+			oldCommitIDs[count] = oldCommitID
+			newCommitIDs[count] = newCommitID
+			refFullNames[count] = refFullName
+			count++
+			fmt.Fprintf(out, "*")
+
+			if count >= hookBatchSize {
+				fmt.Fprintf(out, " Checking %d references\n", count)
+
+				hookOptions.OldCommitIDs = oldCommitIDs
+				hookOptions.NewCommitIDs = newCommitIDs
+				hookOptions.RefFullNames = refFullNames
+				extra := private.HookPreReceive(ctx, username, reponame, hookOptions)
+				if extra.HasError() {
+					return fail(ctx, extra.UserMsg, "HookPreReceive(batch) failed: %v", extra.Error)
+				}
+				count = 0
+				lastline = 0
+			}
+		} else {
+			fmt.Fprintf(out, ".")
+		}
+		if lastline >= hookBatchSize {
+			fmt.Fprintf(out, "\n")
+			lastline = 0
+		}
+	}
+
+	if count > 0 {
+		hookOptions.OldCommitIDs = oldCommitIDs[:count]
+		hookOptions.NewCommitIDs = newCommitIDs[:count]
+		hookOptions.RefFullNames = refFullNames[:count]
+
+		fmt.Fprintf(out, " Checking %d references\n", count)
+
+		extra := private.HookPreReceive(ctx, username, reponame, hookOptions)
+		if extra.HasError() {
+			return fail(ctx, extra.UserMsg, "HookPreReceive(last) failed: %v", extra.Error)
+		}
+	} else if lastline > 0 {
+		fmt.Fprintf(out, "\n")
+	}
+
+	fmt.Fprintf(out, "Checked %d references in total\n", total)
+	return nil
+}
+
+// runHookUpdate process the update hook: https://git-scm.com/docs/githooks#update
+func runHookUpdate(c *cli.Context) error {
+	// Now if we're an internal don't do anything else
+	if isInternal, _ := strconv.ParseBool(os.Getenv(repo_module.EnvIsInternal)); isInternal {
+		return nil
+	}
+
+	ctx, cancel := installSignals()
+	defer cancel()
+
+	// The last three arguments given to the hook are in order: reference name, old commit ID and new commit ID.
+	args := os.Args[len(os.Args)-3:]
+	refFullName := git.RefName(args[0])
+	newCommitID := args[2]
+
+	// Only process pull references.
+	if !refFullName.IsPull() {
+		return nil
+	}
+
+	// Deletion of the ref means that the new commit ID is only composed of '0'.
+	if strings.ContainsFunc(newCommitID, func(e rune) bool { return e != '0' }) {
+		return nil
+	}
+
+	return fail(ctx, fmt.Sprintf("The deletion of %s is skipped as it's an internal reference.", refFullName), "")
+}
+
+func runHookPostReceive(c *cli.Context) error {
+	ctx, cancel := installSignals()
+	defer cancel()
+
+	setup(ctx, c.Bool("debug"))
+
+	// First of all run update-server-info no matter what
+	if _, _, err := git.NewCommand(ctx, "update-server-info").RunStdString(nil); err != nil {
+		return fmt.Errorf("Failed to call 'git update-server-info': %w", err)
+	}
+
+	// Now if we're an internal don't do anything else
+	if isInternal, _ := strconv.ParseBool(os.Getenv(repo_module.EnvIsInternal)); isInternal {
+		return nil
+	}
+
+	if len(os.Getenv("SSH_ORIGINAL_COMMAND")) == 0 {
+		if setting.OnlyAllowPushIfGiteaEnvironmentSet {
+			return fail(ctx, `Rejecting changes as Forgejo environment not set.
+If you are pushing over SSH you must push with a key managed by
+Forgejo or set your environment appropriately.`, "")
+		}
+		return nil
+	}
+
+	var out io.Writer
+	var dWriter *delayWriter
+	out = &nilWriter{}
+	if setting.Git.VerbosePush {
+		if setting.Git.VerbosePushDelay > 0 {
+			dWriter = newDelayWriter(os.Stdout, setting.Git.VerbosePushDelay)
+			defer dWriter.Close()
+			out = dWriter
+		} else {
+			out = os.Stdout
+		}
+	}
+
+	// the environment is set by serv command
+	repoUser := os.Getenv(repo_module.EnvRepoUsername)
+	isWiki, _ := strconv.ParseBool(os.Getenv(repo_module.EnvRepoIsWiki))
+	repoName := os.Getenv(repo_module.EnvRepoName)
+	pusherID, _ := strconv.ParseInt(os.Getenv(repo_module.EnvPusherID), 10, 64)
+	pusherName := os.Getenv(repo_module.EnvPusherName)
+
+	hookOptions := private.HookOptions{
+		UserName:                        pusherName,
+		UserID:                          pusherID,
+		GitAlternativeObjectDirectories: os.Getenv(private.GitAlternativeObjectDirectories),
+		GitObjectDirectory:              os.Getenv(private.GitObjectDirectory),
+		GitQuarantinePath:               os.Getenv(private.GitQuarantinePath),
+		GitPushOptions:                  pushOptions(),
+	}
+	oldCommitIDs := make([]string, hookBatchSize)
+	newCommitIDs := make([]string, hookBatchSize)
+	refFullNames := make([]git.RefName, hookBatchSize)
+	count := 0
+	total := 0
+	wasEmpty := false
+	masterPushed := false
+	results := make([]private.HookPostReceiveBranchResult, 0)
+
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		// TODO: support news feeds for wiki
+		if isWiki {
+			continue
+		}
+
+		fields := bytes.Fields(scanner.Bytes())
+		if len(fields) != 3 {
+			continue
+		}
+
+		fmt.Fprintf(out, ".")
+		oldCommitIDs[count] = string(fields[0])
+		newCommitIDs[count] = string(fields[1])
+		refFullNames[count] = git.RefName(fields[2])
+
+		commitID, _ := git.NewIDFromString(newCommitIDs[count])
+		if refFullNames[count] == git.BranchPrefix+"master" && !commitID.IsZero() && count == total {
+			masterPushed = true
+		}
+		count++
+		total++
+
+		if count >= hookBatchSize {
+			fmt.Fprintf(out, " Processing %d references\n", count)
+			hookOptions.OldCommitIDs = oldCommitIDs
+			hookOptions.NewCommitIDs = newCommitIDs
+			hookOptions.RefFullNames = refFullNames
+			resp, extra := private.HookPostReceive(ctx, repoUser, repoName, hookOptions)
+			if extra.HasError() {
+				_ = dWriter.Close()
+				hookPrintResults(results)
+				return fail(ctx, extra.UserMsg, "HookPostReceive failed: %v", extra.Error)
+			}
+			wasEmpty = wasEmpty || resp.RepoWasEmpty
+			results = append(results, resp.Results...)
+			count = 0
+		}
+	}
+
+	if count == 0 {
+		if wasEmpty && masterPushed {
+			// We need to tell the repo to reset the default branch to master
+			extra := private.SetDefaultBranch(ctx, repoUser, repoName, "master")
+			if extra.HasError() {
+				return fail(ctx, extra.UserMsg, "SetDefaultBranch failed: %v", extra.Error)
+			}
+		}
+		fmt.Fprintf(out, "Processed %d references in total\n", total)
+
+		_ = dWriter.Close()
+		hookPrintResults(results)
+		return nil
+	}
+
+	hookOptions.OldCommitIDs = oldCommitIDs[:count]
+	hookOptions.NewCommitIDs = newCommitIDs[:count]
+	hookOptions.RefFullNames = refFullNames[:count]
+
+	fmt.Fprintf(out, " Processing %d references\n", count)
+
+	resp, extra := private.HookPostReceive(ctx, repoUser, repoName, hookOptions)
+	if resp == nil {
+		_ = dWriter.Close()
+		hookPrintResults(results)
+		return fail(ctx, extra.UserMsg, "HookPostReceive failed: %v", extra.Error)
+	}
+	wasEmpty = wasEmpty || resp.RepoWasEmpty
+	results = append(results, resp.Results...)
+
+	fmt.Fprintf(out, "Processed %d references in total\n", total)
+
+	if wasEmpty && masterPushed {
+		// We need to tell the repo to reset the default branch to master
+		extra := private.SetDefaultBranch(ctx, repoUser, repoName, "master")
+		if extra.HasError() {
+			return fail(ctx, extra.UserMsg, "SetDefaultBranch failed: %v", extra.Error)
+		}
+	}
+	_ = dWriter.Close()
+	hookPrintResults(results)
+
+	return nil
+}
+
+func hookPrintResults(results []private.HookPostReceiveBranchResult) {
+	for _, res := range results {
+		if !res.Message {
+			continue
+		}
+
+		fmt.Fprintln(os.Stderr, "")
+		if res.Create {
+			fmt.Fprintf(os.Stderr, "Create a new pull request for '%s':\n", res.Branch)
+			fmt.Fprintf(os.Stderr, "  %s\n", res.URL)
+		} else {
+			fmt.Fprint(os.Stderr, "Visit the existing pull request:\n")
+			fmt.Fprintf(os.Stderr, "  %s\n", res.URL)
+		}
+		fmt.Fprintln(os.Stderr, "")
+		os.Stderr.Sync()
+	}
+}
+
+func pushOptions() map[string]string {
+	opts := make(map[string]string)
+	if pushCount, err := strconv.Atoi(os.Getenv(private.GitPushOptionCount)); err == nil {
+		for idx := 0; idx < pushCount; idx++ {
+			opt := os.Getenv(fmt.Sprintf("GIT_PUSH_OPTION_%d", idx))
+			kv := strings.SplitN(opt, "=", 2)
+			if len(kv) == 2 {
+				opts[kv[0]] = kv[1]
+			}
+		}
+	}
+	return opts
+}
+
+func runHookProcReceive(c *cli.Context) error {
+	ctx, cancel := installSignals()
+	defer cancel()
+
+	setup(ctx, c.Bool("debug"))
+
+	if len(os.Getenv("SSH_ORIGINAL_COMMAND")) == 0 {
+		if setting.OnlyAllowPushIfGiteaEnvironmentSet {
+			return fail(ctx, `Rejecting changes as Forgejo environment not set.
+If you are pushing over SSH you must push with a key managed by
+Forgejo or set your environment appropriately.`, "")
+		}
+		return nil
+	}
+
+	if git.CheckGitVersionAtLeast("2.29") != nil {
+		return fail(ctx, "No proc-receive support", "current git version doesn't support proc-receive.")
+	}
+
+	reader := bufio.NewReader(os.Stdin)
+	repoUser := os.Getenv(repo_module.EnvRepoUsername)
+	repoName := os.Getenv(repo_module.EnvRepoName)
+	pusherID, _ := strconv.ParseInt(os.Getenv(repo_module.EnvPusherID), 10, 64)
+	pusherName := os.Getenv(repo_module.EnvPusherName)
+
+	// 1. Version and features negotiation.
+	// S: PKT-LINE(version=1\0push-options atomic...) / PKT-LINE(version=1\n)
+	// S: flush-pkt
+	// H: PKT-LINE(version=1\0push-options...)
+	// H: flush-pkt
+
+	rs, err := readPktLine(ctx, reader, pktLineTypeData)
+	if err != nil {
+		return err
+	}
+
+	const VersionHead string = "version=1"
+
+	var (
+		hasPushOptions bool
+		response       = []byte(VersionHead)
+		requestOptions []string
+	)
+
+	index := bytes.IndexByte(rs.Data, byte(0))
+	if index >= len(rs.Data) {
+		return fail(ctx, "Protocol: format error", "pkt-line: format error "+fmt.Sprint(rs.Data))
+	}
+
+	if index < 0 {
+		if len(rs.Data) == 10 && rs.Data[9] == '\n' {
+			index = 9
+		} else {
+			return fail(ctx, "Protocol: format error", "pkt-line: format error "+fmt.Sprint(rs.Data))
+		}
+	}
+
+	if string(rs.Data[0:index]) != VersionHead {
+		return fail(ctx, "Protocol: version error", "Received unsupported version: %s", string(rs.Data[0:index]))
+	}
+	requestOptions = strings.Split(string(rs.Data[index+1:]), " ")
+
+	for _, option := range requestOptions {
+		if strings.HasPrefix(option, "push-options") {
+			response = append(response, byte(0))
+			response = append(response, []byte("push-options")...)
+			hasPushOptions = true
+		}
+	}
+	response = append(response, '\n')
+
+	_, err = readPktLine(ctx, reader, pktLineTypeFlush)
+	if err != nil {
+		return err
+	}
+
+	err = writeDataPktLine(ctx, os.Stdout, response)
+	if err != nil {
+		return err
+	}
+
+	err = writeFlushPktLine(ctx, os.Stdout)
+	if err != nil {
+		return err
+	}
+
+	// 2. receive commands from server.
+	// S: PKT-LINE(<old-oid> <new-oid> <ref>)
+	// S: ... ...
+	// S: flush-pkt
+	// # [receive push-options]
+	// S: PKT-LINE(push-option)
+	// S: ... ...
+	// S: flush-pkt
+	hookOptions := private.HookOptions{
+		UserName: pusherName,
+		UserID:   pusherID,
+	}
+	hookOptions.OldCommitIDs = make([]string, 0, hookBatchSize)
+	hookOptions.NewCommitIDs = make([]string, 0, hookBatchSize)
+	hookOptions.RefFullNames = make([]git.RefName, 0, hookBatchSize)
+
+	for {
+		// note: pktLineTypeUnknow means pktLineTypeFlush and pktLineTypeData all allowed
+		rs, err = readPktLine(ctx, reader, pktLineTypeUnknown)
+		if err != nil {
+			return err
+		}
+
+		if rs.Type == pktLineTypeFlush {
+			break
+		}
+		t := strings.SplitN(string(rs.Data), " ", 3)
+		if len(t) != 3 {
+			continue
+		}
+		hookOptions.OldCommitIDs = append(hookOptions.OldCommitIDs, t[0])
+		hookOptions.NewCommitIDs = append(hookOptions.NewCommitIDs, t[1])
+		hookOptions.RefFullNames = append(hookOptions.RefFullNames, git.RefName(t[2]))
+	}
+
+	hookOptions.GitPushOptions = make(map[string]string)
+
+	if hasPushOptions {
+		for {
+			rs, err = readPktLine(ctx, reader, pktLineTypeUnknown)
+			if err != nil {
+				return err
+			}
+
+			if rs.Type == pktLineTypeFlush {
+				break
+			}
+
+			kv := strings.SplitN(string(rs.Data), "=", 2)
+			if len(kv) == 2 {
+				hookOptions.GitPushOptions[kv[0]] = kv[1]
+			}
+		}
+	}
+
+	// 3. run hook
+	resp, extra := private.HookProcReceive(ctx, repoUser, repoName, hookOptions)
+	if extra.HasError() {
+		return fail(ctx, extra.UserMsg, "HookProcReceive failed: %v", extra.Error)
+	}
+
+	// 4. response result to service
+	// # a. OK, but has an alternate reference.  The alternate reference name
+	// # and other status can be given in option directives.
+	// H: PKT-LINE(ok <ref>)
+	// H: PKT-LINE(option refname <refname>)
+	// H: PKT-LINE(option old-oid <old-oid>)
+	// H: PKT-LINE(option new-oid <new-oid>)
+	// H: PKT-LINE(option forced-update)
+	// H: ... ...
+	// H: flush-pkt
+	// # b. NO, I reject it.
+	// H: PKT-LINE(ng <ref> <reason>)
+	// # c. Fall through, let 'receive-pack' to execute it.
+	// H: PKT-LINE(ok <ref>)
+	// H: PKT-LINE(option fall-through)
+
+	for _, rs := range resp.Results {
+		if len(rs.Err) > 0 {
+			err = writeDataPktLine(ctx, os.Stdout, []byte("ng "+rs.OriginalRef.String()+" "+rs.Err))
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		if rs.IsNotMatched {
+			err = writeDataPktLine(ctx, os.Stdout, []byte("ok "+rs.OriginalRef.String()))
+			if err != nil {
+				return err
+			}
+			err = writeDataPktLine(ctx, os.Stdout, []byte("option fall-through"))
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		err = writeDataPktLine(ctx, os.Stdout, []byte("ok "+rs.OriginalRef))
+		if err != nil {
+			return err
+		}
+		err = writeDataPktLine(ctx, os.Stdout, []byte("option refname "+rs.Ref))
+		if err != nil {
+			return err
+		}
+		commitID, _ := git.NewIDFromString(rs.OldOID)
+		if !commitID.IsZero() {
+			err = writeDataPktLine(ctx, os.Stdout, []byte("option old-oid "+rs.OldOID))
+			if err != nil {
+				return err
+			}
+		}
+		err = writeDataPktLine(ctx, os.Stdout, []byte("option new-oid "+rs.NewOID))
+		if err != nil {
+			return err
+		}
+		if rs.IsForcePush {
+			err = writeDataPktLine(ctx, os.Stdout, []byte("option forced-update"))
+			if err != nil {
+				return err
+			}
+		}
+	}
+	err = writeFlushPktLine(ctx, os.Stdout)
+
+	return err
+}
+
+// git PKT-Line api
+// pktLineType message type of pkt-line
+type pktLineType int64
+
+const (
+	// Unknown type
+	pktLineTypeUnknown pktLineType = 0
+	// flush-pkt "0000"
+	pktLineTypeFlush pktLineType = iota
+	// data line
+	pktLineTypeData
+)
+
+// gitPktLine pkt-line api
+type gitPktLine struct {
+	Type   pktLineType
+	Length uint64
+	Data   []byte
+}
+
+// Reads an Pkt-Line from `in`. If requestType is not unknown, it will a
+func readPktLine(ctx context.Context, in *bufio.Reader, requestType pktLineType) (*gitPktLine, error) {
+	// Read length prefix
+	lengthBytes := make([]byte, 4)
+	if n, err := in.Read(lengthBytes); n != 4 || err != nil {
+		return nil, fail(ctx, "Protocol: stdin error", "Pkt-Line: read stdin failed : %v", err)
+	}
+
+	var err error
+	r := &gitPktLine{}
+	r.Length, err = strconv.ParseUint(string(lengthBytes), 16, 32)
+	if err != nil {
+		return nil, fail(ctx, "Protocol: format parse error", "Pkt-Line format is wrong :%v", err)
+	}
+
+	if r.Length == 0 {
+		if requestType == pktLineTypeData {
+			return nil, fail(ctx, "Protocol: format data error", "Pkt-Line format is wrong")
+		}
+		r.Type = pktLineTypeFlush
+		return r, nil
+	}
+
+	if r.Length <= 4 || r.Length > 65520 || requestType == pktLineTypeFlush {
+		return nil, fail(ctx, "Protocol: format length error", "Pkt-Line format is wrong")
+	}
+
+	r.Data = make([]byte, r.Length-4)
+	if n, err := io.ReadFull(in, r.Data); uint64(n) != r.Length-4 || err != nil {
+		return nil, fail(ctx, "Protocol: stdin error", "Pkt-Line: read stdin failed : %v", err)
+	}
+
+	r.Type = pktLineTypeData
+
+	return r, nil
+}
+
+func writeFlushPktLine(ctx context.Context, out io.Writer) error {
+	l, err := out.Write([]byte("0000"))
+	if err != nil || l != 4 {
+		return fail(ctx, "Protocol: write error", "Pkt-Line response failed: %v", err)
+	}
+	return nil
+}
+
+// Write an Pkt-Line based on `data` to `out` according to the specifcation.
+// https://git-scm.com/docs/protocol-common
+func writeDataPktLine(ctx context.Context, out io.Writer, data []byte) error {
+	// Implementations SHOULD NOT send an empty pkt-line ("0004").
+	if len(data) == 0 {
+		return fail(ctx, "Protocol: write error", "Not allowed to write empty Pkt-Line")
+	}
+
+	length := uint64(len(data) + 4)
+
+	// The maximum length of a pkt-line’s data component is 65516 bytes.
+	// Implementations MUST NOT send pkt-line whose length exceeds 65520 (65516 bytes of payload + 4 bytes of length data).
+	if length > 65520 {
+		return fail(ctx, "Protocol: write error", "Pkt-Line exceeds maximum of 65520 bytes")
+	}
+
+	lr, err := fmt.Fprintf(out, "%04x", length)
+	if err != nil || lr != 4 {
+		return fail(ctx, "Protocol: write error", "Pkt-Line response failed: %v", err)
+	}
+
+	lr, err = out.Write(data)
+	if err != nil || int(length-4) != lr {
+		return fail(ctx, "Protocol: write error", "Pkt-Line response failed: %v", err)
+	}
+
+	return nil
+}