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-rw-r--r--plumbing/transport/internal/common/common.go295
1 files changed, 295 insertions, 0 deletions
diff --git a/plumbing/transport/internal/common/common.go b/plumbing/transport/internal/common/common.go
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+++ b/plumbing/transport/internal/common/common.go
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+// Package common implements the git pack protocol with a pluggable transport.
+// This is a low-level package to implement new transports. Use a concrete
+// implementation instead (e.g. http, file, ssh).
+//
+// A simple example of usage can be found in the file package.
+package common
+
+import (
+ "bufio"
+ "bytes"
+ "errors"
+ "fmt"
+ "io"
+ "strings"
+
+ "gopkg.in/src-d/go-git.v4/plumbing/format/pktline"
+ "gopkg.in/src-d/go-git.v4/plumbing/protocol/packp"
+ "gopkg.in/src-d/go-git.v4/plumbing/transport"
+ "gopkg.in/src-d/go-git.v4/utils/ioutil"
+)
+
+// Commander creates Command instances. This is the main entry point for
+// transport implementations.
+type Commander interface {
+ // Command creates a new Command for the given git command and
+ // endpoint. cmd can be git-upload-pack or git-receive-pack. An
+ // error should be returned if the endpoint is not supported or the
+ // command cannot be created (e.g. binary does not exist, connection
+ // cannot be established).
+ Command(cmd string, ep transport.Endpoint) (Command, error)
+}
+
+// Command is used for a single command execution.
+// This interface is modeled after exec.Cmd and ssh.Session in the standard
+// library.
+type Command interface {
+ // SetAuth sets the authentication method.
+ SetAuth(transport.AuthMethod) error
+ // StderrPipe returns a pipe that will be connected to the command's
+ // standard error when the command starts. It should not be called after
+ // Start.
+ StderrPipe() (io.Reader, error)
+ // StdinPipe returns a pipe that will be connected to the command's
+ // standard input when the command starts. It should not be called after
+ // Start. The pipe should be closed when no more input is expected.
+ StdinPipe() (io.WriteCloser, error)
+ // StdoutPipe returns a pipe that will be connected to the command's
+ // standard output when the command starts. It should not be called after
+ // Start.
+ StdoutPipe() (io.Reader, error)
+ // Start starts the specified command. It does not wait for it to
+ // complete.
+ Start() error
+ // Wait waits for the command to exit. It must have been started by
+ // Start. The returned error is nil if the command runs, has no
+ // problems copying stdin, stdout, and stderr, and exits with a zero
+ // exit status.
+ Wait() error
+ // Close closes the command without waiting for it to exit and releases
+ // any resources. It can be called to forcibly finish the command
+ // without calling to Wait or to release resources after calling
+ // Wait.
+ Close() error
+}
+
+type client struct {
+ cmdr Commander
+}
+
+// NewClient creates a new client using the given Commander.
+func NewClient(runner Commander) transport.Client {
+ return &client{runner}
+}
+
+// NewFetchPackSession creates a new FetchPackSession.
+func (c *client) NewFetchPackSession(ep transport.Endpoint) (
+ transport.FetchPackSession, error) {
+
+ return c.newSession(transport.UploadPackServiceName, ep)
+}
+
+// NewSendPackSession creates a new SendPackSession.
+func (c *client) NewSendPackSession(ep transport.Endpoint) (
+ transport.SendPackSession, error) {
+
+ return nil, errors.New("git send-pack not supported")
+}
+
+type session struct {
+ Stdin io.WriteCloser
+ Stdout io.Reader
+ Stderr io.Reader
+ Command Command
+
+ advRefsRun bool
+}
+
+func (c *client) newSession(s string, ep transport.Endpoint) (*session, error) {
+ cmd, err := c.cmdr.Command(s, ep)
+ if err != nil {
+ return nil, err
+ }
+
+ stdin, err := cmd.StdinPipe()
+ if err != nil {
+ return nil, err
+ }
+
+ stdout, err := cmd.StdoutPipe()
+ if err != nil {
+ return nil, err
+ }
+
+ stderr, err := cmd.StderrPipe()
+ if err != nil {
+ return nil, err
+ }
+
+ if err := cmd.Start(); err != nil {
+ return nil, err
+ }
+
+ return &session{
+ Stdin: stdin,
+ Stdout: stdout,
+ Stderr: stderr,
+ Command: cmd,
+ }, nil
+}
+
+// SetAuth delegates to the command's SetAuth.
+func (s *session) SetAuth(auth transport.AuthMethod) error {
+ return s.Command.SetAuth(auth)
+}
+
+// AdvertisedReferences retrieves the advertised references from the server.
+func (s *session) AdvertisedReferences() (*packp.AdvRefs, error) {
+ if s.advRefsRun {
+ return nil, transport.ErrAdvertistedReferencesAlreadyCalled
+ }
+
+ defer func() { s.advRefsRun = true }()
+
+ ar := packp.NewAdvRefs()
+ if err := ar.Decode(s.Stdout); err != nil {
+ if err != packp.ErrEmptyAdvRefs {
+ return nil, err
+ }
+
+ _ = s.Stdin.Close()
+ err = transport.ErrEmptyRemoteRepository
+
+ scan := bufio.NewScanner(s.Stderr)
+ if !scan.Scan() {
+ return nil, transport.ErrEmptyRemoteRepository
+ }
+
+ if isRepoNotFoundError(string(scan.Bytes())) {
+ return nil, transport.ErrRepositoryNotFound
+ }
+
+ return nil, err
+ }
+
+ return ar, nil
+}
+
+// FetchPack performs a request to the server to fetch a packfile. A reader is
+// returned with the packfile content. The reader must be closed after reading.
+func (s *session) FetchPack(req *packp.UploadPackRequest) (io.ReadCloser, error) {
+ if req.IsEmpty() {
+ return nil, transport.ErrEmptyUploadPackRequest
+ }
+
+ if !s.advRefsRun {
+ if _, err := s.AdvertisedReferences(); err != nil {
+ return nil, err
+ }
+ }
+
+ if err := fetchPack(s.Stdin, s.Stdout, req); err != nil {
+ return nil, err
+ }
+
+ r, err := ioutil.NonEmptyReader(s.Stdout)
+ if err == ioutil.ErrEmptyReader {
+ if c, ok := s.Stdout.(io.Closer); ok {
+ _ = c.Close()
+ }
+
+ return nil, transport.ErrEmptyUploadPackRequest
+ }
+
+ if err != nil {
+ return nil, err
+ }
+
+ wc := &waitCloser{s.Command}
+ rc := ioutil.NewReadCloser(r, wc)
+
+ return rc, nil
+}
+
+func (s *session) Close() error {
+ return s.Command.Close()
+}
+
+const (
+ githubRepoNotFoundErr = "ERROR: Repository not found."
+ bitbucketRepoNotFoundErr = "conq: repository does not exist."
+ localRepoNotFoundErr = "does not appear to be a git repository"
+)
+
+func isRepoNotFoundError(s string) bool {
+ if strings.HasPrefix(s, githubRepoNotFoundErr) {
+ return true
+ }
+
+ if strings.HasPrefix(s, bitbucketRepoNotFoundErr) {
+ return true
+ }
+
+ if strings.HasSuffix(s, localRepoNotFoundErr) {
+ return true
+ }
+
+ return false
+}
+
+var (
+ nak = []byte("NAK")
+ eol = []byte("\n")
+)
+
+// fetchPack implements the git-fetch-pack protocol.
+//
+// TODO support multi_ack mode
+// TODO support multi_ack_detailed mode
+// TODO support acks for common objects
+// TODO build a proper state machine for all these processing options
+func fetchPack(w io.WriteCloser, r io.Reader,
+ req *packp.UploadPackRequest) error {
+
+ if err := req.UploadRequest.Encode(w); err != nil {
+ return fmt.Errorf("sending upload-req message: %s", err)
+ }
+
+ if err := req.UploadHaves.Encode(w); err != nil {
+ return fmt.Errorf("sending haves message: %s", err)
+ }
+
+ if err := sendDone(w); err != nil {
+ return fmt.Errorf("sending done message: %s", err)
+ }
+
+ if err := w.Close(); err != nil {
+ return fmt.Errorf("closing input: %s", err)
+ }
+
+ if err := readNAK(r); err != nil {
+ return fmt.Errorf("reading NAK: %s", err)
+ }
+
+ return nil
+}
+
+func sendDone(w io.Writer) error {
+ e := pktline.NewEncoder(w)
+
+ return e.Encodef("done\n")
+}
+
+func readNAK(r io.Reader) error {
+ s := pktline.NewScanner(r)
+ if !s.Scan() {
+ return s.Err()
+ }
+
+ b := s.Bytes()
+ b = bytes.TrimSuffix(b, eol)
+ if !bytes.Equal(b, nak) {
+ return fmt.Errorf("expecting NAK, found %q instead", string(b))
+ }
+
+ return nil
+}
+
+type waitCloser struct {
+ Command Command
+}
+
+// Close waits until the command exits and returns error, if any.
+func (c *waitCloser) Close() error {
+ return c.Command.Wait()
+}