server: add git server implementation (#190)

* server: add generic server implementation (transport-independent),
  both for git-upload-pack and git-receive-pack.
* server: move internal functions to internal/common.
* cli: add git-receive-pack and git-upload-pack implementations.
* format/packfile: add UpdateObjectStorage function, extracted from
  Remote.
* transport: implement tranport RPC-like, only with git-upload-pack and
  git-receive-pack methods. Client renamed to Transport.
* storer: add storer.Storer interface.
* protocol/packp: add UploadPackResponse constructor with packfile.
* protocol/packp: fix UploadPackResponse encoding, add tests.
* protocol/packp/capability: implement All.

1 files changed, 82 insertions, 0 deletions

diff --git a/plumbing/transport/file/client.go b/plumbing/transport/file/client.go
new file mode 100644
index 0000000..5484009
--- /dev/null
+++ b/plumbing/transport/file/client.go
@@ -0,0 +1,82 @@
+package file
+
+import (
+	"io"
+	"os/exec"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/transport"
+	"gopkg.in/src-d/go-git.v4/plumbing/transport/internal/common"
+)
+
+// DefaultClient is the default local client.
+var DefaultClient = NewClient(
+	transport.UploadPackServiceName,
+	transport.ReceivePackServiceName,
+)
+
+type runner struct {
+	UploadPackBin  string
+	ReceivePackBin string
+}
+
+// NewClient returns a new local client using the given git-upload-pack and
+// git-receive-pack binaries.
+func NewClient(uploadPackBin, receivePackBin string) transport.Transport {
+	return common.NewClient(&runner{
+		UploadPackBin:  uploadPackBin,
+		ReceivePackBin: receivePackBin,
+	})
+}
+
+func (r *runner) Command(cmd string, ep transport.Endpoint) (common.Command, error) {
+	switch cmd {
+	case transport.UploadPackServiceName:
+		cmd = r.UploadPackBin
+	case transport.ReceivePackServiceName:
+		cmd = r.ReceivePackBin
+	}
+	return &command{cmd: exec.Command(cmd, ep.Path)}, nil
+}
+
+type command struct {
+	cmd    *exec.Cmd
+	closed bool
+}
+
+func (c *command) SetAuth(auth transport.AuthMethod) error {
+	if auth != nil {
+		return transport.ErrInvalidAuthMethod
+	}
+
+	return nil
+}
+
+func (c *command) Start() error {
+	return c.cmd.Start()
+}
+
+func (c *command) StderrPipe() (io.Reader, error) {
+	return c.cmd.StderrPipe()
+}
+
+func (c *command) StdinPipe() (io.WriteCloser, error) {
+	return c.cmd.StdinPipe()
+}
+
+func (c *command) StdoutPipe() (io.Reader, error) {
+	return c.cmd.StdoutPipe()
+}
+
+// Close waits for the command to exit.
+func (c *command) Close() error {
+	if c.closed {
+		return nil
+	}
+
+	return c.cmd.Process.Kill()
+}
+
+func (c *command) Wait() error {
+	defer func() { c.closed = true }()
+	return c.cmd.Wait()
+}