From 09f5f2a35f0f4c42b2def0642540f32e59fdeeb3 Mon Sep 17 00:00:00 2001
From: "Santiago M. Mola" <santi@mola.io>
Date: Mon, 10 Jul 2017 18:25:28 +0200
Subject: improve delete support on push

* server: implement delete-refs and announce it.
* remote: check if server announced delete-refs before trying
  to delete and fail fast if it does not.

Note that the client does not need no send 'delete-refs' back
to the server to be able to delete references:

```
delete-refs
-----------

If the server sends back the 'delete-refs' capability, it means that
it is capable of accepting a zero-id value as the target
value of a reference update.  It is not sent back by the client, it
simply informs the client that it can be sent zero-id values
to delete references.
```

So our server implementation does not check if the client sent
delete-refs back, it just accepts deletes if it receives them.
---
 remote.go | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

(limited to 'remote.go')

diff --git a/remote.go b/remote.go
index 9bc31ff..7ebb843 100644
--- a/remote.go
+++ b/remote.go
@@ -21,7 +21,10 @@ import (
 	"gopkg.in/src-d/go-git.v4/utils/ioutil"
 )
 
-var NoErrAlreadyUpToDate = errors.New("already up-to-date")
+var (
+	NoErrAlreadyUpToDate     = errors.New("already up-to-date")
+	ErrDeleteRefNotSupported = errors.New("server does not support delete-refs")
+)
 
 // Remote represents a connection to a remote repository.
 type Remote struct {
@@ -56,7 +59,6 @@ func (r *Remote) Fetch(o *FetchOptions) error {
 // Push performs a push to the remote. Returns NoErrAlreadyUpToDate if the
 // remote was already up-to-date.
 func (r *Remote) Push(o *PushOptions) (err error) {
-	// TODO: Support deletes.
 	// TODO: Sideband support
 
 	if o.RemoteName == "" {
@@ -88,6 +90,18 @@ func (r *Remote) Push(o *PushOptions) (err error) {
 		return err
 	}
 
+	isDelete := false
+	for _, rs := range o.RefSpecs {
+		if rs.IsDelete() {
+			isDelete = true
+			break
+		}
+	}
+
+	if isDelete && !ar.Capabilities.Supports(capability.DeleteRefs) {
+		return ErrDeleteRefNotSupported
+	}
+
 	req := packp.NewReferenceUpdateRequestFromCapabilities(ar.Capabilities)
 	if err := r.addReferencesToUpdate(o.RefSpecs, remoteRefs, req); err != nil {
 		return err
@@ -284,8 +298,8 @@ func (r *Remote) deleteReferences(rs config.RefSpec,
 
 		cmd := &packp.Command{
 			Name: ref.Name(),
-			Old: ref.Hash(),
-			New: plumbing.ZeroHash,
+			Old:  ref.Hash(),
+			New:  plumbing.ZeroHash,
 		}
 		req.Commands = append(req.Commands, cmd)
 		return nil
-- 
cgit