git: enable fetch with unqualified references

Signed-off-by: Arieh Schneier <15041913+AriehSchneier@users.noreply.github.com>

4 files changed, 130 insertions, 57 deletions

diff --git a/plumbing/reference.go b/plumbing/reference.go
index aeb4227..5a67f69 100644
--- a/plumbing/reference.go
+++ b/plumbing/reference.go
@@ -15,10 +15,11 @@ const (
 	symrefPrefix    = "ref: "
 )
 
-// RefRevParseRules are a set of rules to parse references into short names.
-// These are the same rules as used by git in shorten_unambiguous_ref.
+// RefRevParseRules are a set of rules to parse references into short names, or expand into a full reference.
+// These are the same rules as used by git in shorten_unambiguous_ref and expand_ref.
 // See: https://github.com/git/git/blob/e0aaa1b6532cfce93d87af9bc813fb2e7a7ce9d7/refs.c#L417
 var RefRevParseRules = []string{
+	"%s",
 	"refs/%s",
 	"refs/tags/%s",
 	"refs/heads/%s",
@@ -113,7 +114,7 @@ func (r ReferenceName) String() string {
 func (r ReferenceName) Short() string {
 	s := string(r)
 	res := s
-	for _, format := range RefRevParseRules {
+	for _, format := range RefRevParseRules[1:] {
 		_, err := fmt.Sscanf(s, format, &res)
 		if err == nil {
 			continue
diff --git a/remote.go b/remote.go
index 0e72aad..6ea275c 100644
--- a/remote.go
+++ b/remote.go
@@ -445,7 +445,7 @@ func (r *Remote) fetch(ctx context.Context, o *FetchOptions) (sto storer.Referen
 		return nil, err
 	}
 
-	refs, err := calculateRefs(o.RefSpecs, remoteRefs, o.Tags)
+	refs, specToRefs, err := calculateRefs(o.RefSpecs, remoteRefs, o.Tags)
 	if err != nil {
 		return nil, err
 	}
@@ -469,7 +469,7 @@ func (r *Remote) fetch(ctx context.Context, o *FetchOptions) (sto storer.Referen
 		}
 	}
 
-	updated, err := r.updateLocalReferenceStorage(o.RefSpecs, refs, remoteRefs, o.Tags, o.Force)
+	updated, err := r.updateLocalReferenceStorage(o.RefSpecs, refs, remoteRefs, specToRefs, o.Tags, o.Force)
 	if err != nil {
 		return nil, err
 	}
@@ -929,42 +929,41 @@ func calculateRefs(
 	spec []config.RefSpec,
 	remoteRefs storer.ReferenceStorer,
 	tagMode TagMode,
-) (memory.ReferenceStorage, error) {
+) (memory.ReferenceStorage, [][]*plumbing.Reference, error) {
 	if tagMode == AllTags {
 		spec = append(spec, refspecAllTags)
 	}
 
 	refs := make(memory.ReferenceStorage)
-	for _, s := range spec {
-		if err := doCalculateRefs(s, remoteRefs, refs); err != nil {
-			return nil, err
+	// list of references matched for each spec
+	specToRefs := make([][]*plumbing.Reference, len(spec))
+	for i := range spec {
+		var err error
+		specToRefs[i], err = doCalculateRefs(spec[i], remoteRefs, refs)
+		if err != nil {
+			return nil, nil, err
 		}
 	}
 
-	return refs, nil
+	return refs, specToRefs, nil
 }
 
 func doCalculateRefs(
 	s config.RefSpec,
 	remoteRefs storer.ReferenceStorer,
 	refs memory.ReferenceStorage,
-) error {
-	iter, err := remoteRefs.IterReferences()
-	if err != nil {
-		return err
-	}
+) ([]*plumbing.Reference, error) {
+	var refList []*plumbing.Reference
 
 	if s.IsExactSHA1() {
 		ref := plumbing.NewHashReference(s.Dst(""), plumbing.NewHash(s.Src()))
-		return refs.SetReference(ref)
+
+		refList = append(refList, ref)
+		return refList, refs.SetReference(ref)
 	}
 
 	var matched bool
-	err = iter.ForEach(func(ref *plumbing.Reference) error {
-		if !s.Match(ref.Name()) {
-			return nil
-		}
-
+	onMatched := func(ref *plumbing.Reference) error {
 		if ref.Type() == plumbing.SymbolicReference {
 			target, err := storer.ResolveReference(remoteRefs, ref.Name())
 			if err != nil {
@@ -979,22 +978,37 @@ func doCalculateRefs(
 		}
 
 		matched = true
-		if err := refs.SetReference(ref); err != nil {
-			return err
-		}
+		refList = append(refList, ref)
+		return refs.SetReference(ref)
+	}
 
-		if !s.IsWildcard() {
-			return storer.ErrStop
+	var ret error
+	if s.IsWildcard() {
+		iter, err := remoteRefs.IterReferences()
+		if err != nil {
+			return nil, err
 		}
+		ret = iter.ForEach(func(ref *plumbing.Reference) error {
+			if !s.Match(ref.Name()) {
+				return nil
+			}
 
-		return nil
-	})
+			return onMatched(ref)
+		})
+	} else {
+		var resolvedRef *plumbing.Reference
+		src := s.Src()
+		resolvedRef, ret = expand_ref(remoteRefs, plumbing.ReferenceName(src))
+		if ret == nil {
+			ret = onMatched(resolvedRef)
+		}
+	}
 
 	if !matched && !s.IsWildcard() {
-		return NoMatchingRefSpecError{refSpec: s}
+		return nil, NoMatchingRefSpecError{refSpec: s}
 	}
 
-	return err
+	return refList, ret
 }
 
 func getWants(localStorer storage.Storer, refs memory.ReferenceStorage) ([]plumbing.Hash, error) {
@@ -1154,27 +1168,28 @@ func buildSidebandIfSupported(l *capability.List, reader io.Reader, p sideband.P
 func (r *Remote) updateLocalReferenceStorage(
 	specs []config.RefSpec,
 	fetchedRefs, remoteRefs memory.ReferenceStorage,
+	specToRefs [][]*plumbing.Reference,
 	tagMode TagMode,
 	force bool,
 ) (updated bool, err error) {
 	isWildcard := true
 	forceNeeded := false
 
-	for _, spec := range specs {
+	for i, spec := range specs {
 		if !spec.IsWildcard() {
 			isWildcard = false
 		}
 
-		for _, ref := range fetchedRefs {
-			if !spec.Match(ref.Name()) && !spec.IsExactSHA1() {
-				continue
-			}
-
+		for _, ref := range specToRefs[i] {
 			if ref.Type() != plumbing.HashReference {
 				continue
 			}
 
 			localName := spec.Dst(ref.Name())
+			// If localName doesn't start with "refs/" then treat as a branch.
+			if !strings.HasPrefix(localName.String(), "refs/") {
+				localName = plumbing.NewBranchReferenceName(localName.String())
+			}
 			old, _ := storer.ResolveReference(r.s, localName)
 			new := plumbing.NewHashReference(localName, ref.Hash())
 
diff --git a/remote_test.go b/remote_test.go
index f8a0bdb..ca5f261 100644
--- a/remote_test.go
+++ b/remote_test.go
@@ -140,6 +140,62 @@ func (s *RemoteSuite) TestFetch(c *C) {
 	})
 }
 
+func (s *RemoteSuite) TestFetchToNewBranch(c *C) {
+	r := NewRemote(memory.NewStorage(), &config.RemoteConfig{
+		URLs: []string{s.GetLocalRepositoryURL(fixtures.ByTag("tags").One())},
+	})
+
+	s.testFetch(c, r, &FetchOptions{
+		RefSpecs: []config.RefSpec{
+			// qualified branch to unqualified branch
+			"refs/heads/master:foo",
+			// unqualified branch to unqualified branch
+			"+master:bar",
+			// unqualified tag to unqualified branch
+			config.RefSpec("tree-tag:tree-tag"),
+			// unqualified tag to qualified tag
+			config.RefSpec("+commit-tag:refs/tags/renamed-tag"),
+		},
+	}, []*plumbing.Reference{
+		plumbing.NewReferenceFromStrings("refs/heads/foo", "f7b877701fbf855b44c0a9e86f3fdce2c298b07f"),
+		plumbing.NewReferenceFromStrings("refs/heads/bar", "f7b877701fbf855b44c0a9e86f3fdce2c298b07f"),
+		plumbing.NewReferenceFromStrings("refs/heads/tree-tag", "152175bf7e5580299fa1f0ba41ef6474cc043b70"),
+		plumbing.NewReferenceFromStrings("refs/tags/tree-tag", "152175bf7e5580299fa1f0ba41ef6474cc043b70"),
+		plumbing.NewReferenceFromStrings("refs/tags/renamed-tag", "ad7897c0fb8e7d9a9ba41fa66072cf06095a6cfc"),
+		plumbing.NewReferenceFromStrings("refs/tags/commit-tag", "ad7897c0fb8e7d9a9ba41fa66072cf06095a6cfc"),
+	})
+}
+
+func (s *RemoteSuite) TestFetchToNewBranchWithAllTags(c *C) {
+	r := NewRemote(memory.NewStorage(), &config.RemoteConfig{
+		URLs: []string{s.GetLocalRepositoryURL(fixtures.ByTag("tags").One())},
+	})
+
+	s.testFetch(c, r, &FetchOptions{
+		Tags: AllTags,
+		RefSpecs: []config.RefSpec{
+			// qualified branch to unqualified branch
+			"+refs/heads/master:foo",
+			// unqualified branch to unqualified branch
+			"master:bar",
+			// unqualified tag to unqualified branch
+			config.RefSpec("+tree-tag:tree-tag"),
+			// unqualified tag to qualified tag
+			config.RefSpec("commit-tag:refs/tags/renamed-tag"),
+		},
+	}, []*plumbing.Reference{
+		plumbing.NewReferenceFromStrings("refs/heads/foo", "f7b877701fbf855b44c0a9e86f3fdce2c298b07f"),
+		plumbing.NewReferenceFromStrings("refs/heads/bar", "f7b877701fbf855b44c0a9e86f3fdce2c298b07f"),
+		plumbing.NewReferenceFromStrings("refs/heads/tree-tag", "152175bf7e5580299fa1f0ba41ef6474cc043b70"),
+		plumbing.NewReferenceFromStrings("refs/tags/tree-tag", "152175bf7e5580299fa1f0ba41ef6474cc043b70"),
+		plumbing.NewReferenceFromStrings("refs/tags/renamed-tag", "ad7897c0fb8e7d9a9ba41fa66072cf06095a6cfc"),
+		plumbing.NewReferenceFromStrings("refs/tags/commit-tag", "ad7897c0fb8e7d9a9ba41fa66072cf06095a6cfc"),
+		plumbing.NewReferenceFromStrings("refs/tags/annotated-tag", "b742a2a9fa0afcfa9a6fad080980fbc26b007c69"),
+		plumbing.NewReferenceFromStrings("refs/tags/blob-tag", "fe6cb94756faa81e5ed9240f9191b833db5f40ae"),
+		plumbing.NewReferenceFromStrings("refs/tags/lightweight-tag", "f7b877701fbf855b44c0a9e86f3fdce2c298b07f"),
+	})
+}
+
 func (s *RemoteSuite) TestFetchNonExistantReference(c *C) {
 	r := NewRemote(memory.NewStorage(), &config.RemoteConfig{
 		URLs: []string{s.GetLocalRepositoryURL(fixtures.ByTag("tags").One())},
diff --git a/repository.go b/repository.go
index f3540c6..17fa5dd 100644
--- a/repository.go
+++ b/repository.go
@@ -1029,21 +1029,9 @@ func (r *Repository) fetchAndUpdateReferences(
 		return nil, err
 	}
 
-	var resolvedRef *plumbing.Reference
-	// return error from checking the raw ref passed in
-	var rawRefError error
-	for _, rule := range append([]string{"%s"}, plumbing.RefRevParseRules...) {
-		resolvedRef, err = storer.ResolveReference(remoteRefs, plumbing.ReferenceName(fmt.Sprintf(rule, ref)))
-
-		if err == nil {
-			break
-		} else if rawRefError == nil {
-			rawRefError = err
-		}
-	}
-
+	resolvedRef, err := expand_ref(remoteRefs, ref)
 	if err != nil {
-		return nil, rawRefError
+		return nil, err
 	}
 
 	refsUpdated, err := r.updateReferences(remote.c.Fetch, resolvedRef)
@@ -1489,6 +1477,23 @@ func (r *Repository) Worktree() (*Worktree, error) {
 	return &Worktree{r: r, Filesystem: r.wt}, nil
 }
 
+func expand_ref(s storer.ReferenceStorer, ref plumbing.ReferenceName) (*plumbing.Reference, error) {
+	// For improving troubleshooting, this preserves the error for the provided `ref`,
+	// and returns the error for that specific ref in case all parse rules fails.
+	var ret error
+	for _, rule := range plumbing.RefRevParseRules {
+		resolvedRef, err := storer.ResolveReference(s, plumbing.ReferenceName(fmt.Sprintf(rule, ref)))
+
+		if err == nil {
+			return resolvedRef, nil
+		} else if ret == nil {
+			ret = err
+		}
+	}
+
+	return nil, ret
+}
+
 // ResolveRevision resolves revision to corresponding hash. It will always
 // resolve to a commit hash, not a tree or annotated tag.
 //
@@ -1518,13 +1523,9 @@ func (r *Repository) ResolveRevision(in plumbing.Revision) (*plumbing.Hash, erro
 
 			tryHashes = append(tryHashes, r.resolveHashPrefix(string(revisionRef))...)
 
-			for _, rule := range append([]string{"%s"}, plumbing.RefRevParseRules...) {
-				ref, err := storer.ResolveReference(r.Storer, plumbing.ReferenceName(fmt.Sprintf(rule, revisionRef)))
-
-				if err == nil {
-					tryHashes = append(tryHashes, ref.Hash())
-					break
-				}
+			ref, err := expand_ref(r.Storer, plumbing.ReferenceName(revisionRef))
+			if err == nil {
+				tryHashes = append(tryHashes, ref.Hash())
 			}
 
 			// in ambiguous cases, `git rev-parse` will emit a warning, but