pkg/vcs: add ReleaseTag

Add ReleaseTag method that returns last release tag
for the given commit.

Update #2171

7 files changed, 36 insertions, 20 deletions

diff --git a/pkg/vcs/fuchsia.go b/pkg/vcs/fuchsia.go
index 9b052e0de..97e5f8b47 100644
--- a/pkg/vcs/fuchsia.go
+++ b/pkg/vcs/fuchsia.go
@@ -89,3 +89,7 @@ func (ctx *fuchsia) ListRecentCommits(baseCommit string) ([]string, error) {
 func (ctx *fuchsia) ExtractFixTagsFromCommits(baseCommit, email string) ([]*Commit, error) {
 	return ctx.repo.ExtractFixTagsFromCommits(baseCommit, email)
 }
+
+func (ctx *fuchsia) ReleaseTag(commit string) (string, error) {
+	return "", fmt.Errorf("not implemented for fuchsia")
+}
diff --git a/pkg/vcs/git.go b/pkg/vcs/git.go
index 025fab69e..f487b60c2 100644
--- a/pkg/vcs/git.go
+++ b/pkg/vcs/git.go
@@ -482,36 +482,47 @@ func (git *git) bisectInconclusive(output []byte) ([]*Commit, error) {
 	return commits, nil
 }
 
-func (git *git) previousReleaseTags(commit string, self bool) ([]string, error) {
+func (git *git) ReleaseTag(commit string) (string, error) {
+	tags, err := git.previousReleaseTags(commit, true, true)
+	if err != nil {
+		return "", err
+	}
+	if len(tags) == 0 {
+		return "", fmt.Errorf("no release tags found for commit %v", commit)
+	}
+	return tags[0], nil
+}
+
+func (git *git) previousReleaseTags(commit string, self, onlyTop bool) ([]string, error) {
 	var tags []string
 	if self {
 		output, err := git.git("tag", "--list", "--points-at", commit, "--merged", commit, "v*.*")
 		if err != nil {
 			return nil, err
 		}
-		tags, err = gitParseReleaseTags(output)
-		if err != nil {
-			return nil, err
+		tags = gitParseReleaseTags(output)
+		if onlyTop && len(tags) != 0 {
+			return tags, nil
 		}
 	}
 	output, err := git.git("tag", "--no-contains", commit, "--merged", commit, "v*.*")
 	if err != nil {
 		return nil, err
 	}
-	tags1, err := gitParseReleaseTags(output)
-	if err != nil {
-		return nil, err
-	}
+	tags1 := gitParseReleaseTags(output)
 	tags = append(tags, tags1...)
+	if len(tags) == 0 {
+		return nil, fmt.Errorf("no release tags found for commit %v", commit)
+	}
 	return tags, nil
 }
 
 func (git *git) IsRelease(commit string) (bool, error) {
-	tags1, err := git.previousReleaseTags(commit, true)
+	tags1, err := git.previousReleaseTags(commit, true, false)
 	if err != nil {
 		return false, err
 	}
-	tags2, err := git.previousReleaseTags(commit, false)
+	tags2, err := git.previousReleaseTags(commit, false, false)
 	if err != nil {
 		return false, err
 	}
diff --git a/pkg/vcs/git_test.go b/pkg/vcs/git_test.go
index 053dc6d33..4648f04f1 100644
--- a/pkg/vcs/git_test.go
+++ b/pkg/vcs/git_test.go
@@ -121,10 +121,7 @@ v1.
 		"v2.6.13",
 		"v2.6.12",
 	}
-	got, err := gitParseReleaseTags([]byte(input))
-	if err != nil {
-		t.Fatal(err)
-	}
+	got := gitParseReleaseTags([]byte(input))
 	if !reflect.DeepEqual(got, want) {
 		t.Fatalf("got bad tags\ngot:  %+v\nwant: %+v", got, want)
 	}
diff --git a/pkg/vcs/git_test_util.go b/pkg/vcs/git_test_util.go
index 09f5a6af6..5ef6c50c3 100644
--- a/pkg/vcs/git_test_util.go
+++ b/pkg/vcs/git_test_util.go
@@ -90,7 +90,7 @@ func (repo *TestRepo) SetTag(tag string) {
 
 func (repo *TestRepo) SupportsBisection() bool {
 	// Detect too old git binary. --no-contains appeared in git 2.13.
-	_, err := repo.repo.previousReleaseTags("HEAD", true)
+	_, err := repo.repo.previousReleaseTags("HEAD", true, false)
 	return err == nil ||
 		!strings.Contains(err.Error(), "usage: git tag") &&
 			!strings.Contains(err.Error(), "error: unknown option")
diff --git a/pkg/vcs/linux.go b/pkg/vcs/linux.go
index 8e4f17d4a..c4e2a90a5 100644
--- a/pkg/vcs/linux.go
+++ b/pkg/vcs/linux.go
@@ -39,7 +39,7 @@ func newLinux(dir string) *linux {
 }
 
 func (ctx *linux) PreviousReleaseTags(commit string) ([]string, error) {
-	tags, err := ctx.git.previousReleaseTags(commit, false)
+	tags, err := ctx.git.previousReleaseTags(commit, false, false)
 	if err != nil {
 		return nil, err
 	}
@@ -71,7 +71,7 @@ func (ctx *linux) PreviousReleaseTags(commit string) ([]string, error) {
 	return tags, nil
 }
 
-func gitParseReleaseTags(output []byte) ([]string, error) {
+func gitParseReleaseTags(output []byte) []string {
 	var tags []string
 	for _, tag := range bytes.Split(output, []byte{'\n'}) {
 		if releaseTagRe.Match(tag) && gitReleaseTagToInt(string(tag)) != 0 {
@@ -81,7 +81,7 @@ func gitParseReleaseTags(output []byte) ([]string, error) {
 	sort.Slice(tags, func(i, j int) bool {
 		return gitReleaseTagToInt(tags[i]) > gitReleaseTagToInt(tags[j])
 	})
-	return tags, nil
+	return tags
 }
 
 func gitReleaseTagToInt(tag string) uint64 {
@@ -105,7 +105,7 @@ func gitReleaseTagToInt(tag string) uint64 {
 }
 
 func (ctx *linux) EnvForCommit(binDir, commit string, kernelConfig []byte) (*BisectEnv, error) {
-	tagList, err := ctx.previousReleaseTags(commit, true)
+	tagList, err := ctx.previousReleaseTags(commit, true, false)
 	if err != nil {
 		return nil, err
 	}
diff --git a/pkg/vcs/testos.go b/pkg/vcs/testos.go
index ea369f529..ad6df6b1e 100644
--- a/pkg/vcs/testos.go
+++ b/pkg/vcs/testos.go
@@ -21,7 +21,7 @@ func newTestos(dir string) *testos {
 }
 
 func (ctx *testos) PreviousReleaseTags(commit string) ([]string, error) {
-	return ctx.git.previousReleaseTags(commit, false)
+	return ctx.git.previousReleaseTags(commit, false, false)
 }
 
 func (ctx *testos) EnvForCommit(binDir, commit string, kernelConfig []byte) (*BisectEnv, error) {
diff --git a/pkg/vcs/vcs.go b/pkg/vcs/vcs.go
index 72484203d..1f12fa85a 100644
--- a/pkg/vcs/vcs.go
+++ b/pkg/vcs/vcs.go
@@ -102,6 +102,9 @@ type Repo interface {
 	// Given email = "user@domain.com", it searches for tags of the form "user+tag@domain.com"
 	// and returns commits with these tags.
 	ExtractFixTagsFromCommits(baseCommit, email string) ([]*Commit, error)
+
+	// ReleaseTag returns the latest release tag that is reachable from the given commit.
+	ReleaseTag(commit string) (string, error)
 }
 
 // Bisecter may be optionally implemented by Repo.
@@ -115,6 +118,7 @@ type Bisecter interface {
 	Bisect(bad, good string, trace io.Writer, pred func() (BisectResult, error)) ([]*Commit, error)
 
 	// PreviousReleaseTags returns list of preceding release tags that are reachable from the given commit.
+	// If the commit itself has a release tag, this tag is not included.
 	PreviousReleaseTags(commit string) ([]string, error)
 
 	IsRelease(commit string) (bool, error)