pkg/bisect: detect wrong bisections

Detect bisection to merge commits and to commits that don't affect
kernel binary (comments, other arches, whitespaces, etc).
Such bisections are not reported in emails (but shown on web).

Update #1271

3 files changed, 11 insertions, 3 deletions

diff --git a/pkg/vcs/git.go b/pkg/vcs/git.go
index 359c3d68e..5a6de4b3f 100644
--- a/pkg/vcs/git.go
+++ b/pkg/vcs/git.go
@@ -153,7 +153,7 @@ func (git *git) HeadCommit() (*Commit, error) {
 }
 
 func (git *git) getCommit(commit string) (*Commit, error) {
-	output, err := git.git("log", "--format=%H%n%s%n%ae%n%an%n%ad%n%b", "-n", "1", commit)
+	output, err := git.git("log", "--format=%H%n%s%n%ae%n%an%n%ad%n%P%n%b", "-n", "1", commit)
 	if err != nil {
 		return nil, err
 	}
@@ -182,7 +182,7 @@ func gitParseCommit(output, user, domain []byte, ignoreCC map[string]bool) (*Com
 	cc := make(map[string]bool)
 	cc[strings.ToLower(string(lines[2]))] = true
 	var tags []string
-	bodyLines := lines[5:]
+	bodyLines := lines[6:]
 	if isEmpty(bodyLines) {
 		// Body is empty, use summary instead.
 		bodyLines = [][]byte{lines[1]}
@@ -231,11 +231,13 @@ func gitParseCommit(output, user, domain []byte, ignoreCC map[string]bool) (*Com
 		sortedCC = append(sortedCC, addr)
 	}
 	sort.Strings(sortedCC)
+	parents := strings.Split(string(lines[5]), " ")
 	com := &Commit{
 		Hash:       string(lines[0]),
 		Title:      string(lines[1]),
 		Author:     string(lines[2]),
 		AuthorName: string(lines[3]),
+		Parents:    parents,
 		CC:         sortedCC,
 		Tags:       tags,
 		Date:       date,
@@ -303,7 +305,7 @@ func (git *git) ExtractFixTagsFromCommits(baseCommit, email string) ([]*Commit,
 
 func (git *git) fetchCommits(since, base, user, domain string, greps []string, fixedStrings bool) ([]*Commit, error) {
 	const commitSeparator = "---===syzkaller-commit-separator===---"
-	args := []string{"log", "--since", since, "--format=%H%n%s%n%ae%n%an%n%ad%n%b%n" + commitSeparator}
+	args := []string{"log", "--since", since, "--format=%H%n%s%n%ae%n%an%n%ad%n%P%n%b%n" + commitSeparator}
 	if fixedStrings {
 		args = append(args, "--fixed-strings")
 	}
diff --git a/pkg/vcs/git_repo_test.go b/pkg/vcs/git_repo_test.go
index 227834b71..e1d317ea2 100644
--- a/pkg/vcs/git_repo_test.go
+++ b/pkg/vcs/git_repo_test.go
@@ -116,6 +116,7 @@ func TestMetadata(t *testing.T) {
 	}
 	defer os.RemoveAll(repoDir)
 	repo := MakeTestRepo(t, repoDir)
+	prevHash := ""
 	for i, test := range metadataTests {
 		repo.CommitChange(test.description)
 		com, err := repo.repo.HeadCommit()
@@ -123,6 +124,10 @@ func TestMetadata(t *testing.T) {
 			t.Fatal(err)
 		}
 		checkCommit(t, i, test, com, false)
+		if len(com.Parents) != 1 || com.Parents[0] != prevHash {
+			t.Fatalf("bad parents: %+q, expect %q", com.Parents, prevHash)
+		}
+		prevHash = com.Hash
 	}
 	commits, err := repo.repo.ExtractFixTagsFromCommits("HEAD", extractFixTagsEmail)
 	if err != nil {
diff --git a/pkg/vcs/vcs.go b/pkg/vcs/vcs.go
index 12130d594..777f0f7e7 100644
--- a/pkg/vcs/vcs.go
+++ b/pkg/vcs/vcs.go
@@ -74,6 +74,7 @@ type Commit struct {
 	AuthorName string
 	CC         []string
 	Tags       []string
+	Parents    []string
 	Date       time.Time
 }