feat: allow "." as valid source_roots entry (#2396)

Towards #2218

Author: chingor13

internal/config/state.go

@@ -21,6 +21,7 @@ import (
 	"strings"
 
 	"github.com/googleapis/librarian/internal/conventionalcommits"
+	"github.com/googleapis/librarian/internal/gitrepo"
 )
 
 const (
@@ -241,6 +242,10 @@ func isValidRelativePath(pathString string) bool {
 		return false
 	}
 
+	if pathString == gitrepo.RootPath {
+		return true
+	}
+
 	// The paths are expected to be relative and use the OS-specific path separator.
 	// We clean the path to resolve ".." and check that it doesn't try to
 	// escape the root.

internal/config/state_test.go

@@ -392,7 +392,7 @@ func TestIsValidDirPath(t *testing.T) {
 		{"absolute", "/a/b", false},
 		{"up traversal", "../a", false},
 		{"double dot", "..", false},
-		{"single dot", ".", false},
+		{"single dot", ".", true},
 		{"invalid chars", "a/b<c", false},
 		{"invalid null byte", "a/b\x00c", false},
 	} {

internal/gitrepo/gitrepo.go

@@ -51,6 +51,8 @@ type Repository interface {
 	pushRefSpec(refSpec string) error
 }
 
+const RootPath = "."
+
 // LocalRepository represents a git repository.
 type LocalRepository struct {
 	Dir         string
@@ -335,18 +337,13 @@ func (r *LocalRepository) GetCommitsForPathsSinceCommit(paths []string, sinceCom
 		// In theory, we should be able to remember our "current" commit for each
 		// path, but that's likely to be significantly more complex.
 		for _, candidatePath := range paths {
-			currentPathHash, err := getHashForPathOrEmpty(commit, candidatePath)
-			if err != nil {
-				return err
-			}
-			parentPathHash, err := getHashForPathOrEmpty(parentCommit, candidatePath)
+			matching, err := commitMatchesPath(candidatePath, commit, parentCommit)
 			if err != nil {
 				return err
 			}
 			// If we've found a change (including a path being added or removed),
 			// add it to our list of commits and proceed to the next commit.
-			if currentPathHash != parentPathHash {
-
+			if matching {
 				commits = append(commits, &Commit{
 					Hash:    commit.Hash,
 					Message: commit.Message,
@@ -367,6 +364,21 @@ func (r *LocalRepository) GetCommitsForPathsSinceCommit(paths []string, sinceCom
 	return commits, nil
 }
 
+func commitMatchesPath(path string, commit *object.Commit, parentCommit *object.Commit) (bool, error) {
+	if path == RootPath {
+		return true, nil
+	}
+	currentPathHash, err := getHashForPathOrEmpty(commit, path)
+	if err != nil {
+		return false, err
+	}
+	parentPathHash, err := getHashForPathOrEmpty(parentCommit, path)
+	if err != nil {
+		return false, err
+	}
+	return currentPathHash != parentPathHash, nil
+}
+
 // getHashForPathOrEmpty returns the hash for a path at a given commit, or an
 // empty string if the path (file or directory) did not exist.
 func getHashForPathOrEmpty(commit *object.Commit, path string) (string, error) {

internal/gitrepo/gitrepo_test.go

@@ -975,6 +975,13 @@ func TestGetCommitsForPathsSinceCommit(t *testing.T) {
 			wantErr:       true,
 			wantErrPhrase: "did not find commit",
 		},
+		{
+			name:        "root path matches all commits",
+			paths:       []string{"."},
+			sinceCommit: "",
+			// The current implementation skips the initial commit.
+			wantCommits: []string{"feat: commit 3", "feat: commit 2"},
+		},
 	} {
 
 		t.Run(test.name, func(t *testing.T) {