follow symlinks, but skip dot-prefixes

3 files changed, 91 insertions, 25 deletions

diff --git a/README.md b/README.md
index f0d82ae..3a19cb4 100644
--- a/README.md
+++ b/README.md
@@ -107,7 +107,9 @@ the flag, Weft does not touch `.gitignore`.
 Weft validates generated internal links and XML before changing the site. It
 tracks ownership in `.weft-generated.json`, refuses to replace untracked files,
 removes only tracked stale outputs, and installs a completed build with rollback
-on write failure. Files and whole subtrees beginning with `_` are ignored.
+on write failure. Files and whole subtrees beginning with `_` or `.` are ignored.
+Symlinked files and directories are followed under their logical site paths;
+cycles fail the build.
 
 For cron, schedule the build after Syncthing's settling window and use the
 host's lock and logging tools, for example:
diff --git a/main.go b/main.go
index 7f49389..ec081ba 100644
--- a/main.go
+++ b/main.go
@@ -133,7 +133,7 @@ func buildWithFallback(root, canonicalRoot, fallback string, manageGitignore boo
 
 func excluded(rel string) bool {
 	for _, part := range strings.Split(filepath.ToSlash(rel), "/") {
-		if strings.HasPrefix(part, "_") || part == ".git" || part == ".jj" || strings.HasPrefix(part, ".weft-txn-") {
+		if strings.HasPrefix(part, "_") || strings.HasPrefix(part, ".") {
 			return true
 		}
 	}
@@ -143,28 +143,7 @@ func excluded(rel string) bool {
 func (s *site) discover() error {
 	outputs := map[string]string{}
 	var templatePaths []string
-	err := filepath.WalkDir(s.root, func(full string, entry fs.DirEntry, walkErr error) error {
-		if walkErr != nil {
-			return walkErr
-		}
-		rel, err := filepath.Rel(s.root, full)
-		if err != nil || rel == "." {
-			return err
-		}
-		if excluded(rel) {
-			if entry.IsDir() {
-				return filepath.SkipDir
-			}
-			return nil
-		}
-		if entry.IsDir() {
-			return nil
-		}
-		rel = filepath.ToSlash(rel)
-		info, err := entry.Info()
-		if err != nil {
-			return err
-		}
+	err := walkFiles(s.root, func(rel string, info fs.FileInfo) error {
 		switch {
 		case strings.HasSuffix(rel, ".md"):
 			out := strings.TrimSuffix(rel, ".md") + ".html"
@@ -212,6 +191,49 @@ func (s *site) discover() error {
 	return nil
 }
 
+func walkFiles(root string, visit func(string, fs.FileInfo) error) error {
+	active := map[string]bool{}
+	var walk func(string, string) error
+	walk = func(full, relDir string) error {
+		real, err := filepath.EvalSymlinks(full)
+		if err != nil {
+			return err
+		}
+		if active[real] {
+			return fmt.Errorf("symlink cycle at %s", filepath.ToSlash(relDir))
+		}
+		active[real] = true
+		defer delete(active, real)
+
+		entries, err := os.ReadDir(full)
+		if err != nil {
+			return err
+		}
+		for _, entry := range entries {
+			rel := filepath.Join(relDir, entry.Name())
+			if excluded(rel) {
+				continue
+			}
+			name := filepath.Join(full, entry.Name())
+			info, err := os.Stat(name)
+			if err != nil {
+				return err
+			}
+			if info.IsDir() {
+				if err := walk(name, rel); err != nil {
+					return err
+				}
+				continue
+			}
+			if err := visit(filepath.ToSlash(rel), info); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+	return walk(root, "")
+}
+
 func claim(outputs map[string]string, output, input string) error {
 	if previous, ok := outputs[output]; ok {
 		return fmt.Errorf("output collision: %s and %s both target %s", previous, input, output)
diff --git a/main_test.go b/main_test.go
index cbb102c..c4b0ec7 100644
--- a/main_test.go
+++ b/main_test.go
@@ -97,6 +97,8 @@ func TestRecursiveInventoryAndUnderscoreExclusion(t *testing.T) {
 	writeTestFile(t, root, "notes/recipes/cocktails/old.md", "# Old\n")
 	writeTestFile(t, root, "notes/_private/secret.md", "# Secret\n")
 	writeTestFile(t, root, "notes/_draft.md", "# Draft\n")
+	writeTestFile(t, root, "notes/.private/secret.md", "# Secret\n")
+	writeTestFile(t, root, "notes/.draft.md", "# Draft\n")
 	s := &site{root: root, pages: map[string][]*Page{}}
 	if err := s.discover(); err != nil {
 		t.Fatal(err)
@@ -107,7 +109,47 @@ func TestRecursiveInventoryAndUnderscoreExclusion(t *testing.T) {
 		}
 	}
 	if len(s.sources) != 1 {
-		t.Fatalf("underscore sources were discovered: %#v", s.sources)
+		t.Fatalf("private sources were discovered: %#v", s.sources)
+	}
+}
+
+func TestDiscoveryFollowsSymlinksAndRejectsCycles(t *testing.T) {
+	root := t.TempDir()
+	vault := t.TempDir()
+	writeTestFile(t, root, "layouts.tmpl", testLayouts())
+	writeTestFile(t, vault, "recipe.md", "# Recipe\n")
+	writeTestFile(t, vault, "_private/secret.md", "# Secret\n")
+	if err := os.Symlink(vault, filepath.Join(root, "notes")); err != nil {
+		t.Skipf("symlinks unavailable: %v", err)
+	}
+	s := &site{root: root, pages: map[string][]*Page{}}
+	if err := s.discover(); err != nil {
+		t.Fatal(err)
+	}
+	found := false
+	for _, source := range s.sources {
+		if source.path == "notes/recipe.md" {
+			found = true
+		}
+		if strings.Contains(source.path, "_private") {
+			t.Fatalf("private symlink source discovered: %s", source.path)
+		}
+	}
+	if !found {
+		t.Fatalf("symlink sources = %#v", s.sources)
+	}
+	if err := build(root); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(vault, "recipe.html")); err != nil {
+		t.Fatalf("symlinked page was not generated: %v", err)
+	}
+	if err := os.Symlink(root, filepath.Join(root, "loop")); err != nil {
+		t.Fatal(err)
+	}
+	s = &site{root: root, pages: map[string][]*Page{}}
+	if err := s.discover(); err == nil || !strings.Contains(err.Error(), "symlink cycle") {
+		t.Fatalf("cycle error = %v", err)
 	}
 }