literal braces are text, not placeholders, for containment and walk exclusion

1 files changed, 26 insertions, 11 deletions

diff --git a/internal/plan/fuzz_test.go b/internal/plan/fuzz_test.go
index c7261ec..91a8421 100644
--- a/internal/plan/fuzz_test.go
+++ b/internal/plan/fuzz_test.go
@@ -56,7 +56,7 @@ func FuzzExpand(f *testing.F) {
 			if got == "" {
 				continue
 			}
-			if base := textDir(dest, "/r", xdg.Home()); !underDir(got, base) {
+			if base, templated := textDir(dest, "/r", xdg.Home()); templated && !underDir(got, base) {
 				t.Fatalf("destination %q planned %q for %q, outside %q, the directory its text names", dest, got, name, base)
 			}
 		}
@@ -79,28 +79,43 @@ func plannedDir(dest, name string, captures []string, facts Facts) string {
 }
 
 // textDir is the directory a destination's text names before its first
-// '{' (spec 15.1), worked out here by hand rather than by staticDir: the
-// text up to the last '/' before the brace, "~" as the home directory, a
-// relative path under root.
-func textDir(dest, root, home string) string {
-	prefix := dest[:strings.IndexByte(dest, '{')]
+// placeholder (spec 15.1), worked out here by hand rather than by staticDir:
+// the text up to the last '/' before the first '{' that is not "{{", with
+// "{{" and "}}" read as braces, "~" as the home directory, a relative path
+// under root. templated is false when dest has no placeholder, only literal
+// braces: then a ".." in it is the rule's own.
+func textDir(dest, root, home string) (dir string, templated bool) {
+	open := 0
+	for {
+		j := strings.IndexByte(dest[open:], '{')
+		if j < 0 {
+			return "", false
+		}
+		if open+j+1 < len(dest) && dest[open+j+1] == '{' {
+			open += j + 2
+			continue
+		}
+		open += j
+		break
+	}
+	prefix := strings.NewReplacer("{{", "{", "}}", "}").Replace(dest[:open])
 	switch cut := strings.LastIndexByte(prefix, '/'); {
 	case cut < 0:
 		prefix = ""
 	case cut == 0:
-		return "/"
+		return "/", true
 	default:
 		prefix = prefix[:cut]
 	}
 	switch {
 	case prefix == "~":
-		return home
+		return home, true
 	case strings.HasPrefix(prefix, "~/"):
-		return path.Join(home, prefix[2:])
+		return path.Join(home, prefix[2:]), true
 	case strings.HasPrefix(prefix, "/"):
-		return path.Clean(prefix)
+		return path.Clean(prefix), true
 	}
-	return path.Join(root, prefix)
+	return path.Join(root, prefix), true
 }
 
 // underDir reports whether path is dir or lies under it, by whole segments.