From e938d642201e32027e9c5cfab692e2d31a5b490e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20Mur=C3=A9?= <michael.mure@consensys.net>
Date: Tue, 12 Nov 2024 18:42:59 +0100
Subject: [PATCH 1/2] command: add Covers() for attenuation test, fix incorrect
 Segments()

---
 pkg/command/command.go      | 19 ++++++++++++++++++-
 pkg/command/command_test.go | 15 +++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/pkg/command/command.go b/pkg/command/command.go
index 618f023..45b40f5 100644
--- a/pkg/command/command.go
+++ b/pkg/command/command.go
@@ -98,7 +98,24 @@ func (c Command) Join(segments ...string) Command {
 // Segments returns the ordered segments that comprise the Command as a
 // slice of strings.
 func (c Command) Segments() []string {
-	return strings.Split(string(c), separator)
+	if c == separator {
+		return nil
+	}
+	return strings.Split(string(c), separator)[1:]
+}
+
+// Covers returns true if the command is identical or a parent of the given other command.
+func (c Command) Covers(other Command) bool {
+	otherSegments := other.Segments()
+	if len(otherSegments) < len(c.Segments()) {
+		return false
+	}
+	for i, s := range c.Segments() {
+		if otherSegments[i] != s {
+			return false
+		}
+	}
+	return true
 }
 
 // String returns the composed representation the command.  This is also
diff --git a/pkg/command/command_test.go b/pkg/command/command_test.go
index ed7b86f..07b4c01 100644
--- a/pkg/command/command_test.go
+++ b/pkg/command/command_test.go
@@ -73,6 +73,21 @@ func TestJoin(t *testing.T) {
 	require.Equal(t, "/faz/boz/foo/bar", command.MustParse("/faz/boz").Join("foo", "bar").String())
 }
 
+func TestSegments(t *testing.T) {
+	require.Empty(t, command.Top().Segments())
+	require.Equal(t, []string{"foo", "bar", "baz"}, command.MustParse("/foo/bar/baz").Segments())
+}
+
+func TestCovers(t *testing.T) {
+	require.True(t, command.MustParse("/foo/bar/baz").Covers(command.MustParse("/foo/bar/baz")))
+	require.True(t, command.MustParse("/foo/bar").Covers(command.MustParse("/foo/bar/baz")))
+	require.False(t, command.MustParse("/foo/bar/baz").Covers(command.MustParse("/foo/bar")))
+	require.True(t, command.MustParse("/").Covers(command.MustParse("/foo")))
+	require.True(t, command.MustParse("/").Covers(command.MustParse("/foo/bar/baz")))
+	require.False(t, command.MustParse("/foo").Covers(command.MustParse("/foo00")))
+	require.False(t, command.MustParse("/foo/bar").Covers(command.MustParse("/foo/bar00")))
+}
+
 type testcase struct {
 	name string
 	inp  string

From 98d9cadcbd9de58b4c0629a5a70cda3024452a71 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20Mur=C3=A9?= <michael.mure@consensys.net>
Date: Tue, 12 Nov 2024 18:59:02 +0100
Subject: [PATCH 2/2] command: fast-path for Covers()

---
 pkg/command/command.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pkg/command/command.go b/pkg/command/command.go
index 45b40f5..605aca8 100644
--- a/pkg/command/command.go
+++ b/pkg/command/command.go
@@ -106,6 +106,14 @@ func (c Command) Segments() []string {
 
 // Covers returns true if the command is identical or a parent of the given other command.
 func (c Command) Covers(other Command) bool {
+	// fast-path, equivalent to the code below (verified with fuzzing)
+	if !strings.HasPrefix(string(other), string(c)) {
+		return false
+	}
+	return c == separator || len(c) == len(other) || other[len(c)] == separator[0]
+
+	/* -------
+
 	otherSegments := other.Segments()
 	if len(otherSegments) < len(c.Segments()) {
 		return false
@@ -116,6 +124,8 @@ func (c Command) Covers(other Command) bool {
 		}
 	}
 	return true
+
+	*/
 }
 
 // String returns the composed representation the command.  This is also