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Commit bf9ed3fb authored by Colin Cross's avatar Colin Cross
Browse files

Optimize out empty path components 

filepath.Join("foo", "") returns a newly allocated copy of "foo",
while filepath.Join("foo") does not.  Strip out any empty path
components before calling filepath.Join.

Test: TestValidatePath
Change-Id: Ib47dbcd9d6463809acfe260dfd9af87ea280b4de
parent 9ae2999d

android/paths.go

+18 −2
Original line number Diff line number Diff line
@@ -1915,7 +1915,9 @@ func (p InstallPaths) Strings() []string { 
// validatePathInternal ensures that a path does not leave its component, and

// optionally doesn't contain Ninja variables.

func validatePathInternal(allowNinjaVariables bool, pathComponents ...string) (string, error) {

	for _, path := range pathComponents {

	initialEmpty := 0

	finalEmpty := 0

	for i, path := range pathComponents {

		if !allowNinjaVariables && strings.Contains(path, "$") {

			return "", fmt.Errorf("Path contains invalid character($): %s", path)

		}
@@ -1924,11 +1926,25 @@ func validatePathInternal(allowNinjaVariables bool, pathComponents ...string) (s 
		if path == ".." || strings.HasPrefix(path, "../") || strings.HasPrefix(path, "/") {

			return "", fmt.Errorf("Path is outside directory: %s", path)

		}



		if i == initialEmpty && pathComponents[i] == "" {

			initialEmpty++

		}

		if i == finalEmpty && pathComponents[len(pathComponents)-1-i] == "" {

			finalEmpty++

		}

	}

	// Optimization: filepath.Join("foo", "") returns a newly allocated copy

	// of "foo", while filepath.Join("foo") does not.  Strip out any empty

	// path components.

	if initialEmpty == len(pathComponents) {

		return "", nil

	}

	nonEmptyPathComponents := pathComponents[initialEmpty : len(pathComponents)-finalEmpty]

	// TODO: filepath.Join isn't necessarily correct with embedded ninja

	// variables. '..' may remove the entire ninja variable, even if it

	// will be expanded to multiple nested directories.

	return filepath.Join(pathComponents...), nil

	return filepath.Join(nonEmptyPathComponents...), nil

}



// validateSafePath validates a path that we trust (may contain ninja

android/paths_test.go

+16 −0
Original line number Diff line number Diff line
@@ -36,6 +36,22 @@ var commonValidatePathTestCases = []strsTestCase{ 
		in:  []string{""},

		out: "",

	},

	{

		in:  []string{"", ""},

		out: "",

	},

	{

		in:  []string{"a", ""},

		out: "a",

	},

	{

		in:  []string{"", "a"},

		out: "a",

	},

	{

		in:  []string{"", "a", ""},

		out: "a",

	},

	{

		in:  []string{"a/b"},

		out: "a/b",