Merge changes from topic "buildnumberfromfile"

* changes:
  Allow jar wrapper to take quoted arguments
  Add rspfile support to RuleBuilder
  Prepare droiddoc for using RuleBuilder
  Manually escape BuildNumberFromFile
  Fix android.Expand and ninja escaping
  Add RuleBuilder helper functions for built and prebuilt tools
  Add documentation to droiddoc.go module types
diff --git a/android/expand.go b/android/expand.go
index 527c4ac..67fb4ee 100644
--- a/android/expand.go
+++ b/android/expand.go
@@ -18,12 +18,30 @@
 	"fmt"
 	"strings"
 	"unicode"
+
+	"github.com/google/blueprint/proptools"
 )
 
+// ExpandNinjaEscaped substitutes $() variables in a string
+// $(var) is passed to mapping(var), which should return the expanded value, a bool for whether the result should
+// be left unescaped when using in a ninja value (generally false, true if the expanded value is a ninja variable like
+// '${in}'), and an error.
+// $$ is converted to $, which is escaped back to $$.
+func ExpandNinjaEscaped(s string, mapping func(string) (string, bool, error)) (string, error) {
+	return expand(s, true, mapping)
+}
+
 // Expand substitutes $() variables in a string
-// $(var) is passed to Expander(var)
-// $$ is converted to $
+// $(var) is passed to mapping(var), which should return the expanded value and an error.
+// $$ is converted to $.
 func Expand(s string, mapping func(string) (string, error)) (string, error) {
+	return expand(s, false, func(s string) (string, bool, error) {
+		s, err := mapping(s)
+		return s, false, err
+	})
+}
+
+func expand(s string, ninjaEscape bool, mapping func(string) (string, bool, error)) (string, error) {
 	// based on os.Expand
 	buf := make([]byte, 0, 2*len(s))
 	i := 0
@@ -33,10 +51,13 @@
 				return "", fmt.Errorf("expected character after '$'")
 			}
 			buf = append(buf, s[i:j]...)
-			value, w, err := getMapping(s[j+1:], mapping)
+			value, ninjaVariable, w, err := getMapping(s[j+1:], mapping)
 			if err != nil {
 				return "", err
 			}
+			if !ninjaVariable && ninjaEscape {
+				value = proptools.NinjaEscape(value)
+			}
 			buf = append(buf, value...)
 			j += w
 			i = j + 1
@@ -45,26 +66,26 @@
 	return string(buf) + s[i:], nil
 }
 
-func getMapping(s string, mapping func(string) (string, error)) (string, int, error) {
+func getMapping(s string, mapping func(string) (string, bool, error)) (string, bool, int, error) {
 	switch s[0] {
 	case '(':
 		// Scan to closing brace
 		for i := 1; i < len(s); i++ {
 			if s[i] == ')' {
-				ret, err := mapping(strings.TrimSpace(s[1:i]))
-				return ret, i + 1, err
+				ret, ninjaVariable, err := mapping(strings.TrimSpace(s[1:i]))
+				return ret, ninjaVariable, i + 1, err
 			}
 		}
-		return "", len(s), fmt.Errorf("missing )")
+		return "", false, len(s), fmt.Errorf("missing )")
 	case '$':
-		return "$$", 1, nil
+		return "$", false, 1, nil
 	default:
 		i := strings.IndexFunc(s, unicode.IsSpace)
 		if i == 0 {
-			return "", 0, fmt.Errorf("unexpected character '%c' after '$'", s[0])
+			return "", false, 0, fmt.Errorf("unexpected character '%c' after '$'", s[0])
 		} else if i == -1 {
 			i = len(s)
 		}
-		return "", 0, fmt.Errorf("expected '(' after '$', did you mean $(%s)?", s[:i])
+		return "", false, 0, fmt.Errorf("expected '(' after '$', did you mean $(%s)?", s[:i])
 	}
 }
diff --git a/android/expand_test.go b/android/expand_test.go
index 128de8a..12179ed 100644
--- a/android/expand_test.go
+++ b/android/expand_test.go
@@ -20,88 +20,111 @@
 )
 
 var vars = map[string]string{
-	"var1": "abc",
-	"var2": "",
-	"var3": "def",
-	"💩":    "😃",
+	"var1":   "abc",
+	"var2":   "",
+	"var3":   "def",
+	"💩":      "😃",
+	"escape": "${in}",
 }
 
-func expander(s string) (string, error) {
+func expander(s string) (string, bool, error) {
 	if val, ok := vars[s]; ok {
-		return val, nil
+		return val, s == "escape", nil
 	} else {
-		return "", fmt.Errorf("unknown variable %q", s)
+		return "", false, fmt.Errorf("unknown variable %q", s)
 	}
 }
 
 var expandTestCases = []struct {
-	in  string
-	out string
-	err bool
+	in          string
+	out         string
+	out_escaped string
+	err         bool
 }{
 	{
-		in:  "$(var1)",
-		out: "abc",
+		in:          "$(var1)",
+		out:         "abc",
+		out_escaped: "abc",
 	},
 	{
-		in:  "$( var1 )",
-		out: "abc",
+		in:          "$( var1 )",
+		out:         "abc",
+		out_escaped: "abc",
 	},
 	{
-		in:  "def$(var1)",
-		out: "defabc",
+		in:          "def$(var1)",
+		out:         "defabc",
+		out_escaped: "defabc",
 	},
 	{
-		in:  "$(var1)def",
-		out: "abcdef",
+		in:          "$(var1)def",
+		out:         "abcdef",
+		out_escaped: "abcdef",
 	},
 	{
-		in:  "def$(var1)def",
-		out: "defabcdef",
+		in:          "def$(var1)def",
+		out:         "defabcdef",
+		out_escaped: "defabcdef",
 	},
 	{
-		in:  "$(var2)",
-		out: "",
+		in:          "$(var2)",
+		out:         "",
+		out_escaped: "",
 	},
 	{
-		in:  "def$(var2)",
-		out: "def",
+		in:          "def$(var2)",
+		out:         "def",
+		out_escaped: "def",
 	},
 	{
-		in:  "$(var2)def",
-		out: "def",
+		in:          "$(var2)def",
+		out:         "def",
+		out_escaped: "def",
 	},
 	{
-		in:  "def$(var2)def",
-		out: "defdef",
+		in:          "def$(var2)def",
+		out:         "defdef",
+		out_escaped: "defdef",
 	},
 	{
-		in:  "$(var1)$(var3)",
-		out: "abcdef",
+		in:          "$(var1)$(var3)",
+		out:         "abcdef",
+		out_escaped: "abcdef",
 	},
 	{
-		in:  "$(var1)g$(var3)",
-		out: "abcgdef",
+		in:          "$(var1)g$(var3)",
+		out:         "abcgdef",
+		out_escaped: "abcgdef",
 	},
 	{
-		in:  "$$",
-		out: "$$",
+		in:          "$$",
+		out:         "$",
+		out_escaped: "$$",
 	},
 	{
-		in:  "$$(var1)",
-		out: "$$(var1)",
+		in:          "$$(var1)",
+		out:         "$(var1)",
+		out_escaped: "$$(var1)",
 	},
 	{
-		in:  "$$$(var1)",
-		out: "$$abc",
+		in:          "$$$(var1)",
+		out:         "$abc",
+		out_escaped: "$$abc",
 	},
 	{
-		in:  "$(var1)$$",
-		out: "abc$$",
+		in:          "$(var1)$$",
+		out:         "abc$",
+		out_escaped: "abc$$",
 	},
 	{
-		in:  "$(💩)",
-		out: "😃",
+		in:          "$(💩)",
+		out:         "😃",
+		out_escaped: "😃",
+	},
+	{
+		in:          "$$a$(escape)$$b",
+		out:         "$a${in}$b",
+		out_escaped: "$$a${in}$$b",
 	},
 
 	// Errors
@@ -141,7 +164,10 @@
 
 func TestExpand(t *testing.T) {
 	for _, test := range expandTestCases {
-		got, err := Expand(test.in, expander)
+		got, err := Expand(test.in, func(s string) (string, error) {
+			s, _, err := expander(s)
+			return s, err
+		})
 		if err != nil && !test.err {
 			t.Errorf("%q: unexpected error %s", test.in, err.Error())
 		} else if err == nil && test.err {
@@ -151,3 +177,16 @@
 		}
 	}
 }
+
+func TestExpandNinjaEscaped(t *testing.T) {
+	for _, test := range expandTestCases {
+		got, err := ExpandNinjaEscaped(test.in, expander)
+		if err != nil && !test.err {
+			t.Errorf("%q: unexpected error %s", test.in, err.Error())
+		} else if err == nil && test.err {
+			t.Errorf("%q: expected error, got %q", test.in, got)
+		} else if !test.err && got != test.out_escaped {
+			t.Errorf("%q: expected %q, got %q", test.in, test.out, got)
+		}
+	}
+}
diff --git a/android/proto.go b/android/proto.go
index 5247c68..c8ade45 100644
--- a/android/proto.go
+++ b/android/proto.go
@@ -135,7 +135,7 @@
 	}
 
 	rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "aprotoc")).
+		BuiltTool(ctx, "aprotoc").
 		FlagWithArg(flags.OutTypeFlag+"=", strings.Join(flags.OutParams, ",")+":"+outDir.String()).
 		FlagWithDepFile("--dependency_out=", depFile).
 		FlagWithArg("-I ", protoBase).
@@ -145,5 +145,5 @@
 		ImplicitOutputs(outputs)
 
 	rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "dep_fixer")).Flag(depFile.String())
+		BuiltTool(ctx, "dep_fixer").Flag(depFile.String())
 }
diff --git a/android/rule_builder.go b/android/rule_builder.go
index e53eb0d..1238ddc 100644
--- a/android/rule_builder.go
+++ b/android/rule_builder.go
@@ -263,11 +263,36 @@
 	return toolsList
 }
 
-// Commands returns a slice containing a the built command line for each call to RuleBuilder.Command.
+// RspFileInputs returns the list of paths that were passed to the RuleBuilderCommand.FlagWithRspFileInputList method.
+func (r *RuleBuilder) RspFileInputs() Paths {
+	var rspFileInputs Paths
+	for _, c := range r.commands {
+		if c.rspFileInputs != nil {
+			if rspFileInputs != nil {
+				panic("Multiple commands in a rule may not have rsp file inputs")
+			}
+			rspFileInputs = c.rspFileInputs
+		}
+	}
+
+	return rspFileInputs
+}
+
+// Commands returns a slice containing the built command line for each call to RuleBuilder.Command.
 func (r *RuleBuilder) Commands() []string {
 	var commands []string
 	for _, c := range r.commands {
-		commands = append(commands, c.buf.String())
+		commands = append(commands, c.String())
+	}
+	return commands
+}
+
+// NinjaEscapedCommands returns a slice containin the built command line after ninja escaping for each call to
+// RuleBuilder.Command.
+func (r *RuleBuilder) NinjaEscapedCommands() []string {
+	var commands []string
+	for _, c := range r.commands {
+		commands = append(commands, c.NinjaEscapedString())
 	}
 	return commands
 }
@@ -284,7 +309,7 @@
 
 func (r *RuleBuilder) depFileMergerCmd(ctx PathContext, depFiles WritablePaths) *RuleBuilderCommand {
 	return r.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "dep_fixer")).
+		BuiltTool(ctx, "dep_fixer").
 		Inputs(depFiles.Paths())
 }
 
@@ -324,7 +349,7 @@
 	}
 
 	tools := r.Tools()
-	commands := r.Commands()
+	commands := r.NinjaEscapedCommands()
 	outputs := r.Outputs()
 
 	if len(commands) == 0 {
@@ -334,7 +359,7 @@
 		panic("No outputs specified from any Commands")
 	}
 
-	commandString := strings.Join(proptools.NinjaEscapeList(commands), " && ")
+	commandString := strings.Join(commands, " && ")
 
 	if r.sbox {
 		sboxOutputs := make([]string, len(outputs))
@@ -352,7 +377,7 @@
 		}
 
 		sboxCmd := &RuleBuilderCommand{}
-		sboxCmd.Tool(ctx.Config().HostToolPath(ctx, "sbox")).
+		sboxCmd.BuiltTool(ctx, "sbox").
 			Flag("-c").Text(commandString).
 			Flag("--sandbox-path").Text(shared.TempDirForOutDir(PathForOutput(ctx).String())).
 			Flag("--output-root").Text(r.sboxOutDir.String()).
@@ -363,17 +388,27 @@
 	}
 
 	// Ninja doesn't like multiple outputs when depfiles are enabled, move all but the first output to
-	// ImplicitOutputs.  RuleBuilder never uses "$out", so the distinction between Outputs and ImplicitOutputs
-	// doesn't matter.
+	// ImplicitOutputs.  RuleBuilder only uses "$out" for the rsp file location, so the distinction between Outputs and
+	// ImplicitOutputs doesn't matter.
 	output := outputs[0]
 	implicitOutputs := outputs[1:]
 
+	var rspFile, rspFileContent string
+	rspFileInputs := r.RspFileInputs()
+	if rspFileInputs != nil {
+		rspFile = "$out.rsp"
+		rspFileContent = "$in"
+	}
+
 	ctx.Build(pctx, BuildParams{
 		Rule: ctx.Rule(pctx, name, blueprint.RuleParams{
-			Command:     commandString,
-			CommandDeps: tools.Strings(),
-			Restat:      r.restat,
+			Command:        commandString,
+			CommandDeps:    tools.Strings(),
+			Restat:         r.restat,
+			Rspfile:        rspFile,
+			RspfileContent: rspFileContent,
 		}),
+		Inputs:          rspFileInputs,
 		Implicits:       r.Inputs(),
 		Output:          output,
 		ImplicitOutputs: implicitOutputs,
@@ -388,11 +423,15 @@
 // RuleBuilderCommand, so they can be used chained or unchained.  All methods that add text implicitly add a single
 // space as a separator from the previous method.
 type RuleBuilderCommand struct {
-	buf      strings.Builder
-	inputs   Paths
-	outputs  WritablePaths
-	depFiles WritablePaths
-	tools    Paths
+	buf           strings.Builder
+	inputs        Paths
+	outputs       WritablePaths
+	depFiles      WritablePaths
+	tools         Paths
+	rspFileInputs Paths
+
+	// spans [start,end) of the command that should not be ninja escaped
+	unescapedSpans [][2]int
 
 	sbox       bool
 	sboxOutDir WritablePath
@@ -478,6 +517,24 @@
 	return c.Text(path.String())
 }
 
+// BuiltTool adds the specified tool path that was built using a host Soong module to the command line.  The path will
+// be also added to the dependencies returned by RuleBuilder.Tools.
+//
+// It is equivalent to:
+//  cmd.Tool(ctx.Config().HostToolPath(ctx, tool))
+func (c *RuleBuilderCommand) BuiltTool(ctx PathContext, tool string) *RuleBuilderCommand {
+	return c.Tool(ctx.Config().HostToolPath(ctx, tool))
+}
+
+// PrebuiltBuildTool adds the specified tool path from prebuils/build-tools.  The path will be also added to the
+// dependencies returned by RuleBuilder.Tools.
+//
+// It is equivalent to:
+//  cmd.Tool(ctx.Config().PrebuiltBuildTool(ctx, tool))
+func (c *RuleBuilderCommand) PrebuiltBuildTool(ctx PathContext, tool string) *RuleBuilderCommand {
+	return c.Tool(ctx.Config().PrebuiltBuildTool(ctx, tool))
+}
+
 // Input adds the specified input path to the command line.  The path will also be added to the dependencies returned by
 // RuleBuilder.Inputs.
 func (c *RuleBuilderCommand) Input(path Path) *RuleBuilderCommand {
@@ -606,11 +663,56 @@
 	return c.Text(flag + c.outputStr(path))
 }
 
+// FlagWithRspFileInputList adds the specified flag and path to an rspfile to the command line, with no separator
+// between them.  The paths will be written to the rspfile.
+func (c *RuleBuilderCommand) FlagWithRspFileInputList(flag string, paths Paths) *RuleBuilderCommand {
+	if c.rspFileInputs != nil {
+		panic("FlagWithRspFileInputList cannot be called if rsp file inputs have already been provided")
+	}
+
+	// Use an empty slice if paths is nil, the non-nil slice is used as an indicator that the rsp file must be
+	// generated.
+	if paths == nil {
+		paths = Paths{}
+	}
+
+	c.rspFileInputs = paths
+
+	rspFile := "$out.rsp"
+	c.FlagWithArg(flag, rspFile)
+	c.unescapedSpans = append(c.unescapedSpans, [2]int{c.buf.Len() - len(rspFile), c.buf.Len()})
+	return c
+}
+
 // String returns the command line.
 func (c *RuleBuilderCommand) String() string {
 	return c.buf.String()
 }
 
+// String returns the command line.
+func (c *RuleBuilderCommand) NinjaEscapedString() string {
+	return ninjaEscapeExceptForSpans(c.String(), c.unescapedSpans)
+}
+
+func ninjaEscapeExceptForSpans(s string, spans [][2]int) string {
+	if len(spans) == 0 {
+		return proptools.NinjaEscape(s)
+	}
+
+	sb := strings.Builder{}
+	sb.Grow(len(s) * 11 / 10)
+
+	i := 0
+	for _, span := range spans {
+		sb.WriteString(proptools.NinjaEscape(s[i:span[0]]))
+		sb.WriteString(s[span[0]:span[1]])
+		i = span[1]
+	}
+	sb.WriteString(proptools.NinjaEscape(s[i:]))
+
+	return sb.String()
+}
+
 func ninjaNameEscape(s string) string {
 	b := []byte(s)
 	escaped := false
diff --git a/android/rule_builder_test.go b/android/rule_builder_test.go
index cfbc2ab..6eba4f1 100644
--- a/android/rule_builder_test.go
+++ b/android/rule_builder_test.go
@@ -38,6 +38,7 @@
 			"ls":      nil,
 			"turbine": nil,
 			"java":    nil,
+			"javac":   nil,
 		})
 }
 
@@ -235,6 +236,34 @@
 	// ls --sort=time,size
 }
 
+func ExampleRuleBuilderCommand_FlagWithRspFileInputList() {
+	ctx := pathContext()
+	fmt.Println(NewRuleBuilder().Command().
+		Tool(PathForSource(ctx, "javac")).
+		FlagWithRspFileInputList("@", PathsForTesting("a.java", "b.java")).
+		NinjaEscapedString())
+	// Output:
+	// javac @$out.rsp
+}
+
+func ExampleRuleBuilderCommand_String() {
+	fmt.Println(NewRuleBuilder().Command().
+		Text("FOO=foo").
+		Text("echo $FOO").
+		String())
+	// Output:
+	// FOO=foo echo $FOO
+}
+
+func ExampleRuleBuilderCommand_NinjaEscapedString() {
+	fmt.Println(NewRuleBuilder().Command().
+		Text("FOO=foo").
+		Text("echo $FOO").
+		NinjaEscapedString())
+	// Output:
+	// FOO=foo echo $$FOO
+}
+
 func TestRuleBuilder(t *testing.T) {
 	fs := map[string][]byte{
 		"dep_fixer": nil,
@@ -503,3 +532,77 @@
 			"cp bar "+outFile, outFile, outFile+".d", true, nil)
 	})
 }
+
+func Test_ninjaEscapeExceptForSpans(t *testing.T) {
+	type args struct {
+		s     string
+		spans [][2]int
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "empty",
+			args: args{
+				s: "",
+			},
+			want: "",
+		},
+		{
+			name: "unescape none",
+			args: args{
+				s: "$abc",
+			},
+			want: "$$abc",
+		},
+		{
+			name: "unescape all",
+			args: args{
+				s:     "$abc",
+				spans: [][2]int{{0, 4}},
+			},
+			want: "$abc",
+		},
+		{
+			name: "unescape first",
+			args: args{
+				s:     "$abc$",
+				spans: [][2]int{{0, 1}},
+			},
+			want: "$abc$$",
+		},
+		{
+			name: "unescape last",
+			args: args{
+				s:     "$abc$",
+				spans: [][2]int{{4, 5}},
+			},
+			want: "$$abc$",
+		},
+		{
+			name: "unescape middle",
+			args: args{
+				s:     "$a$b$c$",
+				spans: [][2]int{{2, 5}},
+			},
+			want: "$$a$b$c$$",
+		},
+		{
+			name: "unescape multiple",
+			args: args{
+				s:     "$a$b$c$",
+				spans: [][2]int{{2, 3}, {4, 5}},
+			},
+			want: "$$a$b$c$$",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := ninjaEscapeExceptForSpans(tt.args.s, tt.args.spans); got != tt.want {
+				t.Errorf("ninjaEscapeExceptForSpans() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/cc/gen.go b/cc/gen.go
index 7516b28..e5c4194 100644
--- a/cc/gen.go
+++ b/cc/gen.go
@@ -99,7 +99,7 @@
 
 	cmd.Text("BISON_PKGDATADIR=prebuilts/build-tools/common/bison").
 		FlagWithInput("M4=", ctx.Config().PrebuiltBuildTool(ctx, "m4")).
-		Tool(ctx.Config().PrebuiltBuildTool(ctx, "bison")).
+		PrebuiltBuildTool(ctx, "bison").
 		Flag("-d").
 		Flags(flags).
 		FlagWithOutput("--defines=", headerFile).
@@ -121,7 +121,7 @@
 	headerBp := outDir.Join(ctx, aidlPackage, "Bp"+shortName+".h")
 
 	cmd := rule.Command()
-	cmd.Tool(ctx.Config().HostToolPath(ctx, "aidl-cpp")).
+	cmd.BuiltTool(ctx, "aidl-cpp").
 		FlagWithDepFile("-d", depFile).
 		Flag("--ninja").
 		Flag(aidlFlags).
diff --git a/cc/linker.go b/cc/linker.go
index dda2fcb..fa3b0a6 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -483,7 +483,7 @@
 		Input:       in,
 		Output:      out,
 		Args: map[string]string{
-			"buildNumberFromFile": ctx.Config().BuildNumberFromFile(),
+			"buildNumberFromFile": proptools.NinjaEscape(ctx.Config().BuildNumberFromFile()),
 		},
 	})
 }
diff --git a/genrule/genrule.go b/genrule/genrule.go
index b0657ff..411da05 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -284,12 +284,12 @@
 
 	referencedDepfile := false
 
-	rawCommand, err := android.Expand(task.cmd, func(name string) (string, error) {
+	rawCommand, err := android.ExpandNinjaEscaped(task.cmd, func(name string) (string, bool, error) {
 		// report the error directly without returning an error to android.Expand to catch multiple errors in a
 		// single run
-		reportError := func(fmt string, args ...interface{}) (string, error) {
+		reportError := func(fmt string, args ...interface{}) (string, bool, error) {
 			ctx.PropertyErrorf("cmd", fmt, args...)
-			return "SOONG_ERROR", nil
+			return "SOONG_ERROR", false, nil
 		}
 
 		switch name {
@@ -304,19 +304,19 @@
 				return reportError("default label %q has multiple files, use $(locations %s) to reference it",
 					firstLabel, firstLabel)
 			}
-			return locationLabels[firstLabel][0], nil
+			return locationLabels[firstLabel][0], false, nil
 		case "in":
-			return "${in}", nil
+			return "${in}", true, nil
 		case "out":
-			return "__SBOX_OUT_FILES__", nil
+			return "__SBOX_OUT_FILES__", false, nil
 		case "depfile":
 			referencedDepfile = true
 			if !Bool(g.properties.Depfile) {
 				return reportError("$(depfile) used without depfile property")
 			}
-			return "__SBOX_DEPFILE__", nil
+			return "__SBOX_DEPFILE__", false, nil
 		case "genDir":
-			return "__SBOX_OUT_DIR__", nil
+			return "__SBOX_OUT_DIR__", false, nil
 		default:
 			if strings.HasPrefix(name, "location ") {
 				label := strings.TrimSpace(strings.TrimPrefix(name, "location "))
@@ -327,7 +327,7 @@
 						return reportError("label %q has multiple files, use $(locations %s) to reference it",
 							label, label)
 					}
-					return paths[0], nil
+					return paths[0], false, nil
 				} else {
 					return reportError("unknown location label %q", label)
 				}
@@ -337,7 +337,7 @@
 					if len(paths) == 0 {
 						return reportError("label %q has no files", label)
 					}
-					return strings.Join(paths, " "), nil
+					return strings.Join(paths, " "), false, nil
 				} else {
 					return reportError("unknown locations label %q", label)
 				}
diff --git a/java/app.go b/java/app.go
index 3442658..a679e88 100644
--- a/java/app.go
+++ b/java/app.go
@@ -816,7 +816,7 @@
 	rule := android.NewRuleBuilder()
 	rule.Command().
 		Textf(`if (zipinfo %s 'lib/*.so' 2>/dev/null | grep -v ' stor ' >/dev/null) ; then`, inputPath).
-		Tool(ctx.Config().HostToolPath(ctx, "zip2zip")).
+		BuiltTool(ctx, "zip2zip").
 		FlagWithInput("-i ", inputPath).
 		FlagWithOutput("-o ", outputPath).
 		FlagWithArg("-0 ", "'lib/**/*.so'").
@@ -843,7 +843,7 @@
 	rule := android.NewRuleBuilder()
 	rule.Command().
 		Textf(`if (zipinfo %s '*.dex' 2>/dev/null | grep -v ' stor ' >/dev/null) ; then`, inputPath).
-		Tool(ctx.Config().HostToolPath(ctx, "zip2zip")).
+		BuiltTool(ctx, "zip2zip").
 		FlagWithInput("-i ", inputPath).
 		FlagWithOutput("-o ", outputPath).
 		FlagWithArg("-0 ", "'classes*.dex'").
@@ -1067,7 +1067,7 @@
 	outputFile := android.PathForModuleOut(ctx, "manifest_check", "AndroidManifest.xml")
 
 	rule := android.NewRuleBuilder()
-	cmd := rule.Command().Tool(ctx.Config().HostToolPath(ctx, "manifest_check")).
+	cmd := rule.Command().BuiltTool(ctx, "manifest_check").
 		Flag("--enforce-uses-libraries").
 		Input(manifest).
 		FlagWithOutput("-o ", outputFile)
diff --git a/java/dexpreopt_bootjars.go b/java/dexpreopt_bootjars.go
index fe468a9..4ef5bcf 100644
--- a/java/dexpreopt_bootjars.go
+++ b/java/dexpreopt_bootjars.go
@@ -229,7 +229,7 @@
 	if image.zip != nil {
 		rule := android.NewRuleBuilder()
 		rule.Command().
-			Tool(ctx.Config().HostToolPath(ctx, "soong_zip")).
+			BuiltTool(ctx, "soong_zip").
 			FlagWithOutput("-o ", image.zip).
 			FlagWithArg("-C ", image.dir.String()).
 			FlagWithInputList("-f ", allFiles, " -f ")
@@ -438,7 +438,7 @@
 		rule := android.NewRuleBuilder()
 		rule.Command().
 			// TODO: for now, use the debug version for better error reporting
-			Tool(ctx.Config().HostToolPath(ctx, "oatdumpd")).
+			BuiltTool(ctx, "oatdumpd").
 			FlagWithInputList("--runtime-arg -Xbootclasspath:", image.dexPaths.Paths(), ":").
 			FlagWithList("--runtime-arg -Xbootclasspath-locations:", image.dexLocations, ":").
 			FlagWithArg("--image=", dexpreopt.PathToLocation(image.images[arch], arch)).Implicit(image.images[arch]).
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 25101de..ae810e1 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -500,6 +500,7 @@
 	}
 }
 
+// javadoc converts .java source files to documentation using javadoc.
 func JavadocFactory() android.Module {
 	module := &Javadoc{}
 
@@ -509,6 +510,7 @@
 	return module
 }
 
+// javadoc_host converts .java source files to documentation using javadoc.
 func JavadocHostFactory() android.Module {
 	module := &Javadoc{}
 
@@ -798,7 +800,7 @@
 			"srcJarDir":         android.PathForModuleOut(ctx, "srcjars").String(),
 			"stubsDir":          android.PathForModuleOut(ctx, "stubsDir").String(),
 			"srcJars":           strings.Join(j.srcJars.Strings(), " "),
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"bootclasspathArgs": bootClasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
@@ -831,6 +833,7 @@
 	apiFilePath android.Path
 }
 
+// droiddoc converts .java source files to documentation using doclava or dokka.
 func DroiddocFactory() android.Module {
 	module := &Droiddoc{}
 
@@ -841,6 +844,7 @@
 	return module
 }
 
+// droiddoc_host converts .java source files to documentation using doclava or dokka.
 func DroiddocHostFactory() android.Module {
 	module := &Droiddoc{}
 
@@ -918,7 +922,7 @@
 	args := " -source 1.8 -J-Xmx1600m -J-XX:-OmitStackTraceInFastThrow -XDignore.symbol.file " +
 		"-doclet com.google.doclava.Doclava -docletpath " + jsilver.String() + ":" + doclava.String() + " " +
 		"-hdf page.build " + ctx.Config().BuildId() + "-" + ctx.Config().BuildNumberFromFile() + " " +
-		`-hdf page.now "$$(` + date + ` @$$(cat ` + ctx.Config().Getenv("BUILD_DATETIME_FILE") + `) "+%d %b %Y %k:%M")" `
+		`-hdf page.now "$(` + date + ` @$(cat ` + ctx.Config().Getenv("BUILD_DATETIME_FILE") + `) "+%d %b %Y %k:%M")" `
 
 	if String(d.properties.Custom_template) == "" {
 		// TODO: This is almost always droiddoc-templates-sdk
@@ -1095,7 +1099,7 @@
 			"srcJarDir":         android.PathForModuleOut(ctx, "srcjars").String(),
 			"stubsDir":          android.PathForModuleOut(ctx, "stubsDir").String(),
 			"srcJars":           strings.Join(d.Javadoc.srcJars.Strings(), " "),
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
@@ -1117,7 +1121,7 @@
 		Args: map[string]string{
 			"msg":                   msg,
 			"classpath":             checkApiClasspath.FormJavaClassPath(""),
-			"opts":                  opts,
+			"opts":                  proptools.NinjaEscape(opts),
 			"apiFile":               apiFile.String(),
 			"apiFileToCheck":        d.apiFile.String(),
 			"removedApiFile":        removedApiFile.String(),
@@ -1140,7 +1144,7 @@
 			"stubsDir":      android.PathForModuleOut(ctx, "dokka-stubsDir").String(),
 			"srcJars":       strings.Join(d.Javadoc.srcJars.Strings(), " "),
 			"classpathArgs": classpathArgs,
-			"opts":          opts,
+			"opts":          proptools.NinjaEscape(opts),
 			"docZip":        d.Javadoc.docZip.String(),
 		},
 	})
@@ -1258,6 +1262,9 @@
 	jdiffStubsSrcJar android.WritablePath
 }
 
+// droidstubs passes sources files through Metalava to generate stub .java files that only contain the API to be
+// documented, filtering out hidden classes and methods.  The resulting .java files are intended to be passed to
+// a droiddoc module to generate documentation.
 func DroidstubsFactory() android.Module {
 	module := &Droidstubs{}
 
@@ -1268,6 +1275,10 @@
 	return module
 }
 
+// droidstubs_host passes sources files through Metalava to generate stub .java files that only contain the API
+// to be documented, filtering out hidden classes and methods.  The resulting .java files are intended to be
+// passed to a droiddoc_host module to generate documentation.  Use a droidstubs_host instead of a droidstubs
+// module when symbols needed by the source files are provided by java_library_host modules.
 func DroidstubsHostFactory() android.Module {
 	module := &Droidstubs{}
 
@@ -1558,7 +1569,7 @@
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 		},
 	})
 }
@@ -1581,7 +1592,7 @@
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"msg":               msg,
 		},
 	})
@@ -1602,7 +1613,7 @@
 			"srcJarDir":         android.PathForModuleOut(ctx, "jdiff-srcjars").String(),
 			"stubsDir":          android.PathForModuleOut(ctx, "jdiff-stubsDir").String(),
 			"srcJars":           strings.Join(d.Javadoc.srcJars.Strings(), " "),
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
@@ -1781,6 +1792,7 @@
 	dir  android.Path
 }
 
+// droiddoc_exported_dir exports a directory of html templates or nullability annotations for use by doclava.
 func ExportedDroiddocDirFactory() android.Module {
 	module := &ExportedDroiddocDir{}
 	module.AddProperties(&module.properties)
diff --git a/java/java.go b/java/java.go
index f9ec27e..a49aad7 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2088,14 +2088,14 @@
 
 		// use zip2zip to uncompress classes*.dex files
 		rule.Command().
-			Tool(ctx.Config().HostToolPath(ctx, "zip2zip")).
+			BuiltTool(ctx, "zip2zip").
 			FlagWithInput("-i ", inputJar).
 			FlagWithOutput("-o ", temporary).
 			FlagWithArg("-0 ", "'classes*.dex'")
 
 		// use zipalign to align uncompressed classes*.dex files
 		rule.Command().
-			Tool(ctx.Config().HostToolPath(ctx, "zipalign")).
+			BuiltTool(ctx, "zipalign").
 			Flag("-f").
 			Text("4").
 			Input(temporary).
diff --git a/java/proto.go b/java/proto.go
index 37de1d2..0ec6499 100644
--- a/java/proto.go
+++ b/java/proto.go
@@ -34,7 +34,7 @@
 	// Proto generated java files have an unknown package name in the path, so package the entire output directory
 	// into a srcjar.
 	rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "soong_zip")).
+		BuiltTool(ctx, "soong_zip").
 		Flag("-jar").
 		FlagWithOutput("-o ", srcJarFile).
 		FlagWithArg("-C ", outDir.String()).
diff --git a/java/sdk.go b/java/sdk.go
index 7b79a49..d1e2ae4 100644
--- a/java/sdk.go
+++ b/java/sdk.go
@@ -296,7 +296,7 @@
 			rule.Command().
 				Text("rm -f").Output(aidl)
 			rule.Command().
-				Tool(ctx.Config().HostToolPath(ctx, "sdkparcelables")).
+				BuiltTool(ctx, "sdkparcelables").
 				Input(jar).
 				Output(aidl)
 
diff --git a/python/proto.go b/python/proto.go
index 85ed1a5..b71e047 100644
--- a/python/proto.go
+++ b/python/proto.go
@@ -34,7 +34,7 @@
 	// Proto generated python files have an unknown package name in the path, so package the entire output directory
 	// into a srcszip.
 	zipCmd := rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "soong_zip")).
+		BuiltTool(ctx, "soong_zip").
 		FlagWithOutput("-o ", srcsZipFile)
 	if pkgPath != "" {
 		zipCmd.FlagWithArg("-P ", pkgPath)
diff --git a/scripts/jar-wrapper.sh b/scripts/jar-wrapper.sh
index 71c1d90..b468041 100644
--- a/scripts/jar-wrapper.sh
+++ b/scripts/jar-wrapper.sh
@@ -48,11 +48,11 @@
     exit 1
 fi
 
-javaOpts=""
+declare -a javaOpts=()
 while expr "x$1" : 'x-J' >/dev/null; do
-    opt=`expr "$1" : '-J\(.*\)'`
-    javaOpts="${javaOpts} -${opt}"
+    opt=`expr "$1" : '-J-\{0,1\}\(.*\)'`
+    javaOpts+=("-${opt}")
     shift
 done
 
-exec java ${javaOpts} -jar ${jardir}/${jarfile} "$@"
+exec java "${javaOpts[@]}" -jar ${jardir}/${jarfile} "$@"