Merge "Add $(build_number_file) support to genrules" into main
diff --git a/android/rule_builder.go b/android/rule_builder.go
index 8b03124..464aca4 100644
--- a/android/rule_builder.go
+++ b/android/rule_builder.go
@@ -554,6 +554,12 @@
 					To:   proto.String(r.sboxPathForInputRel(input)),
 				})
 			}
+			for _, input := range r.OrderOnlys() {
+				command.CopyBefore = append(command.CopyBefore, &sbox_proto.Copy{
+					From: proto.String(input.String()),
+					To:   proto.String(r.sboxPathForInputRel(input)),
+				})
+			}
 
 			// If using rsp files copy them and their contents into the sbox directory with
 			// the appropriate path mappings.
diff --git a/genrule/genrule.go b/genrule/genrule.go
index 2557922..9195643 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -147,6 +147,21 @@
 
 	// Enable restat to update the output only if the output is changed
 	Write_if_changed *bool
+
+	// When set to true, an additional $(build_number_file) label will be available
+	// to use in the cmd. This will be the location of a text file containing the
+	// build number. The dependency on this file will be "order-only", meaning that
+	// the genrule will not rerun when only this file changes, to avoid rerunning
+	// the genrule every build, because the build number changes every build.
+	// This also means that you should not attempt to consume the build number from
+	// the result of this genrule in another build rule. If you do, the build number
+	// in the second build rule will be stale when the second build rule rebuilds
+	// but this genrule does not. Only certain allowlisted modules are allowed to
+	// use this property, usages of the build number should be kept to the absolute
+	// minimum. Particularly no modules on the system image may include the build
+	// number. Prefer using libbuildversion via the use_version_lib property on
+	// cc modules.
+	Uses_order_only_build_number_file *bool
 }
 
 type Module struct {
@@ -228,6 +243,15 @@
 	}
 }
 
+// This allowlist should be kept to the bare minimum, it's
+// intended for things that existed before the build number
+// was tightly controlled. Prefer using libbuildversion
+// via the use_version_lib property of cc modules.
+var genrule_build_number_allowlist = map[string]bool{
+	"build/soong/tests:gen":                   true,
+	"tools/tradefederation/core:tradefed_zip": true,
+}
+
 // generateCommonBuildActions contains build action generation logic
 // common to both the mixed build case and the legacy case of genrule processing.
 // To fully support genrule in mixed builds, the contents of this function should
@@ -470,6 +494,11 @@
 				return strings.Join(proptools.ShellEscapeList(sandboxOuts), " "), nil
 			case "genDir":
 				return proptools.ShellEscape(cmd.PathForOutput(task.genDir)), nil
+			case "build_number_file":
+				if !proptools.Bool(g.properties.Uses_order_only_build_number_file) {
+					return reportError("to use the $(build_number_file) label, you must set uses_order_only_build_number_file: true")
+				}
+				return proptools.ShellEscape(cmd.PathForInput(ctx.Config().BuildNumberFile(ctx))), nil
 			default:
 				if strings.HasPrefix(name, "location ") {
 					label := strings.TrimSpace(strings.TrimPrefix(name, "location "))
@@ -516,6 +545,12 @@
 		cmd.Implicits(task.in)
 		cmd.ImplicitTools(tools)
 		cmd.ImplicitPackagedTools(packagedTools)
+		if proptools.Bool(g.properties.Uses_order_only_build_number_file) {
+			if _, ok := genrule_build_number_allowlist[ctx.ModuleDir()+":"+ctx.ModuleName()]; !ok {
+				ctx.ModuleErrorf("Only allowlisted modules may use uses_order_only_build_number_file: true")
+			}
+			cmd.OrderOnly(ctx.Config().BuildNumberFile(ctx))
+		}
 
 		// Create the rule to run the genrule command inside sbox.
 		rule.Build(name, desc)
diff --git a/genrule/genrule_test.go b/genrule/genrule_test.go
index 444aedb..9278f15 100644
--- a/genrule/genrule_test.go
+++ b/genrule/genrule_test.go
@@ -19,6 +19,7 @@
 	"os"
 	"regexp"
 	"strconv"
+	"strings"
 	"testing"
 
 	"android/soong/android"
@@ -1192,6 +1193,68 @@
 	}
 }
 
+func TestGenruleUsesOrderOnlyBuildNumberFile(t *testing.T) {
+	testCases := []struct {
+		name            string
+		bp              string
+		fs              android.MockFS
+		expectedError   string
+		expectedCommand string
+	}{
+		{
+			name: "not allowed when not in allowlist",
+			fs: android.MockFS{
+				"foo/Android.bp": []byte(`
+genrule {
+	name: "gen",
+	uses_order_only_build_number_file: true,
+	cmd: "cp $(build_number_file) $(out)",
+	out: ["out.txt"],
+}
+`),
+			},
+			expectedError: `Only allowlisted modules may use uses_order_only_build_number_file: true`,
+		},
+		{
+			name: "normal",
+			fs: android.MockFS{
+				"build/soong/tests/Android.bp": []byte(`
+genrule {
+	name: "gen",
+	uses_order_only_build_number_file: true,
+	cmd: "cp $(build_number_file) $(out)",
+	out: ["out.txt"],
+}
+`),
+			},
+			expectedCommand: `cp BUILD_NUMBER_FILE __SBOX_SANDBOX_DIR__/out/out.txt`,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			fixtures := android.GroupFixturePreparers(
+				prepareForGenRuleTest,
+				android.PrepareForTestWithVisibility,
+				android.FixtureMergeMockFs(tc.fs),
+				android.FixtureModifyConfigAndContext(func(config android.Config, ctx *android.TestContext) {
+					config.TestProductVariables.BuildNumberFile = proptools.StringPtr("build_number.txt")
+				}),
+			)
+			if tc.expectedError != "" {
+				fixtures = fixtures.ExtendWithErrorHandler(android.FixtureExpectsOneErrorPattern(tc.expectedError))
+			}
+			result := fixtures.RunTest(t)
+
+			if tc.expectedError == "" {
+				tc.expectedCommand = strings.ReplaceAll(tc.expectedCommand, "BUILD_NUMBER_FILE", result.Config.SoongOutDir()+"/build_number.txt")
+				gen := result.Module("gen", "").(*Module)
+				android.AssertStringEquals(t, "raw commands", tc.expectedCommand, gen.rawCommands[0])
+			}
+		})
+	}
+}
+
 type testTool struct {
 	android.ModuleBase
 	outputFile android.Path