Merge "NDK library: collect NDK headers for ABI monitoring" into main
diff --git a/cc/ndk_headers.go b/cc/ndk_headers.go
index d0ae4a5..1a8e90f 100644
--- a/cc/ndk_headers.go
+++ b/cc/ndk_headers.go
@@ -82,6 +82,7 @@
 
 	properties headerProperties
 
+	srcPaths     android.Paths
 	installPaths android.Paths
 	licensePath  android.Path
 }
@@ -125,8 +126,8 @@
 
 	m.licensePath = android.PathForModuleSrc(ctx, String(m.properties.License))
 
-	srcFiles := android.PathsForModuleSrcExcludes(ctx, m.properties.Srcs, m.properties.Exclude_srcs)
-	for _, header := range srcFiles {
+	m.srcPaths = android.PathsForModuleSrcExcludes(ctx, m.properties.Srcs, m.properties.Exclude_srcs)
+	for _, header := range m.srcPaths {
 		installDir := getHeaderInstallDir(ctx, header, String(m.properties.From),
 			String(m.properties.To))
 		installedPath := ctx.InstallFile(installDir, header.Base(), header)
@@ -193,6 +194,7 @@
 
 	properties versionedHeaderProperties
 
+	srcPaths     android.Paths
 	installPaths android.Paths
 	licensePath  android.Path
 }
@@ -211,9 +213,9 @@
 
 	fromSrcPath := android.PathForModuleSrc(ctx, String(m.properties.From))
 	toOutputPath := getCurrentIncludePath(ctx).Join(ctx, String(m.properties.To))
-	srcFiles := ctx.GlobFiles(headerGlobPattern(fromSrcPath.String()), nil)
+	m.srcPaths = ctx.GlobFiles(headerGlobPattern(fromSrcPath.String()), nil)
 	var installPaths []android.WritablePath
-	for _, header := range srcFiles {
+	for _, header := range m.srcPaths {
 		installDir := getHeaderInstallDir(ctx, header, String(m.properties.From), String(m.properties.To))
 		installPath := installDir.Join(ctx, header.Base())
 		installPaths = append(installPaths, installPath)
@@ -224,11 +226,11 @@
 		ctx.ModuleErrorf("glob %q matched zero files", String(m.properties.From))
 	}
 
-	processHeadersWithVersioner(ctx, fromSrcPath, toOutputPath, srcFiles, installPaths)
+	processHeadersWithVersioner(ctx, fromSrcPath, toOutputPath, m.srcPaths, installPaths)
 }
 
 func processHeadersWithVersioner(ctx android.ModuleContext, srcDir, outDir android.Path,
-	srcFiles android.Paths, installPaths []android.WritablePath) android.Path {
+	srcPaths android.Paths, installPaths []android.WritablePath) android.Path {
 	// The versioner depends on a dependencies directory to simplify determining include paths
 	// when parsing headers. This directory contains architecture specific directories as well
 	// as a common directory, each of which contains symlinks to the actually directories to
@@ -253,7 +255,7 @@
 		Rule:            versionBionicHeaders,
 		Description:     "versioner preprocess " + srcDir.Rel(),
 		Output:          timestampFile,
-		Implicits:       append(srcFiles, depsGlob...),
+		Implicits:       append(srcPaths, depsGlob...),
 		ImplicitOutputs: installPaths,
 		Args: map[string]string{
 			"depsPath": depsPath.String(),
@@ -317,6 +319,7 @@
 
 	properties preprocessedHeadersProperties
 
+	srcPaths     android.Paths
 	installPaths android.Paths
 	licensePath  android.Path
 }
@@ -329,9 +332,9 @@
 	preprocessor := android.PathForModuleSrc(ctx, String(m.properties.Preprocessor))
 	m.licensePath = android.PathForModuleSrc(ctx, String(m.properties.License))
 
-	srcFiles := android.PathsForModuleSrcExcludes(ctx, m.properties.Srcs, m.properties.Exclude_srcs)
+	m.srcPaths = android.PathsForModuleSrcExcludes(ctx, m.properties.Srcs, m.properties.Exclude_srcs)
 	installDir := getCurrentIncludePath(ctx).Join(ctx, String(m.properties.To))
-	for _, src := range srcFiles {
+	for _, src := range m.srcPaths {
 		installPath := installDir.Join(ctx, src.Base())
 		m.installPaths = append(m.installPaths, installPath)
 
diff --git a/cc/ndk_library.go b/cc/ndk_library.go
index 9281aeb..b201dd8 100644
--- a/cc/ndk_library.go
+++ b/cc/ndk_library.go
@@ -43,11 +43,17 @@
 			CommandDeps: []string{"$ndkStubGenerator"},
 		}, "arch", "apiLevel", "apiMap", "flags")
 
+	// $headersList should include paths to public headers. All types
+	// that are defined outside of public headers will be excluded from
+	// ABI monitoring.
+	//
+	// STG tool doesn't access content of files listed in $headersList,
+	// so there is no need to add them to dependencies.
 	stg = pctx.AndroidStaticRule("stg",
 		blueprint.RuleParams{
-			Command:     "$stg -S :$symbolList --elf $in -o $out",
+			Command:     "$stg -S :$symbolList --file-filter :$headersList --elf $in -o $out",
 			CommandDeps: []string{"$stg"},
-		}, "symbolList")
+		}, "symbolList", "headersList")
 
 	stgdiff = pctx.AndroidStaticRule("stgdiff",
 		blueprint.RuleParams{
@@ -347,14 +353,19 @@
 	this.abiDumpPath = getNdkAbiDumpInstallBase(ctx).Join(ctx,
 		this.apiLevel.String(), ctx.Arch().ArchType.String(),
 		this.libraryName(ctx), "abi.stg")
+	headersList := getNdkABIHeadersFile(ctx)
 	ctx.Build(pctx, android.BuildParams{
 		Rule:        stg,
 		Description: fmt.Sprintf("stg %s", implementationLibrary),
 		Input:       implementationLibrary,
-		Implicit:    symbolList,
-		Output:      this.abiDumpPath,
+		Implicits: []android.Path{
+			symbolList,
+			headersList,
+		},
+		Output: this.abiDumpPath,
 		Args: map[string]string{
-			"symbolList": symbolList.String(),
+			"symbolList":  symbolList.String(),
+			"headersList": headersList.String(),
 		},
 	})
 }
diff --git a/cc/ndk_sysroot.go b/cc/ndk_sysroot.go
index feb3880..9ec2ae4 100644
--- a/cc/ndk_sysroot.go
+++ b/cc/ndk_sysroot.go
@@ -54,6 +54,7 @@
 
 import (
 	"android/soong/android"
+	"strings"
 )
 
 func init() {
@@ -96,15 +97,56 @@
 	return android.PathForOutput(ctx, "ndk.timestamp")
 }
 
+// The list of all NDK headers as they are located in the repo.
+// Used for ABI monitoring to track only structures defined in NDK headers.
+func getNdkABIHeadersFile(ctx android.PathContext) android.WritablePath {
+	return android.PathForOutput(ctx, "ndk_abi_headers.txt")
+}
+
 func NdkSingleton() android.Singleton {
 	return &ndkSingleton{}
 }
 
+// Collect all NDK exported headers paths into a file that is used to
+// detect public types that should be ABI monitored.
+//
+// Assume that we have the following code in exported header:
+//
+//	typedef struct Context Context;
+//	typedef struct Output {
+//	    ...
+//	} Output;
+//	void DoSomething(Context* ctx, Output* output);
+//
+// If none of public headers exported to end-users contain definition of
+// "struct Context", then "struct Context" layout and members shouldn't be
+// monitored. However we use DWARF information from a real library, which
+// may have access to the definition of "string Context" from
+// implementation headers, and it will leak to ABI.
+//
+// STG tool doesn't access source and header files, only DWARF information
+// from compiled library. And the DWARF contains file name where a type is
+// defined. So we need a rule to build a list of paths to public headers,
+// so STG can distinguish private types from public and do not monitor
+// private types that are not accessible to library users.
+func writeNdkAbiSrcFilter(ctx android.BuilderContext,
+	headerSrcPaths android.Paths, outputFile android.WritablePath) {
+	var filterBuilder strings.Builder
+	filterBuilder.WriteString("[decl_file_allowlist]\n")
+	for _, headerSrcPath := range headerSrcPaths {
+		filterBuilder.WriteString(headerSrcPath.String())
+		filterBuilder.WriteString("\n")
+	}
+
+	android.WriteFileRule(ctx, outputFile, filterBuilder.String())
+}
+
 type ndkSingleton struct{}
 
 func (n *ndkSingleton) GenerateBuildActions(ctx android.SingletonContext) {
 	var staticLibInstallPaths android.Paths
-	var headerPaths android.Paths
+	var headerSrcPaths android.Paths
+	var headerInstallPaths android.Paths
 	var installPaths android.Paths
 	var licensePaths android.Paths
 	ctx.VisitAllModules(func(module android.Module) {
@@ -113,19 +155,22 @@
 		}
 
 		if m, ok := module.(*headerModule); ok {
-			headerPaths = append(headerPaths, m.installPaths...)
+			headerSrcPaths = append(headerSrcPaths, m.srcPaths...)
+			headerInstallPaths = append(headerInstallPaths, m.installPaths...)
 			installPaths = append(installPaths, m.installPaths...)
 			licensePaths = append(licensePaths, m.licensePath)
 		}
 
 		if m, ok := module.(*versionedHeaderModule); ok {
-			headerPaths = append(headerPaths, m.installPaths...)
+			headerSrcPaths = append(headerSrcPaths, m.srcPaths...)
+			headerInstallPaths = append(headerInstallPaths, m.installPaths...)
 			installPaths = append(installPaths, m.installPaths...)
 			licensePaths = append(licensePaths, m.licensePath)
 		}
 
 		if m, ok := module.(*preprocessedHeadersModule); ok {
-			headerPaths = append(headerPaths, m.installPaths...)
+			headerSrcPaths = append(headerSrcPaths, m.srcPaths...)
+			headerInstallPaths = append(headerInstallPaths, m.installPaths...)
 			installPaths = append(installPaths, m.installPaths...)
 			licensePaths = append(licensePaths, m.licensePath)
 		}
@@ -175,9 +220,11 @@
 	ctx.Build(pctx, android.BuildParams{
 		Rule:      android.Touch,
 		Output:    getNdkHeadersTimestampFile(ctx),
-		Implicits: headerPaths,
+		Implicits: headerInstallPaths,
 	})
 
+	writeNdkAbiSrcFilter(ctx, headerSrcPaths, getNdkABIHeadersFile(ctx))
+
 	fullDepPaths := append(staticLibInstallPaths, getNdkBaseTimestampFile(ctx))
 
 	// There's a phony "ndk" rule defined in core/main.mk that depends on this.