Makefile: make unstripped libtailscale and debug symbols

- Added Makefile targets to build an unstripped version of the libtailscale AAR.
- Extracted the native .so (libgojni.so) from the unstripped AAR.
- Generated a debug symbols file (libgojni.so.debug) using llvm-objcopy with --only-keep-debug.
- Stripped the native library (libgojni.so.stripped) with --strip-debug and repackaged the final AAR.

This allows the build chain to produce a stripped AAR for the app and a separate debug symbols file that can be uploaded to Google Play for crash deobfuscation.

Signed-off-by: kari-ts <[email protected]>
Updates tailscale/tailscale#15210

Author: kari-ts

.gitignore

@@ -35,6 +35,13 @@ tailscale.jks
 .vscode
 .idea
 
+# Native libraries
+*.stripped
+*.unstripped
+
+# Debug symbols
+*.debug
+
 libtailscale.aar
 libtailscale-sources.jar
 .DS_Store

Makefile

@@ -14,7 +14,7 @@ DOCKER_IMAGE=tailscale-android-build-amd64-191124
 export TS_USE_TOOLCHAIN=1
 
 NDK_ROOT := $(ANDROID_HOME)/ndk/23.1.7779620
-STRIP_TOOL := $(NDK_ROOT)/toolchains/llvm/prebuilt/darwin-x86_64/bin/llvm-strip
+STRIP_TOOL := $(NDK_ROOT)/toolchains/llvm/prebuilt/darwin-x86_64/bin/llvm-objcopy
 
 DEBUG_APK=tailscale-debug.apk
 RELEASE_AAB=tailscale-release.aab
@@ -151,22 +151,51 @@ $(GOBIN)/gomobile: $(GOBIN)/gobind go.mod go.sum
 $(GOBIN)/gobind: go.mod go.sum
 	./tool/go install golang.org/x/mobile/cmd/gobind
 
-# Build the unstripped version with full debug symbols.
-$(UNSTRIPPED_LIB): Makefile android/libs $(shell find libtailscale -name *.go) go.mod go.sum $(GOBIN)/gomobile tailscale.version
+LIBTAILSCALE_AAR := android/libs/libtailscale.aar
+UNSTRIPPED_AAR := android/libs/libtailscale_unstripped.aar
+ARM64_SO_PATH := jni/arm64-v8a/libgojni.so
+
+# Build the unstripped AAR.
+$(UNSTRIPPED_AAR): Makefile android/libs $(shell find libtailscale -name *.go) go.mod go.sum $(GOBIN)/gomobile tailscale.version
 	$(GOBIN)/gomobile bind -target android -androidapi 26 \
 		-tags "$$(./build-tags.sh)" \
 		-ldflags "$$(./version-ldflags.sh)" \
 		-o $@ ./libtailscale
 
-# Generate the final library by extracting debug symbols and stripping them.
-$(LIBTAILSCALE): $(UNSTRIPPED_LIB)
-	@echo "Extracting debug symbols from $<..."
-	$(STRIP_TOOL) --only-keep-debug $< -o $@.debug
-	@echo "Stripping debug symbols from $<..."
-	$(STRIP_TOOL) --strip-debug $< -o $@
+# Extract the .so file from the unstripped AAR.
+libgojni.so.unstripped:
+	@echo "Extracting libgojni.so from unstripped AAR..."
+	unzip -p $(UNSTRIPPED_AAR) "$(ARM64_SO_PATH)" > libgojni.so.unstripped
+
+# Generate the debug symbol file from the extracted .so file.
+libgojni.so.debug: libgojni.so.unstripped
+	@echo "Extracting debug symbols from libgojni.so..."
+	$(STRIP_TOOL) --only-keep-debug libgojni.so.unstripped libgojni.so.debug
+
+# Generate the stripped .so file from the extracted file.
+libgojni.so.stripped: libgojni.so.unstripped
+	@echo "Stripping debug symbols from libgojni.so..."
+	$(STRIP_TOOL) --strip-debug libgojni.so.unstripped libgojni.so.stripped
+
+# Repackage the AAR with the stripped .so file.
+$(LIBTAILSCALE_AAR): libgojni.so.stripped $(UNSTRIPPED_AAR)
+	@echo "Repackaging AAR with stripped libgojni.so..."
+	rm -rf temp_aar
+	mkdir temp_aar
+	unzip $(UNSTRIPPED_AAR) -d temp_aar
+	cp libgojni.so.stripped temp_aar/$(ARM64_SO_PATH)
+	(cd temp_aar && zip -r ../$(LIBTAILSCALE_AAR) .)
+	rm -rf temp_aar
 
 .PHONY: libtailscale
-libtailscale: $(LIBTAILSCALE) ## Build the libtailscale AAR
+libtailscale: $(LIBTAILSCALE_AAR) ## Build the stripped libtailscale AAR
+
+.PHONY: debug-symbols
+debug-symbols: libgojni.so.debug
+
+.PHONY: all
+all: libtailscale debug-symbols
+	@echo "Build complete: Stripped AAR is $(LIBTAILSCALE_AAR) and debug symbols are in libgojni.so.debug"
 
 #
 # Utility tasks:
@@ -207,7 +236,7 @@ androidpath:
 	@echo 'export PATH=$(ANDROID_HOME)/cmdline-tools/latest/bin:$(ANDROID_HOME)/platform-tools:$$PATH'
 
 .PHONY: tag_release
-tag_release: tailscale.version ## Tag the current commit with the current version
+tag_release: debug-symbols tailscale.version ## Tag the current commit with the current version and generate debug symbols
 	source tailscale.version && git tag -a "$${VERSION_LONG}" -m "OSS and Version updated to $${VERSION_LONG}"