Add prebuilt ELF binaries checker
This commit introduces a prebuilt ELF binaries checker. The checker
will check:
1. Whether all DT_NEEDED shared libraries are specified in
`shared_libs` (Android.bp) or `LOCAL_SHARED_LIBRARIES` (Android.mk).
2. Whether all undefined symbols in the prebuilt binary can be resolved
to defined symbols exported by its dependencies.
This ensures that prebuilt binaries won't silently become ABI
incompatible.
To check the prebuilt binaries, all of the dependencies must be
specified in `shared_libs` (Android.bp) or `LOCAL_SHARED_LIBRARIES`
(Android.mk).
If your prebuilt binaries cannot be checked for some reason, you may add
the following property to Android.bp:
check_elf_files: false,
Or, add the following setting to Android.mk:
LOCAL_CHECK_ELF_FILES := false
Bug: 119084334
Test: CHECK_ELF_FILES=true make check-elf-files
Change-Id: I523d3083f22fd4053c096d26f61f8375800281c8
diff --git a/core/check_elf_file.mk b/core/check_elf_file.mk
new file mode 100644
index 0000000..69d891c
--- /dev/null
+++ b/core/check_elf_file.mk
@@ -0,0 +1,45 @@
+# Check the correctness of the prebuilt ELF files
+#
+# This check ensures that DT_SONAME matches with the filename, DT_NEEDED
+# matches the shared libraries specified in LOCAL_SHARED_LIBRARIES, and all
+# undefined symbols in the prebuilt binary can be found in one of the shared
+# libraries specified in LOCAL_SHARED_LIBRARIES.
+#
+# Inputs:
+# - LOCAL_ALLOW_UNDEFINED_SYMBOLS
+# - LOCAL_BUILT_MODULE
+# - LOCAL_IS_HOST_MODULE
+# - LOCAL_MODULE_CLASS
+# - intermediates
+# - my_installed_module_stem
+# - my_prebuilt_src_file
+
+ifndef LOCAL_IS_HOST_MODULE
+ifneq ($(filter $(LOCAL_MODULE_CLASS),SHARED_LIBRARIES EXECUTABLES NATIVE_TESTS),)
+check_elf_files_stamp := $(intermediates)/check_elf_files.timestamp
+$(check_elf_files_stamp): PRIVATE_SONAME := $(if $(filter $(LOCAL_MODULE_CLASS),SHARED_LIBRARIES),$(my_installed_module_stem))
+$(check_elf_files_stamp): PRIVATE_ALLOW_UNDEFINED_SYMBOLS := $(LOCAL_ALLOW_UNDEFINED_SYMBOLS)
+$(check_elf_files_stamp): PRIVATE_SHARED_LIBRARY_FILES := # This variable will be set by `core/main.mk`
+$(check_elf_files_stamp): $(my_prebuilt_src_file) $(CHECK_ELF_FILE) $(LLVM_READOBJ)
+ @echo Check prebuilt ELF binary: $<
+ $(hide) mkdir -p $(dir $@)
+ $(hide) rm -f $@
+ $(hide) $(CHECK_ELF_FILE) \
+ --skip-bad-elf-magic \
+ --skip-unknown-elf-machine \
+ $(if $(PRIVATE_SONAME),--soname $(PRIVATE_SONAME)) \
+ $(foreach l,$(PRIVATE_SHARED_LIBRARY_FILES),--shared-lib $(l)) \
+ $(if $(PRIVATE_ALLOW_UNDEFINED_SYMBOLS),--allow-undefined-symbols) \
+ --llvm-readobj=$(LLVM_READOBJ) \
+ $<
+ $(hide) touch $@
+
+ifneq ($(PRODUCT_CHECK_ELF_FILES)$(CHECK_ELF_FILES),)
+ifneq ($(LOCAL_CHECK_ELF_FILES),false)
+$(LOCAL_BUILT_MODULE): $(check_elf_files_stamp)
+check-elf-files: $(check_elf_files_stamp)
+endif # LOCAL_CHECK_ELF_FILES
+endif # PRODUCT_CHECK_ELF_FILES or CHECK_ELF_FILES
+
+endif # SHARED_LIBRARIES, EXECUTABLES, NATIVE_TESTS
+endif # !LOCAL_IS_HOST_MODULE