From 751a987bccc252b5b8855124d8a37cb660ead463 Mon Sep 17 00:00:00 2001
From: Logan Chien <loganchien@google.com>
Date: Mon, 16 Dec 2019 15:55:16 -0800
Subject: [PATCH] Exclude system shared libs from fix suggestion

This commit removes system shared libs (e.g. libc, libdl, or libm) from
the prebuilt ELF check fix suggestion.

Bug: 141925662
Test: Write a bad Android.mk module and check fix suggestions
Change-Id: I4a827d07b24a976c1910b814126790abbeccc793
---
 core/check_elf_file.mk  |  3 +++
 tools/check_elf_file.py | 14 ++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/core/check_elf_file.mk b/core/check_elf_file.mk
index d54a5b70b..b5be81f9d 100644
--- a/core/check_elf_file.mk
+++ b/core/check_elf_file.mk
@@ -14,12 +14,14 @@
 # - my_installed_module_stem
 # - my_prebuilt_src_file
 # - my_check_elf_file_shared_lib_files
+# - my_system_shared_libraries
 
 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_SYSTEM_SHARED_LIBRARIES := $(my_system_shared_libraries)
 # PRIVATE_SHARED_LIBRARY_FILES are file paths to built shared libraries.
 # In addition to $(my_check_elf_file_shared_lib_files), some file paths are
 # added by `resolve-shared-libs-for-elf-file-check` from `core/main.mk`.
@@ -33,6 +35,7 @@ $(check_elf_files_stamp): $(my_prebuilt_src_file) $(my_check_elf_file_shared_lib
 	    --skip-unknown-elf-machine \
 	    $(if $(PRIVATE_SONAME),--soname $(PRIVATE_SONAME)) \
 	    $(foreach l,$(PRIVATE_SHARED_LIBRARY_FILES),--shared-lib $(l)) \
+	    $(foreach l,$(PRIVATE_SYSTEM_SHARED_LIBRARIES),--system-shared-lib $(l)) \
 	    $(if $(PRIVATE_ALLOW_UNDEFINED_SYMBOLS),--allow-undefined-symbols) \
 	    --llvm-readobj=$(LLVM_READOBJ) \
 	    $<
diff --git a/tools/check_elf_file.py b/tools/check_elf_file.py
index 372404b90..ca2b93fda 100755
--- a/tools/check_elf_file.py
+++ b/tools/check_elf_file.py
@@ -397,7 +397,7 @@ class Checker(object):
       sys.exit(2)
 
 
-  def check_dt_needed(self):
+  def check_dt_needed(self, system_shared_lib_names):
     """Check whether all DT_NEEDED entries are specified in the build
     system."""
 
@@ -417,6 +417,11 @@ class Checker(object):
       dt_needed = sorted(set(self._file_under_test.dt_needed))
       modules = [re.sub('\\.so$', '', lib) for lib in dt_needed]
 
+      # Remove system shared libraries from the suggestion since they are added
+      # by default.
+      modules = [name for name in modules
+                 if name not in system_shared_lib_names]
+
       self._note()
       self._note('Fix suggestions:')
       self._note(
@@ -502,6 +507,11 @@ def _parse_args():
   parser.add_argument('--shared-lib', action='append', default=[],
                       help='Path to shared library dependencies')
 
+  # System Shared library names
+  parser.add_argument('--system-shared-lib', action='append', default=[],
+                      help='System shared libraries to be hidden from fix '
+                      'suggestions')
+
   # Check options
   parser.add_argument('--skip-bad-elf-magic', action='store_true',
                       help='Ignore the input file without the ELF magic word')
@@ -535,7 +545,7 @@ def main():
   if args.soname:
     checker.check_dt_soname(args.soname)
 
-  checker.check_dt_needed()
+  checker.check_dt_needed(args.system_shared_lib)
 
   if not args.allow_undefined_symbols:
     checker.check_symbols()