Port Minijail unit tests to Google Test.

Remove the duplicate unit test files.

Google Test is designed to be included directly with the project using
it, so add a simple shell script to get the sources.

Bug: 34520446
Test: Builds on Android, desktop Linux.
Change-Id: Iabc63fa1cb847b668645dbf5468454f025c93721
diff --git a/Makefile b/Makefile
index 1a6601c..b9e7ad8 100644
--- a/Makefile
+++ b/Makefile
@@ -19,13 +19,25 @@
 CFLAGS += -Wextra
 CXXFLAGS += -Wextra
 
+USE_SYSTEM_GTEST ?= no
+ifeq ($(USE_SYSTEM_GTEST),no)
+GTEST_CXXFLAGS :=
+GTEST_MAIN := gtest_main.a
+GTEST_LIBS := gtest.a
+else
+GTEST_CXXFLAGS := $(gtest-config --cxxflags)
+GTEST_MAIN := -lgtest_main
+GTEST_LIBS := $(gtest-config --libs)
+endif
+
 all: CC_BINARY(minijail0) CC_LIBRARY(libminijail.so) \
-		CC_LIBRARY(libminijailpreload.so)
+	CC_LIBRARY(libminijailpreload.so)
 
 parse_seccomp_policy: CXX_BINARY(parse_seccomp_policy)
 
 # TODO(jorgelo): convert to TEST().
-tests: CC_BINARY(libminijail_unittest) CC_BINARY(syscall_filter_unittest)
+tests: CXX_BINARY(libminijail_unittest) CXX_BINARY(syscall_filter_unittest)
+
 
 CC_BINARY(minijail0): LDLIBS += -lcap -ldl
 CC_BINARY(minijail0): libconstants.gen.o libsyscalls.gen.o libminijail.o \
@@ -33,32 +45,50 @@
 		syscall_wrapper.o minijail0.o
 clean: CLEAN(minijail0)
 
+
 CC_LIBRARY(libminijail.so): LDLIBS += -lcap
 CC_LIBRARY(libminijail.so): libminijail.o syscall_filter.o signal_handler.o \
 		bpf.o util.o syscall_wrapper.o libconstants.gen.o \
 		libsyscalls.gen.o
 clean: CLEAN(libminijail.so)
 
-CC_BINARY(libminijail_unittest): LDLIBS += -lcap
-CC_BINARY(libminijail_unittest): libminijail_unittest.o libminijail.o \
+
+CXX_BINARY(libminijail_unittest): CXXFLAGS += -Wno-write-strings \
+						$(GTEST_CXXFLAGS)
+CXX_BINARY(libminijail_unittest): LDLIBS += -lcap $(GTEST_MAIN)
+ifeq ($(USE_SYSTEM_GTEST),no)
+CXX_BINARY(libminijail_unittest): $(GTEST_MAIN)
+endif
+CXX_BINARY(libminijail_unittest): libminijail_unittest.o libminijail.o \
 		syscall_filter.o signal_handler.o bpf.o util.o \
 		syscall_wrapper.o libconstants.gen.o libsyscalls.gen.o
 clean: CLEAN(libminijail_unittest)
 
+
 CC_LIBRARY(libminijailpreload.so): LDLIBS += -lcap -ldl
 CC_LIBRARY(libminijailpreload.so): libminijailpreload.o libminijail.o \
 		libconstants.gen.o libsyscalls.gen.o syscall_filter.o \
 		signal_handler.o bpf.o util.o syscall_wrapper.o
 clean: CLEAN(libminijailpreload.so)
 
-CC_BINARY(syscall_filter_unittest): syscall_filter_unittest.o syscall_filter.o \
-		bpf.o util.o libconstants.gen.o libsyscalls.gen.o
+
+CXX_BINARY(syscall_filter_unittest): CXXFLAGS += -Wno-write-strings \
+						$(GTEST_CXXFLAGS)
+CXX_BINARY(syscall_filter_unittest): LDLIBS += -lcap $(GTEST_MAIN)
+ifeq ($(USE_SYSTEM_GTEST),no)
+CXX_BINARY(syscall_filter_unittest): $(GTEST_MAIN)
+endif
+CXX_BINARY(syscall_filter_unittest): syscall_filter_unittest.o \
+		syscall_filter.o bpf.o util.o libconstants.gen.o \
+		libsyscalls.gen.o
 clean: CLEAN(syscall_filter_unittest)
 
+
 CXX_BINARY(parse_seccomp_policy): parse_seccomp_policy.o syscall_filter.o \
 		bpf.o util.o libconstants.gen.o libsyscalls.gen.o
 clean: CLEAN(parse_policy)
 
+
 libsyscalls.gen.o: CPPFLAGS += -I$(SRC)
 
 libsyscalls.gen.o.depends: libsyscalls.gen.c
@@ -86,3 +116,58 @@
 clean: CLEAN(libconstants.gen.c)
 
 $(eval $(call add_object_rules,libconstants.gen.o,CC,c,CFLAGS))
+
+
+################################################################################
+# Google Test
+
+ifeq ($(USE_SYSTEM_GTEST),no)
+# Points to the root of Google Test, relative to where this file is.
+# Remember to tweak this if you move this file.
+GTEST_DIR = googletest-release-1.8.0/googletest
+
+# Flags passed to the preprocessor.
+# Set Google Test's header directory as a system directory, such that
+# the compiler doesn't generate warnings in Google Test headers.
+CPPFLAGS += -isystem $(GTEST_DIR)/include
+
+# Flags passed to the C++ compiler.
+GTEST_CXXFLAGS := -pthread
+
+# All Google Test headers.  Usually you shouldn't change this
+# definition.
+GTEST_HEADERS = $(GTEST_DIR)/include/gtest/*.h \
+		$(GTEST_DIR)/include/gtest/internal/*.h
+
+# House-keeping build targets.
+clean: clean_gtest
+
+clean_gtest:
+	rm -f gtest.a gtest_main.a *.o
+
+# Builds gtest.a and gtest_main.a.
+
+# Usually you shouldn't tweak such internal variables, indicated by a
+# trailing _.
+GTEST_SRCS_ = $(GTEST_DIR)/src/*.cc $(GTEST_DIR)/src/*.h $(GTEST_HEADERS)
+
+# For simplicity and to avoid depending on Google Test's
+# implementation details, the dependencies specified below are
+# conservative and not optimized.  This is fine as Google Test
+# compiles fast and for ordinary users its source rarely changes.
+gtest-all.o : $(GTEST_SRCS_)
+	$(CXX) $(CPPFLAGS) -I$(GTEST_DIR) $(CXXFLAGS) $(GTEST_CXXFLAGS) -c \
+		$(GTEST_DIR)/src/gtest-all.cc -o $@
+
+gtest_main.o : $(GTEST_SRCS_)
+	$(CXX) $(CPPFLAGS) -I$(GTEST_DIR) $(CXXFLAGS) $(GTEST_CXXFLAGS) -c \
+		$(GTEST_DIR)/src/gtest_main.cc -o $@
+
+gtest.a : gtest-all.o
+	$(AR) $(ARFLAGS) $@ $^
+
+gtest_main.a : gtest-all.o gtest_main.o
+	$(AR) $(ARFLAGS) $@ $^
+
+endif
+################################################################################