Fix potential null read for truncated dex files

In the case where a dex file is truncated, don't attempt to read the
header.

Added regression test.

Bug: 63756964
Bug: 72826975
Test: mm test-art-host-gtest-dex2oat_test -j64
Test: mm test-art-target-gtest-dex2oat_test -j64
Change-Id: I9bd6bb445ef2eb1c961044f43ac71f04ef8c04a5
diff --git a/build/Android.gtest.mk b/build/Android.gtest.mk
index c8f6615..894b33b 100644
--- a/build/Android.gtest.mk
+++ b/build/Android.gtest.mk
@@ -78,6 +78,11 @@
 ART_TEST_HOST_GTEST_MainUncompressed_DEX := $(basename $(ART_TEST_HOST_GTEST_Main_DEX))Uncompressed$(suffix $(ART_TEST_HOST_GTEST_Main_DEX))
 ART_TEST_TARGET_GTEST_MainUncompressed_DEX := $(basename $(ART_TEST_TARGET_GTEST_Main_DEX))Uncompressed$(suffix $(ART_TEST_TARGET_GTEST_Main_DEX))
 
+# Create rules for UncompressedEmpty, a classes.dex that is empty and uncompressed
+# for the dex2oat tests.
+ART_TEST_HOST_GTEST_EmptyUncompressed_DEX := $(basename $(ART_TEST_HOST_GTEST_Main_DEX))EmptyUncompressed$(suffix $(ART_TEST_HOST_GTEST_Main_DEX))
+ART_TEST_TARGET_GTEST_EmptyUncompressed_DEX := $(basename $(ART_TEST_TARGET_GTEST_Main_DEX))EmptyUncompressed$(suffix $(ART_TEST_TARGET_GTEST_Main_DEX))
+
 $(ART_TEST_HOST_GTEST_MainStripped_DEX): $(ART_TEST_HOST_GTEST_Main_DEX)
 	cp $< $@
 	$(call dexpreopt-remove-classes.dex,$@)
@@ -96,6 +101,16 @@
 	$(call uncompress-dexs, $@)
 	$(call align-package, $@)
 
+$(ART_TEST_HOST_GTEST_EmptyUncompressed_DEX): $(ZIPALIGN)
+	touch $(dir $@)classes.dex
+	zip -j -qD -X -0 $@ $(dir $@)classes.dex
+	rm $(dir $@)classes.dex
+
+$(ART_TEST_TARGET_GTEST_EmptyUncompressed_DEX): $(ZIPALIGN)
+	touch $(dir $@)classes.dex
+	zip -j -qD -X -0 $@ $(dir $@)classes.dex
+	rm $(dir $@)classes.dex
+
 ART_TEST_GTEST_VerifierDeps_SRC := $(abspath $(wildcard $(LOCAL_PATH)/VerifierDeps/*.smali))
 ART_TEST_GTEST_VerifierDepsMulti_SRC := $(abspath $(wildcard $(LOCAL_PATH)/VerifierDepsMulti/*.smali))
 ART_TEST_HOST_GTEST_VerifierDeps_DEX := $(dir $(ART_TEST_HOST_GTEST_Main_DEX))$(subst Main,VerifierDeps,$(basename $(notdir $(ART_TEST_HOST_GTEST_Main_DEX))))$(suffix $(ART_TEST_HOST_GTEST_Main_DEX))
@@ -126,7 +141,7 @@
 ART_GTEST_dex_cache_test_DEX_DEPS := Main Packages MethodTypes
 ART_GTEST_dex_file_test_DEX_DEPS := GetMethodSignature Main Nested MultiDex
 ART_GTEST_dexlayout_test_DEX_DEPS := ManyMethods
-ART_GTEST_dex2oat_test_DEX_DEPS := $(ART_GTEST_dex2oat_environment_tests_DEX_DEPS) ManyMethods Statics VerifierDeps MainUncompressed
+ART_GTEST_dex2oat_test_DEX_DEPS := $(ART_GTEST_dex2oat_environment_tests_DEX_DEPS) ManyMethods Statics VerifierDeps MainUncompressed EmptyUncompressed
 ART_GTEST_dex2oat_image_test_DEX_DEPS := $(ART_GTEST_dex2oat_environment_tests_DEX_DEPS) Statics VerifierDeps
 ART_GTEST_exception_test_DEX_DEPS := ExceptionHandle
 ART_GTEST_hiddenapi_test_DEX_DEPS := HiddenApi
@@ -750,6 +765,8 @@
 ART_TEST_TARGET_GTEST_MainStripped_DEX :=
 ART_TEST_HOST_GTEST_MainUncompressed_DEX :=
 ART_TEST_TARGET_GTEST_MainUncompressed_DEX :=
+ART_TEST_HOST_GTEST_EmptyUncompressed_DEX :=
+ART_TEST_TARGET_GTEST_EmptyUncompressed_DEX :=
 ART_TEST_GTEST_VerifierDeps_SRC :=
 ART_TEST_HOST_GTEST_VerifierDeps_DEX :=
 ART_TEST_TARGET_GTEST_VerifierDeps_DEX :=