Tests & stronger guarantees for hidl_* pads.

- Test that pads are zero (for future proofing, also ran tests
  on original implementation and bugfix).
- Use -Wpadded so that compiler guarantees there aren't padding
  bits hiding elsewhere (there aren't)

Bug: 131356202
Test: libhidl_test
  (without fixes, with fixes, and with this CL)

Change-Id: Ib52a16015b0393c104cd984376328cb0da888b03
Merged-In: Ib52a16015b0393c104cd984376328cb0da888b03

1 files changed, 4 insertions, 9 deletions

diff --git a/base/HidlSupport.cpp b/base/HidlSupport.cpp
index f97f216..af805b9 100644
--- a/base/HidlSupport.cpp
+++ b/base/HidlSupport.cpp
@@ -35,10 +35,8 @@ bool debuggable() {
 }
 }  // namespace details
 
-hidl_handle::hidl_handle() {
-    memset(this, 0, sizeof(*this));
-    // mHandle = nullptr;
-    // mOwnsHandle = false;
+hidl_handle::hidl_handle() : mHandle(nullptr), mOwnsHandle(false) {
+    memset(mPad, 0, sizeof(mPad));
 }
 
 hidl_handle::~hidl_handle() {
@@ -138,11 +136,8 @@ void hidl_handle::freeHandle() {
 
 static const char *const kEmptyString = "";
 
-hidl_string::hidl_string() {
-    memset(this, 0, sizeof(*this));
-    // mSize is zero
-    // mOwnsBuffer is false
-    mBuffer = kEmptyString;
+hidl_string::hidl_string() : mBuffer(kEmptyString), mSize(0), mOwnsBuffer(false) {
+    memset(mPad, 0, sizeof(mPad));
 }
 
 hidl_string::~hidl_string() {