Don't assume c-strings are 4 byte aligned.
The Undefined Behavior sanitizer flags one part of the unittests for this.
For default values for `bytes` we write a length on the front of a c-string
in the static data, apparently the compiler/linker doesn't always make this
4 byte aligned, so it get flagged for undefined/degraded performance. Avoid
this by using memcpy instead.
diff --git a/objectivec/GPBDescriptor.m b/objectivec/GPBDescriptor.m
index 3c3844d..615d223 100644
--- a/objectivec/GPBDescriptor.m
+++ b/objectivec/GPBDescriptor.m
@@ -548,7 +548,8 @@
// descriptor structure.
const uint8_t *bytes = (const uint8_t *)defaultValue_.valueData;
if (bytes) {
- uint32_t length = *((uint32_t *)bytes);
+ uint32_t length;
+ memcpy(&length, bytes, sizeof(length));
length = ntohl(length);
bytes += sizeof(length);
defaultValue_.valueData =
@@ -963,7 +964,8 @@
const uint8_t *bytes =
(const uint8_t *)description->defaultValue.valueData;
if (bytes) {
- uint32_t length = *((uint32_t *)bytes);
+ uint32_t length;
+ memcpy(&length, bytes, sizeof(length));
// The length is stored in network byte order.
length = ntohl(length);
bytes += sizeof(length);
