[GitHub] [arrow] cyb70289 commented on a change in pull request #11789: ARROW-14898: [C++][Compute] Fix crash of out-of-bounds memory accessing in key_hash if a key is smaller than int64

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cyb70289 commented on a change in pull request #11789:
URL: https://github.com/apache/arrow/pull/11789#discussion_r763701245



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File path: cpp/src/arrow/util/ubsan.h
##########
@@ -52,20 +52,42 @@ inline T* MakeNonNull(T* maybe_null = NULLPTR) {
   return const_cast<T*>(reinterpret_cast<const T*>(&internal::kNonNullFiller));
 }
 
+// SafeLoadAs with a specific number of bytes
+// The returned bytes whose position is greater than `num_bytes` will be initialized to 0
+template <typename T>
+inline typename std::enable_if<std::is_trivial<T>::value, T>::type SafeLoadAs(
+    const uint8_t* unaligned, uint32_t num_bytes) {

Review comment:
       Agreed that it doesn't look like a generally useful function.
   IMHO, directly write `r = 0; std::memcpy(&r, ...)` at the caller side is better, a function is not necessary.




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