[compiler-rt] [scudo] Add hooks to mark the range of realloc (PR #73883)

[Christopher Ferris via llvm-commits]

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@@ -27,6 +27,51 @@ static void reportDeallocation(void *ptr) {
     if (__scudo_deallocate_hook)
       __scudo_deallocate_hook(ptr);
 }
+static void reportReallocBegin(void *old_ptr) {
+  if (SCUDO_ENABLE_HOOKS)
+    if (__scudo_realloc_begin_hook)
+      __scudo_realloc_begin_hook(old_ptr);
+}
+static void reportReallocEnd(void *old_ptr) {
+  if (SCUDO_ENABLE_HOOKS)
+    if (__scudo_realloc_end_hook)
+      __scudo_realloc_end_hook(old_ptr);
+}
+
+static void *reallocImpl(void *ptr, size_t size) {
+  if (!ptr) {
+    void *Ptr = SCUDO_ALLOCATOR.allocate(size, scudo::Chunk::Origin::Malloc,
+                                         SCUDO_MALLOC_ALIGNMENT);
+    reportAllocation(Ptr, size);
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cferris1000 wrote:

I know this isn't your problem, but if Ptr is nullptr, should the reportAllocation hook be called? This wouldn't normally happen, but if you are working with user data setting the size, I can see cases where an invalid size is passed in and fails to allocate.

https://github.com/llvm/llvm-project/pull/73883