Merge "Copy the M_THREAD_DISABLE_MEM_INIT constant value into malloc.h." am: 155901898d

Original change: https://android-review.googlesource.com/c/platform/bionic/+/1433459

Change-Id: Id6eafdd634cf64fc514bbce5cb81ed452102649a

libc/include/malloc.h

@@ -170,6 +170,16 @@ int malloc_info(int __must_be_zero, FILE* __fp) __INTRODUCED_IN(23);
  * Available since API level 28.
  */
 #define M_PURGE (-101)
+/*
+ * mallopt() option for per-thread memory initialization tuning.
+ * The value argument should be one of:
+ * 1: Disable automatic heap initialization and, where possible, memory tagging,
+ *    on this thread.
+ * 0: Normal behavior.
+ *
+ * Available since API level 31.
+ */
+#define M_THREAD_DISABLE_MEM_INIT (-103)
 /**
  * mallopt() option to set the maximum number of items in the secondary
  * cache of the scudo allocator.

tests/malloc_test.cpp

@@ -84,6 +84,24 @@ TEST(malloc, calloc_std) {
   free(ptr);
 }
 
+TEST(malloc, calloc_mem_init_disabled) {
+#if defined(__BIONIC__)
+  // calloc should still zero memory if mem-init is disabled.
+  // With jemalloc the mallopts will fail but that shouldn't affect the
+  // execution of the test.
+  mallopt(M_THREAD_DISABLE_MEM_INIT, 1);
+  size_t alloc_len = 100;
+  char *ptr = reinterpret_cast<char*>(calloc(1, alloc_len));
+  for (size_t i = 0; i < alloc_len; i++) {
+    ASSERT_EQ(0, ptr[i]);
+  }
+  free(ptr);
+  mallopt(M_THREAD_DISABLE_MEM_INIT, 0);
+#else
+  GTEST_SKIP() << "bionic-only test";
+#endif
+}
+
 TEST(malloc, calloc_illegal) {
   SKIP_WITH_HWASAN;
   errno = 0;