src: remove UncheckedMalloc(0) workaround

Assuming that UncheckedMalloc(0) returns a non-nullptr is non-standard
and we use other allocators as well (e.g., OPENSSL_malloc) that do not
guarantee this behavior. It is the caller's responsibility to check that
size != 0 implies UncheckedMalloc(size) != nullptr, and that's exactly
what the checked variants (Malloc etc.) already do.

The current behavior is also inconsistent with UncheckedRealloc(), which
always returns a nullptr when the size is 0, and with the documentation
in src/README.md.

Refs: nodejs#8571
Refs: nodejs#8572

src/util-inl.h

@@ -361,13 +361,11 @@ T* UncheckedRealloc(T* pointer, size_t n) {
 // As per spec realloc behaves like malloc if passed nullptr.
 template <typename T>
 inline T* UncheckedMalloc(size_t n) {
-  if (n == 0) n = 1;
   return UncheckedRealloc<T>(nullptr, n);
 }
 
 template <typename T>
 inline T* UncheckedCalloc(size_t n) {
-  if (n == 0) n = 1;
   MultiplyWithOverflowCheck(sizeof(T), n);
   return static_cast<T*>(calloc(n, sizeof(T)));
 }

test/cctest/test_util.cc

@@ -97,39 +97,39 @@ TEST(UtilTest, ToLower) {
   EXPECT_EQ('a', ToLower('A'));
 }
 
-#define TEST_AND_FREE(expression)                                             \
-  do {                                                                        \
-    auto pointer = expression;                                                \
-    EXPECT_NE(nullptr, pointer);                                              \
-    free(pointer);                                                            \
+#define TEST_AND_FREE(expression, size)                                        \
+  do {                                                                         \
+    auto pointer = expression(size);                                           \
+    if (size != 0) EXPECT_NE(pointer, nullptr);                                \
+    free(pointer);                                                             \
   } while (0)
 
 TEST(UtilTest, Malloc) {
-  TEST_AND_FREE(Malloc<char>(0));
-  TEST_AND_FREE(Malloc<char>(1));
-  TEST_AND_FREE(Malloc(0));
-  TEST_AND_FREE(Malloc(1));
+  TEST_AND_FREE(Malloc<char>, 0);
+  TEST_AND_FREE(Malloc<char>, 1);
+  TEST_AND_FREE(Malloc, 0);
+  TEST_AND_FREE(Malloc, 1);
 }
 
 TEST(UtilTest, Calloc) {
-  TEST_AND_FREE(Calloc<char>(0));
-  TEST_AND_FREE(Calloc<char>(1));
-  TEST_AND_FREE(Calloc(0));
-  TEST_AND_FREE(Calloc(1));
+  TEST_AND_FREE(Calloc<char>, 0);
+  TEST_AND_FREE(Calloc<char>, 1);
+  TEST_AND_FREE(Calloc, 0);
+  TEST_AND_FREE(Calloc, 1);
 }
 
 TEST(UtilTest, UncheckedMalloc) {
-  TEST_AND_FREE(UncheckedMalloc<char>(0));
-  TEST_AND_FREE(UncheckedMalloc<char>(1));
-  TEST_AND_FREE(UncheckedMalloc(0));
-  TEST_AND_FREE(UncheckedMalloc(1));
+  TEST_AND_FREE(UncheckedMalloc<char>, 0);
+  TEST_AND_FREE(UncheckedMalloc<char>, 1);
+  TEST_AND_FREE(UncheckedMalloc, 0);
+  TEST_AND_FREE(UncheckedMalloc, 1);
 }
 
 TEST(UtilTest, UncheckedCalloc) {
-  TEST_AND_FREE(UncheckedCalloc<char>(0));
-  TEST_AND_FREE(UncheckedCalloc<char>(1));
-  TEST_AND_FREE(UncheckedCalloc(0));
-  TEST_AND_FREE(UncheckedCalloc(1));
+  TEST_AND_FREE(UncheckedCalloc<char>, 0);
+  TEST_AND_FREE(UncheckedCalloc<char>, 1);
+  TEST_AND_FREE(UncheckedCalloc, 0);
+  TEST_AND_FREE(UncheckedCalloc, 1);
 }
 
 template <typename T>