Fix bug in dlmalloc's version of calloc.

Under some circumstances, doing a calloc will make sure that the memory
returned will be zero up to the size of the requested size. However, if
there is more usable size than the requested size, that extra part
of the allocation will not be zeroed. This change fixes it so that the
entire usable memory is always zeroed.

Change-Id: I8a66d6767c074023c4ba3568bf2705e1886740fc

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/malloc_test.cpp b/tests/malloc_test.cpp
index b76625a7a..5af5a6fb5 100644
--- a/tests/malloc_test.cpp
+++ b/tests/malloc_test.cpp
@@ -372,3 +372,22 @@ TEST(malloc, malloc_info) {
   }
 #endif
 }
+
+TEST(malloc, calloc_usable_size) {
+  for (size_t size = 1; size <= 2048; size++) {
+    void* pointer = malloc(size);
+    ASSERT_TRUE(pointer != nullptr);
+    memset(pointer, 0xeb, malloc_usable_size(pointer));
+    free(pointer);
+
+    // We should get a previous pointer that has been set to non-zero.
+    // If calloc does not zero out all of the data, this will fail.
+    uint8_t* zero_mem = reinterpret_cast<uint8_t*>(calloc(1, size));
+    ASSERT_TRUE(pointer != nullptr);
+    size_t usable_size = malloc_usable_size(zero_mem);
+    for (size_t i = 0; i < usable_size; i++) {
+      ASSERT_EQ(0, zero_mem[i]) << "Failed at allocation size " << size << " at byte " << i;
+    }
+    free(zero_mem);
+  }
+}