wmem: ensure wmem_memdup(..., NULL, 0) returns NULL

Rather than requiring all callers to pass a non-null source argument,
explicitly allow a NULL source when the size is zero. This is consistent
with g_memdup behavior.

While at it, fix a memleak and avoid memset(0,0,0) in tests.

Change-Id: I86a092625a508544d180da959e4afdd0366539f4
Reviewed-on: https://code.wireshark.org/review/26496
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Mališa Vučinić <malishav@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Evan Huus <eapache@gmail.com>

3 files changed, 10 insertions, 2 deletions

diff --git a/epan/wmem/wmem_miscutl.c b/epan/wmem/wmem_miscutl.c
index d0ef1b18f1..33d5089e6c 100644
--- a/epan/wmem/wmem_miscutl.c
+++ b/epan/wmem/wmem_miscutl.c
@@ -20,6 +20,9 @@ wmem_memdup(wmem_allocator_t *allocator, const void *source, const size_t size)
 {
     void *dest;
 
+    if (!size)
+        return NULL;
+
     dest = wmem_alloc(allocator, size);
     memcpy(dest, source, size);
 
diff --git a/epan/wmem/wmem_miscutl.h b/epan/wmem/wmem_miscutl.h
index c77e569d4d..012d60a7bb 100644
--- a/epan/wmem/wmem_miscutl.h
+++ b/epan/wmem/wmem_miscutl.h
@@ -33,7 +33,7 @@ extern "C" {
  * @param allocator The allocator object to use to allocate memory to copy into.
  * @param source The pointer to the memory block to copy.
  * @param size The amount of memory to copy.
- * @return The location of the memory copy.
+ * @return The location of the memory copy or NULL if size is 0.
  */
 WS_DLL_PUBLIC
 void *
diff --git a/epan/wmem/wmem_test.c b/epan/wmem/wmem_test.c
index 80044b740b..e3dfdda4c9 100644
--- a/epan/wmem/wmem_test.c
+++ b/epan/wmem/wmem_test.c
@@ -321,7 +321,8 @@ wmem_test_allocator(wmem_allocator_type_t type, wmem_verify_func verify,
             ptrs[ptrs_index] = (char *) wmem_realloc(allocator,
                     ptrs[ptrs_index], new_size);
 
-            memset(ptrs[ptrs_index], 0, new_size);
+            if (new_size)
+                memset(ptrs[ptrs_index], 0, new_size);
         }
         else {
             /* the index is used, and our random bit has determined we will be
@@ -379,6 +380,9 @@ wmem_test_miscutls(void)
 
     allocator = wmem_allocator_new(WMEM_ALLOCATOR_STRICT);
 
+    ret = (char*) wmem_memdup(allocator, NULL, 0);
+    g_assert(ret == NULL);
+
     ret = (char*) wmem_memdup(allocator, source, 5);
     ret[4] = '\0';
     g_assert_cmpstr(ret, ==, "ABCD");
@@ -608,6 +612,7 @@ wmem_test_stringperf(void)
         "wmem_strconcat 5 strings: u %.3f ms s %.3f ms", utime_ms, stime_ms);
 
     wmem_destroy_allocator(allocator);
+    g_free(str_ptr);
 }
 
 /* DATA STRUCTURE TESTING FUNCTIONS (/wmem/datastruct/) */