Bug 1161240 - Make sure that NS_CloneInputStream correctly deals with null input; r=froydnj

xpcom/io/nsStreamUtils.cpp

@@ -853,6 +853,10 @@ nsresult
 NS_CloneInputStream(nsIInputStream* aSource, nsIInputStream** aCloneOut,
                     nsIInputStream** aReplacementOut)
 {
+  if (NS_WARN_IF(!aSource)) {
+    return NS_ERROR_FAILURE;
+  }
+
   // Attempt to perform the clone directly on the source stream
   nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource);
   if (cloneable && cloneable->GetCloneable()) {

xpcom/tests/gtest/TestCloneInputStream.cpp

@@ -12,6 +12,14 @@
 #include "nsStreamUtils.h"
 #include "nsStringStream.h"
 
+TEST(CloneInputStream, InvalidInput)
+{
+  nsCOMPtr<nsIInputStream> clone;
+  nsresult rv = NS_CloneInputStream(nullptr, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+  ASSERT_FALSE(clone);
+}
+
 TEST(CloneInputStream, CloneableInput)
 {
   nsTArray<char> inputData;