Bug 1249389 - part 2 - change NewBufferFromStorageStream's outparam into a UniquePtr; r=erahm

Similar to the previous change to NewObjectInputStreamFromBuffer, we
want to make the ownership transfer out of NewBufferFromStorageStream
more obvious.  Doing this also lets us get rid of some uses of
nsAutoArrayPtr, which is less idiomatic than UniquePtr.

dom/xbl/nsXBLDocumentInfo.cpp

@@ -290,11 +290,11 @@ nsXBLDocumentInfo::WritePrototypeBindings()
   NS_ENSURE_SUCCESS(rv, rv);
 
   uint32_t len;
-  nsAutoArrayPtr<char> buf;
-  rv = NewBufferFromStorageStream(storageStream, getter_Transfers(buf), &len);
+  UniquePtr<char[]> buf;
+  rv = NewBufferFromStorageStream(storageStream, &buf, &len);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  return startupCache->PutBuffer(spec.get(), buf, len);
+  return startupCache->PutBuffer(spec.get(), buf.get(), len);
 }
 
 void

dom/xul/nsXULPrototypeCache.cpp

@@ -401,10 +401,9 @@ nsXULPrototypeCache::FinishOutputStream(nsIURI* uri)
         = do_QueryInterface(storageStream);
     outputStream->Close();
 
-    nsAutoArrayPtr<char> buf;
+    UniquePtr<char[]> buf;
     uint32_t len;
-    rv = NewBufferFromStorageStream(storageStream, getter_Transfers(buf),
-                                    &len);
+    rv = NewBufferFromStorageStream(storageStream, &buf, &len);
     NS_ENSURE_SUCCESS(rv, rv);
 
     if (!mStartupCacheURITable.GetEntry(uri)) {
@@ -412,7 +411,7 @@ nsXULPrototypeCache::FinishOutputStream(nsIURI* uri)
         rv = PathifyURI(uri, spec);
         if (NS_FAILED(rv))
             return NS_ERROR_NOT_AVAILABLE;
-        rv = sc->PutBuffer(spec.get(), buf, len);
+        rv = sc->PutBuffer(spec.get(), buf.get(), len);
         if (NS_SUCCEEDED(rv)) {
             mOutputStreamTable.Remove(uri);
             mStartupCacheURITable.PutEntry(uri);

startupcache/StartupCacheUtils.cpp

@@ -73,7 +73,7 @@ NewObjectOutputWrappedStorageStream(nsIObjectOutputStream **wrapperStream,
 
 NS_EXPORT nsresult
 NewBufferFromStorageStream(nsIStorageStream *storageStream, 
-                           char** buffer, uint32_t* len) 
+                           UniquePtr<char[]>* buffer, uint32_t* len) 
 {
   nsresult rv;
   nsCOMPtr<nsIInputStream> inputStream;
@@ -86,9 +86,9 @@ NewBufferFromStorageStream(nsIStorageStream *storageStream,
   NS_ENSURE_TRUE(avail64 <= UINT32_MAX, NS_ERROR_FILE_TOO_BIG);
 
   uint32_t avail = (uint32_t)avail64;
-  nsAutoArrayPtr<char> temp (new char[avail]);
+  auto temp = MakeUnique<char[]>(avail);
   uint32_t read;
-  rv = inputStream->Read(temp, avail, &read);
+  rv = inputStream->Read(temp.get(), avail, &read);
   if (NS_SUCCEEDED(rv) && avail != read)
     rv = NS_ERROR_UNEXPECTED;
   
@@ -97,7 +97,7 @@ NewBufferFromStorageStream(nsIStorageStream *storageStream,
   }
   
   *len = avail;
-  *buffer = temp.forget();
+  *buffer = Move(temp);
   return NS_OK;
 }
 

startupcache/StartupCacheUtils.h

@@ -29,11 +29,11 @@ NewObjectOutputWrappedStorageStream(nsIObjectOutputStream **wrapperStream,
                                     bool wantDebugStream);
 
 // Creates a buffer for storing the stream into the cache. The buffer is
-// allocated with 'new []'. Typically, the caller would store the buffer in
-// an nsAutoArrayPtr<char> and then call nsIStartupCache::PutBuffer with it.
+// allocated with 'new []'.  After calling this function, the caller would
+// typically call nsIStartupCache::PutBuffer with the returned buffer.
 NS_EXPORT nsresult
 NewBufferFromStorageStream(nsIStorageStream *storageStream, 
-                           char** buffer, uint32_t* len);
+                           UniquePtr<char[]>* buffer, uint32_t* len);
 
 NS_EXPORT nsresult
 PathifyURI(nsIURI *in, nsACString &out);

startupcache/test/TestStartupCache.cpp

@@ -42,7 +42,7 @@ NewObjectOutputWrappedStorageStream(nsIObjectOutputStream **wrapperStream,
 
 NS_IMPORT nsresult
 NewBufferFromStorageStream(nsIStorageStream *storageStream, 
-                           char** buffer, uint32_t* len);
+                           UniquePtr<char[]>* buffer, uint32_t* len);
 } // namespace scache
 } // namespace mozilla
 
@@ -197,13 +197,13 @@ TestWriteObject() {
     return rv;
   }
 
-  nsAutoArrayPtr<char> buf;
+  UniquePtr<char[]> buf;
   uint32_t len;
-  NewBufferFromStorageStream(storageStream, getter_Transfers(buf), &len);
+  NewBufferFromStorageStream(storageStream, &buf, &len);
 
   // Since this is a post-startup write, it should be written and
   // available.
-  rv = sc->PutBuffer(id, buf, len);
+  rv = sc->PutBuffer(id, buf.get(), len);
   if (NS_FAILED(rv)) {
     fail("failed to insert input stream");
     return rv;