Bug 507970, part 1: nsIStreamLoader changes to support downloadable font code, r=bzbarsky

--HG--
extra : rebase_source : d0142c7afc7b7788a76caf2a2508e7604c2b74f1

netwerk/base/public/nsIStreamLoader.idl

@@ -55,6 +55,13 @@ interface nsIStreamLoaderObserver : nsISupports
      * This method will always be called asynchronously by the
      * nsIStreamLoader involved, on the thread that called the
      * loader's init() method.
+     *
+     * If the observer wants to take over responsibility for the
+     * data buffer (result), it returns NS_SUCCESS_ADOPTED_DATA
+     * in place of NS_OK as its success code. The loader will then
+     * "forget" about the data, and not free() it in its own
+     * destructor; observer must call free() when the data is
+     * no longer required.
      */
     void onStreamComplete(in nsIStreamLoader loader,
                           in nsISupports ctxt,

netwerk/base/public/nsNetError.h

@@ -362,4 +362,17 @@
     NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 81)
 
 
+/******************************************************************************
+ * StreamLoader specific result codes:
+ */
+
+/**
+ * Result code returned by nsIStreamLoaderObserver to indicate that
+ * the observer is taking over responsibility for the data buffer,
+ * and the loader should NOT free it.
+ */
+#define NS_SUCCESS_ADOPTED_DATA \
+    NS_ERROR_GENERATE_SUCCESS(NS_ERROR_MODULE_NETWORK, 90)
+
+
 #endif // !nsNetError_h__

netwerk/base/src/nsStreamLoader.cpp

@@ -38,6 +38,23 @@
 #include "nsStreamLoader.h"
 #include "nsIInputStream.h"
 #include "nsIChannel.h"
+#include "nsNetError.h"
+
+#include <stdlib.h>
+
+nsStreamLoader::nsStreamLoader()
+  : mData(nsnull),
+    mAllocated(0),
+    mLength(0)
+{
+}
+
+nsStreamLoader::~nsStreamLoader()
+{
+  if (mData) {
+    ::free(mData);
+  }
+}
 
 NS_IMETHODIMP
 nsStreamLoader::Init(nsIStreamLoaderObserver* observer)
@@ -67,7 +84,7 @@ NS_IMPL_ISUPPORTS3(nsStreamLoader, nsIStreamLoader,
 NS_IMETHODIMP 
 nsStreamLoader::GetNumBytesRead(PRUint32* aNumBytes)
 {
-  *aNumBytes = mData.Length();
+  *aNumBytes = mLength;
   return NS_OK;
 }
 
@@ -88,7 +105,11 @@ nsStreamLoader::OnStartRequest(nsIRequest* request, nsISupports *ctxt)
     chan->GetContentLength(&contentLength);
     if (contentLength >= 0) {
       // preallocate buffer
-      mData.SetCapacity(contentLength + 1);
+      mData = static_cast<PRUint8*>(::malloc(contentLength));
+      if (!mData) {
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+      mAllocated = contentLength;
     }
   }
   mContext = ctxt;
@@ -102,10 +123,15 @@ nsStreamLoader::OnStopRequest(nsIRequest* request, nsISupports *ctxt,
   if (mObserver) {
     // provide nsIStreamLoader::request during call to OnStreamComplete
     mRequest = request;
-    mObserver->OnStreamComplete(this, mContext, aStatus, 
-                                mData.Length(),
-                                reinterpret_cast<const PRUint8*>
-                                                (mData.get()));
+    nsresult rv = mObserver->OnStreamComplete(this, mContext, aStatus,
+                                              mLength, mData);
+    if (rv == NS_SUCCESS_ADOPTED_DATA) {
+      // the observer now owns the data buffer, and the loader must
+      // not deallocate it
+      mData = nsnull;
+      mLength = 0;
+      mAllocated = 0;
+    }
     // done.. cleanup
     mRequest = 0;
     mObserver = 0;
@@ -124,7 +150,24 @@ nsStreamLoader::WriteSegmentFun(nsIInputStream *inStr,
 {
   nsStreamLoader *self = (nsStreamLoader *) closure;
 
-  self->mData.Append(fromSegment, count);
+  if (count > 0xffffffffU - self->mLength) {
+    return NS_ERROR_ILLEGAL_VALUE; // is there a better error to use here?
+  }
+
+  if (self->mLength + count > self->mAllocated) {
+    self->mData = static_cast<PRUint8*>(::realloc(self->mData,
+                                                  self->mLength + count));
+    if (!self->mData) {
+      self->mLength = 0;
+      self->mAllocated = 0;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    self->mAllocated = self->mLength + count;
+  }
+
+  ::memcpy(self->mData + self->mLength, fromSegment, count);
+  self->mLength += count;
+
   *writeCount = count;
 
   return NS_OK;

netwerk/base/src/nsStreamLoader.h

@@ -51,8 +51,8 @@ public:
   NS_DECL_NSIREQUESTOBSERVER
   NS_DECL_NSISTREAMLISTENER
 
-  nsStreamLoader() { }
-  ~nsStreamLoader() {}
+  nsStreamLoader();
+  ~nsStreamLoader();
 
   static NS_METHOD
   Create(nsISupports *aOuter, REFNSIID aIID, void **aResult);
@@ -63,8 +63,11 @@ protected:
 
   nsCOMPtr<nsIStreamLoaderObserver> mObserver;
   nsCOMPtr<nsISupports>             mContext;  // the observer's context
-  nsCString                         mData;
   nsCOMPtr<nsIRequest>              mRequest;
+
+  PRUint8  *mData;
+  PRUint32  mAllocated;
+  PRUint32  mLength;
 };
 
 #endif // nsStreamLoader_h__