Bug 1494176 - nsHttpChannel must clone the upload stream if it doesn't implement ::Seek(), r=mayhemer

netwerk/protocol/http/HttpBaseChannel.cpp

@@ -914,9 +914,20 @@ HttpBaseChannel::EnsureUploadStreamIsCloneable(nsIRunnable* aCallback)
   // this is called more than once simultaneously.
   NS_ENSURE_FALSE(mUploadCloneableCallback, NS_ERROR_UNEXPECTED);
 
-  // If the CloneUploadStream() will succeed, then synchronously invoke
-  // the callback to indicate we're already cloneable.
-  if (!mUploadStream || NS_InputStreamIsCloneable(mUploadStream)) {
+  // We can immediately exec the callback if we don't have an upload stream.
+  if (!mUploadStream) {
+    aCallback->Run();
+    return NS_OK;
+  }
+
+  // Some nsSeekableStreams do not implement ::Seek() (see nsPipeInputStream).
+  // In this case, we must clone the uploadStream into a memory stream in order
+  // to have it seekable.  If the CloneUploadStream() will succeed, then
+  // synchronously invoke the callback to indicate we're already cloneable.
+  nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(mUploadStream);
+  if (seekable &&
+      NS_SUCCEEDED(seekable->Seek(nsISeekableStream::NS_SEEK_SET, 0)) &&
+      NS_InputStreamIsCloneable(mUploadStream)) {
     aCallback->Run();
     return NS_OK;
   }

netwerk/protocol/http/HttpChannelParent.cpp

@@ -718,6 +718,15 @@ HttpChannelParent::DoAsyncOpen(  const URIParams&           aURI,
                 })
          ->Track(mRequest);
 
+  // The stream, received from the child process, must be cloneable and seekable
+  // in order to allow devtools to inspect its content.
+  nsCOMPtr<nsIRunnable> r =
+    NS_NewRunnableFunction("HttpChannelParent::EnsureUploadStreamIsCloneable",
+      [self]() {
+        self->TryInvokeAsyncOpen(NS_OK);
+      });
+  ++mAsyncOpenBarrier;
+  mChannel->EnsureUploadStreamIsCloneable(r);
   return true;
 }
 
@@ -741,7 +750,7 @@ HttpChannelParent::WaitForBgParent()
     return promise.forget();
   }
 
-  return mPromise.Ensure(__func__);;
+  return mPromise.Ensure(__func__);
 }
 
 bool

xpcom/io/nsPipe3.cpp

@@ -1528,7 +1528,6 @@ nsPipeInputStream::AsyncWait(nsIInputStreamCallback* aCallback,
 NS_IMETHODIMP
 nsPipeInputStream::Seek(int32_t aWhence, int64_t aOffset)
 {
-  MOZ_ASSERT_UNREACHABLE("nsPipeInputStream::Seek");
   return NS_ERROR_NOT_IMPLEMENTED;
 }