Issue #1442 - Part 16 - Report stream errors during consumption.

https://bugzilla.mozilla.org/show_bug.cgi?id=1128959

2 files changed, 75 insertions, 0 deletions

diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 8dac3e70d4..4c00f358f2 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -39,6 +39,8 @@
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/CustomElementRegistry.h"
 #include "mozilla/dom/DocumentFragment.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/DOMExceptionBinding.h"
 #include "mozilla/dom/DOMTypes.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/FileSystemSecurity.h"
@@ -10079,3 +10081,72 @@ void nsContentUtils::StructuredClone(JSContext* aCx,
   nsTArray<RefPtr<MessagePort>> ports = holder.TakeTransferredPorts();
   Unused << ports;
 }
+
+/* static */ void
+nsContentUtils::ExtractErrorValues(JSContext* aCx,
+                                   JS::Handle<JS::Value> aValue,
+                                   nsACString& aSourceSpecOut,
+                                   uint32_t* aLineOut,
+                                   uint32_t* aColumnOut,
+                                   nsString& aMessageOut)
+{
+  MOZ_ASSERT(aLineOut);
+  MOZ_ASSERT(aColumnOut);
+
+  if (aValue.isObject()) {
+    JS::Rooted<JSObject*> obj(aCx, &aValue.toObject());
+    RefPtr<dom::DOMException> domException;
+
+    // Try to process as an Error object.  Use the file/line/column values
+    // from the Error as they will be more specific to the root cause of
+    // the problem.
+    JSErrorReport* err = obj ? JS_ErrorFromException(aCx, obj) : nullptr;
+    if (err) {
+      // Use xpc to extract the error message only.  We don't actually send
+      // this report anywhere.
+      RefPtr<xpc::ErrorReport> report = new xpc::ErrorReport();
+      report->Init(err,
+                   "<unknown>", // toString result
+                   false,       // chrome
+                   0);          // window ID
+
+      if (!report->mFileName.IsEmpty()) {
+        CopyUTF16toUTF8(report->mFileName, aSourceSpecOut);
+        *aLineOut = report->mLineNumber;
+        *aColumnOut = report->mColumn;
+      }
+      aMessageOut.Assign(report->mErrorMsg);
+    }
+
+    // Next, try to unwrap the rejection value as a DOMException.
+    else if(NS_SUCCEEDED(UNWRAP_OBJECT(DOMException, obj, domException))) {
+
+      nsAutoString filename;
+      domException->GetFilename(aCx, filename);
+      if (!filename.IsEmpty()) {
+        CopyUTF16toUTF8(filename, aSourceSpecOut);
+        *aLineOut = domException->LineNumber(aCx);
+        *aColumnOut = domException->ColumnNumber();
+      }
+
+      domException->GetName(aMessageOut);
+      aMessageOut.AppendLiteral(": ");
+
+      nsAutoString message;
+      domException->GetMessageMoz(message);
+      aMessageOut.Append(message);
+    }
+  }
+
+  // If we could not unwrap a specific error type, then perform default safe
+  // string conversions on primitives.  Objects will result in "[Object]"
+  // unfortunately.
+  if (aMessageOut.IsEmpty()) {
+    nsAutoJSString jsString;
+    if (jsString.init(aCx, aValue)) {
+      aMessageOut = jsString;
+    } else {
+      JS_ClearPendingException(aCx);
+    }
+  }
+}
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index 9bfb91add2..6e9f23054a 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -1010,6 +1010,10 @@ public:
 
   static bool PrefetchEnabled(nsIDocShell* aDocShell);
 
+  static void ExtractErrorValues(JSContext* aCx, JS::Handle<JS::Value> aValue,
+                                 nsACString& aSourceSpecOut, uint32_t *aLineOut,
+                                 uint32_t *aColumnOut, nsString& aMessageOut);
+
   static nsresult CalculateBufferSizeForImage(const uint32_t& aStride,
                                               const mozilla::gfx::IntSize& aImageSize,
                                               const mozilla::gfx::SurfaceFormat& aFormat,