Fix for 86501 - bookmarks truncated when disk full

allow file streams to store and report on the status of the write operation.
r=darin, sr=brendan

xpcom/io/nsFileStream.cpp

@@ -126,7 +126,7 @@ PRInt32 nsOutputStream::write(const void* s, PRInt32 n)
   if (!mOutputStream)
       return 0;
   PRInt32 result = 0;
-  mOutputStream->Write((char*)s, n, (PRUint32*)&result);
+  mWriteStatus = mOutputStream->Write((char*)s, n, (PRUint32*)&result);
   return result;
 } // nsOutputStream::write
 
@@ -137,6 +137,13 @@ nsresult nsOutputStream::flush()
   return NS_OK;
 }
 
+//----------------------------------------------------------------------------------------
+nsresult nsOutputStream::lastWriteStatus()
+//----------------------------------------------------------------------------------------
+{
+  return mWriteStatus;
+}
+
 //----------------------------------------------------------------------------------------
 nsOutputStream& nsOutputStream::operator << (char c)
 //----------------------------------------------------------------------------------------

xpcom/io/nsFileStream.h

@@ -270,6 +270,7 @@ public:
     void                              put(char c);
     PRInt32                           write(const void* s, PRInt32 n);
     virtual nsresult                  flush();
+    nsresult                          lastWriteStatus();
 
     // Output streamers.  Add more as needed (but you have to add delegators to the derived
     // classes, too, because these operators don't inherit).
@@ -294,9 +295,11 @@ private:
                                       nsOutputStream(const nsOutputStream& rhs);
     nsOutputStream&                   operator=(const nsOutputStream& rhs);
 
+    nsresult                          mWriteStatus;
+
 // DATA
 protected:
-    nsCOMPtr<nsIOutputStream>          mOutputStream;
+    nsCOMPtr<nsIOutputStream>         mOutputStream;
 }; // class nsOutputStream
 
 typedef nsOutputStream nsBasicOutStream; // Historic support for this name