Bug 507312 - nsFileInputStream::available() throws for files >= 4,294,967,295 bytes (4 GB). r=cbiesinger

netwerk/base/src/nsFileStreams.cpp

@@ -278,11 +278,15 @@ nsFileInputStream::Available(PRUint32* aResult)
         return NS_BASE_STREAM_CLOSED;
     }
 
-    PRInt32 avail = PR_Available(mFD);
+    // PR_Available with files over 4GB returns an error, so we have to
+    // use the 64-bit version of PR_Available.
+    PRInt64 avail = PR_Available64(mFD);
     if (avail == -1) {
         return NS_ErrorAccordingToNSPR();
     }
-    *aResult = avail;
+
+    // If available is greater than 4GB, return 4GB
+    *aResult = avail > PR_UINT32_MAX ? PR_UINT32_MAX : (PRUint32)avail;
     return NS_OK;
 }