From 9c3c5c10465f18f1082ce1bcfe5393eb98ef053c Mon Sep 17 00:00:00 2001
From: Leo Ufimtsev
Date: Fri, 29 Sep 2017 11:57:53 -0400
Subject: Bug 525340 [Gtk][Webkit2] Javascript evaluate fails with
 "SyntaxError: Return statements are only valid inside functions"

Wrapping evaluate logic into a function to deal with corner
case where 'return' is not at the beginnign of the script.

Tested with all Browser jUnit tests.

Change-Id: Icb7c6d29006a0382fb5525bd7184101c3ea0cbdd
Signed-off-by: Leo Ufimtsev <lufimtse@redhat.com>
---
 .../gtk/org/eclipse/swt/browser/WebKit.java        | 26 ++++++++++------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/browser/WebKit.java b/eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/browser/WebKit.java
index f9361e1..1227298 100644
--- a/eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/browser/WebKit.java	
+++ b/eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/browser/WebKit.java	
@@ -1216,7 +1216,7 @@
 		// Mechanism to generate unique ID's
 		private static int nextCallbackId = 1;
 		private static HashSet<Integer> usedCallbackIds = new HashSet<>();
-		private static int getNextId() {
+		static int getNextId() {
 			int value = 0;
 			boolean unique = false;
 			while (unique == false) {
@@ -1236,28 +1236,26 @@
 	}
 
 	static Object evaluate(String script, Browser browser, long /*int*/ webView, boolean doNotBlock) {
-		/* Webkit2: We remove the 'return' prefix that normally comes with the script.
-		 * The reason is that in Webkit1, script was wrapped into a function and if an exception occured
-		 * it was caught on Javascript side and a callback to java was made.
-		 * In Webkit2, we handle errors in the callback, no need to wrap them in a function anymore.
+		/* Wrap script around a function for backwards compatibility,
+		 * user can specify 'return', which may not be at the beginning of the script.
+		 *  Valid scripts:
+		 *      'hi'
+		 *      return 'hi'
+		 *      var x = 1; return 'hi'
 		 */
-		String fixedScript;
-		if (script.length() > 7 && script.substring(0, 7).equals("return ")) {
-			fixedScript = script.substring(7);
-		} else {
-			fixedScript = script;
-		}
+		String swtUniqueExecFunc = "SWTWebkit2TempFunc" + CallBackMap.getNextId() + "()";
+		String wrappedScript = "function " + swtUniqueExecFunc +"{" + script + "}; " + swtUniqueExecFunc;
 
 		if (doNotBlock) {
 			// Execute script, but do not wait for async call to complete. (assume it does). Bug 512001.
-			WebKitGTK.webkit_web_view_run_javascript(webView, Converter.wcsToMbcs(fixedScript, true), 0, 0, 0);
+			WebKitGTK.webkit_web_view_run_javascript(webView, Converter.wcsToMbcs(wrappedScript, true), 0, 0, 0);
 			return null;
 		} else {
 			// Callback logic: Initiate an async callback and wait for it to finish.
 			// The callback comes back in javascriptExecutionFinishedProc(..) below.
 			Webkit2EvalReturnObj retObj = new Webkit2EvalReturnObj();
 			int callbackId = CallBackMap.putObject(retObj);
-			WebKitGTK.webkit_web_view_run_javascript(webView, Converter.wcsToMbcs(fixedScript, true), 0, callback.getAddress(), callbackId);
+			WebKitGTK.webkit_web_view_run_javascript(webView, Converter.wcsToMbcs(wrappedScript, true), 0, callback.getAddress(), callbackId);
 			Shell shell = browser.getShell();
 			Display display = browser.getDisplay();
 			while (!shell.isDisposed()) {
@@ -1270,7 +1268,7 @@
 			CallBackMap.removeObject(callbackId);
 
 			if (retObj.errorNum != 0) {
-				throw new SWTException(retObj.errorNum, retObj.errorMsg);
+				throw new SWTException(retObj.errorNum, retObj.errorMsg +"\nScript that was evaluated:\n" + wrappedScript);
 			} else {
 				return retObj.returnValue;
 			}
-- 
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