From acfa734cf87036d903ce5352bc44a9b3426a00c4 Mon Sep 17 00:00:00 2001
From: Christopher Hermann <christopher.hermann@sap.com>
Date: Tue, 7 Jan 2025 10:45:10 +0100
Subject: [PATCH] Display.withCrLf() is producing wrong line breaks on Windows

Replacing all line breaks on windows with CrLf using regex, which is much safer.

Fixes #1557
---
 .../org/eclipse/swt/widgets/Display.java      | 79 ++-----------------
 .../Test_org_eclipse_swt_widgets_Display.java | 11 +++
 2 files changed, 16 insertions(+), 74 deletions(-)

diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java
index 100b47e6daf..7a8d39b7f56 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java	
+++ b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java	
@@ -5152,85 +5152,16 @@ String wrapText (String text, long handle, int width) {
 }
 
 static String withCrLf (String string) {
-
-	/* If the string is empty, return the string. */
-	int length = string.length ();
-	if (length == 0) return string;
-
-	/*
-	* Check for an LF or CR/LF and assume the rest of
-	* the string is formated that way.  This will not
-	* work if the string contains mixed delimiters.
-	*/
-	int i = string.indexOf ('\n', 0);
-	if (i == -1) return string;
-	if (i > 0 && string.charAt (i - 1) == '\r') {
+	if (string == null) {
 		return string;
 	}
-
-	/*
-	* The string is formatted with LF.  Compute the
-	* number of lines and the size of the buffer
-	* needed to hold the result
-	*/
-	i++;
-	int count = 1;
-	while (i < length) {
-		if ((i = string.indexOf ('\n', i)) == -1) break;
-		count++; i++;
-	}
-	count += length;
-
-	/* Create a new string with the CR/LF line terminator. */
-	i = 0;
-	StringBuilder result = new StringBuilder (count);
-	while (i < length) {
-		int j = string.indexOf ('\n', i);
-		if (j == -1) j = length;
-		result.append (string.substring (i, j));
-		if ((i = j) < length) {
-			result.append ("\r\n"); //$NON-NLS-1$
-			i++;
-		}
-	}
-	return result.toString ();
+	// Replace \r\n, \r, or \n with \r\n return input.replaceAll("(\r\n|\r|\n)", "\r\n");
+	return string.replaceAll("(\r\n|\r|\n)", "\r\n");
 }
 
 static char [] withCrLf (char [] string) {
-	/* If the string is empty, return the string. */
-	int length = string.length;
-	if (length == 0) return string;
-
-	/*
-	* Check for an LF or CR/LF and assume the rest of
-	* the string is formated that way.  This will not
-	* work if the string contains mixed delimiters.
-	* Also, compute the number of lines.
-	*/
-	int count = 0;
-	for (int i = 0; i < string.length; i++) {
-		if (string [i] == '\n') {
-			count++;
-			if (count == 1 && i > 0 && string [i - 1] == '\r') return string;
-		}
-	}
-	if (count == 0) return string;
-
-	/*
-	* The string is formatted with LF.
-	*/
-	count += length;
-
-	/* Create a new string with the CR/LF line terminator. */
-	char [] result = new char [count];
-	for (int i = 0, j = 0; i < length && j < count; i++) {
-		if (string [i] == '\n') {
-			result [j++] = '\r';
-		}
-		result [j++] = string [i];
-	}
-
-	return result;
+	String withCrLf = withCrLf(new String(string));
+	return withCrLf.toCharArray();
 }
 
 static boolean isActivateShellOnForceFocus() {
diff --git a/tests/org.eclipse.swt.tests.win32/JUnit Tests/org/eclipse/swt/tests/win32/widgets/Test_org_eclipse_swt_widgets_Display.java b/tests/org.eclipse.swt.tests.win32/JUnit Tests/org/eclipse/swt/tests/win32/widgets/Test_org_eclipse_swt_widgets_Display.java
index 316fec13d82..2f17f5aed2c 100644
--- a/tests/org.eclipse.swt.tests.win32/JUnit Tests/org/eclipse/swt/tests/win32/widgets/Test_org_eclipse_swt_widgets_Display.java	
+++ b/tests/org.eclipse.swt.tests.win32/JUnit Tests/org/eclipse/swt/tests/win32/widgets/Test_org_eclipse_swt_widgets_Display.java	
@@ -13,6 +13,8 @@
  *******************************************************************************/
 package org.eclipse.swt.tests.win32.widgets;
 
+import static org.junit.Assert.assertEquals;
+
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 
@@ -35,4 +37,13 @@ public void test_isXMouseActive() throws NoSuchMethodException, SecurityExceptio
 			display.dispose();
 		}
 	}
+
+	@Test
+	public void test_mixedLfAndCrfl() {
+		String actString = Display.withCrLf("First Line \n second line \r\n third line");
+		assertEquals("First Line \r\n second line \r\n third line", actString);
+
+		char[] actCharArray = Display.withCrLf("First Line \n second line \r\n third line".toCharArray());
+		assertEquals("First Line \r\n second line \r\n third line", new String(actCharArray));
+	}
 }