Bug #3508602. Avoid hang with diff files. From zenico.

1 files changed, 16 insertions, 5 deletions

diff --git a/lexers/LexOthers.cxx b/lexers/LexOthers.cxx
index 5f4eaed2d..259059fd9 100644
--- a/lexers/LexOthers.cxx
+++ b/lexers/LexOthers.cxx
@@ -500,6 +500,10 @@ static void ColouriseBatchDoc(
 	}
 }
 
+#define DIFF_BUFFER_START_SIZE 16
+// Note that ColouriseDiffLine analyzes only the first DIFF_BUFFER_START_SIZE
+// characters of each line to classify the line.
+
 static void ColouriseDiffLine(char *lineBuffer, int endLine, Accessor &styler) {
 	// It is needed to remember the current state to recognize starting
 	// comment lines before the first "diff " or "--- ". If a real
@@ -556,20 +560,27 @@ static void ColouriseDiffLine(char *lineBuffer, int endLine, Accessor &styler) {
 }
 
 static void ColouriseDiffDoc(unsigned int startPos, int length, int, WordList *[], Accessor &styler) {
-	char lineBuffer[1024];
+	char lineBuffer[DIFF_BUFFER_START_SIZE];
 	styler.StartAt(startPos);
 	styler.StartSegment(startPos);
 	unsigned int linePos = 0;
 	for (unsigned int i = startPos; i < startPos + length; i++) {
-		lineBuffer[linePos++] = styler[i];
-		if (AtEOL(styler, i) || (linePos >= sizeof(lineBuffer) - 1)) {
-			// End of line (or of line buffer) met, colourise it
-			lineBuffer[linePos] = '\0';
+		if (AtEOL(styler, i)) {
+			if (linePos < DIFF_BUFFER_START_SIZE) {
+				lineBuffer[linePos] = 0;
+			}
 			ColouriseDiffLine(lineBuffer, i, styler);
 			linePos = 0;
+		} else if (linePos < DIFF_BUFFER_START_SIZE - 1) {
+			lineBuffer[linePos++] = styler[i];
+		} else if (linePos == DIFF_BUFFER_START_SIZE - 1) {
+			lineBuffer[linePos++] = 0;
 		}
 	}
 	if (linePos > 0) {	// Last line does not have ending characters
+		if (linePos < DIFF_BUFFER_START_SIZE) {
+			lineBuffer[linePos] = 0;
+		}
 		ColouriseDiffLine(lineBuffer, startPos + length - 1, styler);
 	}
 }