(svn r11601) -Codechange: more strict break conditions for _userstring, assert when it overflows anyway (eg. code change without proper check change)

1 files changed, 5 insertions, 1 deletions

diff --git a/src/misc_gui.cpp b/src/misc_gui.cpp
index 47780867c..81dd3db97 100644
--- a/src/misc_gui.cpp
+++ b/src/misc_gui.cpp
@@ -772,7 +772,7 @@ static void DrawStationCoverageText(const AcceptedCargo accepts,
 	b = InlineString(b, STR_000D_ACCEPTS);
 
 	for (CargoID i = 0; i < NUM_CARGO; i++) {
-		if (b >= lastof(_userstring) - 5) break;
+		if (b >= lastof(_userstring) - (1 + 2 * 4)) break; // ',' or ' ' and two calls to Utf8Encode()
 		switch (sct) {
 			case SCT_PASSENGERS_ONLY: if (!IsCargoInClass(i, CC_PASSENGERS)) continue; break;
 			case SCT_NON_PASSENGERS_ONLY: if (IsCargoInClass(i, CC_PASSENGERS)) continue; break;
@@ -795,6 +795,10 @@ static void DrawStationCoverageText(const AcceptedCargo accepts,
 	if (first) b = InlineString(b, STR_00D0_NOTHING);
 
 	*b = '\0';
+
+	/* Make sure we detect any buffer overflow */
+	assert(b < endof(_userstring));
+
 	DrawStringMultiLine(str_x, str_y, STR_SPEC_USERSTRING, 144);
 }