From 5609d8c92b02b292ddc0148e30be7b38a5c207f6 Mon Sep 17 00:00:00 2001
From: Enyby <enyby@yandex.ru>
Date: Sat, 19 Oct 2019 20:53:56 +0300
Subject: [PATCH] Add check mode for io.open. #57

---
 src/core/org/luaj/vm2/lib/IoLib.java | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/core/org/luaj/vm2/lib/IoLib.java b/src/core/org/luaj/vm2/lib/IoLib.java
index 98c220b5..13f6f986 100644
--- a/src/core/org/luaj/vm2/lib/IoLib.java
+++ b/src/core/org/luaj/vm2/lib/IoLib.java
@@ -583,6 +583,17 @@ public class IoLib extends TwoArgFunction {
 	}
 
 	private File rawopenfile(int filetype, String filename, String mode) throws IOException {
+		int len = mode.length();
+		for (int i = 0; i < len; i++) { // [rwa][+]?b*
+			char ch = mode.charAt(i);
+			if (i == 0 && "rwa".indexOf(ch) >= 0) continue;
+			if (i == 1 && ch == '+') continue;
+			if (i >= 1 && ch == 'b') continue;
+			len = -1;
+			break;
+		}
+		if (len <= 0) argerror(2, "invalid mode: '" + mode + "'");
+		
 		switch (filetype) {
 		case FTYPE_STDIN: return wrapStdin();
 		case FTYPE_STDOUT: return wrapStdout();