From 14595634df55b698f0b924e75572df6f0b809555 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Tue, 16 Jul 2024 03:07:35 -0400
Subject: listbas: handle A+ ERROR- token (required bas.c changes); don't
 segfault on runaway variable name lookup.

---
 bas.c     | 13 +++++++++++++
 bas.h     |  1 +
 listbas.c | 15 +++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/bas.c b/bas.c
index 5321070..110e625 100644
--- a/bas.c
+++ b/bas.c
@@ -22,6 +22,11 @@ int verbose = 0;
    in sync with the token stream. */
 int allow_hex_const = 0;
 
+/* BASIC/A+ uses the same cmd tokens for REM and DATA that BASIC does,
+   but not for the ERROR- token. Unfortunately bas.c needs to know it's
+   an A+ program so it can handle this token correctly. */
+int aplus_errtok_hack = 0;
+
 unsigned short lomem;
 unsigned short vntp;
 unsigned short vntd;
@@ -376,6 +381,14 @@ void walk_code(unsigned int startlineno, unsigned int endlineno) {
 						CALL(on_text);
 						pos = end;
 						break;
+					case 0x53: /* BASIC/A+'s ERROR- token */
+						if(aplus_errtok_hack) {
+							pos++;
+							CALL(on_text);
+							pos = end;
+							break;
+						}
+						/* fall thru */
 					default:
 						pos++;
 						break;
diff --git a/bas.h b/bas.h
index 4374543..7faa2bb 100644
--- a/bas.h
+++ b/bas.h
@@ -203,6 +203,7 @@ extern char *output_filename;
 
 extern int verbose;
 extern int allow_hex_const;
+extern int aplus_errtok_hack;
 
 extern void set_self(const char *argv0);
 extern void die(const char *msg);
diff --git a/listbas.c b/listbas.c
index d542bcd..884f763 100644
--- a/listbas.c
+++ b/listbas.c
@@ -441,6 +441,12 @@ CALLBACK(print_cmd) {
 }
 
 void aplus_op_color_on(unsigned char tok) {
+	switch(tok) {
+		default:
+			break;
+	}
+
+	color_on(color_op);
 }
 
 void op_color_on(unsigned char tok) {
@@ -535,9 +541,15 @@ CALLBACK(print_varname) {
 	if(color) color_on(color_varnames);
 
 	tok &= 0x7f;
+
 	for(i = vnstart, count = 0; count < tok; i++) {
 		if(program[i] & 0x80) count++;
+		if(i == codestart) {
+			fprintf(outfh, "(bad var tok $%02x)", tok | 0x80);
+			return;
+		}
 	}
+
 	do {
 		c = program[i++];
 		if(color && c == ('(' | 0x80)) {
@@ -640,6 +652,9 @@ int main(int argc, char **argv) {
 	if(bas_type != B_ATARI && bas_type != B_APLUS)
 		allow_hex_const = 1;
 
+	if(bas_type == B_APLUS)
+		aplus_errtok_hack = 1;
+
 	init_token_tables();
 
 	readfile();
-- 
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