1 files changed, 11 insertions, 1 deletions
diff --git a/listamsb.c b/listamsb.c
index ee0d9a1..1a0bec9 100644
--- a/listamsb.c
+++ b/listamsb.c
@@ -19,6 +19,10 @@
 
 #define MAX_LINENO 63999
 
+/* a program bigger than this can't possibly fit into memory,
+   even with cart-based AMSB2 and no DOS loaded. */
+#define MAX_PROGLEN 30000
+
 const char *self;
 
 char pipe_command[BUFSIZ + 1] = { "a8cat" };
@@ -77,7 +81,11 @@ int read_header(void) {
 
 	proglen = read_word();
 
-	/* TODO: sanity check proglen */
+	if(proglen > MAX_PROGLEN) {
+		fprintf(stderr, "%s: program too big (%d bytes), won't fit in Atari memory\n",
+				self, proglen);
+	}
+
 	return proglen;
 }
 
@@ -212,10 +220,12 @@ void parse_args(int argc, char **argv) {
 	}
 
 	if(optind >= argc) {
+		freopen(NULL, "rb", stdin);
 		infile = stdin;
 	} else {
 		infile = fopen(argv[optind], "rb");
 		if(!infile) {
+			fprintf(stderr, "%s: ", self);
 			perror(argv[optind]);
 			exit(1);
 		}