From 0044a85e0ab54ebec7e1ba47f4a4a6ac2ad29360 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Fri, 24 May 2024 04:10:16 -0400
Subject: unprotbas: implement protection (-p/-pc/-pv).

---
 unprotbas.c | 120 +++++++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 90 insertions(+), 30 deletions(-)

(limited to 'unprotbas.c')

diff --git a/unprotbas.c b/unprotbas.c
index a3ae9cf..8540e6a 100644
--- a/unprotbas.c
+++ b/unprotbas.c
@@ -61,6 +61,8 @@ int was_protected = 0;
 int verbose = 0;
 int readmap = 0;
 int writemap = 0;
+int protect_vars = 0;
+int protect_code = 0;
 
 /* file handles */
 FILE *input_file = NULL;
@@ -155,14 +157,23 @@ int fixline(int linepos) {
 	/* +3 here to skip the line number + line length */
 	int token, done = 0, offset = data[linepos + 3];
 
+	/* this works for lines with multiple statements (colons): */
 	while(!done) {
+		fprintf(stderr, "offset was %02x\n", offset);
 		offset = data[linepos + offset];
 		token = data[linepos + offset - 1];
-		/* fprintf(stderr, "offset %02x   token %02x\n", offset, token); */
+		fprintf(stderr, "offset %02x   token %02x\n", offset, token);
 		if(token != 0x14)
 			done++;
 	}
 
+	/* otherwise, the first statement being the only statement, use its
+		next-statement offset. */
+	if(!offset) {
+		offset = data[linepos + 3];
+		fprintf(stderr, "offset now %02x\n", offset);
+	}
+
 	data[linepos + 2] = offset;
 	return offset;
 }
@@ -207,6 +218,30 @@ int fixcode(void) {
 	return result;
 }
 
+/* iterate over all the lines, zero out the offset of the last one
+	before line 32768 */
+void breakcode(void) {
+	int pos = codestart, oldpos = 0;
+	int offset, lineno = -1, tmpno = -1;
+
+	while(pos < filelen) {
+		lineno = tmpno;
+		tmpno = getword(pos);
+		if(tmpno == 32768) {
+			break;
+		} else {
+			offset = data[pos + 2];
+			if(!offset)
+				die("program already was code-protected");
+			oldpos = pos;
+			pos += offset;
+		}
+	}
+
+	data[oldpos + 2] = 0;
+	fprintf(stderr, "set invalid line pointer at line %d\n", lineno);
+}
+
 /* sometimes the variable name table isn't large enough to hold
 	the generated variable names. move_code() makes more space,
 	by moving the rest of the program (including the variable value
@@ -539,6 +574,13 @@ void apply_var_map(void) {
 	memmove(data + vnstart, new_vntable, newp);
 }
 
+void scramble_vars(void) {
+	int i;
+
+	for(i = vnstart; i < vvstart - 1; i++)
+		data[i] = '\x9b';
+}
+
 void print_help(void) {
 	fprintf(stderr, "Usage: %s [-v] [-f] [-n] [-g] [-c] [-r|-w] <inputfile> <outputfile>\n", self);
 	fprintf(stderr, "-v: verbose\n");
@@ -613,6 +655,19 @@ void parse_args(int argc, char **argv) {
 				case 'c': checkonly = 1; break;
 				case 'r': readmap = 1; break;
 				case 'w': writemap = 1; break;
+				case 'p': {
+								 switch((*argv)[2]) {
+									 case 'c':
+										 protect_code = 1; break;
+									 case 'v':
+										 protect_vars = 1; break;
+									 case 0:
+										 protect_code = protect_vars = 1; break;
+									 default:
+										 die("invalid -p suboption (only -p, -pc, -pv are valid)");
+								 }
+							 }
+							 break;
 				case 0:
 							 if(!input_file)
 								 open_input(NULL);
@@ -648,41 +703,46 @@ int main(int argc, char **argv) {
 
 	if(lomem) die("This doesn't look like an Atari BASIC program (no $0000 signature)");
 
-	if(readmap) {
-		was_protected = !vntable_ok();
-		read_var_map();
-		apply_var_map();
+	if(protect_code || protect_vars) {
+		if(protect_vars) scramble_vars();
+		if(protect_code) breakcode();
 	} else {
-		if(!keepvars) {
-			if(fixvars()) {
-				was_protected = 1;
-				if(verbose) fprintf(stderr, "Variable names replaced\n");
-			} else {
-				if(verbose) fprintf(stderr, "Variable names were already OK\n");
+		if(readmap) {
+			was_protected = !vntable_ok();
+			read_var_map();
+			apply_var_map();
+		} else {
+			if(!keepvars) {
+				if(fixvars()) {
+					was_protected = 1;
+					if(verbose) fprintf(stderr, "Variable names replaced\n");
+				} else {
+					if(verbose) fprintf(stderr, "Variable names were already OK\n");
+				}
 			}
 		}
-	}
 
-	if(fixcode()) {
-		if(verbose) fprintf(stderr, "Fixed invalid offset in code\n");
-		was_protected = 1;
-	} else {
-		if(verbose) fprintf(stderr, "No invalid offsets\n");
-	}
+		if(fixcode()) {
+			if(verbose) fprintf(stderr, "Fixed invalid offset in code\n");
+			was_protected = 1;
+		} else {
+			if(verbose) fprintf(stderr, "No invalid offsets\n");
+		}
 
-	if(verbose) {
-		if(was_protected)
-			fprintf(stderr, "Program was protected.\n");
-		else
-			fprintf(stderr, "Program was NOT protected.\n");
-	}
+		if(verbose) {
+			if(was_protected)
+				fprintf(stderr, "Program was protected.\n");
+			else
+				fprintf(stderr, "Program was NOT protected.\n");
+		}
 
-	if(checkonly) {
-		if(verbose) fprintf(stderr, "Check-only mode; no output written.\n");
-		if(was_protected)
-			return 0;
-		else
-			return 2;
+		if(checkonly) {
+			if(verbose) fprintf(stderr, "Check-only mode; no output written.\n");
+			if(was_protected)
+				return 0;
+			else
+				return 2;
+		}
 	}
 
 	int got = fwrite(data, 1, filelen, output_file);
-- 
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