Oops, I forgot to actually implement the checksumming code for the new

savefile format, so any savefiles generated yesterday can be tampered
with. Oh well. While here, tidy up the crc code.

3 files changed, 65 insertions, 38 deletions

diff --git a/adventure/crc.c b/adventure/crc.c
index 8626f348..dafd7626 100644
--- a/adventure/crc.c
+++ b/adventure/crc.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: crc.c,v 1.12 2012/01/07 18:08:35 dholland Exp $	*/
+/*	$NetBSD: crc.c,v 1.13 2012/01/08 18:16:00 dholland Exp $	*/
 
 /*-
  * Copyright (c) 1993
@@ -38,13 +38,13 @@
 static char sccsid[] = "@(#)crc.c	8.1 (Berkeley) 5/31/93";
 static char ORIGINAL_sccsid[] = "@(#)crc.c	5.2 (Berkeley) 4/4/91";
 #else
-__RCSID("$NetBSD: crc.c,v 1.12 2012/01/07 18:08:35 dholland Exp $");
+__RCSID("$NetBSD: crc.c,v 1.13 2012/01/08 18:16:00 dholland Exp $");
 #endif
 #endif /* not lint */
 
 #include "extern.h"
 
-static const unsigned long crctab[] = {
+static const uint32_t crctab[256] = {
 	0x7fffffff,
 	0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
 	0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e,
@@ -98,6 +98,7 @@ static const unsigned long crctab[] = {
 	0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02,
 	0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
 };
+
 /*
  * crc --
  *      Compute a POSIX.2 checksum.  This routine modified by Jim Gillogly
@@ -106,31 +107,39 @@ static const unsigned long crctab[] = {
  *      it.
  */
 
-static unsigned long crcval;
-static unsigned int step;
-
 void
-crc_start(void)
+crc_start(struct crcstate *c)
 {
-	crcval = step = 0;
+	c->crcval = 0;
+	c->step = 0;
 }
 
-/* Process nr bytes at a time; ptr points to them */
-unsigned long
-crc(const char *ptr, int nr)
+/*
+ * Process NUM bytes pointed to by DATA
+ */
+void
+crc_add(struct crcstate *c, const void *data, size_t num)
 {
-	int     i;
-	const char   *p;
+	const unsigned char *udata;
+	size_t pos;
+	unsigned x;
 
-	while (nr > 0)
-		for (p = ptr; nr--; ++p) {
-			i = (crcval >> 24 ^ (unsigned char)*p) & 0xff;
-			if (i == 0) {
-				i = step++;
-				if (step >= sizeof(crctab) / sizeof(crctab[0]))
-					step = 0;
+	udata = data;
+	pos = 0;
+	while (pos < num) {
+		x = (c->crcval >> 24 ^ udata[pos++]) & 0xff;
+		if (x == 0) {
+			x = c->step++;
+			if (c->step >= __arraycount(crctab)) {
+				c->step = 0;
 			}
-			crcval = (crcval << 8) ^ crctab[i];
 		}
-	return crcval & 0xffffffff;	/* Mask to 32 bits. */
+		c->crcval = (c->crcval << 8) ^ crctab[x];
+	}
+}
+
+uint32_t
+crc_get(struct crcstate *c)
+{
+	return c->crcval;
 }
diff --git a/adventure/extern.h b/adventure/extern.h
index 0e87e070..548a270c 100644
--- a/adventure/extern.h
+++ b/adventure/extern.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: extern.h,v 1.14 2009/10/21 01:07:44 snj Exp $	*/
+/*	$NetBSD: extern.h,v 1.15 2012/01/08 18:16:00 dholland Exp $	*/
 
 /*
  * Copyright (c) 1997 Christos Zoulas.  All rights reserved.
@@ -27,8 +27,14 @@
 #include <string.h>
 
 /* crc.c */
-void crc_start(void);
-unsigned long crc(const char *, int);
+struct crcstate {
+	uint32_t crcval;
+	unsigned step;
+};
+
+void crc_start(struct crcstate *);
+void crc_add(struct crcstate *, const void *, size_t);
+uint32_t crc_get(struct crcstate *);
 
 /* done.c */
 int score(void);
diff --git a/adventure/save.c b/adventure/save.c
index b0c92c2b..7392c695 100644
--- a/adventure/save.c
+++ b/adventure/save.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: save.c,v 1.12 2012/01/07 22:23:16 dholland Exp $	*/
+/*	$NetBSD: save.c,v 1.13 2012/01/08 18:16:00 dholland Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -39,7 +39,7 @@
 #if 0
 static char sccsid[] = "@(#)save.c	8.1 (Berkeley) 5/31/93";
 #else
-__RCSID("$NetBSD: save.c,v 1.12 2012/01/07 22:23:16 dholland Exp $");
+__RCSID("$NetBSD: save.c,v 1.13 2012/01/08 18:16:00 dholland Exp $");
 #endif
 #endif				/* not lint */
 
@@ -60,13 +60,14 @@ struct savefile {
 	bool warned;
 	unsigned bintextpos;
 	uint32_t key;
-	uint32_t sum;
+	struct crcstate crc;
 	unsigned char pad[8];
 	unsigned padpos;
 };
 
 #define BINTEXT_WIDTH 60
-#define FORMAT_VERSION 1
+#define FORMAT_VERSION 2
+#define FORMAT_VERSION_NOSUM 1
 static const char header[] = "Adventure save file\n";
 
 ////////////////////////////////////////////////////////////
@@ -133,7 +134,7 @@ savefile_open(const char *name, bool forwrite)
 	sf->warned = false;
 	sf->bintextpos = 0;
 	sf->key = 0;
-	sf->sum = 0;
+	crc_start(&sf->crc);
 	memset(sf->pad, 0, sizeof(sf->pad));
 	sf->padpos = 0;
 	return sf;
@@ -362,7 +363,7 @@ static void
 savefile_key(struct savefile *sf, uint32_t key)
 {
 	sf->key = 0;
-	sf->sum = 0;
+	crc_start(&sf->crc);
 	hash(&sf->key, sizeof(sf->key), sf->pad, sizeof(sf->pad));
 	sf->padpos = 0;
 }
@@ -412,6 +413,7 @@ savefile_cread(struct savefile *sf, void *data, size_t len)
 		}
 		pos += amt;
 	}
+	crc_add(&sf->crc, data, len);
 	return 0;
 }
 
@@ -443,6 +445,7 @@ savefile_cwrite(struct savefile *sf, const void *data, size_t len)
 		}
 		pos += amt;
 	}
+	crc_add(&sf->crc, data, len);
 	return 0;
 }
 
@@ -528,6 +531,7 @@ compat_restore(const char *infile)
 	char   *s;
 	long    sum, cksum = 0;
 	int     i;
+	struct crcstate crc;
 
 	if ((in = fopen(infile, "rb")) == NULL) {
 		fprintf(stderr,
@@ -544,9 +548,10 @@ compat_restore(const char *infile)
 	}
 	fclose(in);
 
-	crc_start();		/* See if she cheated */
+	crc_start(&crc);		/* See if she cheated */
 	for (p = compat_savearray; p->address != NULL; p++)
-		cksum = crc(p->address, p->width);
+		crc_add(&crc, p->address, p->width);
+	cksum = crc_get(&crc);
 	if (sum != cksum)	/* Tsk tsk */
 		return 2;	/* Altered the file */
 	/* We successfully restored, so this really was a save file */
@@ -661,7 +666,7 @@ save(const char *outfile)
 	uint32_t key, writeable_key;
 	uint32_t version;
 	unsigned i, j, n;
-	uint32_t val;
+	uint32_t val, sum;
 
 	sf = savefile_open(outfile, true);
 	if (sf == NULL) {
@@ -732,8 +737,8 @@ save(const char *outfile)
 	}
 #endif
 
-	sf->sum = htonl(sf->sum);
-	if (savefile_binwrite(sf, &sf->sum, sizeof(&sf->sum))) {
+	sum = htonl(crc_get(&sf->crc));
+	if (savefile_binwrite(sf, &sum, sizeof(&sum))) {
 		savefile_close(sf);
 		return 1;
 	}
@@ -753,6 +758,7 @@ restore(const char *infile)
 	uint32_t version, key, sum;
 	unsigned i, j, n;
 	uint32_t val;
+	bool skipsum = false;
 
 	sf = savefile_open(infile, false);
 	if (sf == NULL) {
@@ -777,7 +783,13 @@ restore(const char *infile)
 		return 1;
 	}
 	version = ntohl(version);
-	if (version != FORMAT_VERSION) {
+	switch (version) {
+	    case FORMAT_VERSION:
+		break;
+	    case FORMAT_VERSION_NOSUM:
+		skipsum = true;
+		break;
+	    default:
 		savefile_close(sf);
 		fprintf(stderr,
 		    "Oh dear, that file must be from the future. I don't know"
@@ -840,7 +852,7 @@ restore(const char *infile)
 	}
 	sum = ntohl(sum);
 	/* See if she cheated */
-	if (sum != sf->sum) {
+	if (!skipsum && sum != crc_get(&sf->crc)) {
 		/* Tsk tsk, altered the file */
 		savefile_close(sf);
 		return 2;