Resume now detects if a save has incompatible endianness.

[open-adventure.git] / saveresume.c

diff --git a/saveresume.c b/saveresume.c
index dedb5bbe288a03b6581ad18895ea4183984f83ba..c6d0ba0f274d3e73271e92b171a95521caf96694 100644 (file)
--- a/saveresume.c
+++ b/saveresume.c
@@ -4,9 +4,9 @@
  * (ESR) This replaces  a bunch of particularly nasty FORTRAN-derived code;
  * see the history.adoc file in the source distribution for discussion.
  *
- * Copyright (c) 1977, 2005 by Will Crowther and Don Woods
- * Copyright (c) 2017 by Eric S. Raymond
- * SPDX-License-Identifier: BSD-2-clause
+ * SPDX-FileCopyrightText: 1977, 2005 by Will Crowther and Don Woods
+ * SPDX-FileCopyrightText: 2017 by Eric S. Raymond
+ * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <stdlib.h>
@@ -19,36 +19,22 @@
 #include "dungeon.h"
 
 /*
- * Bump on save format change.
- *
- * Note: Verify that the tests run clean before bumping this, then rebuild the check
- * files afterwards.  Otherwise you will get a spurious failure due to the old version
- * having been generated into a check file.
+ * Use this to detect endianness mismatch.  Can't be unchanges by byte-swapping.
  */
-#define VRSION 29
+#define ENDIAN_MAGIC   2317
 
-/*
- * If you change the first three members, the resume function may not properly
- * reject saves from older versions.  Yes, this glues us to a hardware-
- * dependent length of int.  Later members can change, but bump the version
- * when you do that.
- */
-struct save_t {
-    int64_t savetime;
-    int32_t mode;              /* not used, must be present for version detection */
-    int32_t version;
-    struct game_t game;
-};
 struct save_t save;
 
 #define IGNORE(r) do{if (r){}}while(0)
 
-int savefile(FILE *fp, int32_t version)
+int savefile(FILE *fp)
 /* Save game to file. No input or output from user. */
 {
-    save.savetime = time(NULL);
-    save.mode = -1;
-    save.version = (version == 0) ? VRSION : version;
+    memcpy(&save.magic, ADVENT_MAGIC, sizeof(ADVENT_MAGIC));
+    if (save.version == 0)
+       save.version = SAVE_VERSION;
+    if (save.canary == 0)
+       save.canary = ENDIAN_MAGIC;
 
     save.game = game;
     IGNORE(fwrite(&save, sizeof(struct save_t), 1, fp));
@@ -106,7 +92,7 @@ int suspend(void)
         free(name);
     }
 
-    savefile(fp, VRSION);
+    savefile(fp);
     fclose(fp);
     rspeak(RESUME_HELP);
     exit(EXIT_SUCCESS);
@@ -123,8 +109,7 @@ int resume(void)
 #endif
     FILE *fp = NULL;
 
-    if (game.loc != 1 ||
-        game.abbrev[1] != 1) {
+    if (game.loc != LOC_START || game.abbrev[LOC_START] != 1) {
         rspeak(RESUME_ABANDON);
         if (!yes_or_no(arbitrary_messages[THIS_ACCEPTABLE], arbitrary_messages[OK_MAN], arbitrary_messages[OK_MAN]))
             return GO_CLEAROBJ;
@@ -158,8 +143,10 @@ int restore(FILE* fp)
 
     IGNORE(fread(&save, sizeof(struct save_t), 1, fp));
     fclose(fp);
-    if (save.version != VRSION) {
-        rspeak(VERSION_SKEW, save.version / 10, MOD(save.version, 10), VRSION / 10, MOD(VRSION, 10));
+    if (memcmp(save.magic, ADVENT_MAGIC, sizeof(ADVENT_MAGIC)) != 0 || save.canary != ENDIAN_MAGIC)
+       rspeak(BAD_SAVE);
+    else if (save.version != SAVE_VERSION) {
+        rspeak(VERSION_SKEW, save.version / 10, MOD(save.version, 10), SAVE_VERSION / 10, MOD(SAVE_VERSION, 10));
     } else if (!is_valid(save.game)) {
        rspeak(SAVE_TAMPERING);
        exit(EXIT_SUCCESS);