Resume now detects if a save has incompatible endianness.

diff --git a/NEWS.adoc b/NEWS.adoc
index f01d4f30f32a796815e09abe30bcd38d4bbb0490..da58c799e98161d0a38a731be4ec25530e668c3f 100644 (file)
--- a/NEWS.adoc
+++ b/NEWS.adoc
@@ -2,6 +2,10 @@
 // SPDX-FileCopyrightText: Eric S. Raymond <esr@thyrsus.com>
 // SPDX-License-Identifier: CC-BY-4.0
 
+Reoisitory head::
+  Savefiles now have an identigting magic cookie at the front.
+  Resume detects if a save has incompatible endianness.
+
 1.15: 2023-04-03::
   Commands in magic-word sequence now interrupt it, as in original.
   Bug fix for bird not starting caged in endgame.

diff --git a/saveresume.c b/saveresume.c
index 0b71319c0dc835368eb95f0df39d1dc6e8f5d292..c6d0ba0f274d3e73271e92b171a95521caf96694 100644 (file)
--- a/saveresume.c
+++ b/saveresume.c
@@ -18,6 +18,11 @@
 #include "advent.h"
 #include "dungeon.h"
 
+/*
+ * Use this to detect endianness mismatch.  Can't be unchanges by byte-swapping.
+ */
+#define ENDIAN_MAGIC   2317
+
 struct save_t save;
 
 #define IGNORE(r) do{if (r){}}while(0)
@@ -28,6 +33,8 @@ int savefile(FILE *fp)
     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));
@@ -136,7 +143,7 @@ int restore(FILE* fp)
 
     IGNORE(fread(&save, sizeof(struct save_t), 1, fp));
     fclose(fp);
-    if (memcmp(save.magic, ADVENT_MAGIC, sizeof(ADVENT_MAGIC)) != 0)
+    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));