From 7b0be4885117b95a169274fd922680eb20d43ce8 Mon Sep 17 00:00:00 2001
From: Petter Urkedal <paurkedal@gmail.com>
Date: Mon, 19 May 2014 22:36:55 +0200
Subject: [PATCH] Use magic header on objects to improve disclaim_test

* tests/disclaim_test.c (my_assert): Call fflush().
* tests/disclaim_test.c (pair_s): Replace is_valid with "magic" field.
* tests/disclaim_test.c (pair_magic): New const static variable.
* tests/disclaim_test.c (is_pair): New function.
* tests/disclaim_test.c (pair_dct, pair_new): Set "magic" field and
use is_pair() instead of is_valid for assertion checking.
---
 tests/disclaim_test.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/tests/disclaim_test.c b/tests/disclaim_test.c
index 7bba6fb8..659bf106 100644
--- a/tests/disclaim_test.c
+++ b/tests/disclaim_test.c
@@ -29,6 +29,7 @@
 
 #define my_assert(e) \
     if (!(e)) { \
+        fflush(stdout); \
         fprintf(stderr, "Assertion failure, line %d: " #e "\n", __LINE__); \
         exit(-1); \
     }
@@ -73,12 +74,19 @@ void test_misc_sizes(void)
 typedef struct pair_s *pair_t;
 
 struct pair_s {
-    int is_valid;
+    char magic[16];
     int checksum;
     pair_t car;
     pair_t cdr;
 };
 
+static const char *pair_magic = "PAIR_MAGIC_BYTES";
+
+int is_pair(pair_t p)
+{
+    return memcmp(p->magic, pair_magic, sizeof(p->magic)) == 0;
+}
+
 void GC_CALLBACK pair_dct(void *obj, void *cd)
 {
     pair_t p = obj;
@@ -90,16 +98,16 @@ void GC_CALLBACK pair_dct(void *obj, void *cd)
              (void *)p, (void *)p->car, (void *)p->cdr);
 #   endif
     my_assert(GC_base(obj));
-    my_assert(p->is_valid);
-    my_assert(!p->car || p->car->is_valid);
-    my_assert(!p->cdr || p->cdr->is_valid);
+    my_assert(is_pair(p));
+    my_assert(!p->car || is_pair(p->car));
+    my_assert(!p->cdr || is_pair(p->cdr));
     checksum = 782;
     if (p->car) checksum += p->car->checksum;
     if (p->cdr) checksum += p->cdr->checksum;
     my_assert(p->checksum == checksum);
 
     /* Invalidate it. */
-    p->is_valid = 0;
+    memset(p->magic, '*', sizeof(p->magic));
     p->checksum = 0;
     p->car = cd;
     p->cdr = NULL;
@@ -112,12 +120,13 @@ pair_new(pair_t car, pair_t cdr)
     static const struct GC_finalizer_closure fc = { pair_dct, NULL };
 
     p = GC_finalized_malloc(sizeof(struct pair_s), &fc);
+    my_assert(!is_pair(p));
     if (p == NULL) {
         fprintf(stderr, "Out of memory!\n");
         exit(3);
     }
     my_assert(memeq(p, 0, sizeof(struct pair_s)));
-    p->is_valid = 1;
+    memcpy(p->magic, pair_magic, sizeof(p->magic));
     p->checksum = 782 + (car? car->checksum : 0) + (cdr? cdr->checksum : 0);
     p->car = car;
     p->cdr = cdr;
-- 
2.50.1