check-structures-sanity: Allow running without MALLOC_PERTURB_, and adjust bool check accordingly

plugins/devel/check-structures-sanity/check-structures-sanity.h

@@ -82,6 +82,7 @@ public:
     bool failfast;
     bool noprogress;
     bool maybepointer;
+    uint8_t perturb_byte;
 
     Checker(color_ostream & out);
     bool queue_item(const QueueItem & item, CheckedStructure cs);

plugins/devel/check-structures-sanity/dispatch.cpp

@@ -296,7 +296,7 @@ void Checker::dispatch_primitive(const QueueItem & item, const CheckedStructure
     else if (cs.identity == df::identity_traits<bool>::get())
     {
         auto val = *reinterpret_cast<const uint8_t *>(item.ptr);
-        if (val > 1 && val != 0xd2)
+        if (val > 1 && perturb_byte && val != perturb_byte && val != (perturb_byte ^ 0xff))
         {
             FAIL("invalid value for bool: " << int(val));
         }

plugins/devel/check-structures-sanity/main.cpp

@@ -33,28 +33,33 @@ DFhackCExport command_result plugin_init(color_ostream &, std::vector<PluginComm
     return CR_OK;
 }
 
-bool check_malloc_perturb()
+// returns 0 if MALLOC_PERTURB_ is unset, or if set to 0, because 0 is not useful
+uint8_t check_malloc_perturb()
 {
-    struct T_test {
+    const size_t TEST_DATA_LEN = 5000;  // >1 4kb page
-        uint32_t data[1024];
+    std::unique_ptr<uint8_t[]> test_data{new uint8_t[TEST_DATA_LEN]};
-    };
+
-    auto test = new T_test;
+    uint8_t expected_perturb = test_data[0];
-    bool ret = (test->data[0] == 0xd2d2d2d2);
+    if (getenv("MALLOC_PERTURB_"))
-    delete test;
+        expected_perturb = 0xff ^ static_cast<uint8_t>(atoi(getenv("MALLOC_PERTURB_")));
-    return ret;
+
+    for (size_t i = 0; i < TEST_DATA_LEN; i++)
+        if (expected_perturb != test_data[i])
+            return 0;
+
+    return expected_perturb;
 }
 
 static command_result command(color_ostream & out, std::vector<std::string> & parameters)
 {
-    if (!check_malloc_perturb())
+    uint8_t perturb_byte = check_malloc_perturb();
-    {
+    if (!perturb_byte)
-        out.printerr("check-structures-sanity: MALLOC_PERTURB_ not set, cannot continue\n");
+        out.printerr("check-structures-sanity: MALLOC_PERTURB_ not set. Some checks may be bypassed or fail.\n");
-        return CR_FAILURE;
-    }
 
     CoreSuspender suspend;
 
     Checker checker(out);
+    checker.perturb_byte = perturb_byte;
 
     // check parameters with values first
 #define VAL_PARAM(name, expr_using_value) \