Bug 530448 - Make TestPoisonArea.cpp compile on new mingw, r=zwol

layout/base/tests/TestPoisonArea.cpp

@@ -394,6 +394,27 @@ ReserveNegativeControl()
   return (uintptr_t)result;
 }
 
+#ifdef _WIN32
+static BOOL
+IsBadExecPtr(uintptr_t ptr)
+{
+  BOOL ret = true;
+
+#ifdef _MSC_VER
+  __try {
+    ((void (*)())ptr)();
+  } __except (EXCEPTION_EXECUTE_HANDLER) {
+    ret = false;
+  }
+#else
+  printf("INFO | exec test not supported on MinGW build\n");
+  // We do our best
+  ret = IsBadReadPtr((const void*)ptr, 1);
+#endif
+  return ret;
+}
+#endif
+
 /* Test each page.  */
 static bool
 TestPage(const char *pagelabel, uintptr_t pageaddr, int should_succeed)
@@ -413,15 +434,23 @@ TestPage(const char *pagelabel, uintptr_t pageaddr, int should_succeed)
     }
 
 #ifdef _WIN32
-    __try {
-      unsigned char scratch;
-      switch (test) {
-      case 0: scratch = *(volatile unsigned char *)opaddr; break;
-      case 1: ((void (*)())opaddr)(); break;
-      case 2: *(volatile unsigned char *)opaddr = 0; break;
-      default: abort();
-      }
+    BOOL badptr;
 
+    switch (test) {
+    case 0: badptr = IsBadReadPtr((const void*)opaddr, 1); break;
+    case 1: badptr = IsBadExecPtr(opaddr); break;
+    case 2: badptr = IsBadWritePtr((void*)opaddr, 1); break;
+    default: abort();
+    }
+
+    if (badptr) {
+      if (should_succeed) {
+        printf("TEST-UNEXPECTED-FAIL | %s %s\n", oplabel, pagelabel);
+        failed = true;
+      } else {
+        printf("TEST-PASS | %s %s\n", oplabel, pagelabel);
+      }
+    } else {
       // if control reaches this point the probe succeeded
       if (should_succeed) {
         printf("TEST-PASS | %s %s\n", oplabel, pagelabel);
@@ -429,17 +458,6 @@ TestPage(const char *pagelabel, uintptr_t pageaddr, int should_succeed)
         printf("TEST-UNEXPECTED-FAIL | %s %s\n", oplabel, pagelabel);
         failed = true;
       }
-    } __except (EXCEPTION_EXECUTE_HANDLER) {
-      // Unfortunately, there is no equivalent of strsignal().
-      DWORD code = GetExceptionCode();
-      if (should_succeed) {
-        printf("TEST-UNEXPECTED-FAIL | %s %s | exception code %x\n",
-               oplabel, pagelabel, code);
-        failed = true;
-      } else {
-        printf("TEST-PASS | %s %s | exception code %x\n",
-               oplabel, pagelabel, code);
-      }
     }
 #else
     pid_t pid = fork();