From b2a387a3f1a0603482d184241979f0172cba45cf Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marko=20M=C3=A4kel=C3=A4?= Date: Mon, 12 Aug 2019 14:05:26 +0300 Subject: Document TRASH_FILL, TRASH_ALLOC, TRASH_FREE --- include/my_valgrind.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'include/my_valgrind.h') diff --git a/include/my_valgrind.h b/include/my_valgrind.h index ad22f0cad40..7a56b28c0f0 100644 --- a/include/my_valgrind.h +++ b/include/my_valgrind.h @@ -1,4 +1,4 @@ -/* Copyright (C) 2010 Monty Program Ab +/* Copyright (C) 2010, 2019, MariaDB Corporation. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -55,11 +55,19 @@ https://github.com/google/sanitizers/wiki/AddressSanitizerManualPoisoning */ #endif /* HAVE_VALGRIND */ #ifndef DBUG_OFF +/* NOTE: Do not invoke TRASH_FILL directly! Use TRASH_ALLOC or TRASH_FREE. + +The MEM_UNDEFINED() call before memset() is for canceling the effect +of any previous MEM_NOACCESS(). We must invoke MEM_UNDEFINED() after +writing the dummy pattern, unless MEM_NOACCESS() is going to be invoked. +On AddressSanitizer, the MEM_UNDEFINED() in TRASH_ALLOC() has no effect. */ #define TRASH_FILL(A,B,C) do { const size_t trash_tmp= (B); MEM_UNDEFINED(A, trash_tmp); memset(A, C, trash_tmp); } while (0) #else #define TRASH_FILL(A,B,C) do { MEM_UNDEFINED((A), (B)); } while (0) #endif +/** Note that some memory became allocated or uninitialized. */ #define TRASH_ALLOC(A,B) do { TRASH_FILL(A,B,0xA5); MEM_UNDEFINED(A,B); } while(0) +/** Note that some memory became freed. (Prohibit further access to it.) */ #define TRASH_FREE(A,B) do { TRASH_FILL(A,B,0x8F); MEM_NOACCESS(A,B); } while(0) #endif /* MY_VALGRIND_INCLUDED */ -- cgit v1.2.1