Document TRASH_FILL, TRASH_ALLOC, TRASH_FREE

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Marko Mäkelä 2019-08-12 14:05:26 +03:00
parent cabf10b640
commit b2a387a3f1

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@ -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 */