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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
#ifndef __LIBPERF_INTERNAL_RC_CHECK_H
#define __LIBPERF_INTERNAL_RC_CHECK_H
#include <stdlib.h>
#include <linux/zalloc.h>
/*
* Enable reference count checking implicitly with leak checking, which is
* integrated into address sanitizer.
*/
#if defined(LEAK_SANITIZER) || defined(ADDRESS_SANITIZER)
#define REFCNT_CHECKING 1
#endif
/*
* Shared reference count checking macros.
*
* Reference count checking is an approach to sanitizing the use of reference
* counted structs. It leverages address and leak sanitizers to make sure gets
* are paired with a put. Reference count checking adds a malloc-ed layer of
* indirection on a get, and frees it on a put. A missed put will be reported as
* a memory leak. A double put will be reported as a double free. Accessing
* after a put will cause a use-after-free and/or a segfault.
*/
#ifndef REFCNT_CHECKING
/* Replaces "struct foo" so that the pointer may be interposed. */
#define DECLARE_RC_STRUCT(struct_name) \
struct struct_name
/* Declare a reference counted struct variable. */
#define RC_STRUCT(struct_name) struct struct_name
/*
* Interpose the indirection. Result will hold the indirection and object is the
* reference counted struct.
*/
#define ADD_RC_CHK(result, object) (result = object, object)
/* Strip the indirection layer. */
#define RC_CHK_ACCESS(object) object
/* Frees the object and the indirection layer. */
#define RC_CHK_FREE(object) free(object)
/* A get operation adding the indirection layer. */
#define RC_CHK_GET(result, object) ADD_RC_CHK(result, object)
/* A put operation removing the indirection layer. */
#define RC_CHK_PUT(object) {}
#else
/* Replaces "struct foo" so that the pointer may be interposed. */
#define DECLARE_RC_STRUCT(struct_name) \
struct original_##struct_name; \
struct struct_name { \
struct original_##struct_name *orig; \
}; \
struct original_##struct_name
/* Declare a reference counted struct variable. */
#define RC_STRUCT(struct_name) struct original_##struct_name
/*
* Interpose the indirection. Result will hold the indirection and object is the
* reference counted struct.
*/
#define ADD_RC_CHK(result, object) \
( \
object ? (result = malloc(sizeof(*result)), \
result ? (result->orig = object, result) \
: (result = NULL, NULL)) \
: (result = NULL, NULL) \
)
/* Strip the indirection layer. */
#define RC_CHK_ACCESS(object) object->orig
/* Frees the object and the indirection layer. */
#define RC_CHK_FREE(object) \
do { \
zfree(&object->orig); \
free(object); \
} while(0)
/* A get operation adding the indirection layer. */
#define RC_CHK_GET(result, object) ADD_RC_CHK(result, (object ? object->orig : NULL))
/* A put operation removing the indirection layer. */
#define RC_CHK_PUT(object) \
do { \
if (object) { \
object->orig = NULL; \
free(object); \
} \
} while(0)
#endif
#endif /* __LIBPERF_INTERNAL_RC_CHECK_H */
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