[lttng-tools.git] / src / common / macros.hpp

/*
 * Copyright (C) 2011 EfficiOS Inc.
 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#ifndef _MACROS_H
#define _MACROS_H

#include <common/compat/string.hpp>

#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include <memory>
#include <pthread.h>
#include <type_traits>

/*
 * Takes a pointer x and transform it so we can use it to access members
 * without a function call. Here an example:
 *
 *    #define GET_SIZE(x) LTTNG_REF(x)->size
 *
 *    struct { int size; } s;
 *
 *    printf("size : %d\n", GET_SIZE(&s));
 *
 * For this example we can't use something like this for compatibility purpose
 * since this will fail:
 *
 *    #define GET_SIZE(x) x->size;
 *
 * This is mostly use for the compatibility layer of lttng-tools. See
 * poll/epoll for a good example. Since x can be on the stack or allocated
 * memory using malloc(), we must use generic accessors for compat in order to
 * *not* use a function to access members and not the variable name.
 */
#define LTTNG_REF(x) ((typeof(*(x)) *) (x))

#ifdef NDEBUG
/*
* Force usage of the assertion condition to prevent unused variable warnings
* when `assert()` are disabled by the `NDEBUG` definition.
*/
# define LTTNG_ASSERT(_cond) ((void) sizeof((void) (_cond), 0))
#else
# include <assert.h>
# define LTTNG_ASSERT(_cond) assert(_cond)
#endif

/*
 * Memory allocation zeroed
 */

static inline
void *zmalloc_internal(size_t size)
{
	return calloc(1, size);
}

template <typename T>
struct can_malloc
{
	/*
	 * gcc versions before 5.0 lack some type traits defined in C++11.
	 * Since in this instance we use the trait to prevent misuses
	 * of malloc (and statically assert) and not to generate different
	 * code based on this property, simply set value to true and allow
	 * the code to compile. Anyone using a contemporary compiler will
	 * catch the error.
	 */
#if __GNUG__ && __GNUC__ < 5
	static constexpr bool value = true;
#else
	static constexpr bool value = std::is_trivially_constructible<T>::value;
#endif
};

/*
 * Malloc and zero-initialize an object of type T, asserting that T can be
 * safely malloc-ed (is trivially constructible).
 */
template<typename T>
T *zmalloc()
{
	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	return (T *) zmalloc_internal(sizeof(T)); /* NOLINT sizeof potentially used on a pointer. */
}

/*
 * Malloc and zero-initialize a buffer of size `size`, asserting that type T
 * can be safely malloc-ed (is trivially constructible).
 */
template<typename T>
T *zmalloc(size_t size)
{
	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	LTTNG_ASSERT(size >= sizeof(T));
	return (T *) zmalloc_internal(size);
}

/*
 * Malloc and zero-initialize an array of `nmemb` elements of type T,
 * asserting that T can be safely malloc-ed (is trivially constructible).
 */
template<typename T>
T *calloc(size_t nmemb)
{
	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	return (T *) zmalloc_internal(nmemb * sizeof(T)); /* NOLINT sizeof potentially used on a pointer. */
}

/*
 * Malloc an object of type T, asserting that T can be safely malloc-ed (is
 * trivially constructible).
 */
template<typename T>
T *malloc()
{
	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	return (T *) malloc(sizeof(T));
}

/*
 * Malloc a buffer of size `size`, asserting that type T can be safely
 * malloc-ed (is trivially constructible).
 */
template<typename T>
T *malloc(size_t size)
{
	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	return (T *) malloc(size);
}

/*
 * Prevent using `free` on types that are non-POD.
 *
 * Declare a delete prototype of free if the parameter type is not safe to free
 * (non-POD).
 *
 * If the parameter is a pointer to void, we can't check if what is pointed
 * to is safe to free or not, as we don't know what is pointed to.  Ideally,
 * all calls to free would be with a typed pointer, but there are too many
 * instances of passing a pointer to void to enforce that right now.  So allow
 * pointers to void, these will not be checked.
 */

template<typename T>
struct can_free
{
	/*
	 * gcc versions before 5.0 lack some type traits defined in C++11.
	 * Since in this instance we use the trait to prevent misuses
	 * of free (and statically assert) and not to generate different
	 * code based on this property, simply set value to true and allow
	 * the code to compile. Anyone using a contemporary compiler will
	 * catch the error.
	 */
#if __GNUG__ && __GNUC__ < 5
	static constexpr bool value = true;
#else
	static constexpr bool value = std::is_trivially_destructible<T>::value || std::is_void<T>::value;
#endif
};

template<typename T, typename = typename std::enable_if<!can_free<T>::value>::type>
void free(T *p) = delete;

template<typename T>
struct can_memset
{
	static constexpr bool value = std::is_pod<T>::value || std::is_void<T>::value;
};

template <typename T, typename = typename std::enable_if<!can_memset<T>::value>::type>
void *memset(T *s, int c, size_t n) = delete;

template<typename T>
struct can_memcpy
{
	/*
	 * gcc versions before 5.0 lack some type traits defined in C++11.
	 * Since in this instance we use the trait to prevent misuses
	 * of memcpy (and statically assert) and not to generate different
	 * code based on this property, simply set value to true and allow
	 * the code to compile. Anyone using a contemporary compiler will
	 * catch the error.
	 */
#if __GNUG__ && __GNUC__ < 5
	static constexpr bool value = true;
#else
	static constexpr bool value = std::is_trivially_copyable<T>::value;
#endif
};

template <typename T, typename U,
		typename = typename std::enable_if<!can_memcpy<T>::value>::type,
		typename = typename std::enable_if<!can_memcpy<U>::value>::type>
void *memcpy(T *d, const U *s, size_t n) = delete;

template<typename T>
struct can_memmove
{
	/*
	 * gcc versions before 5.0 lack some type traits defined in C++11.
	 * Since in this instance we use the trait to prevent misuses
	 * of memmove (and statically assert) and not to generate different
	 * code based on this property, simply set value to true and allow
	 * the code to compile. Anyone using a contemporary compiler will
	 * catch the error.
	 */
#if __GNUG__ && __GNUC__ < 5
	static constexpr bool value = true;
#else
	static constexpr bool value = std::is_trivially_copyable<T>::value;
#endif
};

template <typename T, typename U,
		typename = typename std::enable_if<!can_memmove<T>::value>::type,
		typename = typename std::enable_if<!can_memmove<U>::value>::type>
void *memmove(T *d, const U *s, size_t n) = delete;

#ifndef ARRAY_SIZE
#define ARRAY_SIZE(array)   (sizeof(array) / (sizeof((array)[0])))
#endif

#ifndef LTTNG_PACKED
#define LTTNG_PACKED __attribute__((__packed__))
#endif

#ifndef LTTNG_NO_SANITIZE_ADDRESS
#if defined(__clang__) || defined (__GNUC__)
#define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
#else
#define LTTNG_NO_SANITIZE_ADDRESS
#endif
#endif

#define member_sizeof(type, field)	sizeof(((type *) 0)->field)

#define ASSERT_LOCKED(lock)	     LTTNG_ASSERT(pthread_mutex_trylock(&(lock)))
#define ASSERT_RCU_READ_LOCKED(lock) LTTNG_ASSERT(rcu_read_ongoing())

/* Attribute suitable to tag functions as having printf()-like arguments. */
#define ATTR_FORMAT_PRINTF(_string_index, _first_to_check) \
	__attribute__((format(printf, _string_index, _first_to_check)))

/* Attribute suitable to tag functions as having strftime()-like arguments. */
#define ATTR_FORMAT_STRFTIME(_string_index) \
	__attribute__((format(strftime, _string_index, 0)))

/* Macros used to ignore specific compiler diagnostics. */

#define DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
#define DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")

#if defined(__clang__)
  /* Clang */
# define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT
# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
	_Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
# define DIAGNOSTIC_IGNORE_LOGICAL_OP
# define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
# define DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
	_Pragma("GCC diagnostic ignored \"-Winvalid-offsetof\"")
#else
  /* GCC */
# define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT \
	_Pragma("GCC diagnostic ignored \"-Wsuggest-attribute=format\"")
# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
	_Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
# define DIAGNOSTIC_IGNORE_LOGICAL_OP \
	_Pragma("GCC diagnostic ignored \"-Wlogical-op\"")
#if __GNUG__ && __GNUC__ >= 7
# define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES				\
	_Pragma("GCC diagnostic ignored \"-Wduplicated-branches\"")
#else
# define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
#endif /* __GNUG__ && __GNUC__ >= 7 */
# define DIAGNOSTIC_IGNORE_INVALID_OFFSETOF				\
	_Pragma("GCC diagnostic ignored \"-Winvalid-offsetof\"")
#endif

/* Used to make specific C++ functions to C code. */
#ifdef __cplusplus
#define C_LINKAGE extern "C"
#else
#define C_LINKAGE
#endif

/*
 * lttng_strncpy returns 0 on success, or nonzero on failure.
 * It checks that the @src string fits into @dst_len before performing
 * the copy. On failure, no copy has been performed.
 *
 * Assumes that 'src' is null-terminated.
 *
 * dst_len includes the string's trailing NULL.
 */
static inline
int lttng_strncpy(char *dst, const char *src, size_t dst_len)
{
	if (strlen(src) >= dst_len) {
		/* Fail since copying would result in truncation. */
		return -1;
	}
	strcpy(dst, src);
	return 0;
}

namespace lttng {
namespace utils {
template <class Parent, class Member>
Parent *container_of(const Member *member, const Member Parent::*ptr_to_member)
{
	const Parent *dummy_parent = nullptr;
	auto *offset_of_member = reinterpret_cast<const char *>(&(dummy_parent->*ptr_to_member));
	auto address_of_parent = reinterpret_cast<const char *>(member) - offset_of_member;

	return reinterpret_cast<Parent *>(address_of_parent);
}
} /* namespace utils */
} /* namespace lttng */

#endif /* _MACROS_H */
Commit	Line	Data
990570ed	1	/*
21cf9b6b	2	* Copyright (C) 2011 EfficiOS Inc.
ab5be9fa	3	* Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
990570ed	4	*
ab5be9fa	5	* SPDX-License-Identifier: GPL-2.0-only
990570ed	6	*
990570ed DG	7	*/
	8
	9	#ifndef _MACROS_H
	10	#define _MACROS_H
	11
64803277 SM	12	#include <common/compat/string.hpp>
64803277 SM	13
93375aa6	14	#include <stddef.h>
64803277	15	#include <stdlib.h>
f6835b82	16	#include <string.h>
64803277	17
f1ca0880 JG	18	#include <memory>
f1ca0880 JG	19	#include <pthread.h>
64803277	20	#include <type_traits>
990570ed DG	21
	22	/*
	23	* Takes a pointer x and transform it so we can use it to access members
	24	* without a function call. Here an example:
	25	*
	26	* #define GET_SIZE(x) LTTNG_REF(x)->size
	27	*
	28	* struct { int size; } s;
	29	*
	30	* printf("size : %d\n", GET_SIZE(&s));
	31	*
	32	* For this example we can't use something like this for compatibility purpose
	33	* since this will fail:
	34	*
	35	* #define GET_SIZE(x) x->size;
	36	*
	37	* This is mostly use for the compatibility layer of lttng-tools. See
	38	* poll/epoll for a good example. Since x can be on the stack or allocated
	39	* memory using malloc(), we must use generic accessors for compat in order to
	40	* not use a function to access members and not the variable name.
	41	*/
5c7248cd	42	#define LTTNG_REF(x) ((typeof((x)) ) (x))
990570ed	43
64803277 SM	44	#ifdef NDEBUG
	45	/*
	46	* Force usage of the assertion condition to prevent unused variable warnings
	47	* when `assert()` are disabled by the `NDEBUG` definition.
	48	*/
	49	# define LTTNG_ASSERT(_cond) ((void) sizeof((void) (_cond), 0))
	50	#else
	51	# include <assert.h>
	52	# define LTTNG_ASSERT(_cond) assert(_cond)
	53	#endif
	54
990570ed DG	55	/*
	56	* Memory allocation zeroed
	57	*/
64803277	58
4616a46c	59	static inline
64803277 SM	60	void *zmalloc_internal(size_t size)
	61	{
	62	return calloc(1, size);
	63	}
	64
	65	template <typename T>
	66	struct can_malloc
	67	{
f12e33ba JG	68	/*
	69	* gcc versions before 5.0 lack some type traits defined in C++11.
	70	* Since in this instance we use the trait to prevent misuses
	71	* of malloc (and statically assert) and not to generate different
	72	* code based on this property, simply set value to true and allow
	73	* the code to compile. Anyone using a contemporary compiler will
	74	* catch the error.
	75	*/
	76	#if __GNUG__ && __GNUC__ < 5
	77	static constexpr bool value = true;
	78	#else
64803277	79	static constexpr bool value = std::is_trivially_constructible<T>::value;
f12e33ba	80	#endif
64803277 SM	81	};
	82
	83	/*
	84	* Malloc and zero-initialize an object of type T, asserting that T can be
	85	* safely malloc-ed (is trivially constructible).
	86	*/
	87	template<typename T>
	88	T *zmalloc()
	89	{
	90	static_assert (can_malloc<T>::value, "type can be malloc'ed");
5c7248cd	91	return (T ) zmalloc_internal(sizeof(T)); / NOLINT sizeof potentially used on a pointer. */
64803277 SM	92	}
	93
	94	/*
	95	* Malloc and zero-initialize a buffer of size `size`, asserting that type T
	96	* can be safely malloc-ed (is trivially constructible).
	97	*/
	98	template<typename T>
	99	T *zmalloc(size_t size)
	100	{
	101	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	102	LTTNG_ASSERT(size >= sizeof(T));
	103	return (T *) zmalloc_internal(size);
	104	}
	105
	106	/*
	107	* Malloc and zero-initialize an array of `nmemb` elements of type T,
	108	* asserting that T can be safely malloc-ed (is trivially constructible).
	109	*/
	110	template<typename T>
	111	T *calloc(size_t nmemb)
	112	{
	113	static_assert (can_malloc<T>::value, "type can be malloc'ed");
5c7248cd	114	return (T ) zmalloc_internal(nmemb sizeof(T)); /* NOLINT sizeof potentially used on a pointer. */
64803277 SM	115	}
	116
	117	/*
	118	* Malloc an object of type T, asserting that T can be safely malloc-ed (is
	119	* trivially constructible).
	120	*/
	121	template<typename T>
	122	T *malloc()
4616a46c	123	{
64803277 SM	124	static_assert (can_malloc<T>::value, "type can be malloc'ed");
64803277 SM	125	return (T *) malloc(sizeof(T));
4616a46c	126	}
990570ed	127
64803277 SM	128	/*
	129	* Malloc a buffer of size `size`, asserting that type T can be safely
	130	* malloc-ed (is trivially constructible).
	131	*/
	132	template<typename T>
	133	T *malloc(size_t size)
	134	{
	135	static_assert (can_malloc<T>::value, "type can be malloc'ed");
	136	return (T *) malloc(size);
	137	}
	138
	139	/*
	140	* Prevent using `free` on types that are non-POD.
	141	*
	142	* Declare a delete prototype of free if the parameter type is not safe to free
	143	* (non-POD).
	144	*
	145	* If the parameter is a pointer to void, we can't check if what is pointed
	146	* to is safe to free or not, as we don't know what is pointed to. Ideally,
	147	* all calls to free would be with a typed pointer, but there are too many
	148	* instances of passing a pointer to void to enforce that right now. So allow
	149	* pointers to void, these will not be checked.
	150	*/
	151
	152	template<typename T>
a8e336c2	153	struct can_free
64803277	154	{
f12e33ba JG	155	/*
	156	* gcc versions before 5.0 lack some type traits defined in C++11.
	157	* Since in this instance we use the trait to prevent misuses
	158	* of free (and statically assert) and not to generate different
	159	* code based on this property, simply set value to true and allow
	160	* the code to compile. Anyone using a contemporary compiler will
	161	* catch the error.
	162	*/
	163	#if __GNUG__ && __GNUC__ < 5
	164	static constexpr bool value = true;
	165	#else
a8e336c2	166	static constexpr bool value = std::is_trivially_destructible<T>::value \|\| std::is_void<T>::value;
f12e33ba	167	#endif
64803277 SM	168	};
64803277 SM	169
a8e336c2	170	template<typename T, typename = typename std::enable_if<!can_free<T>::value>::type>
64803277 SM	171	void free(T *p) = delete;
64803277 SM	172
a8e336c2 SM	173	template<typename T>
	174	struct can_memset
	175	{
	176	static constexpr bool value = std::is_pod<T>::value \|\| std::is_void<T>::value;
	177	};
	178
	179	template <typename T, typename = typename std::enable_if<!can_memset<T>::value>::type>
	180	void memset(T s, int c, size_t n) = delete;
	181
	182	template<typename T>
	183	struct can_memcpy
	184	{
f12e33ba JG	185	/*
	186	* gcc versions before 5.0 lack some type traits defined in C++11.
	187	* Since in this instance we use the trait to prevent misuses
	188	* of memcpy (and statically assert) and not to generate different
	189	* code based on this property, simply set value to true and allow
	190	* the code to compile. Anyone using a contemporary compiler will
	191	* catch the error.
	192	*/
	193	#if __GNUG__ && __GNUC__ < 5
	194	static constexpr bool value = true;
	195	#else
a8e336c2	196	static constexpr bool value = std::is_trivially_copyable<T>::value;
f12e33ba	197	#endif
a8e336c2 SM	198	};
	199
	200	template <typename T, typename U,
	201	typename = typename std::enable_if<!can_memcpy<T>::value>::type,
	202	typename = typename std::enable_if<!can_memcpy<U>::value>::type>
	203	void memcpy(T d, const U *s, size_t n) = delete;
	204
	205	template<typename T>
	206	struct can_memmove
	207	{
f12e33ba JG	208	/*
	209	* gcc versions before 5.0 lack some type traits defined in C++11.
	210	* Since in this instance we use the trait to prevent misuses
	211	* of memmove (and statically assert) and not to generate different
	212	* code based on this property, simply set value to true and allow
	213	* the code to compile. Anyone using a contemporary compiler will
	214	* catch the error.
	215	*/
	216	#if __GNUG__ && __GNUC__ < 5
	217	static constexpr bool value = true;
	218	#else
a8e336c2	219	static constexpr bool value = std::is_trivially_copyable<T>::value;
f12e33ba	220	#endif
a8e336c2 SM	221	};
	222
	223	template <typename T, typename U,
	224	typename = typename std::enable_if<!can_memmove<T>::value>::type,
	225	typename = typename std::enable_if<!can_memmove<U>::value>::type>
	226	void memmove(T d, const U *s, size_t n) = delete;
	227
990570ed DG	228	#ifndef ARRAY_SIZE
	229	#define ARRAY_SIZE(array) (sizeof(array) / (sizeof((array)[0])))
	230	#endif
	231
54c90d10 DG	232	#ifndef LTTNG_PACKED
	233	#define LTTNG_PACKED __attribute__((__packed__))
	234	#endif
	235
1405051a FD	236	#ifndef LTTNG_NO_SANITIZE_ADDRESS
	237	#if defined(__clang__) \|\| defined (__GNUC__)
	238	#define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
	239	#else
	240	#define LTTNG_NO_SANITIZE_ADDRESS
	241	#endif
	242	#endif
	243
f8f3885c MD	244	#define member_sizeof(type, field) sizeof(((type *) 0)->field)
f8f3885c MD	245
5c7248cd	246	#define ASSERT_LOCKED(lock) LTTNG_ASSERT(pthread_mutex_trylock(&(lock)))
48b7cdc2	247	#define ASSERT_RCU_READ_LOCKED(lock) LTTNG_ASSERT(rcu_read_ongoing())
5e5c14ce	248
d22ad5f8 SM	249	/* Attribute suitable to tag functions as having printf()-like arguments. */
	250	#define ATTR_FORMAT_PRINTF(_string_index, _first_to_check) \
	251	__attribute__((format(printf, _string_index, _first_to_check)))
	252
411b3154 SM	253	/* Attribute suitable to tag functions as having strftime()-like arguments. */
	254	#define ATTR_FORMAT_STRFTIME(_string_index) \
	255	__attribute__((format(strftime, _string_index, 0)))
	256
d22ad5f8 SM	257	/* Macros used to ignore specific compiler diagnostics. */
	258
	259	#define DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
	260	#define DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")
	261
	262	#if defined(__clang__)
	263	/* Clang */
	264	# define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT
411b3154 SM	265	# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
411b3154 SM	266	_Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
942003e5	267	# define DIAGNOSTIC_IGNORE_LOGICAL_OP
05aa7e19	268	# define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
bd2c951e JG	269	# define DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
bd2c951e JG	270	_Pragma("GCC diagnostic ignored \"-Winvalid-offsetof\"")
d22ad5f8 SM	271	#else
	272	/* GCC */
	273	# define DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT \
	274	_Pragma("GCC diagnostic ignored \"-Wsuggest-attribute=format\"")
411b3154 SM	275	# define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
411b3154 SM	276	_Pragma("GCC diagnostic ignored \"-Wformat-nonliteral\"")
942003e5 MJ	277	# define DIAGNOSTIC_IGNORE_LOGICAL_OP \
942003e5 MJ	278	_Pragma("GCC diagnostic ignored \"-Wlogical-op\"")
efc2642c JG	279	#if __GNUG__ && __GNUC__ >= 7
efc2642c JG	280	# define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES \
05aa7e19	281	_Pragma("GCC diagnostic ignored \"-Wduplicated-branches\"")
efc2642c JG	282	#else
	283	# define DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
	284	#endif /* __GNUG__ && __GNUC__ >= 7 */
	285	# define DIAGNOSTIC_IGNORE_INVALID_OFFSETOF \
bd2c951e	286	_Pragma("GCC diagnostic ignored \"-Winvalid-offsetof\"")
d22ad5f8 SM	287	#endif
d22ad5f8 SM	288
d50d200a SM	289	/* Used to make specific C++ functions to C code. */
	290	#ifdef __cplusplus
	291	#define C_LINKAGE extern "C"
	292	#else
	293	#define C_LINKAGE
	294	#endif
	295
f6835b82 MD	296	/*
	297	* lttng_strncpy returns 0 on success, or nonzero on failure.
	298	* It checks that the @src string fits into @dst_len before performing
	299	* the copy. On failure, no copy has been performed.
	300	*
b25a5991 JG	301	* Assumes that 'src' is null-terminated.
b25a5991 JG	302	*
f6835b82 MD	303	* dst_len includes the string's trailing NULL.
	304	*/
	305	static inline
	306	int lttng_strncpy(char dst, const char src, size_t dst_len)
	307	{
b25a5991	308	if (strlen(src) >= dst_len) {
f6835b82 MD	309	/* Fail since copying would result in truncation. */
	310	return -1;
	311	}
c3ef76cd	312	strcpy(dst, src);
f6835b82 MD	313	return 0;
	314	}
	315
0114db0e JG	316	namespace lttng {
	317	namespace utils {
	318	template <class Parent, class Member>
	319	Parent container_of(const Member member, const Member Parent::*ptr_to_member)
	320	{
	321	const Parent *dummy_parent = nullptr;
	322	auto offset_of_member = reinterpret_cast<const char >(&(dummy_parent->*ptr_to_member));
	323	auto address_of_parent = reinterpret_cast<const char *>(member) - offset_of_member;
	324
	325	return reinterpret_cast<Parent *>(address_of_parent);
	326	}
	327	} /* namespace utils */
	328	} /* namespace lttng */
	329
990570ed	330	#endif /* _MACROS_H */