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

/*
 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
 *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef _MACROS_H
#define _MACROS_H

#include <stdlib.h>
#include <string.h>
#include <common/compat/string.h>

/*
 * 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))

/*
 * Memory allocation zeroed
 */
static inline
void *zmalloc(size_t len)
{
	return calloc(1, len);
}

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

#ifndef max
#define max(a, b) ((a) > (b) ? (a) : (b))
#endif

#ifndef max_t
#define max_t(type, a, b)	((type) max(a, b))
#endif

#ifndef min
#define min(a, b) ((a) < (b) ? (a) : (b))
#endif

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

#ifndef LTTNG_HIDDEN
#define LTTNG_HIDDEN __attribute__((visibility("hidden")))
#endif

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

/*
 * 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.
 *
 * dst_len includes the string's trailing NULL.
 */
static inline
int lttng_strncpy(char *dst, const char *src, size_t dst_len)
{
	if (lttng_strnlen(src, dst_len) == dst_len) {
		/* Fail since copying would result in truncation. */
		return -1;
	}
	strncpy(dst, src, dst_len);
	/*
	 * Be extra careful and put final \0 at the end after strncpy(),
	 * even though we checked the length before. This makes Coverity
	 * happy.
	 */
	dst[dst_len - 1] = '\0';
	return 0;
}

#endif /* _MACROS_H */
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
	3	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License, version 2 only,
	7	* as published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope that it will be useful, but WITHOUT
	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	12	* more details.
	13	*
	14	* You should have received a copy of the GNU General Public License along
	15	* with this program; if not, write to the Free Software Foundation, Inc.,
	16	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	17	*/
	18
	19	#ifndef _MACROS_H
	20	#define _MACROS_H
	21
	22	#include <stdlib.h>
	23	#include <string.h>
	24	#include <common/compat/string.h>
	25
	26	/*
	27	* Takes a pointer x and transform it so we can use it to access members
	28	* without a function call. Here an example:
	29	*
	30	* #define GET_SIZE(x) LTTNG_REF(x)->size
	31	*
	32	* struct { int size; } s;
	33	*
	34	* printf("size : %d\n", GET_SIZE(&s));
	35	*
	36	* For this example we can't use something like this for compatibility purpose
	37	* since this will fail:
	38	*
	39	* #define GET_SIZE(x) x->size;
	40	*
	41	* This is mostly use for the compatibility layer of lttng-tools. See
	42	* poll/epoll for a good example. Since x can be on the stack or allocated
	43	* memory using malloc(), we must use generic accessors for compat in order to
	44	* not use a function to access members and not the variable name.
	45	*/
	46	#define LTTNG_REF(x) ((typeof(x) )(x))
	47
	48	/*
	49	* Memory allocation zeroed
	50	*/
	51	static inline
	52	void *zmalloc(size_t len)
	53	{
	54	return calloc(1, len);
	55	}
	56
	57	#ifndef ARRAY_SIZE
	58	#define ARRAY_SIZE(array) (sizeof(array) / (sizeof((array)[0])))
	59	#endif
	60
	61	#ifndef max
	62	#define max(a, b) ((a) > (b) ? (a) : (b))
	63	#endif
	64
	65	#ifndef max_t
	66	#define max_t(type, a, b) ((type) max(a, b))
	67	#endif
	68
	69	#ifndef min
	70	#define min(a, b) ((a) < (b) ? (a) : (b))
	71	#endif
	72
	73	#ifndef LTTNG_PACKED
	74	#define LTTNG_PACKED __attribute__((__packed__))
	75	#endif
	76
	77	#ifndef LTTNG_HIDDEN
	78	#define LTTNG_HIDDEN __attribute__((visibility("hidden")))
	79	#endif
	80
	81	#define member_sizeof(type, field) sizeof(((type *) 0)->field)
	82
	83	/*
	84	* lttng_strncpy returns 0 on success, or nonzero on failure.
	85	* It checks that the @src string fits into @dst_len before performing
	86	* the copy. On failure, no copy has been performed.
	87	*
	88	* dst_len includes the string's trailing NULL.
	89	*/
	90	static inline
	91	int lttng_strncpy(char dst, const char src, size_t dst_len)
	92	{
	93	if (lttng_strnlen(src, dst_len) == dst_len) {
	94	/* Fail since copying would result in truncation. */
	95	return -1;
	96	}
	97	strncpy(dst, src, dst_len);
	98	/*
	99	* Be extra careful and put final \0 at the end after strncpy(),
	100	* even though we checked the length before. This makes Coverity
	101	* happy.
	102	*/
	103	dst[dst_len - 1] = '\0';
	104	return 0;
	105	}
	106
	107	#endif /* _MACROS_H */