[lttng-ust.git] / libringbuffer / shm.h

#ifndef _LIBRINGBUFFER_SHM_H
#define _LIBRINGBUFFER_SHM_H

/*
 * libringbuffer/shm.h
 *
 * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Dual LGPL v2.1/GPL v2 license.
 */

#include <stdint.h>
#include <ust/usterr-signal-safe.h>
#include "ust/core.h"
#include "shm_types.h"

#define SHM_MAGIC	0x54335433
#define SHM_MAJOR	0
#define SHM_MINOR	1

/*
 * Pointer dereferencing. We don't trust the shm_ref, so we validate
 * both the index and offset with known boundaries.
 */
static inline
char *_shmp(struct shm_object_table *table, struct shm_ref *ref)
{
	struct shm_object *obj;
	size_t index, offset;

	index = (size_t) ref->index;
	if (unlikely(index >= table->allocated_len))
		return NULL;
	obj = &table->objects[index];
	offset = (size_t) ref->offset;
	if (unlikely(offset >= obj->memory_map_size))
		return NULL;
	return &obj->memory_map[offset];
}

#define shmp(handle, ref)						\
	({								\
		__typeof__((ref)._type) ____ptr_ret;			\
		____ptr_ret = (__typeof__(____ptr_ret)) _shmp((handle)->table, &(ref)._ref);	\
		____ptr_ret;						\
	})

static inline
void _set_shmp(struct shm_ref *ref, struct shm_ref src)
{
	*ref = src;
}

#define set_shmp(ref, src)	_set_shmp(&(ref)._ref, src)

struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
void shm_object_table_destroy(struct shm_object_table *table);
struct shm_object *shm_object_table_append(struct shm_object_table *table,
					   size_t memory_map_size);

/*
 * zalloc_shm - allocate memory within a shm object.
 *
 * Shared memory is already zeroed by shmget.
 * *NOT* multithread-safe (should be protected by mutex).
 * Returns a -1, -1 tuple on error.
 */
struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
void align_shm(struct shm_object *obj, size_t align);

#endif /* _LIBRINGBUFFER_SHM_H */
Commit	Line	Data
	1	#ifndef _LIBRINGBUFFER_SHM_H
	2	#define _LIBRINGBUFFER_SHM_H
	3
	4	/*
	5	* libringbuffer/shm.h
	6	*
	7	* Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* Dual LGPL v2.1/GPL v2 license.
	10	*/
	11
	12	#include <stdint.h>
	13	#include <ust/usterr-signal-safe.h>
	14	#include "ust/core.h"
	15	#include "shm_types.h"
	16
	17	#define SHM_MAGIC 0x54335433
	18	#define SHM_MAJOR 0
	19	#define SHM_MINOR 1
	20
	21	/*
	22	* Pointer dereferencing. We don't trust the shm_ref, so we validate
	23	* both the index and offset with known boundaries.
	24	*/
	25	static inline
	26	char _shmp(struct shm_object_table table, struct shm_ref *ref)
	27	{
	28	struct shm_object *obj;
	29	size_t index, offset;
	30
	31	index = (size_t) ref->index;
	32	if (unlikely(index >= table->allocated_len))
	33	return NULL;
	34	obj = &table->objects[index];
	35	offset = (size_t) ref->offset;
	36	if (unlikely(offset >= obj->memory_map_size))
	37	return NULL;
	38	return &obj->memory_map[offset];
	39	}
	40
	41	#define shmp(handle, ref) \
	42	({ \
	43	__typeof__((ref)._type) ____ptr_ret; \
	44	____ptr_ret = (__typeof__(____ptr_ret)) _shmp((handle)->table, &(ref)._ref); \
	45	____ptr_ret; \
	46	})
	47
	48	static inline
	49	void _set_shmp(struct shm_ref *ref, struct shm_ref src)
	50	{
	51	*ref = src;
	52	}
	53
	54	#define set_shmp(ref, src) _set_shmp(&(ref)._ref, src)
	55
	56	struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
	57	void shm_object_table_destroy(struct shm_object_table *table);
	58	struct shm_object shm_object_table_append(struct shm_object_table table,
	59	size_t memory_map_size);
	60
	61	/*
	62	* zalloc_shm - allocate memory within a shm object.
	63	*
	64	* Shared memory is already zeroed by shmget.
	65	* NOT multithread-safe (should be protected by mutex).
	66	* Returns a -1, -1 tuple on error.
	67	*/
	68	struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
	69	void align_shm(struct shm_object *obj, size_t align);
	70
	71	#endif /* _LIBRINGBUFFER_SHM_H */