[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"

/*
 * Pointer dereferencing. We don't trust the shm_ref, so we validate
 * both the index and offset with known boundaries.
 *
 * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
 * target type, even in the occurrence of shm_ref modification by an
 * untrusted process having write access to the shm_ref. We return a
 * NULL pointer if the ranges are invalid.
 */
static inline
char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
		   size_t idx, size_t elem_size)
{
	struct shm_object *obj;
	size_t objindex, ref_offset;

	objindex = (size_t) ref->index;
	if (unlikely(objindex >= table->allocated_len))
		return NULL;
	obj = &table->objects[objindex];
	ref_offset = (size_t) ref->offset;
	ref_offset += idx * elem_size;
	/* Check if part of the element returned would exceed the limits. */
	if (unlikely(ref_offset + elem_size > obj->memory_map_size))
		return NULL;
	return &obj->memory_map[ref_offset];
}

#define shmp_index(handle, ref, index)					\
	({								\
		__typeof__((ref)._type) ____ptr_ret;			\
		____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));	\
		____ptr_ret;						\
	})

#define shmp(handle, ref)	shmp_index(handle, ref, 0)

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);

static inline
int shm_get_wakeup_fd(struct shm_handle *handle, struct shm_ref *ref)
{
	struct shm_object_table *table = handle->table;
	struct shm_object *obj;
	size_t index;

	index = (size_t) ref->index;
	if (unlikely(index >= table->allocated_len))
		return -EPERM;
	obj = &table->objects[index];
	return obj->wait_fd[1];

}

static inline
int shm_get_wait_fd(struct shm_handle *handle, struct shm_ref *ref)
{
	struct shm_object_table *table = handle->table;
	struct shm_object *obj;
	size_t index;

	index = (size_t) ref->index;
	if (unlikely(index >= table->allocated_len))
		return -EPERM;
	obj = &table->objects[index];
	return obj->wait_fd[0];
}

#endif /* _LIBRINGBUFFER_SHM_H */
Commit	Line	Data
a6352fd4 MD	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>
1dbfff0c	13	#include <ust/usterr-signal-safe.h>
a6352fd4	14	#include "ust/core.h"
1d498196	15	#include "shm_types.h"
a6352fd4	16
a6352fd4	17	/*
1d498196 MD	18	* Pointer dereferencing. We don't trust the shm_ref, so we validate
1d498196 MD	19	* both the index and offset with known boundaries.
ed5426d3 MD	20	*
	21	* "shmp" and "shmp_index" guarantee that it's safe to use the pointer
	22	* target type, even in the occurrence of shm_ref modification by an
	23	* untrusted process having write access to the shm_ref. We return a
	24	* NULL pointer if the ranges are invalid.
a6352fd4	25	*/
a6352fd4	26	static inline
4746ae29	27	char _shmp_offset(struct shm_object_table table, struct shm_ref *ref,
cba4b7a3	28	size_t idx, size_t elem_size)
a6352fd4	29	{
1d498196	30	struct shm_object *obj;
cba4b7a3	31	size_t objindex, ref_offset;
a6352fd4	32
cba4b7a3 MD	33	objindex = (size_t) ref->index;
cba4b7a3 MD	34	if (unlikely(objindex >= table->allocated_len))
1d498196	35	return NULL;
cba4b7a3	36	obj = &table->objects[objindex];
4746ae29	37	ref_offset = (size_t) ref->offset;
cba4b7a3 MD	38	ref_offset += idx * elem_size;
	39	/* Check if part of the element returned would exceed the limits. */
	40	if (unlikely(ref_offset + elem_size > obj->memory_map_size))
a6352fd4	41	return NULL;
4746ae29	42	return &obj->memory_map[ref_offset];
a6352fd4 MD	43	}
a6352fd4 MD	44
cba4b7a3	45	#define shmp_index(handle, ref, index) \
1d498196 MD	46	({ \
1d498196 MD	47	__typeof__((ref)._type) ____ptr_ret; \
cba4b7a3	48	____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret)); \
1d498196 MD	49	____ptr_ret; \
	50	})
	51
4746ae29 MD	52	#define shmp(handle, ref) shmp_index(handle, ref, 0)
4746ae29 MD	53
431d5cf0	54	static inline
1d498196	55	void _set_shmp(struct shm_ref *ref, struct shm_ref src)
431d5cf0	56	{
1d498196	57	*ref = src;
431d5cf0 MD	58	}
431d5cf0 MD	59
1d498196 MD	60	#define set_shmp(ref, src) _set_shmp(&(ref)._ref, src)
	61
	62	struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
	63	void shm_object_table_destroy(struct shm_object_table *table);
	64	struct shm_object shm_object_table_append(struct shm_object_table table,
	65	size_t memory_map_size);
	66
	67	/*
	68	* zalloc_shm - allocate memory within a shm object.
	69	*
	70	* Shared memory is already zeroed by shmget.
	71	* NOT multithread-safe (should be protected by mutex).
	72	* Returns a -1, -1 tuple on error.
	73	*/
	74	struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
	75	void align_shm(struct shm_object *obj, size_t align);
	76
5d61a504 MD	77	static inline
	78	int shm_get_wakeup_fd(struct shm_handle handle, struct shm_ref ref)
	79	{
	80	struct shm_object_table *table = handle->table;
	81	struct shm_object *obj;
	82	size_t index;
	83
	84	index = (size_t) ref->index;
	85	if (unlikely(index >= table->allocated_len))
	86	return -EPERM;
	87	obj = &table->objects[index];
	88	return obj->wait_fd[1];
	89
	90	}
	91
	92	static inline
	93	int shm_get_wait_fd(struct shm_handle handle, struct shm_ref ref)
	94	{
	95	struct shm_object_table *table = handle->table;
	96	struct shm_object *obj;
	97	size_t index;
	98
	99	index = (size_t) ref->index;
	100	if (unlikely(index >= table->allocated_len))
	101	return -EPERM;
	102	obj = &table->objects[index];
	103	return obj->wait_fd[0];
	104	}
	105
a6352fd4	106	#endif /* _LIBRINGBUFFER_SHM_H */