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

#ifndef _LIBRINGBUFFER_SHM_H
#define _LIBRINGBUFFER_SHM_H

/*
 * libringbuffer/shm.h
 *
 * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdint.h>
#include <usterr-signal-safe.h>
#include <urcu/compiler.h>
#include "shm_types.h"
#include <fcntl.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 (caa_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 (caa_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);
struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
			int shm_fd, int wait_fd, size_t memory_map_size);
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 lttng_ust_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 (caa_unlikely(index >= table->allocated_len))
		return -EPERM;
	obj = &table->objects[index];

	return obj->wait_fd[1];
}

static inline
int shm_open_wakeup_pipe(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
{
	struct shm_object_table *table = handle->table;
	struct shm_object *obj;
	size_t index;
	int fd, ret = -1;

	index = (size_t) ref->index;
	if (caa_unlikely(index >= table->allocated_len))
		return -EPERM;

	obj = &table->objects[index];

	if (obj->wait_fd[1] < 0 && obj->wait_pipe_path != NULL) {
		fd = open(obj->wait_pipe_path, O_WRONLY);
		if (fd < 0) {
			ret = -1;
		} else {
			/* FIXME: What if fcntl fail? */
			fcntl(fd, F_SETFD, FD_CLOEXEC);
			obj->wait_fd[1] = fd;
			ret = 0;
		}
	}

	return ret;
}

static inline
int shm_get_wait_fd(struct lttng_ust_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 (caa_unlikely(index >= table->allocated_len))
		return -EPERM;
	obj = &table->objects[index];
	return obj->wait_fd[0];
}

static inline
int shm_get_object_data(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
			int **shm_fd, char **shm_path,
			int **wait_fd, char **wait_pipe_path,
			uint64_t **memory_map_size)
{
	struct shm_object_table *table = handle->table;
	struct shm_object *obj;
	size_t index;

	index = (size_t) ref->index;
	if (caa_unlikely(index >= table->allocated_len))
		return -EPERM;
	obj = &table->objects[index];
	*shm_fd   = &obj->shm_fd;
	*shm_path = obj->shm_path;
	*wait_fd        = &obj->wait_fd[0];
	*wait_pipe_path = obj->wait_pipe_path;
	*memory_map_size = &obj->allocated_len;
	return 0;
}

#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 (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* This library is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU Lesser General Public
	11	* License as published by the Free Software Foundation; only
	12	* version 2.1 of the License.
	13	*
	14	* This library is distributed in the hope that it will be useful,
	15	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* Lesser General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU Lesser General Public
	20	* License along with this library; if not, write to the Free Software
	21	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
	24	#include <stdint.h>
	25	#include <usterr-signal-safe.h>
	26	#include <urcu/compiler.h>
	27	#include "shm_types.h"
	28	#include <fcntl.h>
	29
	30	/*
	31	* Pointer dereferencing. We don't trust the shm_ref, so we validate
	32	* both the index and offset with known boundaries.
	33	*
	34	* "shmp" and "shmp_index" guarantee that it's safe to use the pointer
	35	* target type, even in the occurrence of shm_ref modification by an
	36	* untrusted process having write access to the shm_ref. We return a
	37	* NULL pointer if the ranges are invalid.
	38	*/
	39	static inline
	40	char _shmp_offset(struct shm_object_table table, struct shm_ref *ref,
	41	size_t idx, size_t elem_size)
	42	{
	43	struct shm_object *obj;
	44	size_t objindex, ref_offset;
	45
	46	objindex = (size_t) ref->index;
	47	if (caa_unlikely(objindex >= table->allocated_len))
	48	return NULL;
	49	obj = &table->objects[objindex];
	50	ref_offset = (size_t) ref->offset;
	51	ref_offset += idx * elem_size;
	52	/* Check if part of the element returned would exceed the limits. */
	53	if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
	54	return NULL;
	55	return &obj->memory_map[ref_offset];
	56	}
	57
	58	#define shmp_index(handle, ref, index) \
	59	({ \
	60	__typeof__((ref)._type) ____ptr_ret; \
	61	____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret)); \
	62	____ptr_ret; \
	63	})
	64
	65	#define shmp(handle, ref) shmp_index(handle, ref, 0)
	66
	67	static inline
	68	void _set_shmp(struct shm_ref *ref, struct shm_ref src)
	69	{
	70	*ref = src;
	71	}
	72
	73	#define set_shmp(ref, src) _set_shmp(&(ref)._ref, src)
	74
	75	struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
	76	struct shm_object shm_object_table_append_shadow(struct shm_object_table table,
	77	int shm_fd, int wait_fd, size_t memory_map_size);
	78	void shm_object_table_destroy(struct shm_object_table *table);
	79	struct shm_object shm_object_table_append(struct shm_object_table table,
	80	size_t memory_map_size);
	81
	82	/*
	83	* zalloc_shm - allocate memory within a shm object.
	84	*
	85	* Shared memory is already zeroed by shmget.
	86	* NOT multithread-safe (should be protected by mutex).
	87	* Returns a -1, -1 tuple on error.
	88	*/
	89	struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
	90	void align_shm(struct shm_object *obj, size_t align);
	91
	92	static inline
	93	int shm_get_wakeup_fd(struct lttng_ust_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 (caa_unlikely(index >= table->allocated_len))
	101	return -EPERM;
	102	obj = &table->objects[index];
	103
	104	return obj->wait_fd[1];
	105	}
	106
	107	static inline
	108	int shm_open_wakeup_pipe(struct lttng_ust_shm_handle handle, struct shm_ref ref)
	109	{
	110	struct shm_object_table *table = handle->table;
	111	struct shm_object *obj;
	112	size_t index;
	113	int fd, ret = -1;
	114
	115	index = (size_t) ref->index;
	116	if (caa_unlikely(index >= table->allocated_len))
	117	return -EPERM;
	118
	119	obj = &table->objects[index];
	120
	121	if (obj->wait_fd[1] < 0 && obj->wait_pipe_path != NULL) {
	122	fd = open(obj->wait_pipe_path, O_WRONLY);
	123	if (fd < 0) {
	124	ret = -1;
	125	} else {
	126	/* FIXME: What if fcntl fail? */
	127	fcntl(fd, F_SETFD, FD_CLOEXEC);
	128	obj->wait_fd[1] = fd;
	129	ret = 0;
	130	}
	131	}
	132
	133	return ret;
	134	}
	135
	136	static inline
	137	int shm_get_wait_fd(struct lttng_ust_shm_handle handle, struct shm_ref ref)
	138	{
	139	struct shm_object_table *table = handle->table;
	140	struct shm_object *obj;
	141	size_t index;
	142
	143	index = (size_t) ref->index;
	144	if (caa_unlikely(index >= table->allocated_len))
	145	return -EPERM;
	146	obj = &table->objects[index];
	147	return obj->wait_fd[0];
	148	}
	149
	150	static inline
	151	int shm_get_object_data(struct lttng_ust_shm_handle handle, struct shm_ref ref,
	152	int shm_fd, char shm_path,
	153	int wait_fd, char wait_pipe_path,
	154	uint64_t **memory_map_size)
	155	{
	156	struct shm_object_table *table = handle->table;
	157	struct shm_object *obj;
	158	size_t index;
	159
	160	index = (size_t) ref->index;
	161	if (caa_unlikely(index >= table->allocated_len))
	162	return -EPERM;
	163	obj = &table->objects[index];
	164	*shm_fd = &obj->shm_fd;
	165	*shm_path = obj->shm_path;
	166	*wait_fd = &obj->wait_fd[0];
	167	*wait_pipe_path = obj->wait_pipe_path;
	168	*memory_map_size = &obj->allocated_len;
	169	return 0;
	170	}
	171
	172	#endif /* _LIBRINGBUFFER_SHM_H */