[babeltrace.git] / include / babeltrace / mmap-align-internal.h

#ifndef _BABELTRACE_MMAP_ALIGN_H
#define _BABELTRACE_MMAP_ALIGN_H

/*
 * BabelTrace mmap-align.h - mmap alignment header
 *
 * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <babeltrace/align-internal.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/mman.h>

/*
 * This header implements a wrapper over mmap (mmap_align) that memory
 * maps a file region that is not necessarily multiple of the page size.
 * It returns a structure (instead of a pointer) that contains the mmap
 * pointer (page-aligned) and a pointer to the offset requested within
 * that page. Note: in the current implementation, the "addr" parameter
 * cannot be forced, so we allocate at an address chosen by the OS.
 */

struct mmap_align {
	void *page_aligned_addr;	/* mmap address, aligned to floor */
	size_t page_aligned_length;	/* mmap length, containing range */

	void *addr;			/* virtual mmap address */
	size_t length;			/* virtual mmap length */
};

static inline
struct mmap_align *mmap_align(size_t length, int prot,
		int flags, int fd, off_t offset)
{
	struct mmap_align *mma;
	off_t page_aligned_offset;	/* mmap offset, aligned to floor */

	mma = malloc(sizeof(*mma));
	if (!mma)
		return MAP_FAILED;
	mma->length = length;
	page_aligned_offset = ALIGN_FLOOR(offset, PAGE_SIZE);
	/*
	 * Page aligned length needs to contain the requested range.
	 * E.g., for a small range that fits within a single page, we might
	 * require a 2 pages page_aligned_length if the range crosses a page
	 * boundary.
	 */
	mma->page_aligned_length = ALIGN(length + offset - page_aligned_offset, PAGE_SIZE);
	mma->page_aligned_addr = mmap(NULL, mma->page_aligned_length,
		prot, flags, fd, page_aligned_offset);
	if (mma->page_aligned_addr == (void *) -1UL) {
		free(mma);
		return MAP_FAILED;
	}
	mma->addr = ((uint8_t *) mma->page_aligned_addr) + (offset - page_aligned_offset);
	return mma;
}

static inline
int munmap_align(struct mmap_align *mma)
{
	void *page_aligned_addr;
	size_t page_aligned_length;

	page_aligned_addr = mma->page_aligned_addr;
	page_aligned_length = mma->page_aligned_length;
	free(mma);
	return munmap(page_aligned_addr, page_aligned_length);
}

static inline
void *mmap_align_addr(struct mmap_align *mma)
{
	return mma->addr;
}

/*
 * Helper for special-cases, normally unused.
 */
static inline
void mmap_align_set_addr(struct mmap_align *mma, void *addr)
{
	mma->addr = addr;
}

#endif /* _BABELTRACE_MMAP_ALIGN_H */
Commit	Line	Data
f7a2be83 MD	1	#ifndef _BABELTRACE_MMAP_ALIGN_H
	2	#define _BABELTRACE_MMAP_ALIGN_H
	3
	4	/*
	5	* BabelTrace mmap-align.h - mmap alignment header
	6	*
	7	* Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* Permission is hereby granted, free of charge, to any person obtaining a copy
	10	* of this software and associated documentation files (the "Software"), to deal
	11	* in the Software without restriction, including without limitation the rights
	12	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	13	* copies of the Software, and to permit persons to whom the Software is
	14	* furnished to do so, subject to the following conditions:
	15	*
	16	* The above copyright notice and this permission notice shall be included in
	17	* all copies or substantial portions of the Software.
c462e188 MD	18	*
	19	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	20	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	21	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	22	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	23	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	24	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	25	* SOFTWARE.
f7a2be83 MD	26	*/
f7a2be83 MD	27
3d9990ac	28	#include <babeltrace/align-internal.h>
f7a2be83	29	#include <stdlib.h>
544d0515	30	#include <stdint.h>
f7a2be83 MD	31	#include <sys/mman.h>
	32
	33	/*
	34	* This header implements a wrapper over mmap (mmap_align) that memory
	35	* maps a file region that is not necessarily multiple of the page size.
	36	* It returns a structure (instead of a pointer) that contains the mmap
	37	* pointer (page-aligned) and a pointer to the offset requested within
	38	* that page. Note: in the current implementation, the "addr" parameter
	39	* cannot be forced, so we allocate at an address chosen by the OS.
	40	*/
	41
	42	struct mmap_align {
	43	void page_aligned_addr; / mmap address, aligned to floor */
	44	size_t page_aligned_length; /* mmap length, containing range */
	45
	46	void addr; / virtual mmap address */
	47	size_t length; /* virtual mmap length */
	48	};
	49
	50	static inline
	51	struct mmap_align *mmap_align(size_t length, int prot,
	52	int flags, int fd, off_t offset)
	53	{
	54	struct mmap_align *mma;
	55	off_t page_aligned_offset; /* mmap offset, aligned to floor */
	56
	57	mma = malloc(sizeof(*mma));
	58	if (!mma)
	59	return MAP_FAILED;
	60	mma->length = length;
	61	page_aligned_offset = ALIGN_FLOOR(offset, PAGE_SIZE);
	62	/*
	63	* Page aligned length needs to contain the requested range.
	64	* E.g., for a small range that fits within a single page, we might
	65	* require a 2 pages page_aligned_length if the range crosses a page
	66	* boundary.
	67	*/
	68	mma->page_aligned_length = ALIGN(length + offset - page_aligned_offset, PAGE_SIZE);
	69	mma->page_aligned_addr = mmap(NULL, mma->page_aligned_length,
	70	prot, flags, fd, page_aligned_offset);
	71	if (mma->page_aligned_addr == (void *) -1UL) {
	72	free(mma);
	73	return MAP_FAILED;
	74	}
544d0515	75	mma->addr = ((uint8_t *) mma->page_aligned_addr) + (offset - page_aligned_offset);
f7a2be83 MD	76	return mma;
	77	}
	78
	79	static inline
	80	int munmap_align(struct mmap_align *mma)
	81	{
	82	void *page_aligned_addr;
	83	size_t page_aligned_length;
	84
	85	page_aligned_addr = mma->page_aligned_addr;
	86	page_aligned_length = mma->page_aligned_length;
	87	free(mma);
	88	return munmap(page_aligned_addr, page_aligned_length);
	89	}
	90
	91	static inline
	92	void mmap_align_addr(struct mmap_align mma)
	93	{
	94	return mma->addr;
	95	}
	96
	97	/*
	98	* Helper for special-cases, normally unused.
	99	*/
	100	static inline
	101	void mmap_align_set_addr(struct mmap_align mma, void addr)
	102	{
	103	mma->addr = addr;
	104	}
	105
	106	#endif /* _BABELTRACE_MMAP_ALIGN_H */