Add missing permission notice in each source file
[babeltrace.git] / include / babeltrace / mmap-align.h
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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.
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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.
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26 */
27
28#include <babeltrace/align.h>
29#include <stdlib.h>
30#include <sys/mman.h>
31
32/*
33 * This header implements a wrapper over mmap (mmap_align) that memory
34 * maps a file region that is not necessarily multiple of the page size.
35 * It returns a structure (instead of a pointer) that contains the mmap
36 * pointer (page-aligned) and a pointer to the offset requested within
37 * that page. Note: in the current implementation, the "addr" parameter
38 * cannot be forced, so we allocate at an address chosen by the OS.
39 */
40
41struct mmap_align {
42 void *page_aligned_addr; /* mmap address, aligned to floor */
43 size_t page_aligned_length; /* mmap length, containing range */
44
45 void *addr; /* virtual mmap address */
46 size_t length; /* virtual mmap length */
47};
48
49static inline
50struct mmap_align *mmap_align(size_t length, int prot,
51 int flags, int fd, off_t offset)
52{
53 struct mmap_align *mma;
54 off_t page_aligned_offset; /* mmap offset, aligned to floor */
55
56 mma = malloc(sizeof(*mma));
57 if (!mma)
58 return MAP_FAILED;
59 mma->length = length;
60 page_aligned_offset = ALIGN_FLOOR(offset, PAGE_SIZE);
61 /*
62 * Page aligned length needs to contain the requested range.
63 * E.g., for a small range that fits within a single page, we might
64 * require a 2 pages page_aligned_length if the range crosses a page
65 * boundary.
66 */
67 mma->page_aligned_length = ALIGN(length + offset - page_aligned_offset, PAGE_SIZE);
68 mma->page_aligned_addr = mmap(NULL, mma->page_aligned_length,
69 prot, flags, fd, page_aligned_offset);
70 if (mma->page_aligned_addr == (void *) -1UL) {
71 free(mma);
72 return MAP_FAILED;
73 }
74 mma->addr = mma->page_aligned_addr + (offset - page_aligned_offset);
75 return mma;
76}
77
78static inline
79int munmap_align(struct mmap_align *mma)
80{
81 void *page_aligned_addr;
82 size_t page_aligned_length;
83
84 page_aligned_addr = mma->page_aligned_addr;
85 page_aligned_length = mma->page_aligned_length;
86 free(mma);
87 return munmap(page_aligned_addr, page_aligned_length);
88}
89
90static inline
91void *mmap_align_addr(struct mmap_align *mma)
92{
93 return mma->addr;
94}
95
96/*
97 * Helper for special-cases, normally unused.
98 */
99static inline
100void mmap_align_set_addr(struct mmap_align *mma, void *addr)
101{
102 mma->addr = addr;
103}
104
105#endif /* _BABELTRACE_MMAP_ALIGN_H */
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