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2714c5f3 | 1 | /* Allocate a memory region shared across processes. |
2b778ceb | 2 | Copyright (C) 2017-2021 Free Software Foundation, Inc. |
2714c5f3 FW |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
2714c5f3 FW |
18 | |
19 | #include <errno.h> | |
20 | #include <stddef.h> | |
21 | #include <support/support.h> | |
22 | #include <support/xunistd.h> | |
23 | #include <sys/mman.h> | |
24 | ||
25 | /* Header for the allocation. It contains the size of the allocation | |
26 | for subsequent unmapping. */ | |
27 | struct header | |
28 | { | |
29 | size_t total_size; | |
30 | char data[] __attribute__ ((aligned (__alignof__ (max_align_t)))); | |
31 | }; | |
32 | ||
33 | void * | |
34 | support_shared_allocate (size_t size) | |
35 | { | |
36 | size_t total_size = size + offsetof (struct header, data); | |
37 | if (total_size < size) | |
38 | { | |
39 | errno = ENOMEM; | |
40 | oom_error (__func__, size); | |
41 | return NULL; | |
42 | } | |
43 | else | |
44 | { | |
45 | struct header *result = xmmap (NULL, total_size, PROT_READ | PROT_WRITE, | |
46 | MAP_ANONYMOUS | MAP_SHARED, -1); | |
47 | result->total_size = total_size; | |
48 | return &result->data; | |
49 | } | |
50 | } | |
51 | ||
52 | void | |
53 | support_shared_free (void *data) | |
54 | { | |
55 | struct header *header = data - offsetof (struct header, data); | |
56 | xmunmap (header, header->total_size); | |
57 | } |