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58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/* Allocate a memory region shared across processes.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stddef.h>
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#include <support/support.h>
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#include <support/xunistd.h>
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#include <sys/mman.h>
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/* Header for the allocation. It contains the size of the allocation
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for subsequent unmapping. */
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struct header
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{
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size_t total_size;
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char data[] __attribute__ ((aligned (__alignof__ (max_align_t))));
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};
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void *
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support_shared_allocate (size_t size)
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{
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size_t total_size = size + offsetof (struct header, data);
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if (total_size < size)
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{
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errno = ENOMEM;
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oom_error (__func__, size);
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return NULL;
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}
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else
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{
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struct header *result = xmmap (NULL, total_size, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_SHARED, -1);
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result->total_size = total_size;
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return &result->data;
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}
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}
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void
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support_shared_free (void *data)
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{
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struct header *header = data - offsetof (struct header, data);
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xmunmap (header, header->total_size);
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}
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