140 lines
3.0 KiB
C
140 lines
3.0 KiB
C
/* threadless.io
|
|
* Copyright (c) 2016 Justin R. Cutler
|
|
* Licensed under the MIT License. See LICENSE file in the project root for
|
|
* full license information.
|
|
*/
|
|
/** @file
|
|
* @c mmap(3) allocator implementation
|
|
* @author Justin R. Cutler <justin.r.cutler@gmail.com>
|
|
*/
|
|
|
|
#define _GNU_SOURCE
|
|
|
|
/* HAVE_* */
|
|
#include "config.h"
|
|
|
|
/* errno, ENOSYS */
|
|
#include <errno.h>
|
|
/* size_t, NULL */
|
|
#include <stddef.h>
|
|
#ifndef HAVE_MREMAP
|
|
/* memcpy */
|
|
# include <string.h>
|
|
#endif
|
|
|
|
/* mmap, munmap, PROT_*, MAP_*, mremap(optional), MREMAP_*(optional) */
|
|
#include <sys/mman.h>
|
|
/* sysconf, _SC_PAGESIZE */
|
|
#include <unistd.h>
|
|
|
|
/* ... */
|
|
#include <threadless/mmap_allocator.h>
|
|
|
|
|
|
#ifndef HAVE_MMAP
|
|
# error Need mmap()
|
|
#endif
|
|
|
|
#if defined(HAVE_MAP_ANONYMOUS) || defined(HAVE_MAP_ANON)
|
|
# ifndef HAVE_MAP_ANONYMOUS
|
|
# define MAP_ANONYMOUS MAP_ANON
|
|
# endif
|
|
#else
|
|
# error Need MAP_ANONYMOUS or MAP_ANON
|
|
#endif
|
|
|
|
|
|
static void *do_mmap(size_t size)
|
|
{
|
|
return mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
|
|
-1, 0);
|
|
}
|
|
|
|
|
|
static void *do_mremap(void *memory, size_t old_size, size_t new_size)
|
|
{
|
|
void *new_memory;
|
|
#ifdef HAVE_MREMAP
|
|
new_memory = mremap(memory, old_size, new_size, MREMAP_MAYMOVE);
|
|
#else
|
|
/* slow remap: mmap + copy + munmap */
|
|
size_t copy_size = (new_size < old_size) ? new_size : old_size;
|
|
new_memory = do_mmap(new_size);
|
|
if (MAP_FAILED != new_memory) {
|
|
memcpy(new_memory, memory, copy_size);
|
|
(void) munmap(memory, old_size);
|
|
}
|
|
#endif
|
|
return new_memory;
|
|
}
|
|
|
|
|
|
static int mmap_allocate(allocation_t *allocation, size_t size)
|
|
{
|
|
static size_t page_size = 0;
|
|
static size_t page_mask = 0;
|
|
void *new_memory = MAP_FAILED;
|
|
|
|
if (!page_size) {
|
|
/* get page size */
|
|
long result = sysconf(_SC_PAGESIZE);
|
|
if (result > 0 && !(result & (result - 1))) {
|
|
page_size = (size_t) result;
|
|
page_mask = page_size - 1;
|
|
} else {
|
|
/* not a power of 2 */
|
|
errno = ENOSYS;
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/* round size up to multiple of page_size */
|
|
size = (size + page_size - 1) & ~page_mask;
|
|
|
|
/* no action required */
|
|
if (size == allocation->size) {
|
|
return 0;
|
|
}
|
|
|
|
if (0 == size) {
|
|
if (NULL != allocation->memory && 0 != allocation->size) {
|
|
(void)munmap(allocation->memory, allocation->size);
|
|
}
|
|
new_memory = NULL;
|
|
} else if (0 == allocation->size) {
|
|
new_memory = do_mmap(size);
|
|
} else {
|
|
new_memory = do_mremap(allocation->memory, allocation->size, size);
|
|
}
|
|
|
|
if (MAP_FAILED == new_memory) {
|
|
/* operation failed */
|
|
return -1;
|
|
}
|
|
|
|
/* update allocation */
|
|
allocation->memory = new_memory;
|
|
allocation->size = size;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static void mmap_destroy(allocator_t *allocator)
|
|
{
|
|
/* ignore allocator */
|
|
(void) allocator;
|
|
}
|
|
|
|
|
|
static allocator_t mmap_allocator = {
|
|
.allocate = mmap_allocate,
|
|
.destroy = mmap_destroy,
|
|
};
|
|
|
|
|
|
allocator_t *allocator_get_mmap(void)
|
|
{
|
|
return &mmap_allocator;
|
|
}
|