root/third_party/ashmem/ashmem-dev.c

DEFINITIONS

1. ashmem_create_region
2. ashmem_set_prot_region
3. ashmem_pin_region
4. ashmem_unpin_region
5. ashmem_get_size_region
6. ashmem_purge_all

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Implementation of the user-space ashmem API for devices, which have our
 * ashmem-enabled kernel. See ashmem-sim.c for the "fake" tmp-based version,
 * used by the simulator.
 */

#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#include <linux/ashmem.h>
#include "ashmem.h"

#define ASHMEM_DEVICE   "/dev/ashmem"

/*
 * ashmem_create_region - creates a new ashmem region and returns the file
 * descriptor, or <0 on error
 *
 * `name' is an optional label to give the region (visible in /proc/pid/maps)
 * `size' is the size of the region, in page-aligned bytes
 */
int ashmem_create_region(const char *name, size_t size)
{
        int fd, ret;

        fd = open(ASHMEM_DEVICE, O_RDWR);
        if (fd < 0)
                return fd;

        if (name) {
                char buf[ASHMEM_NAME_LEN];

                strlcpy(buf, name, sizeof(buf));
                ret = ioctl(fd, ASHMEM_SET_NAME, buf);
                if (ret < 0)
                        goto error;
        }

        ret = ioctl(fd, ASHMEM_SET_SIZE, size);
        if (ret < 0)
                goto error;

        return fd;

error:
        close(fd);
        return ret;
}

int ashmem_set_prot_region(int fd, int prot)
{
        return ioctl(fd, ASHMEM_SET_PROT_MASK, prot);
}

int ashmem_pin_region(int fd, size_t offset, size_t len)
{
        struct ashmem_pin pin = { offset, len };
        return ioctl(fd, ASHMEM_PIN, &pin);
}

int ashmem_unpin_region(int fd, size_t offset, size_t len)
{
        struct ashmem_pin pin = { offset, len };
        return ioctl(fd, ASHMEM_UNPIN, &pin);
}

int ashmem_get_size_region(int fd)
{
  return ioctl(fd, ASHMEM_GET_SIZE, NULL);
}

int ashmem_purge_all(void)
{
  const int fd = open(ASHMEM_DEVICE, O_RDWR);
  if (fd < 0)
    return fd;
  const int ret = ioctl(fd, ASHMEM_PURGE_ALL_CACHES, 0);
  close(fd);
  return ret;
}