src/utils/android/ashmem.cpp

/*
 * Copyright 2008 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/*
 * 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 <android/ashmem.h>

#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 <SkTypes.h>  // SkASSERT

#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)
{
    // Skia only calls this when offset=len=0.
    struct ashmem_pin pin = { static_cast<__u32>(offset),
                              static_cast<__u32>(len) };
    SkASSERT(pin.offset == offset && pin.len == len);
    return ioctl(fd, ASHMEM_PIN, &pin);
}

int ashmem_unpin_region(int fd, size_t offset, size_t len)
{
    // Skia only calls this when offset=len=0.
    struct ashmem_pin pin = { static_cast<__u32>(offset),
                              static_cast<__u32>(len) };
    SkASSERT(pin.offset == offset && pin.len == 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_caches(int fd)
{
  return ioctl(fd, ASHMEM_PURGE_ALL_CACHES, NULL);
}