third_party/ashmem/ashmem-dev.c

   1 /*
   2  * Copyright (C) 2008 The Android Open Source Project
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 /*
  18  * Implementation of the user-space ashmem API for devices, which have our
  19  * ashmem-enabled kernel. See ashmem-sim.c for the "fake" tmp-based version,
  20  * used by the simulator.
  21  */
  22
  23 #include <unistd.h>
  24 #include <string.h>
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <sys/ioctl.h>
  28 #include <fcntl.h>
  29
  30 #include <linux/ashmem.h>
  31 #include "ashmem.h"
  32
  33 #define ASHMEM_DEVICE   "/dev/ashmem"
  34
  35 /*
  36  * ashmem_create_region - creates a new ashmem region and returns the file
  37  * descriptor, or <0 on error
  38  *
  39  * `name' is an optional label to give the region (visible in /proc/pid/maps)
  40  * `size' is the size of the region, in page-aligned bytes
  41  */
  42 int ashmem_create_region(const char *name, size_t size)
  43 {
  44         int fd, ret;
  45
  46         fd = open(ASHMEM_DEVICE, O_RDWR);
  47         if (fd < 0)
  48                 return fd;
  49
  50         if (name) {
  51                 char buf[ASHMEM_NAME_LEN];
  52
  53                 strlcpy(buf, name, sizeof(buf));
  54                 ret = ioctl(fd, ASHMEM_SET_NAME, buf);
  55                 if (ret < 0)
  56                         goto error;
  57         }
  58
  59         ret = ioctl(fd, ASHMEM_SET_SIZE, size);
  60         if (ret < 0)
  61                 goto error;
  62
  63         return fd;
  64
  65 error:
  66         close(fd);
  67         return ret;
  68 }
  69
  70 int ashmem_set_prot_region(int fd, int prot)
  71 {
  72         return ioctl(fd, ASHMEM_SET_PROT_MASK, prot);
  73 }
  74
  75 int ashmem_pin_region(int fd, size_t offset, size_t len)
  76 {
  77         struct ashmem_pin pin = { offset, len };
  78         return ioctl(fd, ASHMEM_PIN, &pin);
  79 }
  80
  81 int ashmem_unpin_region(int fd, size_t offset, size_t len)
  82 {
  83         struct ashmem_pin pin = { offset, len };
  84         return ioctl(fd, ASHMEM_UNPIN, &pin);
  85 }
  86
  87 int ashmem_get_size_region(int fd)
  88 {
  89   return ioctl(fd, ASHMEM_GET_SIZE, NULL);
  90 }
  91
  92 int ashmem_purge_all(void)
  93 {
  94   const int fd = open(ASHMEM_DEVICE, O_RDWR);
  95   if (fd < 0)
  96     return fd;
  97   const int ret = ioctl(fd, ASHMEM_PURGE_ALL_CACHES, 0);
  98   close(fd);
  99   return ret;
 100 }