Home | History | Annotate | Download | only in libcutils
      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 <cutils/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