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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  */
ashmem_create_region(const char * name,size_t size)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] = {0};
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 
ashmem_set_prot_region(int fd,int prot)70 int ashmem_set_prot_region(int fd, int prot)
71 {
72 	return ioctl(fd, ASHMEM_SET_PROT_MASK, prot);
73 }
74 
ashmem_pin_region(int fd,size_t offset,size_t len)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 
ashmem_unpin_region(int fd,size_t offset,size_t len)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 
ashmem_get_size_region(int fd)87 int ashmem_get_size_region(int fd)
88 {
89   return ioctl(fd, ASHMEM_GET_SIZE, NULL);
90 }
91