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 #include <cutils/ashmem.h>
18
19 /*
20 * Implementation of the user-space ashmem API for the simulator, which lacks
21 * an ashmem-enabled kernel. See ashmem-dev.c for the real ashmem-based version.
22 */
23
24 #include <errno.h>
25 #include <fcntl.h>
26 #include <limits.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <sys/stat.h>
31 #include <sys/types.h>
32 #include <time.h>
33 #include <unistd.h>
34
35 #include <utils/Compat.h>
36
ashmem_validate_stat(int fd,struct stat * buf)37 static bool ashmem_validate_stat(int fd, struct stat* buf) {
38 int result = fstat(fd, buf);
39 if (result == -1) {
40 return false;
41 }
42
43 /*
44 * Check if this is an "ashmem" region.
45 * TODO: This is very hacky, and can easily break.
46 * We need some reliable indicator.
47 */
48 if (!(buf->st_nlink == 0 && S_ISREG(buf->st_mode))) {
49 errno = ENOTTY;
50 return false;
51 }
52 return true;
53 }
54
ashmem_valid(int fd)55 int ashmem_valid(int fd) {
56 struct stat buf;
57 return ashmem_validate_stat(fd, &buf);
58 }
59
ashmem_create_region(const char *,size_t size)60 int ashmem_create_region(const char* /*ignored*/, size_t size) {
61 char pattern[PATH_MAX];
62 snprintf(pattern, sizeof(pattern), "/tmp/android-ashmem-%d-XXXXXXXXX", getpid());
63 int fd = mkstemp(pattern);
64 if (fd == -1) return -1;
65
66 unlink(pattern);
67
68 if (TEMP_FAILURE_RETRY(ftruncate(fd, size)) == -1) {
69 close(fd);
70 return -1;
71 }
72
73 return fd;
74 }
75
ashmem_set_prot_region(int,int)76 int ashmem_set_prot_region(int /*fd*/, int /*prot*/) {
77 return 0;
78 }
79
ashmem_pin_region(int,size_t,size_t)80 int ashmem_pin_region(int /*fd*/, size_t /*offset*/, size_t /*len*/) {
81 return 0 /*ASHMEM_NOT_PURGED*/;
82 }
83
ashmem_unpin_region(int,size_t,size_t)84 int ashmem_unpin_region(int /*fd*/, size_t /*offset*/, size_t /*len*/) {
85 return 0 /*ASHMEM_IS_UNPINNED*/;
86 }
87
ashmem_get_size_region(int fd)88 int ashmem_get_size_region(int fd)
89 {
90 struct stat buf;
91 if (!ashmem_validate_stat(fd, &buf)) {
92 return -1;
93 }
94
95 return buf.st_size;
96 }
97