118 lines
3.2 KiB
C
118 lines
3.2 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Implementation of the user-space ashmem API for the simulator, which lacks
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* an ashmem-enabled kernel. See ashmem-dev.c for the real ashmem-based version.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <time.h>
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#include <unistd.h>
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#include <cutils/ashmem.h>
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#ifndef __unused
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#define __unused __attribute__((__unused__))
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#endif
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int ashmem_create_region(const char *ignored __unused, size_t size)
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{
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static const char txt[] = "abcdefghijklmnopqrstuvwxyz"
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
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char name[64];
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unsigned int retries = 0;
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pid_t pid = getpid();
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int fd;
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srand(time(NULL) + pid);
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retry:
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/* not beautiful, its just wolf-like loop unrolling */
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snprintf(name, sizeof(name), "/tmp/android-ashmem-%d-%c%c%c%c%c%c%c%c",
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pid,
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))],
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txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))]);
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/* open O_EXCL & O_CREAT: we are either the sole owner or we fail */
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fd = open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
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if (fd == -1) {
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/* unlikely, but if we failed because `name' exists, retry */
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if (errno == EEXIST && ++retries < 6)
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goto retry;
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return -1;
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}
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/* truncate the file to `len' bytes */
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if (ftruncate(fd, size) == -1)
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goto error;
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if (unlink(name) == -1)
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goto error;
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return fd;
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error:
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close(fd);
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return -1;
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}
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int ashmem_set_prot_region(int fd __unused, int prot __unused)
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{
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return 0;
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}
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int ashmem_pin_region(int fd __unused, size_t offset __unused, size_t len __unused)
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{
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return ASHMEM_NOT_PURGED;
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}
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int ashmem_unpin_region(int fd __unused, size_t offset __unused, size_t len __unused)
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{
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return ASHMEM_IS_UNPINNED;
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}
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int ashmem_get_size_region(int fd)
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{
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struct stat buf;
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int result;
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result = fstat(fd, &buf);
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if (result == -1) {
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return -1;
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}
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// Check if this is an "ashmem" region.
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// TODO: This is very hacky, and can easily break. We need some reliable indicator.
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if (!(buf.st_nlink == 0 && S_ISREG(buf.st_mode))) {
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errno = ENOTTY;
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return -1;
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}
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return (int)buf.st_size; // TODO: care about overflow (> 2GB file)?
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}
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