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