platform_system_core/libcutils/ashmem-host.c
Elliott Hughes 3918090252 Make host ashmem_create_region more robust.
Don't clobber errno if mkstemp failed, always unlink, and only count
mkstemp/ftruncate failures as real failures --- if only the unlink
fails, there's no point not using what we have.

Change-Id: I6bc788682c88651a50a6316b9ca07ba07e9fefa2
2015-12-16 08:33:52 -08:00

89 lines
2.2 KiB
C

/*
* 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 <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <cutils/ashmem.h>
#include <utils/Compat.h>
#ifndef __unused
#define __unused __attribute__((__unused__))
#endif
int ashmem_create_region(const char *ignored __unused, size_t size)
{
char template[PATH_MAX];
snprintf(template, sizeof(template), "/tmp/android-ashmem-%d-XXXXXXXXX", getpid());
int fd = mkstemp(template);
if (fd == -1) return -1;
unlink(template);
if (TEMP_FAILURE_RETRY(ftruncate(fd, size)) == -1) {
close(fd);
return -1;
}
return fd;
}
int ashmem_set_prot_region(int fd __unused, int prot __unused)
{
return 0;
}
int ashmem_pin_region(int fd __unused, size_t offset __unused, size_t len __unused)
{
return ASHMEM_NOT_PURGED;
}
int ashmem_unpin_region(int fd __unused, size_t offset __unused, size_t len __unused)
{
return ASHMEM_IS_UNPINNED;
}
int ashmem_get_size_region(int fd)
{
struct stat buf;
int 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 buf.st_size;
}