/*
* Copyright (C) 2016 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.
*/
#include <errno.h>
#include <stdio.h>
#include <string>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <new>
#include <audio_utils/fifo.h>
#include <cutils/ashmem.h>
#define FRAME_COUNT 2048
#define FRAME_SIZE sizeof(int16_t)
#define BUFFER_SIZE (FRAME_COUNT * FRAME_SIZE)
int main(int argc __unused, char **argv __unused)
{
// TODO Add error checking for ashmem_create_region and mmap
const int frontFd = ashmem_create_region("front", sizeof(audio_utils_fifo_index));
printf("frontFd=%d\n", frontFd);
const int rearFd = ashmem_create_region("rear", sizeof(audio_utils_fifo_index));
printf("rearFd=%d\n", rearFd);
const int dataFd = ashmem_create_region("buffer", BUFFER_SIZE);
printf("dataFd=%d\n", dataFd);
// next two index constructors must execute exactly once, so we do it in the parent
audio_utils_fifo_index *frontIndex = (audio_utils_fifo_index *) mmap(NULL,
sizeof(audio_utils_fifo_index), PROT_READ | PROT_WRITE, MAP_SHARED, frontFd, (off_t) 0);
printf("parent frontIndex=%p\n", frontIndex);
(void) new(frontIndex) audio_utils_fifo_index();
audio_utils_fifo_index *rearIndex = (audio_utils_fifo_index *) mmap(NULL,
sizeof(audio_utils_fifo_index), PROT_READ | PROT_WRITE, MAP_SHARED, rearFd, (off_t) 0);
printf("parent rearIndex=%p\n", rearIndex);
(void) new(rearIndex) audio_utils_fifo_index();
int16_t *data = (int16_t *) mmap(NULL, sizeof(audio_utils_fifo_index), PROT_READ | PROT_WRITE,
MAP_SHARED, dataFd, (off_t) 0);
printf("parent data=%p\n", data);
memset(data, 0, BUFFER_SIZE);
const int pageSize = getpagesize();
printf("page size=%d\n", pageSize);
// create writer
printf("fork writer:\n");
const pid_t pidWriter = fork();
// TODO check if pidWriter < 0
if (!pidWriter) {
// Child inherits the parent's read/write mapping of front index.
// To confirm that there are no attempts to write to the front index,
// unmap it and then re-map it as read-only.
int ok = munmap(frontIndex, sizeof(audio_utils_fifo_index));
printf("writer unmap front ok=%d\n", ok);
ok = ashmem_set_prot_region(frontFd, PROT_READ);
printf("writer prot read front ok=%d\n", ok);
// The pagesize * 4 offset confirms that we don't assume identical mapping in both processes
frontIndex = (audio_utils_fifo_index *) mmap((char *) frontIndex + pageSize * 4,
sizeof(audio_utils_fifo_index), PROT_READ, MAP_SHARED | MAP_FIXED, frontFd,
(off_t) 0);
printf("writer frontIndex=%p\n", frontIndex);
// Retain our read/write mapping of rear index and data
audio_utils_fifo fifo(FRAME_COUNT, FRAME_SIZE, data, *rearIndex, frontIndex);
audio_utils_fifo_writer writer(fifo);
sleep(2);
for (int16_t value = 1; value <= 20; value++) {
printf("writing %d\n", value);
const ssize_t actual = writer.write(&value, 1);
if (actual != 1) {
printf("wrote unexpected actual = %zd\n", actual);
break;
}
// TODO needs a lot of work
switch (value) {
case 10:
sleep(2);
break;
case 14:
sleep(4);
break;
default:
usleep(500000);
break;
}
}
(void) close(frontFd);
(void) close(rearFd);
(void) close(dataFd);
return EXIT_SUCCESS;
}
// The sleep(2) above and sleep(1) here ensure that the order is:
// a. writer initializes
// b. reader initializes
// c. reader starts the read loop
// d. writer starts the write loop
// Actually, as long as (a) precedes (d) and (b) precedes (c), the order does not matter.
// TODO test all valid sequences.
sleep(1);
// create reader
printf("fork reader:\n");
const pid_t pidReader = fork();
// TODO check if pidReader < 0
if (!pidReader) {
// Child inherits the parent's read/write mapping of rear index.
// To confirm that there are no attempts to write to the rear index,
// unmap it and then re-map it as read-only.
int ok = munmap(rearIndex, sizeof(audio_utils_fifo_index));
printf("reader unmap rear ok=%d\n", ok);
ok = ashmem_set_prot_region(rearFd, PROT_READ);
printf("reader prot read rear ok=%d\n", ok);
// The pagesize * 4 offset confirms that we don't assume identical mapping in both processes
rearIndex = (audio_utils_fifo_index *) mmap((char *) rearIndex + pageSize * 4,
sizeof(audio_utils_fifo_index), PROT_READ, MAP_SHARED | MAP_FIXED, rearFd,
(off_t) 0);
printf("reader rearIndex=%p\n", rearIndex);
// Similarly for the data
ok = munmap(data, BUFFER_SIZE);
printf("reader unmap data ok=%d\n", ok);
ok = ashmem_set_prot_region(dataFd, PROT_READ);
printf("reader prot read data ok=%d\n", ok);
// The pagesize * 8 offset confirms that we don't assume identical mapping in both processes
data = (int16_t *) mmap((char *) data + pageSize * 8, BUFFER_SIZE, PROT_READ,
MAP_SHARED | MAP_FIXED, dataFd, (off_t) 0);
printf("reader data=%p\n", data);
// Retain our read/write mapping of front index
audio_utils_fifo fifo(FRAME_COUNT, FRAME_SIZE, data, *rearIndex, frontIndex);
audio_utils_fifo_reader reader(fifo);
for (;;) {
int16_t value;
struct timespec timeout = {
.tv_sec = 1,
.tv_nsec = 0
};
const ssize_t actual = reader.read(&value, 1, &timeout);
switch (actual) {
case 0:
break;
case 1:
printf("read %d\n", value);
if (value == 20) {
goto out;
}
break;
case -ETIMEDOUT:
printf("read timed out\n");
break;
default:
printf("read unexpected actual = %zd\n", actual);
goto out;
}
}
out:
(void) close(frontFd);
(void) close(rearFd);
(void) close(dataFd);
return EXIT_SUCCESS;
}
int status;
pid_t pid = waitpid(pidWriter, &status, 0);
if (pid == pidWriter) {
printf("writer exited with status %d\n", status);
} else {
printf("waitpid on writer = %d\n", pid);
}
pid = waitpid(pidReader, &status, 0);
if (pid == pidReader) {
printf("reader exited with status %d\n", status);
} else {
printf("waitpid on reader = %d\n", pid);
}
// next two index destructors must execute exactly once, so we do it in the parent
frontIndex->~audio_utils_fifo_index();
rearIndex->~audio_utils_fifo_index();
int ok = munmap(frontIndex, sizeof(audio_utils_fifo_index));
printf("parent unmap front ok=%d\n", ok);
ok = munmap(rearIndex, sizeof(audio_utils_fifo_index));
printf("parent unmap rear ok=%d\n", ok);
ok = munmap(data, BUFFER_SIZE);
printf("parent unmap data ok=%d\n", ok);
(void) close(frontFd);
(void) close(rearFd);
(void) close(dataFd);
return EXIT_SUCCESS;
}