Android 进程间使用管道通信

Android 进程间使用管道通信
实现比较简单，直接上代码就可以理解了

#define PATH_CMD_FIFO          "/data/misc/my_fifo"

/* read pipe from path of PATH_CMD_FIFO
 * if read data from pipe, and then send data to uart port
 */
static void * read_fifo_thread(void *arg)
{
    int ret = 0;
    int fd = 0;
    char buf[512] = {0};

    ALOGD("%s Enter\n", __FUNCTION__);

    if (mkfifo(PATH_CMD_FIFO, O_CREAT | O_EXCL | 0777) < 0
        && errno != EEXIST) {
        ALOGE("%s creat fifo server error\n", __FUNCTION__);
        goto err_ret;
    }
    fd = open(PATH_CMD_FIFO, O_CREAT | O_RDONLY | O_NONBLOCK, 0);
    if (fd < 0) {
        ALOGE("%s open fd error=%s\n", __FUNCTION__, strerror(errno));
        goto err_ret;
    }
    ALOGD("%s fd:%d\n", __FUNCTION__, fd);

    while (!stop_flag) {
        memset(buf, 0x0, sizeof(buf));
        ret = read(fd, buf, sizeof(buf));
        if (ret > 0) {
            // Do something
        }
        usleep(1000*1000);
    }
err_ret:
    unlink(PATH_CMD_FIFO);
    pthread_exit(NULL);
}

1、注意 mkfifo 的时候的权限问题，我这边用的是 0777，根据对应的情况而定

2、检查是否生成了管道文件

可以看到在 /data/misc/my_fifo 有这个文件生成

3、读写调试

echo "hello world" > /data/misc/my_fifo

上面的线程中就可以读到这个信息

5、使用mkfifo bin调试

另外调试过程中可以直接在板子上使用mkfifo 命令

NAME
       mkfifo - make FIFOs (named pipes)

SYNOPSIS
       mkfifo [OPTION]... NAME...

DESCRIPTION
       Create named pipes (FIFOs) with the given NAMEs.

       Mandatory arguments to long options are mandatory for short options too.

       -m, --mode=MODE
              set file permission bits to MODE, not a=rw - umask

       -Z, --context=CTX
              set the SELinux security context of each NAME to CTX

       --help display this help and exit

       --version
              output version information and exit

AUTHOR
       Written by David MacKenzie.

REPORTING BUGS
       Report mkfifo bugs to bug-coreutils@gnu.org
       GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
       General help using GNU software: <http://www.gnu.org/gethelp/>
       Report mkfifo translation bugs to <http://translationproject.org/team/>

COPYRIGHT
       Copyright © 2013 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       mkfifo(3)

       The  full  documentation  for mkfifo is maintained as a Texinfo manual.  If the info and mkfifo programs are properly installed at your
       site, the command

              info coreutils 'mkfifo invocation'

       should give you access to the complete manual.