Android 模拟器的上使用GPS的bug

由于最近研究Android 模拟器的GPS模块的实现，发现了模拟器GPS的bug。

启动模拟器，通过DDMS发送经纬度，通过应用可以抓到数据，进入设置，安全与位置，关闭GPS，再打开，再次打开GPS测试软件，再次发送经纬度，怎么也收不到。

查看了代码发现Android模拟器中完成GPS模块的功能主要是一个HAL层代码，通过socket接收发送过来的经纬度信息，其中代码是有问题的，GPS模块的工作主要是一个线程，当关闭GPS模块的时候这个线程结束了，再次打开的时候不会去启动这个线程，所以GPS模块就不工作了，具体看如下代码：

static void
gps_state_thread( void*  arg )
{
    GpsState*   state = (GpsState*) arg;
    NmeaReader  reader[1];
    int         epoll_fd   = epoll_create(2);
    int         started    = 0;
    int         gps_fd     = state->fd;
    int         control_fd = state->control[1];

    nmea_reader_init( reader );

    // register control file descriptors for polling
    epoll_register( epoll_fd, control_fd );
    epoll_register( epoll_fd, gps_fd );

    D("gps thread running");

    // now loop
    for (;;) {
        struct epoll_event   events[2];
        int                  ne, nevents;

        nevents = epoll_wait( epoll_fd, events, 2, -1 );
        if (nevents < 0) {
            if (errno != EINTR)
                LOGE("epoll_wait() unexpected error: %s", strerror(errno));
            continue;
        }
        D("gps thread received %d events", nevents);
        for (ne = 0; ne < nevents; ne++) {
            if ((events[ne].events & (EPOLLERR|EPOLLHUP)) != 0) {
                LOGE("EPOLLERR or EPOLLHUP after epoll_wait() !?");
                return;
            }
            if ((events[ne].events & EPOLLIN) != 0) {
                int  fd = events[ne].data.fd;

                if (fd == control_fd)
                {
                    char  cmd = 255;
                    int   ret;
                    D("gps control fd event");
                    do {
                        ret = read( fd, &cmd, 1 );
                    } while (ret < 0 && errno == EINTR);

                    if (cmd == CMD_QUIT) {
                        D("gps thread quitting on demand");
                        return;
                    }
                    else if (cmd == CMD_START) {
                        if (!started) {
                            D("gps thread starting  location_cb=%p", state->callbacks.location_cb);
                            started = 1;
                            nmea_reader_set_callback( reader, state->callbacks.location_cb );
                        }
                    }
                    else if (cmd == CMD_STOP) {
                        if (started) {
                            D("gps thread stopping");
                            started = 0;
                            nmea_reader_set_callback( reader, NULL );
                        }
                    }
                }
                else if (fd == gps_fd)
                {
                    char  buff[32];
                    D("gps fd event");
                    for (;;) {
                        int  nn, ret;

                        ret = read( fd, buff, sizeof(buff) );
                        if (ret < 0) {
                            if (errno == EINTR)
                                continue;
                            if (errno != EWOULDBLOCK)
                                LOGE("error while reading from gps daemon socket: %s:", strerror(errno));
                            break;
                        }
                        D("received %d bytes: %.*s", ret, ret, buff);
                        for (nn = 0; nn < ret; nn++)
                            nmea_reader_addc( reader, buff[nn] );
                    }
                    D("gps fd event end");
                }
                else
                {
                    LOGE("epoll_wait() returned unkown fd %d ?", fd);
                }
            }
        }
    }
}

以上只是我的拙见。