5 Agile Telnet 移植出现error: 'POLLIN' undeclared (first use in this function)

发布于 2023-07-28 23:29:21 浏览：476 订阅该版

使用rt thread studio 工具环境，使用软件包 agile telnet 和agile conosle后，在serial.c文件 出现
```
/rt-thread/components/drivers/serial/serial.c:61:49: error: 'POLLIN' undeclared (first use in this function) 
```
这个`POLLIN` 未定义， 请问一下这个`POLLIN`是什么的呢，不懂是什么数据，

```c
static rt_err_t serial_fops_rx_ind(rt_device_t dev, rt_size_t size)
{
    rt_wqueue_wakeup(&(dev->wait_queue), (void*)POLLIN);

return RT_EOK;
}

static int serial_fops_poll(struct dfs_fd *fd, struct rt_pollreq *req)
{
    int mask = 0;
    int flags = 0;
    rt_device_t device;
    struct rt_serial_device *serial;

device = (rt_device_t)fd->data;
    RT_ASSERT(device != RT_NULL);

serial = (struct rt_serial_device *)device;

/* only support POLLIN */
    flags = fd->flags & O_ACCMODE;
    if (flags == O_RDONLY || flags == O_RDWR)
    {
        rt_base_t level;
        struct rt_serial_rx_fifo* rx_fifo;

rt_poll_add(&(device->wait_queue), req);

rx_fifo = (struct rt_serial_rx_fifo*) serial->serial_rx;

level = rt_hw_interrupt_disable();
        if ((rx_fifo->get_index != rx_fifo->put_index) || (rx_fifo->get_index == rx_fifo->put_index && rx_fifo->is_full == RT_TRUE))
            mask |= POLLIN;
        rt_hw_interrupt_enable(level);
    }

return mask;
}
```

这里几个地方引用了POLLIN，但不是懂是是哪个数据。。。

WKJay 认证专家 2023-07-29

wkjay.com

`POLLIN`定义在头文件`poll.h`中，具体定义如下：
```c
/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2021-09-11     Meco Man     First version
 */

#ifndef __POLL_H__
#define __POLL_H__

#ifdef __cplusplus
extern "C" {
#endif

#if !defined(POLLIN) && !defined(POLLOUT)
#define POLLIN          (0x01)
#define POLLRDNORM      (0x01)
#define POLLRDBAND      (0x01)
#define POLLPRI         (0x01)

#define POLLOUT         (0x02)
#define POLLWRNORM      (0x02)
#define POLLWRBAND      (0x02)

#define POLLERR         (0x04)
#define POLLHUP         (0x08)
#define POLLNVAL        (0x10)

typedef unsigned int nfds_t;

struct pollfd
{
    int fd;
    short events;
    short revents;
};
#endif /* !defined(POLLIN) && !defined(POLLOUT) */

#define POLLMASK_DEFAULT (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)

int poll(struct pollfd *fds, nfds_t nfds, int timeout);

#ifdef __cplusplus
}
#endif

#endif /* __POLL_H__ */
```
一般`POLLIN`表示有数据可读。

题主关注一下是否包含了对应的头文件。同时检查一下 RT-Thread Settings 中是否打开了如下选项：

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230729/3304ed230afdba74a1dae00558f90197.png)