如何使用nix的ioctl? [英] How to use nix's ioctl?

问题描述

我想从Rust调用 ioctl .我知道我应该使用 nix板条箱，但是究竟是什么?从文档中尚不清楚.

I want to call ioctl from Rust. I know that I should use the nix crate, but how exactly? From the documentation it's not clear.

我有这个C:

int tun_open(char *devname)
{
  struct ifreq ifr;
  int fd, err;

  if ( (fd = open("/dev/net/tun", O_RDWR)) == -1 ) {
       perror("open /dev/net/tun");exit(1);
  }
  memset(&ifr, 0, sizeof(ifr));
  ifr.ifr_flags = IFF_TUN;
  strncpy(ifr.ifr_name, devname, IFNAMSIZ);  

  /* ioctl will use if_name as the name of TUN 
   * interface to open: "tun0", etc. */
  if ( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) == -1 ) {
    perror("ioctl TUNSETIFF");close(fd);exit(1);
  }
  //..........

我如何使用nix板条箱做同样的事情?nix板条箱中没有 TUN * 常量，目前尚不清楚如何使用 ioctl 宏.

How would I do that same thing using the nix crate? There are no TUN* constants in the nix crate and it isn't clear how to use the ioctl macro.

推荐答案

There is some example usage in rust-spidev. I will try to apply that to your code.

TUNSETIFF 是定义的为:

#define TUNSETIFF     _IOW('T', 202, int)

使用nix在Rust中就是这样:

That would be this in Rust using nix:

const TUN_IOC_MAGIC: u8 = 'T' as u8;
const TUN_IOC_SET_IFF: u8 = 202;
ioctl!(write tun_set_iff with TUN_IOC_MAGIC, TUN_IOC_SET_IFF; u32);

上面的宏将定义函数，您可以像这样调用该函数:

The above macro will define the function, which you can call like this:

let err = unsafe { tun_set_iff(fd, ifr) }; // assuming ifr is an u32

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