[问题] go 调用 Linux 系统接口无法关闭 fd

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This topic created in 1766 days ago, the information mentioned may be changed or developed.

项目中需要获取网卡的一些硬件信息，但遇到一点问题，现在用另一种方式解决了；但还是想搞懂为什么会报这个错误，基础太差，希望得到大佬的指导，非常感谢。

package main

import (
	"fmt"
	"golang.org/x/sys/unix"
	"syscall"
	"unsafe"
)

func main() {
	for {
		go func() {
			fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP)
			defer func() {
				if err := unix.Close(fd); err != nil {
					fmt.Println("fd 关闭失败:", err)
				}
			}()
			if err != nil {
				fmt.Println(err)
				return
			}
			var et struct {
				Cmd       uint32
				Supported uint32
			}

			const GSET = 0x1

			et.Cmd = GSET

			var ifr struct {
				Name [16]byte
				Data uintptr
			}

			copy(ifr.Name[:], []byte("网卡名称"))
			ifr.Data = uintptr(unsafe.Pointer(&et))

			const SIOCETHTOOL = 0x8946
            
			// 执行这一步后，fd 就无法关闭，close 返回 bad file descriptor
			_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), uintptr(SIOCETHTOOL), uintptr(unsafe.Pointer(&ifr)))
			if errno != 0 {
				fmt.Println(errno)
			}
		}()
	}
	select {}
}

Supplement 1 · Aug 5, 2021

已解决，结帖；ethtool_cmd结构体不全导致，从c源码抄一份完整的结构就解决了

package main

import (
	"fmt"
	"golang.org/x/sys/unix"
	"syscall"
	"time"
	"unsafe"
)

type EthtoolCmd struct {
	Cmd            uint32
	Supported      uint32
	Advertising    uint32
	Speed          uint16
	Duplex         uint8
	Port           uint8
	Phy_address    uint8
	Transceiver    uint8
	Autoneg        uint8
	Mdio_support   uint8
	Maxtxpkt       uint32
	Maxrxpkt       uint32
	Speed_hi       uint16
	Eth_tp_mdix    uint8
	Reserved2      uint8
	Lp_advertising uint32
	Reserved       [2]uint32
}

type EthtoolValue struct {
	Cmd  uint32
	Data uint32
}

type EthtoolDrvInfo struct {
	cmd          uint32
	driver       [32]byte
	version      [32]byte
	fw_version   [32]byte
	bus_info     [32]byte
	erom_version [32]byte
	reserved2    [12]byte
	n_priv_flags uint32
	n_stats      uint32
	testinfo_len uint32
	eedump_len   uint32
	regdump_len  uint32
}

const IFNAMSIZ = 16

type Ifreq struct {
	ifr_name [IFNAMSIZ]byte
	ifr_data uintptr
}

func main() {
	for {
		func() {
			fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP)
			defer func() {
				if err := unix.Close(fd); err != nil {
					fmt.Println("fd关闭失败:", err)
				}
			}()
			if err != nil {
				fmt.Println(err)
				return
			}

			var ifr Ifreq
			//var drvinfo EthtoolDrvInfo
			var ecmd EthtoolCmd
			//var edata EthtoolValue

			copy(ifr.ifr_name[:], []byte("eno2"))
			ecmd.Cmd = 0x1
			ifr.ifr_data = uintptr(unsafe.Pointer(&ecmd))
			_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(0x8946), uintptr(unsafe.Pointer(&ifr)))
			if errno != 0 {
				panic("ioctl 发送失败")
			}
			time.Sleep(1 * time.Second)
		}()
	}
	select {}

16 replies • 2021-08-06 15:44:37 +08:00