確定Linux的鍵盤事件設備

Question

這另一個問題，Accessing Keys from Linux Input Device

提供對沒有按任何其他按鍵時如何在Linux文本控制檯識別修改按鍵工作的C代碼。

但是，要應用這個技巧，您必須知道記錄鍵盤事件的特定文件/dev/input/event*。

如何確定該文件的名稱？

Answer 1

我有這個完全相同的問題。這是我的解決方案：

#include <iostream> 
#include <string> 
#include <stdio.h> 

static const std::string COMMAND_GET_INPUT_DEVICE_EVENT_NUMBER = 
    "grep -E 'Handlers|EV=' /proc/bus/input/devices |" 
    "grep -B1 'EV=120013' |" 
    "grep -Eo 'event[0-9]+' |" 
    "grep -Eo '[0-9]+' |" 
    "tr -d '\n'"; 

std::string executeCommand(const char *cmd) { 
    FILE *pipe = popen(cmd, "r"); 
    char buffer[128]; 
    std::string result = ""; 
    while (!feof(pipe)) 
    if (fgets(buffer, 128, pipe) != NULL) 
     result += buffer; 
    pclose(pipe); 
    return result; 
} 

std::string getInputDevicePath() { 
    return "/dev/input/event" + 
     executeCommand(COMMAND_GET_INPUT_DEVICE_EVENT_NUMBER.c_str()); 
} 

int main() { 
    std::cout << getInputDevicePath() << std::endl; 
    return 0; 
} 

Answer 2

我更喜歡下一個解決方案，因爲它在內部解析設備文件。
如果我們檢查/ proc /總線/輸入/設備的內容，我們可以發現這樣的事情：

# cat /proc/bus/input/devices 
I: Bus=0019 Vendor=0002 Product=0001 Version=0100 
N: Name="vmouse" 
P: Phys=vmouse/input0 
S: Sysfs=/devices/virtual/input/input0 
U: Uniq= 
H: Handlers=mouse0 event0 
B: PROP=0 
B: EV=7 
B: KEY=70400 0 0 0 0 0 0 0 0 
B: REL=143 

I: Bus=0019 Vendor=0001 Product=0001 Version=0100 
N: Name="sunxi-ths" 
P: Phys=sunxiths/input0 
S: Sysfs=/devices/virtual/input/input3 
U: Uniq= 
H: Handlers=event3 
B: PROP=0 
B: EV=9 
B: ABS=100 0 

I: Bus=0003 Vendor=1220 Product=0008 Version=0100 
N: Name="HID 1220:0008" 
P: Phys=usb-sunxi-ohci-1/input0 
S: Sysfs=/devices/platform/sunxi-ohci.3/usb7/7-1/7-1:1.0/input/input6 
U: Uniq= 
H: Handlers=sysrq kbd event1 
B: PROP=0 
B: EV=120013 
B: KEY=10000 7 ff9f207a c14057ff febeffdf ffefffff ffffffff fffffffe 
B: MSC=10 
B: LED=1f 

I: Bus=0003 Vendor=1220 Product=0008 Version=0100 
N: Name="HID 1220:0008" 
P: Phys=usb-sunxi-ohci-1/input1 
S: Sysfs=/devices/platform/sunxi-ohci.3/usb7/7-1/7-1:1.1/input/input7 
U: Uniq= 
H: Handlers=kbd mouse1 event2 
B: PROP=0 
B: EV=1f 
B: KEY=4837fff 72ff32d bf544446 0 0 1f0001 20f90 8b17c000 677bfa d941dfed 9ed680 4400 0 10000002 
B: REL=143 
B: ABS=1 0 
B: MSC=10 

所以我們唯一需要的就是找塊活動設備數，其中「EV = 120013」串出現：

#include <fcntl.h> 
#include <stdio.h> 
#include <string> 
#include <string.h> 
#include <unistd.h> 

using namespace std; 

string getInputDeviceName() { 
    int rd; 
    std::string devName; 
    const char* pdevsName = "/proc/bus/input/devices"; 

    int devsFile = open(pdevsName, O_RDONLY); 
    if (devsFile == -1) { 
     printf("[ERR] Open input devices file: '%s' is FAILED\n", pdevsName); 
    } 
    else { 
     char devs[2048]; 

     if ((rd = read(devsFile, devs, sizeof(devs) - 1)) < 6) { 
      printf("[ERR] Wrong size was read from devs file\n"); 
     } 
     else { 
      devs[rd] = 0; 

      char *pHandlers, *pEV = devs; 
      do { 
       pHandlers = strstr(pEV, "Handlers="); 
       pEV = strstr(pHandlers, "EV="); 
      } 
      while (pHandlers && pEV && 0 != strncmp(pEV + 3, "120013", 6)); 

      if (pHandlers && pEV) { 
       char* pevent = strstr(pHandlers, "event"); 
       if (pevent) { 
        devName = string("/dev/input/event"); 
        devName.push_back(pevent[5]); 
       } 
       else { 
        printf("[ERR] Abnormal keyboard event device\n"); 
       } 
      } 
      else { 
       printf("[ERR] Keyboard event device not found\n"); 
      } 
     } 
    } 

    return devName; 
} 

NOTE1：此代碼事件設備少於10
NOTE2號碼：請檢查「開發者」緩衝大小，您的系統上2048個字節b電子還不夠。