问题
I am writing a Key board emulator program in Linux, As a start I was able to render key strokes into X11 window but this is not working in virtual terminals and try out a different way. I referred to http://thiemonge.org/getting-started-with-uinput and tried with uinput kernel module. According to the tutorial key strokes can be injected as a uinput event and I wrote below code accordingly.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/input.h>
#include <linux/uinput.h>
#include <iostream>
#include <time.h>
#include <string>
#define die(str, args...) do { \
perror(str); \
exit(EXIT_FAILURE); \
} while(0)
int main(void)
{
int fd_keyEmulator;
struct uinput_user_dev uidev;
struct input_event ev;
int dx, dy;
int i;
fd_keyEmulator = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
if(fd_keyEmulator < 0)
{
std::cout << "error: open : " << strerror(errno) << std::endl;
}
int ret;
//ret = ioctl(fd_keyEmulator, UI_SET_EVBIT, EV_KEY);
//ret = ioctl(fd_keyEmulator, UI_SET_KEYBIT, KEY_D);
//ret = ioctl(fd_keyEmulator, UI_SET_EVBIT, EV_SYN);
sleep(5);
if (ioctl(fd_keyEmulator, UI_SET_EVBIT, EV_KEY) < 0)
{
std::cout << "test 1 ..." << std::endl;
die("error: ioctl");
}
if (ioctl(fd_keyEmulator, UI_SET_KEYBIT, KEY_D) < 0)
{
std::cout << "test 2 ..." << std::endl;
die("error: ioctl");
}
if (ioctl(fd_keyEmulator, UI_SET_EVBIT, EV_REL) < 0)
{
std::cout << "test 3 ..." << std::endl;
die("error: ioctl");
}
memset(&uidev, 0, sizeof(uidev));
snprintf(uidev.name, UINPUT_MAX_NAME_SIZE, "keyboard-emulator");
uidev.id.bustype = BUS_USB;
uidev.id.vendor = 0x1;
uidev.id.product = 0x1;
uidev.id.version = 1;
std::cout << "Writing key press..." << std::endl;
if(write(fd_keyEmulator, &uidev, sizeof(uidev)) < 0)
std::cout << "error: write" << strerror(errno) << std::endl;
if(ioctl(fd_keyEmulator, UI_DEV_CREATE) < 0)
std::cout << "error: ioctl" << strerror(errno) << std::endl;
memset(&ev, 0, sizeof(ev));
ev.type = EV_REL;
ev.code = KEY_D;
ev.value = 1;
//ret = write(fd_keyEmulator, &ev, sizeof(ev));
if (write(fd_keyEmulator, &ev, sizeof (struct input_event)) < 0)
die("error: write");
if (write(fd_keyEmulator, &ev, sizeof (struct input_event)) < 0)
die("error: write");
if (write(fd_keyEmulator, &ev, sizeof (struct input_event)) < 0)
die("error: write");
if (write(fd_keyEmulator, &ev, sizeof (struct input_event)) < 0)
die("error: write");
if(ioctl(fd_keyEmulator, UI_DEV_DESTROY) < 0)
std::cout << "error: ioctl" << strerror(errno) << std::endl;
close(fd_keyEmulator);
}
in this case, what I am trying is to generate a uinput events for key stroke 'd'. but with the program execution I cannot see anything. can somebody help me to verify this program. It is not clear how to inject a key stroke with uinput subsystem in the tutorial as well.
EDIT: I wrote a different program, but I cannot see any output. I got lost and any help appreciate.
#include <cstdlib>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/input.h>
#include <linux/uinput.h>
#include <iostream>
#include <time.h>
#include <string>
using namespace std;
/*
*
*/
int main(int argc, char** argv) {
// create uinput file descriptor
int fd_key_emulator;
// open file descriptor
fd_key_emulator = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
if(fd_key_emulator < 0)
{
std::cout << "error in open : " << strerror(errno) << std::endl;
}
// uinput_user_dev struct for fake keyboard
struct uinput_user_dev dev_fake_keyboard;
memset(&dev_fake_keyboard, 0, sizeof(uinput_user_dev));
snprintf(dev_fake_keyboard.name, UINPUT_MAX_NAME_SIZE, "kb-emulator");
dev_fake_keyboard.id.bustype = BUS_USB;
dev_fake_keyboard.id.vendor = 0x01;
dev_fake_keyboard.id.product = 0x01;
dev_fake_keyboard.id.version = 1;
/**configure the input device to send type of events, inform to subsystem which
* type of input events we are using via ioctl calls.
* UI_SET_EVBIT ioctl request is used to applied on uinput descriptor to enable a type of event.
**/
// enable key press/release event
if(ioctl(fd_key_emulator, UI_SET_EVBIT, EV_KEY))
{
std::cout << "Error in ioctl : UI_SET_EVBIT : EV_KEY : " << strerror(errno) << std::endl;
}
// enable set of KEY events here
if(ioctl(fd_key_emulator, UI_SET_KEYBIT, KEY_A))
{
std::cout << "Error in ioctl : UI_SET_KEYBIT : KEY_A : " << strerror(errno) << std::endl;
}
// enable synchronization event
if(ioctl(fd_key_emulator, UI_SET_EVBIT, EV_SYN))
{
std::cout << "Error in ioctl : UI_SET_EVBIT : EV_SYN : " << strerror(errno) << std::endl;
}
// now write the uinput_user_dev structure into uinput file descriptor
if(write(fd_key_emulator, &dev_fake_keyboard, sizeof(uinput_user_dev)) < 0)
{
std::cout << "Error in write(): uinput_user_dev struct into uinput file descriptor: " << strerror(errno) << std::endl;
}
// create the device via an IOCTL call
if(ioctl(fd_key_emulator, UI_DEV_CREATE))
{
std::cout << "Error in ioctl : UI_DEV_CREATE : " << strerror(errno) << std::endl;
}
// now fd_key_emulator represents the end-point file descriptor of the new input device.
// struct member for input events
struct input_event key_input_event;
memset(&key_input_event, 0, sizeof(input_event));
// key press event for 'a'
key_input_event.type = EV_KEY;
key_input_event.code = KEY_A;
key_input_event.value = 1;
// now write to the file descriptor
if(write(fd_key_emulator, &key_input_event, sizeof(input_event)) < 0)
{
std::cout << "Error write : KEY_A press : " << strerror(errno) << std::endl;
}
memset(&key_input_event, 0, sizeof(input_event));
// EV_SYN for key press event
key_input_event.type = EV_SYN;
key_input_event.code = SYN_REPORT;
key_input_event.value = 0;
// now write to the file descriptor
if(write(fd_key_emulator, &key_input_event, sizeof(input_event)) < 0)
{
std::cout << "Error write : EV_SYN for key press : " << strerror(errno) << std::endl;
}
memset(&key_input_event, 0, sizeof(input_event));
// key release event for 'a'
key_input_event.type = EV_KEY;
key_input_event.code = KEY_A;
key_input_event.value = 0;
// now write to the file descriptor
if(write(fd_key_emulator, &key_input_event, sizeof(input_event)) < 0)
{
std::cout << "Error write : KEY_A release : " << strerror(errno) << std::endl;
}
memset(&key_input_event, 0, sizeof(input_event));
// EV_SYN for key press event
key_input_event.type = EV_SYN;
key_input_event.code = SYN_REPORT;
key_input_event.value = 0;
// now write to the file descriptor
if(write(fd_key_emulator, &key_input_event, sizeof(input_event)) < 0)
{
std::cout << "Error write : EV_SYN for key release : " << strerror(errno) << std::endl;
}
return 0;
}
回答1:
There is nothing wrong with above 2 programs. The problem here is, that this program creates a new input device (probably somewhere in "/dev/input") and that X cannot register the input device fast enough so that it can fetch the input. A simple "sleep(1);" (with the appropriate "#include ") after the creation of the input device solves the problem. To be (probably unnecessary) specific, after changing the code the program will behave as expected because now X had ample time to realize there's a new input device. Add the sleep() statement after below code segment.
// create the device via an IOCTL call
if(ioctl(fd_key_emulator, UI_DEV_CREATE))
{
std::cout << "Error in ioctl : UI_DEV_CREATE : " << strerror(errno) << std::endl;
}
// add 1 second sleep.
sleep (1);
// now fd_key_emulator represents the end-point file descriptor of the new input device.
now program is working as expected. Same occurrence found at http://www.linuxforums.org/forum/ubuntu-linux/161718-its-no-effect-when-using-uinput.html solution is taken from there.
来源：https://stackoverflow.com/questions/40676172/how-to-generate-key-strokes-events-with-the-input-subsystem