Question

I try to control the mouse in Linux. Xlib seems to work, but when I try to use it with OpenCV, it keeps returning:

Resource temporarily unavailable

So I decided to write "/dev/psaux". The code is as follows:

#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


int main() {
    unsigned char a[5] = {0, 0xff, 0, 0x28, 0xff};
    int fp = open ("/dev/psaux", O_WRONLY);
    if(!fp)
        printf("open error:%s\n", strerror(errno));

    for(int i = 0; i < 10; i++)
        printf("write:%d\t\t%s\n", write(fp, a, 5), strerror(errno));
    close(fp);
    return 0;
}

Compile it with:

gcc  my_psaux.c -o my_psaux -std=gnu99 -g

Run

sudo ./my_psaux

and get

write:5    Success
write:5    Success
write:5    Success
write:5    Success
write:5    Success
write:5    Success
write:5    Success
write:5    Success
write:5    Success
write:5    Success

However, the mouse doesn’t move. Then I open a new terminal, type in "sudo cat /dev/psaux" and run "my_psaux". But I just cat nothing. Nothing is written into "/dev/psaux"

How can I fix this?

If this is not a good method to control the mouse, is there another one?

Answer 1

Great thanks to R…
for reminding me of some other ways instead of /dev/psaux

I tried /dev/input/mouse* and /dev/input/event*

By using

cat /proc/bus/input/devices

I get this:

I: Bus=0003 Vendor=0461 Product=4d81 Version=0111
N: Name="USB Optical Mouse"
P: Phys=usb-0000:00:1d.0-1/input0
S: Sysfs=/devices/pci0000:00/0000:00:1d.0/usb6/6-1/6-1:1.0/input/input10
U: Uniq=
H: Handlers=mouse2 event10
B: EV=17
B: KEY=70000 0 0 0 0 0 0 0 0
B: REL=143
B: MSC=10

After testing, only /dev/input/event10 works. The code is as follows:

#include <stdio.h>
#include <unistd.h>
#include <linux/input.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>

int main() {
  struct input_event event, event_end;

  int fd = open("/dev/input/event10", O_RDWR);
  if (fd < 0) {
    printf("Errro open mouse:%s\n", strerror(errno));
    return -1;
  }
  memset(&event, 0, sizeof(event));
  memset(&event, 0, sizeof(event_end));
  gettimeofday(&event.time, NULL);
  event.type = EV_REL;
  event.code = REL_X;
  event.value = 100;
  gettimeofday(&event_end.time, NULL);
  event_end.type = EV_SYN;
  event_end.code = SYN_REPORT;
  event_end.value = 0;
  for (int i=0; i<5; i++) {
    write(fd, &event, sizeof(event)); // Move the mouse
    write(fd, &event_end, sizeof(event_end)); // Show move
    sleep(1); // Wait
  }
  close(fd);
  return 0;
}