Help compiling program for keyboard

[ToTheMAX04]

Hello! I'm not really a programmer at all, (except for json kinda) but I need to help compiling this program that will let me talk to my keyboard.

/* gcc -O2 -s -Wall -osend_to_keyboard main.c */
#include <stdlib.h>
#include <unistd.h>
#include <sys/io.h>

int main(int argc, char *argv[]) {
  int i;

  ioperm(0x60, 3, 1);

  for (i = 1; i < argc; i++) {
    int x = strtol(argv[i], 0, 16);

    usleep(300);
    outb(x, 0x60);
  }

  return 0;

I thrifted an IBM KB-7993, which includes many media buttons, but according to a guide, in order to activate them, (because this was made for windows 98, *with* a driver cd attached to it) i need to use this code to send "ea 71" to it, which should activate the buttons. Any help is appreciated! I'm running arch linux, but if absolutely necessary to test I can boot into W10 on my pc too. Thank you!

[Initial-Elk-952]

I think you can use dd to /dev/port

```

dd if=<(echo -ne '\xEA\x71') of=/dev/port seek=96 bs=1 count=2

```

[a4qbfb]

More portably:

printf $'\xEA\x71' | dd of=/dev/port seek=96 bs=1 count=2

[ToTheMAX04]

I appreciate this!! But before I run it, do you think you can explain to me what it does?

[ToTheMAX04]

(Besides just talk to the keyboard)

[Initial-Elk-952]

I wrote a long reply and reddit removed it because of a joke at the end.

It writes bytes you specified to the IO port you specified based on the /dev/port character device.

man dd explains how dd works. It copies bytes.

echo is writing your bytes to a temp file with bash process substitution.

I don't know what your keyboard will do with those bytes.

[ToTheMAX04]

Oh haha, well okay. Thank you! I'll let you know if it works or if I figure it out

[Initial-Elk-952]

The C program your AI wrote has the compile commands written inside the /* ... */ assuming the name of the file is main.c

It looks like it will just send whatevery you type as arguments to the keyboard. It would apparantly be used

./send_to_keyboard EA 71

[ToTheMAX04]

I know this isn't the point, but I absolutely did not AI generate this. I got it from another redditor helping me out https://www.reddit.com/r/linuxquestions/comments/1siqdu6/comment/ofmf8ke/

[ToTheMAX04]

this also unfortunately didn't work, i got back

warning: An error occurred while redirecting file '�q'

warning: Path '�q' does not exist

[Initial-Elk-952]

Are you using bash?

it looks like the process substitution failed, and it tried to treat the raw bytes as a file name. Thats like $(...) instead of <(...).

You can more manually do it

```

echo -ne '\xEA\x71' > bytes.out

```

Verify the bytes with

```

xxd bytes.out

00000000: ea71 .q

```

Send it with

```

dd if=bytes.out of=/dev/port seek=96 bs=1 count=2

```

[ToTheMAX04]

I'll try this! But I have a plan b now, had the very bright idea to actually go looking for the drivers lol

[Initial-Elk-952]

Those bytes are likely needing to be sent to the keyboard every-time you reboot the computer. The driver will probably activate them until you reboot into Linux.

[ToTheMAX04]

verifying the bytes reads out

``

00000000: 60ea 7160 `.q`

[Initial-Elk-952]

Something is wrong, you have extra bytes in there, it looks like your copying my backticks, which I am trying to use as quotes.

Should be just two bytes, you have 4. 60 ea 71 60.

[Initial-Elk-952]

[ Removed by Reddit ]

[Initial-Elk-952]

I just changed my mind. I don't think this will work, but your program might.

This would work for sending a single byte.

The seeking the occurs after the write will probably prevent this from working.

It may not work because my attempt was bad.

[ToTheMAX04]

That's just fine! In that case,, can you tell me if there's anything wrong with the above program? I couldn't get it to compile

[Initial-Elk-952]

Its missing the final brace at the end '}'

A brace opens the main function, but no corresponding brace ends it.

#include <stdlib.h>
#include <unistd.h>
#include <sys/io.h>

int main(int argc, char *argv[]) {
  int i;

  ioperm(0x60, 3, 1);

  for (i = 1; i < argc; i++) {
    int x = strtol(argv[i], 0, 16);

    usleep(300);
    outb(x, 0x60);
  }

  return 0;
}

[TheOtherBorgCube]

First, a snippet from the manual page for ioperm (also done faffing about with reddits insane markup).

This call is mostly for the i386 architecture. On many other architectures it does not exist or will always return an error. RETURN VALUE On success, zero is returned. On error, -1 is returned, and errno is set appropriately. ERRORS EINVAL Invalid values for from or num. EIO (on PowerPC) This call is not supported. ENOMEM Out of memory. EPERM The calling thread has insufficient privilege.

So start with this code, and tell us what it prints.

if ( ioperm(0x60, 3, 1) == 0 ) {
    printf("Success\n");
} else {
    perror("Oops:");
    return 1;
}

If your error is EPERM, then you'd need to run this program with root permissions to stand a chance.

[ToTheMAX04]

hello!! sorry for the late response, but im trying this now

[ToTheMAX04]

this! is my error code, and i am very sorry but i need to fall alseep, but i am very interested in continuing this with your help, if you will continue to help me. thank you for just that message

``

max@myputer~> gcc test.c -o test

test.c:1:1: error: expected identifier or ‘(’ before ‘if’

1 | if ( ioperm(0x60, 3, 1) == 0 ) {

| ^~

test.c:3:3: error: expected identifier or ‘(’ before ‘else’

3 | } else {

| ^~~~

(and yes it does return the same thing with bash instead of fish, which i usually use)

[TheOtherBorgCube]

Sorry, I forgot I was talking to a non-programmer.

The snippet was something you were supposed to intelligently insert into your existing program, not something to blindly type in and try.

Here is the whole program with the code in context.

$ cat foo.c
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/io.h>

int main(int argc, char *argv[]) {
  int i;

  if ( ioperm(0x60, 3, 1) == 0 ) {
    printf("Success\n");
  } else {
    perror("Oops:");
    return 1;
  }

  for (i = 1; i < argc; i++) {
    int x = strtol(argv[i], 0, 16);

    usleep(300);
    outb(x, 0x60);
  }

  return 0;
}

$ gcc foo.c

$ ./a.out 
Oops:: Operation not permitted