Re: [PATCH] remove TCGETS

On Tue, 28 Oct 2003, Andrew Sharp wrote:
> 
> Can't we add the range of tty ioctls to file_ioctl so that it can return
> ENOTTY so each and every file system driver doesn't have to?

Sure. But the filesystem has to return some error _anyway_ for the other 
ioctl's it doesn't understand. So what errno would you suggest?

ENOTTY is the one that is what a regular file returns to _all_ ioctl's it 
doesn't understand. That's really my point here. ENOTTY is always the 
right thing to return - and it has nothing to do with whether the ioctl 
number was for a TTY-specific ioctl or not.

Yeah, it's not a very well-named error, but if you actually look at what 
glibc prints out, it says

	ENOTTY: Inappropriate ioctl for device

and you can test with this extremely stupid program:

test.c:
	#include <fcntl.h>
	#include <unistd.h>
	#include <stdlib.h>

	int main(int argc, char **argv)
	{
		int i;
		int fd = open("test.c", O_RDONLY);

		srandom(time(NULL));
		for (i = 0; i < 100; i++) {
			ioctl(fd, random(), 0);
			perror("ioctl");
		}
	}

and verify for youself that it returns ENOTTY regardless of whether the 
ioctl number was a TTY-specific one or not.

So to re-iterate: ENOTTY is what everybody _always_ should return if they 
don't recognize a number. No "number ranges" involved.

		Linus

-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html