[MiNT] read() and signals

[Vincent Rivière <vincent.riviere@freesbee.fr>]

Alan Hourihane wrote:
> > The Ctrl+C keystroke requires to press Enter to do its job, it may be related.
> > Alan, by chance, have you investigated this issue ?
>
> I've seen the same problem, but not investigated yet.

I had a look at it, and I think I have found the cause of the bash problem.
Basically, the read() function should fail with EINTR when a signal is 
caught, but in MiNT it continues blocking.

The attached program is a very simple testcase.

On Linux and Cygwin, I get:
$ ./mysig
Please type ^C
^CSIGINT!
ret = -1, errno = 4, msg = Interrupted system call

But on MiNT, I can type ^C several times, it does not exit:
$ ./mysig
Please type ^C
SIGINT!
SIGINT!
SIGINT!
SIGINT!

However it exits if I type a standard key, of course.

I don't know if the problem comes from the kernel or the MiNTLib.

--
Vincent Rivière

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

void myhandler(int sig)
{
	puts("SIGINT!");
}

int main(void)
{
	struct sigaction act, oact;
	int ret;
	unsigned char c;

	act.sa_handler = myhandler;
	act.sa_flags = 0;
	sigemptyset (&act.sa_mask);
	sigemptyset (&oact.sa_mask);
	sigaction (SIGINT, &act, &oact);
	
	puts("Please type ^C");
	errno = 0;
	ret = read (0, &c, sizeof c);
	printf("ret = %d, errno = %d, msg = %s\n", ret, errno, strerror(errno));
	
	return 0;
}