Hi Peter,
On Tue, Feb 17, 2015 at 05:35:10PM -0500, Peter Hurley wrote:
> I realize that. But hanging up the tty that is /dev/console only affects
> open descriptors that are not /dev/console.
>
> So readers using the /dev/ttyS0 file descriptor will see a hungup fops,
> but readers using /dev/console will not, and /dev/ttyS0 will _not_
> be closed or released because of the still-open descriptor on /dev/console.
I see.
> Ok, so the process sleeping on /dev/console read() should have received
> SIGHUP, which would wake the process and cause it to exit the
> n_tty_read() loop, thus dropping the ldisc reference it holds.
> Did it ignore the signal or perhaps the signal is masked?
Not masked on the test case (attached). Sent sighup manually and it did
receive it.
--
Aristeu
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <sys/ioctl.h>
static char *default_console = "/dev/console";
static char *default_tty = "/dev/ttyS0";
struct data {
char *console;
char *tty;
};
static void *reader(void *d)
{
struct data *data = (struct data *)d;
struct termios old_termio;
char buff[512];
int fd = -1, rc;
while (1) {
if (fd == -1) {
fd = open(data->console, O_RDWR);
if (fd < 0)
exit(1);
if (tcgetattr(fd, &old_termio) == -1)
exit(1);
old_termio.c_lflag = ICANON;
if (tcsetattr(fd, 0, &old_termio) == -1)
exit(1);
}
rc = read(fd, buff, sizeof(buff));
if (rc < 0 && errno == EAGAIN)
continue;
close(fd);
fd = -1;
}
}
void launch(void *(*fn)(void *), struct data *data)
{
if (fork() == 0)
fn(data);
}
int main(int argc, char *argv[])
{
struct data data;
int fd;
fd = open("/dev/ttyS0", O_RDWR);
close(0);
close(1);
close(2);
ioctl(fd, TIOCSCTTY, 1);
data.console = default_console;
data.tty = default_tty;
launch(reader, &data);
waitpid(-1, NULL, 0);
return 0;
}
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