Re: NSTask troubles
Re: NSTask troubles
- Subject: Re: NSTask troubles
- From: John Stiles <email@hidden>
- Date: Fri, 13 Jul 2007 10:38:59 -0700
On Jul 12, 2007, at 8:35 PM, Chris Suter wrote:
OK, I've nailed it, but what a pain in the ass! forkpty isn't
documented well anywhere that I could find (on the web at least).
I presume you looked at the man page for forkpty.
I sure did. As well as the man pages for forkpty for several other
Unices (thanks Google), and several tutorials which implement mini-
xterms on Linux.
But note that I said documented well. The man page is not much help
if you don't already understand pseudo-TTYs and termios perfectly.
And as I said before, I hadn't even heard of these things before
yesterday :(
And in its default state, the pseudo-TTY has all sorts of
undesirable behaviors like echoing, and \n becoming \r\n.
I was in the process of responding to your earlier post. I was
going to say that I think you've got confused about what slave FD
and master FD means. You should have set both stdin and stdout for
the task to the slave FD and then handled input and output to the
task via the master FD. To turn off the echo, passing in a zeroed
termios structure would probably suffice.
"Confused" isn't really the right word. I had no idea exactly how
slave and master were supposed to be related, because the docs simply
do not say. They say "there's a slave and a master" and then they
leave you to your own devices.
The following appears to work:
#include <Cocoa/Cocoa.h>
#include <stdlib.h>
#include <util.h>
#include <stdio.h>
#include <string.h>
#include <sys/errno.h>
#include <unistd.h>
@interface NSTask (PseudoTTY)
- (int)usePseudoTTY;
@end
@implementation NSTask (PseudoTTY)
- (int)usePseudoTTY
{
int masterFD, slaveFD;
struct termios t;
bzero (&t, sizeof (t));
if (openpty (&masterFD, &slaveFD, NULL, &t, NULL)) {
fprintf (stderr, "openpty failed %d: %s\n", errno, strerror
(errno));
return -1;
}
[self setStandardOutput:[[[NSFileHandle alloc]
initWithFileDescriptor:slaveFD] autorelease]];
[self setStandardInput:[[[NSFileHandle alloc]
initWithFileDescriptor:slaveFD] autorelease]];
return masterFD;
}
@end
int main (int argc __attribute__ ((__unused__)),
char *argv[] __attribute__ ((__unused__)))
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSTask *atosTask = [[NSTask alloc] init];
[atosTask setLaunchPath:@"/usr/bin/atos"];
[atosTask setArguments:[NSArray arrayWithObjects:
@"-o",
@"test-term",
NULL]];
int masterFD = [atosTask usePseudoTTY];
[atosTask launch];
assert (write (masterFD, "1234567890\n", 11) == 11);
char buffer[1024];
for (;;) {
ssize_t amount_read = read (masterFD, buffer, sizeof (buffer));
if (amount_read < 0) {
fprintf (stderr, "error %d %s", errno, strerror (errno));
return -1;
}
if (!amount_read)
return 0;
write (STDOUT_FILENO, buffer, amount_read);
}
[pool release];
// fail gracefully
return 0;
}
One thing you could do is create a pipe for input into your task
thus bypassing the terminal and avoiding any issues with echo. I'm
no expert on any of this so I might be wrong.
Cool, thanks for the info. Although I've already got it going with
forkpty and it seems solid so I'm hesitant to change anything :)
FWIW, rather than zeroing out the termios, maybe you want to use
cfmakeraw? I experimented with that for a bit but it wasn't helping
so I moved on…
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