[comp.unix.sysv386] How to execute 'sz' and 'rc' ?

nyse@nicedel.north.de (Hermann Behrens) (04/30/91)

Hello.
I have problems to execute an external protocoll, in this case zmodem.
I open the device, let the programm call a mailbox(up to this point no
problems), but when i have to execute the sz, i get errors :-(

this is my routine to start sz:

int	zm_upload()
{
	int	pid, status;

	chdir("/somewhere");
	if((pid = fork()) == 0)  {
		close(fp);
		close(0);
		open("/dev/ttyF00", O_RDONLY | O_NDELAY);

		close(1);
		open("/dev/ttyF00", O_WRONLY | O_NDELAY);

/* I think, that the bug is in the redirecting of stdin and stdout,
but where is the bug?? */

		execl("/bin/sh", "sh", "-c", "sz a_file",NULL);
	}
	else
		wait(&status);
}

int	zm_download()
{
	int	pid, status;

	chdir("/somewhere");
	if((pid = fork()) == 0) {
		close(fp);
		close(0);
		open("/dev/ttyF00", O_RDONLY | O_NDELAY);

		close(1);
		open("/dev/ttyF00", O_RDONLY | O_NDELAY);

		execl("/bin/sh", "sh", "-c", "rz", NULL);
	}
	else
		wait(&status);
}

It would be great, if someone could help me ...

ciao, Hermann Behrens
-- 
Hermann Behrens|Bremerstr. 323|2870 Delmenhorst|04221/71931(DATA)71932(VOICE)

les@chinet.chi.il.us (Leslie Mikesell) (05/01/91)

In article <1991Apr29.221812.5038@nicedel.north.de> nyse@nicedel.north.de (Hermann Behrens) writes:
>	if((pid = fork()) == 0)  {
>		close(fp);
>		close(0);
>		open("/dev/ttyF00", O_RDONLY | O_NDELAY);
>		close(1);
>		open("/dev/ttyF00", O_WRONLY | O_NDELAY);
>/* I think, that the bug is in the redirecting of stdin and stdout,
>but where is the bug?? */
>		execl("/bin/sh", "sh", "-c", "sz a_file",NULL);

On the machines I use, leaving O_NDELAY set will cause very strange
things to happen when you try to write to a device and reads will
complete when no data is present.  I'd suggest leaving out the
O_NDELAY on the open if you have reason to expect that carrier
is already up (but you might want to set an alarm to bail you out
just in case).  Or, use fcntl() to turn it off after the open before
you let another program try to access the line.

Les Mikesell
  les@chinet.chi.il.us