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Old 09-03-2009, 12:51 AM   #1
LQ Newbie
Registered: Aug 2009
Posts: 4

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Thumbs up Ignoring MODEM control commands on pty driver.

i am using the pty driver to communicate between 2 processes. on the master side i am creating a master pty and in the slave side, i am using the slave name to create the slave file descriptor.

On the master side i am trying the ioctl TIOCMGET comamnd for modem control, which is not valid for a pty driver. so i am getting the ioctl failure.

But is there any way, i can ignore the TIOCMGET call and return ioctl success.

Sample Code given below:

int devfd;
char slave[12];
int status = 0;

pid = forkpty(&devfd,slave,NULL,NULL);

status = grantpt(devfd);
if (status != -1)
status = unlockpt(devfd);

status = ioctl(devfd, TIOCMGET,&arg);
printf("ioctl21 TIOCMGET status =%d, errno = %d\n",status,errno);

--- Here i get the status as -1 and errno = 22 (EINVAL).

--- can anybode help me in getting this sattus as 0, for this pty. I dont want any modem commands, only i want the ioctl to succeed.

--Many thanks

Last edited by mrsq; 09-03-2009 at 12:52 AM. Reason: corrected TIOCMGET command!


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