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#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/file.h>
#include <signal.h>
#include <stdio.h>
ptyopen(cmd, ifp, ofp)
char *cmd;
FILE **ifp, **ofp;
{
int i;
char *args[16];
register int tty;
long ldisc, lmode;
register char *s, *t;
struct sgttyb sgttyb;
struct tchars tchars;
struct ltchars ltchars;
char ttybuf[16], ptybuf[16];
/*
* Split up the arguments in the command
* into an argv-like structure.
*/
i = 0;
s = cmd;
while (*s) {
/*
* Skip white space.
*/
while ((*s == ' ') || (*s == '\t'))
*s++ = NULL;
args[i++] = s;
/*
* Skip over this word to next white space.
*/
while ((*s != NULL) && (*s != ' ') && (*s != '\t'))
s++;
}
args[i] = NULL;
/*
* Get a pseudo-tty. We do this by cycling through all
* the possible names. The operating system will not
* allow us to open a master which is already in use,
* so we simply go until the open succeeds.
*/
for (s = "pqrs"; *s != NULL; s++) {
for (t = "0123456789abcdef"; *t != NULL; t++) {
sprintf(ptybuf, "/dev/pty%c%c", *s, *t);
if ((tty = open(ptybuf, O_RDWR)) >= 0)
goto out;
}
}
out:
/*
* If s and t are NULL, we ran out of pseudo ttys
* before we found one we can use.
*/
if ((*s == NULL) && (*t == NULL))
return(-1);
/*
* Change "ptyXX" (master) to "ttyXX" (slave).
*/
strcpy(ttybuf, ptybuf);
ttybuf[5] = 't';
/*
* Get the modes of the current terminal. We
* will duplicate these on the pseudo terminal.
*/
ioctl(0, TIOCGETD, &ldisc);
ioctl(0, TIOCLGET, &lmode);
ioctl(0, TIOCGETP, &sgttyb);
ioctl(0, TIOCGETC, &tchars);
ioctl(0, TIOCGLTC, <chars);
/*
* Fork a child process.
*/
if ((i = fork()) < 0) {
close(tty);
return(-1);
}
/*
* In the child...
*/
if (i == 0) {
/*
* Close all open files.
*/
for (i = 0; i < NOFILE; i++)
close(i);
/*
* Clear the controlling tty. This means
* that we will not have a controlling
* tty until we open another terminal
* device.
*/
if ((i = open("/dev/tty", O_RDWR)) >= 0) {
ioctl(i, TIOCNOTTY, 0);
close(i);
}
/*
* Make our controlling tty the pseudo tty.
* This happens because we cleared our
* original controlling terminal above.
*/
i = open(ttybuf, O_RDWR);
/*
* Set stdin, stdout, and stderr to be the
* pseudo terminal.
*/
dup2(i, 0);
dup2(i, 1);
dup2(i, 2);
/*
* Set the pseudo terminal's tty modes to
* those of the original terminal. We
* turn off ECHO and CBREAK modes, since
* we don't want characters "typed" to be
* printed.
*/
sgttyb.sg_flags &= ~ECHO;
sgttyb.sg_flags &= ~CRMOD;
ioctl(0, TIOCSETD, &ldisc);
ioctl(0, TIOCLGET, &lmode);
ioctl(0, TIOCSETP, &sgttyb);
ioctl(0, TIOCSETC, &tchars);
ioctl(0, TIOCSLTC, <chars);
/*
* Set the process group of the process
* to be the process group of the
* terminal.
*/
ioctl(0, TIOCGPGRP, &i);
setpgrp(0, i);
/*
* Now change the process group of the
* terminal and process to be the
* process id; this takes them out
* of the calling process's process
* group.
*/
i = getpid();
ioctl(0, TIOCSPGRP, &i);
setpgrp(0, i);
/*
* Execute the program.
*/
execv(*args, args);
exit(1);
}
/*
* Set up the input and output file pointers
* so that they can write and read the pseudo
* terminal.
*/
*ifp = fdopen(tty, "w");
*ofp = fdopen(tty, "r");
return(0);
}
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