/*

* openpty() tries to open a pty; applications won't have to

* duplicate this code all the time (or change it if the system

* pty interface changes).

*

* First version by Ben Gras <beng@few.vu.nl>,

* Initially heavily based on telnetd/pty.c

* by Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>.

*

*/

#include <libutil.h>

#include <termios.h>

#include <fcntl.h>

#include <grp.h>

#include <string.h>

#include <stdlib.h>

#include <errno.h>

#include <stdio.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/ioc_tty.h>

#define DEV_DIR "/dev"

/*

* Allocate a PTY, by trying to open one repeatedly.

*/

int openpty(int *amaster, int *aslave, char *name,

struct termios *termp, struct winsize *winp)

{

char buff[128], temp[128];

register int i, j;

int pty_fd = -1, gr;

static char tty_name[128];

struct group *ttygroup;

gid_t tty_gid = 0;

if(!amaster || !aslave) {

errno = EINVAL;

return -1;

}

for(i = 'p'; i < 'w'; i++) {

j = 0;

do {

sprintf(buff, "%s/pty%c%c",

DEV_DIR, i, (j < 10) ? j + '0' : j + 'a' - 10);

if((*amaster = open(buff, O_RDWR)) >= 0) {

sprintf(tty_name, "%s/tty%c%c", DEV_DIR,

i, (j < 10) ? j + '0' : j + 'a' - 10);

if((*aslave = open(tty_name, O_RDWR)) >= 0)

break;

}

close(*amaster);

j++;

if (j == 16) break;

} while(1);

/* Did we find one? */

if (j < 16) break;

}

if (*amaster < 0) { errno = ENOENT; return(-1); }

setgrent();

ttygroup = getgrnam("tty");

endgrent();

if(ttygroup) tty_gid = ttygroup->gr_gid;

if(name) strcpy(name, tty_name);

/* Ignore errors on these. */

chown(tty_name, getuid(), tty_gid);

chmod(tty_name, 0620); /* -rw--w---- */

if(termp) tcsetattr(*aslave, TCSAFLUSH, termp);

if(winp) ioctl(*aslave, TIOCSWINSZ, winp);

return(0);

}