minix/lib/libminixutil/openpty.c

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2005-07-19 18:01:37 +02:00
/*
* 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];
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register int i, j;
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)
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break;
}
close(*amaster);
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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);
}