/* $Id: fallback.c,v 8.2 2010/02/11 20:54:49 ksb Exp $
 *
 * This is a fake library interface to ptyd			    (mtr&ksb)
 *
 * Mike Rowan (mtr@mace.cc.purdue.edu), KS Braunsdorf (at npcguild.org)
 */
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <sys/un.h>
#include <syslog.h>
#include <signal.h>
#include <netdb.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>

#include "cons.h"
#include "machine.h"

#if NEED_UNISTD_H
#include <unistd.h>
#endif

#if USE_STRINGS
#include <strings.h>
#else
#include <string.h>
#endif

#if DO_VIRTUAL && ! HAVE_PTYD

extern int errno;
#if !HAVE_STRERROR
extern char *sys_errlist[], *strchr();
#define strerror(Me) (sys_errlist[Me])
#endif


/* Below is the string for finding /dev/ptyXX.  For each architecture we
 * leave some pty's world writable because we don't have source for
 * everything that uses pty's.  For the most part, we'll be trying to
 * make /dev/ptyq* the "free" pty's.
 */
#if defined(sun)
static char charone[] =
	"prstuvwxyzPQRSTUVWq";
#else
#if defined(dynix)
static char charone[] =
	"prstuvwxyzPQRSTUVWq";
#else
#if defined(ultrix)
static char charone[] =
	"prstuvwxyzPQRSTUVWq";
#else
/* all the world's a vax ;-) */
static char charone[] =
	"prstuvwxyzPQRSTUVWq";
#endif
#endif
#endif

static char chartwo[] =
	"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

#if (defined(_AIX) || defined(PTX4))
static char acMaster[] =
	"/dev/ptc/XXXXXXXXX";
static char acSlave[] =
	"/dev/pts/XXXXXXXXX";
#else
static char acMaster[] =
	"/dev/ptyXX";
static char acSlave[] =
	"/dev/ttyXX";
#endif /* _AIX */

#if !HAVE_GETPSEUDO
#ifdef _AIX
/* get a pty for the user (emulate the neato sequent call)		(mm)
 */
static int
getpseudotty(slave, master)
char **master, **slave;
{
	int fd;
	char *pcName, *pcTmp;

	if (0 > (fd = open("/dev/ptc", O_RDWR|O_NDELAY, 0))) {
		return -1;
	}
	if ((char *)0 == (pcName = ttyname(fd))) {
		return -1;
	}
	(void)strcpy(acSlave, pcName);
	*slave = acSlave;

	(void)strcpy(acMaster, pcName);
	acMaster[7] = 'c';
	*master = acMaster;

	return fd;
}

#else
#if  HAVE_PTSNAME

/* get a pty for the user -- emulate the neato sequent call under	(gregf)
 * DYNIX/ptx v4.0
 */
static int
getpseudotty(slave, master)
char **master, **slave;
{
	register int fd;
	register char *pcName;
	extern char *ptsname(int);

	if (-1 != (fd = open("/dev/ptmx", O_RDWR, 0)) || 0 != grantpt(fd) || 0 != unlockpt(fd)) {
		fprintf(stderr, "%s: ptmx: %s\n", progname, strerror(errno));
		close(fd);
		return -1;
	}
#if HAVE_MASTER_PTY
	if ((char *)0 == (pcName = ttyname(fd))) {
		close(fd);
		return -1;
	}
	(void)strcpy(acMaster, pcName);
#else
	(void)strcpy(acMaster, "/dev/null");
#endif
	*master = acMaster;

	if ((char *) 0 == (pcName = ptsname(fd))) {
		close(fd);
		return -1;
	}

	(void)strcpy(acSlave, pcName);
	*slave = acSlave;

	return fd;
}

#else
/* get a pty for the user (emulate the neato sequent call)		(ksb)
 */
static int
getpseudotty(slave, master)
char **master, **slave;
{
	static char *pcOne = charone, *pcTwo = chartwo;
	auto int fd, iLoop, iIndex = sizeof("/dev/pty")-1;
	auto char *pcOld1;
	auto struct stat statBuf;

	iLoop = 0;
	pcOld1 = pcOne;
	for (;;) {
		if ('\000' == *++pcTwo) {
			pcTwo = chartwo;
			if ('\000' == *++pcOne) {
				pcOne = charone;
				/* XXX 32 is the magic size of a tty slot in
				 * old-school BSD unix -- ksb
				 */
				if ((pcOld1 == pcOne && ++iLoop > 1) || iLoop > 32)
					return -1;
			}
		}
		acMaster[iIndex] = *pcOne;
		acMaster[iIndex+1] = *pcTwo;

		/* Remeber we are root - stat the file
		 * to see if it exists before we open it
		 * for read/write - if it doesn't we don't
		 * have any pty's left in the row
		 */
		if (-1 == stat(acMaster, &statBuf) || S_IFCHR != (statBuf.st_mode&S_IFMT)) {
			pcTwo = "l";
			continue;
		}

		if (0 > (fd = open(acMaster, O_RDWR|O_NDELAY, 0))) {
			continue;
		}
		acSlave[iIndex] = *pcOne;
		acSlave[iIndex+1] = *pcTwo;
		if (-1 == access(acSlave, F_OK)) {
			(void) close(fd);
			continue;
		}
		break;
	}
	*master = acMaster;
	*slave = acSlave;
	return fd;
}
#endif /* PTX version */
#endif /* _AIX */
#endif /* !HAVE_GETPSEUDO */

/* get a Joe pty bacause the daemon is not with us, sadly.		(ksb)
 */
int
FallBack(pcSlave, pcMaster)
char *pcSlave, *pcMaster;
{
	extern char *ptsname(int);
	auto int fd;
	auto char *pcTSlave, *pcTMaster;

	if (-1 != (fd = open("/dev/ptmx", O_RDWR, 0666))) {
		if (0 == grantpt(fd) && 0 == unlockpt(fd)) {
			strcpy(pcSlave, ptsname(fd));
			strcpy(pcMaster, "PTMX");
			return fd;
		}
		close(fd);	/* try the old way */
	}
	if (-1 == (fd = getpseudotty(& pcTSlave, & pcTMaster))) {
		return -1;
	}
	(void) strcpy(pcSlave, pcTSlave);
	(void) strcpy(pcMaster, pcTMaster);
	return fd;
}

#endif /* no code if it is not used */