pty.c

/*

pty.c

Author: Tatu Ylonen <ylo@cs.hut.fi>

Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                   All rights reserved

Created: Fri Mar 17 04:37:25 1995 ylo

Allocating a pseudo-terminal, and making it the controlling tty.

*/

#include "includes.h"
RCSID("$Id: pty.c,v 1.2 1999/11/08 04:30:59 damien Exp $");

#ifdef HAVE_PTY_H
/* Unfortunate namespace collision */
#include <pty.h>
#endif /* HAVE_PTY_H */

#include "pty.h"
#include "ssh.h"

/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
#undef HAVE_DEV_PTMX
#endif

#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif

/* Allocates and opens a pty.  Returns 0 if no pty could be allocated,
   or nonzero if a pty was successfully allocated.  On success, open file
   descriptors for the pty and tty sides and the name of the tty side are 
   returned (the buffer must be able to hold at least 64 characters). */

int pty_allocate(int *ptyfd, int *ttyfd, char *namebuf)
{
#ifdef HAVE_OPENPTY

  /* openpty(3) exists in OSF/1 and some other os'es */

  int i;

  i = openpty(ptyfd, ttyfd, namebuf, NULL, NULL);

  if (i < 0) 
    {
      error("openpty: %.100s", strerror(errno));
      return 0;
    }
  
  return 1;

#else /* HAVE_OPENPTY */
#ifdef HAVE__GETPTY

  /* _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
     pty's automagically when needed */

  char *slave;

  slave = _getpty(ptyfd, O_RDWR, 0622, 0);
  if (slave == NULL)
    {
      error("_getpty: %.100s", strerror(errno));
      return 0;
    }
  strcpy(namebuf, slave);
  /* Open the slave side. */
  *ttyfd = open(namebuf, O_RDWR|O_NOCTTY);
  if (*ttyfd < 0)
    {
      error("%.200s: %.100s", namebuf, strerror(errno));
      close(*ptyfd);
      return 0;
    }
  return 1;

#else /* HAVE__GETPTY */
#ifdef HAVE_DEV_PTMX
  /* This code is used e.g. on Solaris 2.x.  (Note that Solaris 2.3 also has
     bsd-style ptys, but they simply do not work.) */

  int ptm;
  char *pts;
  
  ptm = open("/dev/ptmx", O_RDWR|O_NOCTTY);
  if (ptm < 0)
    {
      error("/dev/ptmx: %.100s", strerror(errno));
      return 0;
    }
  if (grantpt(ptm) < 0)
    {
      error("grantpt: %.100s", strerror(errno));
      return 0;
    }
  if (unlockpt(ptm) < 0)
    {
      error("unlockpt: %.100s", strerror(errno));
      return 0;
    }
  pts = ptsname(ptm);
  if (pts == NULL)
    error("Slave pty side name could not be obtained.");
  strcpy(namebuf, pts);
  *ptyfd = ptm;

  /* Open the slave side. */
  *ttyfd = open(namebuf, O_RDWR|O_NOCTTY);
  if (*ttyfd < 0)
    {
      error("%.100s: %.100s", namebuf, strerror(errno));
      close(*ptyfd);
      return 0;
    }
  /* Push the appropriate streams modules, as described in Solaris pts(7). */
  if (ioctl(*ttyfd, I_PUSH, "ptem") < 0)
    error("ioctl I_PUSH ptem: %.100s", strerror(errno));
  if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0)
    error("ioctl I_PUSH ldterm: %.100s", strerror(errno));
  if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0)
    error("ioctl I_PUSH ttcompat: %.100s", strerror(errno));
  return 1;

#else /* HAVE_DEV_PTMX */
#ifdef HAVE_DEV_PTS_AND_PTC

  /* AIX-style pty code. */

  const char *name;

  *ptyfd = open("/dev/ptc", O_RDWR|O_NOCTTY);
  if (*ptyfd < 0)
    {
      error("Could not open /dev/ptc: %.100s", strerror(errno));
      return 0;
    }
  name = ttyname(*ptyfd);
  if (!name)
    fatal("Open of /dev/ptc returns device for which ttyname fails.");
  strcpy(namebuf, name);
  *ttyfd = open(name, O_RDWR|O_NOCTTY);
  if (*ttyfd < 0)
    {
      error("Could not open pty slave side %.100s: %.100s", 
	    name, strerror(errno));
      close(*ptyfd);
      return 0;
    }
  return 1;

#else /* HAVE_DEV_PTS_AND_PTC */
  /* BSD-style pty code. */

  char buf[64];
  int i;
  const char *ptymajors = 
    "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
  const char *ptyminors = "0123456789abcdef";
  int num_minors = strlen(ptyminors);
  int num_ptys = strlen(ptymajors) * num_minors;

  for (i = 0; i < num_ptys; i++)
    {
      snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors], 
	      ptyminors[i % num_minors]);
      *ptyfd = open(buf, O_RDWR|O_NOCTTY);
      if (*ptyfd < 0)
	continue;
      snprintf(namebuf, sizeof buf, "/dev/tty%c%c", ptymajors[i / num_minors], 
	      ptyminors[i % num_minors]);

      /* Open the slave side. */
      *ttyfd = open(namebuf, O_RDWR|O_NOCTTY);
      if (*ttyfd < 0)
	{
	  error("%.100s: %.100s", namebuf, strerror(errno));
	  close(*ptyfd);
	  return 0;
	}
      return 1;
    }
  return 0;
#endif /* HAVE_DEV_PTS_AND_PTC */
#endif /* HAVE_DEV_PTMX */
#endif /* HAVE__GETPTY */
#endif /* HAVE_OPENPTY */
}

/* Releases the tty.  Its ownership is returned to root, and permissions to
   0666. */

void pty_release(const char *ttyname)
{
  if (chown(ttyname, (uid_t)0, (gid_t)0) < 0)
    debug("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno));
  if (chmod(ttyname, (mode_t)0666) < 0)
    debug("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno));
}

/* Makes the tty the processes controlling tty and sets it to sane modes. */

void pty_make_controlling_tty(int *ttyfd, const char *ttyname)
{
  int fd;

  /* First disconnect from the old controlling tty. */
#ifdef TIOCNOTTY
  fd = open("/dev/tty", O_RDWR|O_NOCTTY);
  if (fd >= 0)
    {
      (void)ioctl(fd, TIOCNOTTY, NULL);
      close(fd);
    }
#endif /* TIOCNOTTY */
  if (setsid() < 0)
    error("setsid: %.100s", strerror(errno));
  
  /* Verify that we are successfully disconnected from the controlling tty. */
  fd = open("/dev/tty", O_RDWR|O_NOCTTY);
  if (fd >= 0)
    {
      error("Failed to disconnect from controlling tty.");
      close(fd);
    }

  /* Make it our controlling tty. */
#ifdef TIOCSCTTY
  debug("Setting controlling tty using TIOCSCTTY.");
  /* We ignore errors from this, because HPSUX defines TIOCSCTTY, but returns
     EINVAL with these arguments, and there is absolutely no documentation. */
  ioctl(*ttyfd, TIOCSCTTY, NULL);
#endif /* TIOCSCTTY */
  fd = open(ttyname, O_RDWR);
  if (fd < 0)
    error("%.100s: %.100s", ttyname, strerror(errno));
  else
    close(fd);

  /* Verify that we now have a controlling tty. */
  fd = open("/dev/tty", O_WRONLY);
  if (fd < 0)
    error("open /dev/tty failed - could not set controlling tty: %.100s",
	  strerror(errno));
  else
    {
      close(fd);
    }
}

/* Changes the window size associated with the pty. */

void pty_change_window_size(int ptyfd, int row, int col,
			    int xpixel, int ypixel)
{
  struct winsize w;
  w.ws_row = row;
  w.ws_col = col;
  w.ws_xpixel = xpixel;  
  w.ws_ypixel = ypixel;
  (void)ioctl(ptyfd, TIOCSWINSZ, &w);
}