12306 XPG4v2 slave pty behaviour should generally be disabled
Reviewed by: Robert Mustacchi <rm@fingolfin.org>
Change-ID: I7ccd399c22866f34dd20c6bb9d28e77ba4e24c67

*** 22,32 ****
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2013 DEY Storage Systems, Inc.
   * Copyright (c) 2014 Gary Mills
   * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
   * Copyright 2019 Joyent, Inc.
!  * Copyright 2019 OmniOS Community Edition (OmniOSce) Association.
   */
  
  /*
   * zlogin provides three types of login which allow users in the global
   * zone to access non-global zones.
--- 22,32 ----
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2013 DEY Storage Systems, Inc.
   * Copyright (c) 2014 Gary Mills
   * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
   * Copyright 2019 Joyent, Inc.
!  * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
   */
  
  /*
   * zlogin provides three types of login which allow users in the global
   * zone to access non-global zones.
*** 113,124 ****
  static int pollerr = 0;
  
  static const char *pname;
  static char *username;
  
- extern int __xpg4;      /* 0 if not an xpg4/6-compiled program */
- 
  /*
   * When forced_login is true, the user is not prompted
   * for an authentication password in the target zone.
   */
  static boolean_t forced_login = B_FALSE;
--- 113,122 ----
*** 768,787 ****
          char ibuf[ZLOGIN_BUFSIZ];
  
          cc = read(in_fd, ibuf, ZLOGIN_BUFSIZ);
          if (cc == -1 && (errno != EINTR || dead))
                  return (-1);
!         if (cc == 0) {
!                 /*
!                  * A return value of 0 when calling read() on a terminal
!                  * indicates end-of-file pre-XPG4 and no data available
!                  * for XPG4 and above.
!                  */
!                 if (__xpg4 == 0)
!                         return (-1);
!                 return (0);
!         }
          if (cc == -1)   /* The read was interrupted. */
                  return (0);
  
          do {
                  int len;
--- 766,777 ----
          char ibuf[ZLOGIN_BUFSIZ];
  
          cc = read(in_fd, ibuf, ZLOGIN_BUFSIZ);
          if (cc == -1 && (errno != EINTR || dead))
                  return (-1);
!         if (cc == 0)
!                 return (-1);    /* EOF */
          if (cc == -1)   /* The read was interrupted. */
                  return (0);
  
          do {
                  int len;