/**
 * @file
 *
 * @brief Shell login prompt functions.
 */

/*
 * Authorship
 * ----------
 * Parts of this software was created by
 *     Till Straumann <strauman@slac.stanford.edu>, 2003-2007
 *         Stanford Linear Accelerator Center, Stanford University.
 *                                                                 
 * Acknowledgement of sponsorship                                  
 * ------------------------------                                  
 * Parts of this software was produced by                                   
 *     the Stanford Linear Accelerator Center, Stanford University,
 *         under Contract DE-AC03-76SFO0515 with the Department of Energy.
 *                                                                        
 * Government disclaimer of liability                                     
 * ----------------------------------                                     
 * Neither the United States nor the United States Department of Energy,  
 * nor any of their employees, makes any warranty, express or implied, or 
 * assumes any legal liability or responsibility for the accuracy,        
 * completeness, or usefulness of any data, apparatus, product, or process
 * disclosed, or represents that its use would not infringe privately owned
 * rights.                                                                 
 *                                                                         
 * Stanford disclaimer of liability                                        
 * --------------------------------                                        
 * Stanford University makes no representations or warranties, express or  
 * implied, nor assumes any liability for the use of this software.        
 *                                                                         
 * Stanford disclaimer of copyright                                        
 * --------------------------------                                        
 * Stanford University, owner of the copyright, hereby disclaims its       
 * copyright and all other rights in this software.  Hence, anyone may     
 * freely use it for any purpose without restriction.                      
 *                                                                         
 * Maintenance of notices                                                  
 * ----------------------                                                  
 * In the interest of clarity regarding the origin and status of this      
 * SLAC software, this and all the preceding Stanford University notices   
 * are to remain affixed to any copy or derivative of this software made   
 * or distributed by the recipient and are to be affixed to any copy of    
 * software made or distributed by the recipient that contains a copy or   
 * derivative of this software.                                            
 *                                                                         
 * ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
 *
 * Copyright (c) 2009 embedded brains GmbH and others.
 *
 * embedded brains GmbH
 * Obere Lagerstr. 30
 * D-82178 Puchheim
 * Germany
 * <rtems@embedded-brains.de>
 *
 * Based on work from Chris Johns, Fernando Ruiz and Till Straumann.
 *
 * Derived from files "cpukit/libmisc/shell/shell.c" and
 * "cpukit/telnetd/check_passwd.c".
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rtems.com/license/LICENSE.
 */

#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <ctype.h>

#include <rtems/shell.h>

static int rtems_shell_discard( int c, FILE *stream)
{
  return c;
}

static void rtems_shell_get_text(
  FILE *in,
  FILE *out,
  char *line,
  size_t size
)
{
  int fd_in = fileno( in);
  int (*put)( int, FILE *) =
    out != NULL && isatty( fd_in)
      ? fputc
      : rtems_shell_discard;
  size_t i = 0;

  if (size < 1) {
    return;
  }

  tcdrain( fd_in);
  if (out != NULL){
    tcdrain( fileno( out));
  }

  while (true) {
    int c = fgetc( in);

    switch (c) {
      case EOF:
        /* Here comes an ugly hack: The Termios driver's read() handler returns
         * 0 to the C library's fgets() if it times out.  fgets() interprets
         * this (correctly) as EOF, a condition we want to undo since it's not
         * really true since we really have a read error (Termios bug?).
         *
         * As a workaround we push something back and read it again.  This
         * should simply reset the EOF condition.
         */
        if (ungetc( '?', in) == '?') {
          fgetc( in);
        }
        break;
      case '\n':
      case '\r':
        put( '\n', out);
        line [i] = '\0';
        return;
      case  127:
      case '\b':
        if (i > 0) {
          put( '\b', out);
          put( ' ', out);
          put( '\b', out);
          --i;
        } else {
          put( '\a', out);
        }
        break;
      default:
        if (!iscntrl( c)) {
          if (i < size - 1) {
            line [i] = (char) c;
            ++i;
            put( c, out);
          } else {
            put( '\a', out);
          }
        } else {
          put( '\a', out);
        }
        break;
    }
  }
}

bool rtems_shell_login_prompt(
  FILE *in,
  FILE *out,
  const char *device,
  rtems_shell_login_check_t check
)
{
  int fd_in = fileno( in);
  struct termios termios_previous;
  bool restore_termios = false;
  int i = 0;
  bool result = false;

  if (tcgetattr( fd_in, &termios_previous) == 0) {
    struct termios termios_new = termios_previous;

    termios_new.c_lflag &= (unsigned char) ~ECHO;
    termios_new.c_lflag &= (unsigned char) ~ICANON;
    termios_new.c_cc [VTIME] = 255;
    termios_new.c_cc [VMIN] = 0;

    restore_termios = tcsetattr( fd_in, TCSANOW, &termios_new) == 0;
  }

  for (i = 0; i < 3; ++i) {
    char user [32];
    char passphrase [128];

    fprintf( out, "%s login: ", device);
    fflush( out);
    rtems_shell_get_text( in, out, user, sizeof( user));

    fflush( in);
    fprintf( out, "Password: ");
    fflush( out);
    rtems_shell_get_text( in, NULL, passphrase, sizeof( passphrase));
    fputc( '\n', out);

    result = check( user, passphrase);
    if (result) {
      break;
    }

    fprintf( out, "Login incorrect\n\n");
    sleep( 2);
  }

  if (restore_termios) {
    /* What to do if restoring the flags fails? */
    tcsetattr( fd_in, TCSANOW, &termios_previous);
  }

  return result;
}