/*  GNU ed - The GNU line editor.

    Copyright (C) 1993, 1994 Andrew Moore, Talke Studio

    Copyright (C) 2006-2017 Antonio Diaz Diaz.

    This program is free software: you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation, either version 2 of the License, or

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include <ctype.h>

#include <setjmp.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "ed.h"

enum Status { QUIT = -1, ERR = -2, EMOD = -3, FATAL = -4 };

static char def_filename[1024] = "";	/* default filename */

static char errmsg[80] = "";		/* error message buffer */

static char prompt_str[80] = "*";	/* command prompt */

static int first_addr = 0, second_addr = 0;

static bool prompt_on = false;		/* if set, show command prompt */

static bool verbose = false;		/* if set, print all error messages */

void set_def_filename( const char * const s )

  {

  strncpy( def_filename, s, sizeof def_filename );

  def_filename[sizeof(def_filename)-1] = 0;

  }

void set_error_msg( const char * msg )

  {

  if( !msg ) msg = "";

  strncpy( errmsg, msg, sizeof errmsg );

  errmsg[sizeof(errmsg)-1] = 0;

  }

void set_prompt( const char * const s )

  {

  prompt_on = true;

  strncpy( prompt_str, s, sizeof prompt_str );

  prompt_str[sizeof(prompt_str)-1] = 0;

  }

void set_verbose( void ) { verbose = true; }

static const line_t * mark[26];			/* line markers */

static int markno;				/* line marker count */

static bool mark_line_node( const line_t * const lp, int c )

  {

  c -= 'a';

  if( c < 0 || c >= 26 )

    { set_error_msg( "Invalid mark character" ); return false; }

  if( !mark[c] ) ++markno;

  mark[c] = lp;

  return true;

  }

void unmark_line_node( const line_t * const lp )

  {

  int i;

  for( i = 0; markno && i < 26; ++i )

    if( mark[i] == lp )

      { mark[i] = 0; --markno; }

  }

/* return address of a marked line */

static int get_marked_node_addr( int c )

  {

  c -= 'a';

  if( c < 0 || c >= 26 )

    { set_error_msg( "Invalid mark character" ); return -1; }

  return get_line_node_addr( mark[c] );

  }

/* Returns pointer to copy of shell command in the command buffer */

static const char * get_shell_command( const char ** const ibufpp )

  {

  static char * buf = 0;		/* temporary buffer */

  static int bufsz = 0;

  static char * shcmd = 0;		/* shell command buffer */

  static int shcmdsz = 0;		/* shell command buffer size */

  static int shcmdlen = 0;		/* shell command length */

  int i = 0, len = 0;

  bool replacement = false;

  if( restricted() ) { set_error_msg( "Shell access restricted" ); return 0; }

  if( !get_extended_line( ibufpp, &len, true ) ) return 0;

  if( !resize_buffer( &buf, &bufsz, len + 1 ) ) return 0;

  if( **ibufpp != '!' ) buf[i++] = '!';		/* prefix command w/ bang */

  else

    {

    if( shcmdlen <= 0 || ( traditional() && !shcmd[1] ) )

      { set_error_msg( "No previous command" ); return 0; }

    memcpy( buf, shcmd, shcmdlen );		/* bufsz >= shcmdlen */

    i += shcmdlen; ++*ibufpp; replacement = true;

    }

  while( **ibufpp != '\n' )

    {

    if( **ibufpp == '%' )

      {

      const char * p;

      if( !def_filename[0] )

        { set_error_msg( "No current filename" ); return 0; }

      p = strip_escapes( def_filename );

      len = strlen( p );

      if( !resize_buffer( &buf, &bufsz, i + len ) ) return 0;

      memcpy( buf + i, p, len );

      i += len; ++*ibufpp; replacement = true;

      }

    else

      {

      if( !resize_buffer( &buf, &bufsz, i + 2 ) ) return 0;

      if( ( buf[i++] = *(*ibufpp)++ ) == '\\' ) buf[i++] = *(*ibufpp)++;

      }

    }

  while( **ibufpp == '\n' ) ++*ibufpp;			/* skip newline */

  if( !resize_buffer( &shcmd, &shcmdsz, i + 1 ) ) return 0;

  memcpy( shcmd, buf, i );

  shcmd[i] = 0; shcmdlen = i;

  if( replacement ) printf( "%s\n", shcmd + 1 );

  return shcmd;

  }

static const char * skip_blanks( const char * p )

  {

  while( isspace( (unsigned char)*p ) && *p != '\n' ) ++p;

  return p;

  }

/* Returns pointer to copy of filename in the command buffer */

static const char * get_filename( const char ** const ibufpp,

                                  const bool traditional_f_command )

  {

  static char * buf = 0;

  static int bufsz = 0;

  const int pmax = path_max( 0 );

  int n;

  *ibufpp = skip_blanks( *ibufpp );

  if( **ibufpp != '\n' )

    {

    int size = 0;

    if( !get_extended_line( ibufpp, &size, true ) ) return 0;

    if( **ibufpp == '!' )

      { ++*ibufpp; return get_shell_command( ibufpp ); }

    else if( size > pmax )

      { set_error_msg( "Filename too long" ); return 0; }

    }

  else if( !traditional_f_command && !def_filename[0] )

    { set_error_msg( "No current filename" ); return 0; }

  if( !resize_buffer( &buf, &bufsz, pmax + 1 ) ) return 0;

  for( n = 0; **ibufpp != '\n'; ++n, ++*ibufpp ) buf[n] = **ibufpp;

  buf[n] = 0;

  while( **ibufpp == '\n' ) ++*ibufpp;			/* skip newline */

  return ( may_access_filename( buf ) ? buf : 0 );

  }

static void invalid_address( void ) { set_error_msg( "Invalid address" ); }

/* Get line addresses from the command buffer until an invalid address

   is seen. Returns the number of addresses read, or -1 if error.

   If no addresses are found, both addresses are set to the current address.

   If one address is found, both addresses are set to that address. */

static int extract_addresses( const char ** const ibufpp )

  {

  bool first = true;			/* true == addr, false == offset */

  first_addr = second_addr = -1;	/* set to undefined */

  *ibufpp = skip_blanks( *ibufpp );

  while( true )

    {

    int n;

    const unsigned char ch = **ibufpp;

    if( isdigit( ch ) )

      {

      if( !parse_int( &n, *ibufpp, ibufpp ) ) return -1;

      if( first ) { first = false; second_addr = n; } else second_addr += n;

      }

    else switch( ch )

      {

      case '\t':

      case ' ': *ibufpp = skip_blanks( ++*ibufpp ); break;

      case '+':

      case '-': if( first ) { first = false; second_addr = current_addr(); }

                if( isdigit( (unsigned char)(*ibufpp)[1] ) )

                  {

                  if( !parse_int( &n, *ibufpp, ibufpp ) ) return -1;

                  second_addr += n;

                  }

                else { ++*ibufpp;

                       if( ch == '+' ) ++second_addr; else --second_addr; }

                break;

      case '.':

      case '$': if( !first ) { invalid_address(); return -1; };

                first = false; ++*ibufpp;

                second_addr = ( ( ch == '.' ) ? current_addr() : last_addr() );

                break;

      case '/':

      case '?': if( !first ) { invalid_address(); return -1; };

                second_addr = next_matching_node_addr( ibufpp, ch == '/' );

                if( second_addr < 0 ) return -1;

                if( ch == **ibufpp ) ++*ibufpp;		/* remove delimiter */

                first = false; break;

      case '\'':if( !first ) { invalid_address(); return -1; };

                first = false; ++*ibufpp;

                second_addr = get_marked_node_addr( *(*ibufpp)++ );

                if( second_addr < 0 ) return -1;

                break;

      case '%':

      case ',':

      case ';': if( first )

                  {

                  if( first_addr < 0 )

                    { first_addr = ( ( ch == ';' ) ? current_addr() : 1 );

                      second_addr = last_addr(); }

                  }

                else

                  {

                  if( second_addr < 0 || second_addr > last_addr() )

                    { invalid_address(); return -1; }

                  if( ch == ';' ) set_current_addr( second_addr );

                  first_addr = second_addr; first = true;

                  }

                ++*ibufpp;

                break;

      default :

        if( !first && ( second_addr < 0 || second_addr > last_addr() ) )

          { invalid_address(); return -1; }

        {

        int addr_cnt = 0;			/* limited to 2 */

        if( second_addr >= 0 ) addr_cnt = ( first_addr >= 0 ) ? 2 : 1;

        if( addr_cnt <= 0 ) second_addr = current_addr();

        if( addr_cnt <= 1 ) first_addr = second_addr;

        return addr_cnt;

        }

      }

    }

  }

/* get a valid address from the command buffer */

static bool get_third_addr( const char ** const ibufpp, int * const addr )

  {

  const int old1 = first_addr;

  const int old2 = second_addr;

  int addr_cnt = extract_addresses( ibufpp );

  if( addr_cnt < 0 ) return false;

  if( traditional() && addr_cnt == 0 )

    { set_error_msg( "Destination expected" ); return false; }

  if( second_addr < 0 || second_addr > last_addr() )

    { invalid_address(); return false; }

  *addr = second_addr;

  first_addr = old1; second_addr = old2;

  return true;

  }

/* set default range and return true if address range is valid */

static bool check_addr_range( const int n, const int m, const int addr_cnt )

  {

  if( addr_cnt == 0 ) { first_addr = n; second_addr = m; }

  if( first_addr < 1 || first_addr > second_addr || second_addr > last_addr() )

    { invalid_address(); return false; }

  return true;

  }

/* set defaults to current_addr and return true if address range is valid */

static bool check_addr_range2( const int addr_cnt )

  {

  return check_addr_range( current_addr(), current_addr(), addr_cnt );

  }

/* set default second_addr and return true if second_addr is valid */

static bool check_second_addr( const int addr, const int addr_cnt )

  {

  if( addr_cnt == 0 ) second_addr = addr;

  if( second_addr < 1 || second_addr > last_addr() )

    { invalid_address(); return false; }

  return true;

  }

/* verify the command suffixes in the command buffer */

static bool get_command_suffix( const char ** const ibufpp,

                                int * const pflagsp, int * const snump )

  {

  bool nos_or_rep = !snump;	/* not s command or repeated g/count */

  bool error = false;

  while( true )

    {

    const unsigned char ch = **ibufpp;

    if( ch >= '1' && ch <= '9' )

      {

      int n = 0;

      if( nos_or_rep || !parse_int( &n, *ibufpp, ibufpp ) || n <= 0 )

        { error = true; break; }

      nos_or_rep = true; *snump = n; continue;

      }

    else if( ch == 'g' )

      { if( nos_or_rep ) break; else { nos_or_rep = true; *snump = 0; } }

    else if( ch == 'l' ) { if( *pflagsp & GLS ) break; else *pflagsp |= GLS; }

    else if( ch == 'n' ) { if( *pflagsp & GNP ) break; else *pflagsp |= GNP; }

    else if( ch == 'p' ) { if( *pflagsp & GPR ) break; else *pflagsp |= GPR; }

    else break;

    ++*ibufpp;

    }

  if( error || *(*ibufpp)++ != '\n' )

    { set_error_msg( "Invalid command suffix" ); return false; }

  return true;

  }

static bool unexpected_address( const int addr_cnt )

  {

  if( addr_cnt > 0 ) { set_error_msg( "Unexpected address" ); return true; }

  return false;

  }

static bool unexpected_command_suffix( const unsigned char ch )

  {

  if( !isspace( ch ) )

    { set_error_msg( "Unexpected command suffix" ); return true; }

  return false;

  }

static bool command_s( const char ** const ibufpp, int * const pflagsp,

                       const int addr_cnt, const bool isglobal )

  {

  static int pflags = 0;	/* print suffixes */

  static int gmask = GPR;	/* the print suffixes to be toggled */

  static int snum = 1;	/* > 0 count, <= 0 global substitute */

  enum Sflags {

    SGG = 0x01,		/* complement previous global substitute suffix */

    SGP = 0x02,		/* complement previous print suffix */

    SGR = 0x04,		/* use regex of last search (if newer) */

    SGF = 0x08

    } sflags = 0;	/* if sflags != 0, repeat last substitution */

  if( !check_addr_range2( addr_cnt ) ) return false;

  do {

    bool error = false;

    if( **ibufpp >= '1' && **ibufpp <= '9' )

      {

      int n = 0;

      if( ( sflags & SGG ) || !parse_int( &n, *ibufpp, ibufpp ) || n <= 0 )

        error = true;

      else

        { sflags |= SGG; snum = n; }

      }

    else switch( **ibufpp )

      {

      case '\n':sflags |= SGF; break;

      case 'g': if( sflags & SGG ) error = true;

                else { sflags |= SGG; snum = !snum; ++*ibufpp; }

                break;

      case 'p': if( sflags & SGP ) error = true;

                else { sflags |= SGP; ++*ibufpp; } break;

      case 'r': if( sflags & SGR ) error = true;

                else { sflags |= SGR; ++*ibufpp; } break;

      default : if( sflags ) error = true;

      }

    if( error ) { set_error_msg( "Invalid command suffix" ); return false; }

    }

  while( sflags && **ibufpp != '\n' );

  if( sflags && !subst_regex() )

    { set_error_msg( "No previous substitution" ); return false; }

  if( ( !sflags || ( sflags & SGR ) ) && !set_subst_regex( ibufpp ) )

    return false;

  if( !sflags )

    {

    const char delimiter = **ibufpp;

    pflags = 0; snum = 1;

    if( !extract_replacement( ibufpp, isglobal ) ) return false;

    if( **ibufpp == '\n' ) pflags = GPR;	/* omitted last delimiter */

    else if( **ibufpp == delimiter ) ++*ibufpp;		/* skip delimiter */

    if( !get_command_suffix( ibufpp, &pflags, &snum ) ) return false;

    gmask = pflags & ( GPR | GLS | GNP ); if( gmask == 0 ) gmask = GPR;

    }

  else if( sflags & SGP ) pflags ^= gmask;

  *pflagsp = pflags;

  if( !isglobal ) clear_undo_stack();

  if( !search_and_replace( first_addr, second_addr, snum, isglobal ) )

    return false;

  return true;

  }

static bool exec_global( const char ** const ibufpp, const int pflags,

                         const bool interactive );

/* execute the next command in command buffer; return error status */

static int exec_command( const char ** const ibufpp, const int prev_status,

                         const bool isglobal )

  {

  const char * fnp;				/* filename */

  int pflags = 0;				/* print suffixes */

  int addr, c, n;

  const int addr_cnt = extract_addresses( ibufpp );

  if( addr_cnt < 0 ) return ERR;

  *ibufpp = skip_blanks( *ibufpp );

  c = *(*ibufpp)++;

  switch( c )

    {

    case 'a': if( !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !append_lines( ibufpp, second_addr, false, isglobal ) )

                return ERR;

              break;

    case 'c': if( first_addr == 0 ) first_addr = 1;

              if( second_addr == 0 ) second_addr = 1;

              if( !check_addr_range2( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !delete_lines( first_addr, second_addr, isglobal ) ||

                  !append_lines( ibufpp, current_addr(),

                                 current_addr() >= first_addr, isglobal ) )

                return ERR;

              break;

    case 'd': if( !check_addr_range2( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !delete_lines( first_addr, second_addr, isglobal ) ) return ERR;

              break;

    case 'e': if( modified() && prev_status != EMOD ) return EMOD;

              /* fall through */

    case 'E': if( unexpected_address( addr_cnt ) ||

                  unexpected_command_suffix( **ibufpp ) ) return ERR;

              fnp = get_filename( ibufpp, false );

              if( !fnp || !delete_lines( 1, last_addr(), isglobal ) ||

                  !close_sbuf() ) return ERR;

              if( !open_sbuf() ) return FATAL;

              if( fnp[0] && fnp[0] != '!' ) set_def_filename( fnp );

              if( read_file( fnp[0] ? fnp : def_filename, 0 ) < 0 )

                return ERR;

              reset_undo_state(); set_modified( false );

              break;

    case 'f': if( unexpected_address( addr_cnt ) ||

                  unexpected_command_suffix( **ibufpp ) ) return ERR;

              fnp = get_filename( ibufpp, traditional() );

              if( !fnp ) return ERR;

              if( fnp[0] == '!' )

                { set_error_msg( "Invalid redirection" ); return ERR; }

              if( fnp[0] ) set_def_filename( fnp );

              printf( "%s\n", strip_escapes( def_filename ) );

              break;

    case 'g':

    case 'v':

    case 'G':

    case 'V': if( isglobal )

                { set_error_msg( "Cannot nest global commands" ); return ERR; }

              n = ( c == 'g' || c == 'G' );	/* mark matching lines */

              if( !check_addr_range( 1, last_addr(), addr_cnt ) ||

                  !build_active_list( ibufpp, first_addr, second_addr, n ) )

                return ERR;

              n = ( c == 'G' || c == 'V' );		/* interactive */

              if( ( n && !get_command_suffix( ibufpp, &pflags, 0 ) ) ||

                  !exec_global( ibufpp, pflags, n ) )

                return ERR;

              break;

    case 'h':

    case 'H': if( unexpected_address( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( c == 'H' ) verbose = !verbose;

              if( ( c == 'h' || verbose ) && errmsg[0] )

                printf( "%s\n", errmsg );

              break;

    case 'i': if( !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !append_lines( ibufpp, second_addr, true, isglobal ) )

                return ERR;

              break;

    case 'j': if( !check_addr_range( current_addr(), current_addr() + 1, addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( first_addr < second_addr &&

                  !join_lines( first_addr, second_addr, isglobal ) ) return ERR;

              break;

    case 'k': n = *(*ibufpp)++;

              if( second_addr == 0 ) { invalid_address(); return ERR; }

              if( !get_command_suffix( ibufpp, &pflags, 0 ) ||

                  !mark_line_node( search_line_node( second_addr ), n ) )

                return ERR;

              break;

    case 'l':

    case 'n':

    case 'p': if( c == 'l' ) n = GLS; else if( c == 'n' ) n = GNP; else n = GPR;

              if( !check_addr_range2( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ||

                  !print_lines( first_addr, second_addr, pflags | n ) )

                return ERR;

              pflags = 0;

              break;

    case 'm': if( !check_addr_range2( addr_cnt ) ||

                  !get_third_addr( ibufpp, &addr ) ) return ERR;

              if( addr >= first_addr && addr < second_addr )

                { set_error_msg( "Invalid destination" ); return ERR; }

              if( !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !move_lines( first_addr, second_addr, addr, isglobal ) )

                return ERR;

              break;

    case 'P':

    case 'q':

    case 'Q': if( unexpected_address( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( c == 'P' ) prompt_on = !prompt_on;

              else if( c == 'q' && modified() && prev_status != EMOD )

                return EMOD;

              else return QUIT;

              break;

    case 'r': if( unexpected_command_suffix( **ibufpp ) ) return ERR;

              if( addr_cnt == 0 ) second_addr = last_addr();

              fnp = get_filename( ibufpp, false );

              if( !fnp ) return ERR;

              if( !def_filename[0] && fnp[0] != '!' ) set_def_filename( fnp );

              if( !isglobal ) clear_undo_stack();

              addr = read_file( fnp[0] ? fnp : def_filename, second_addr );

              if( addr < 0 ) return ERR;

              if( addr ) set_modified( true );

              break;

    case 's': if( !command_s( ibufpp, &pflags, addr_cnt, isglobal ) )

                return ERR;

              break;

    case 't': if( !check_addr_range2( addr_cnt ) ||

                  !get_third_addr( ibufpp, &addr ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !copy_lines( first_addr, second_addr, addr ) ) return ERR;

              break;

    case 'u': if( unexpected_address( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ||

                  !undo( isglobal ) ) return ERR;

              break;

    case 'w':

    case 'W': n = **ibufpp;

              if( n == 'q' || n == 'Q' ) ++*ibufpp;

              if( unexpected_command_suffix( **ibufpp ) ) return ERR;

              fnp = get_filename( ibufpp, false );

              if( !fnp ) return ERR;

              if( addr_cnt == 0 && last_addr() == 0 )

                first_addr = second_addr = 0;

              else if( !check_addr_range( 1, last_addr(), addr_cnt ) )

                return ERR;

              if( !def_filename[0] && fnp[0] != '!' ) set_def_filename( fnp );

              addr = write_file( fnp[0] ? fnp : def_filename,

                     ( c == 'W' ) ? "a" : "w", first_addr, second_addr );

              if( addr < 0 ) return ERR;

              if( addr == last_addr() && fnp[0] != '!' ) set_modified( false );

              else if( n == 'q' && modified() && prev_status != EMOD )

                return EMOD;

              if( n == 'q' || n == 'Q' ) return QUIT;

              break;

    case 'x': if( second_addr < 0 || second_addr > last_addr() )

                { invalid_address(); return ERR; }

              if( !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              if( !isglobal ) clear_undo_stack();

              if( !put_lines( second_addr ) ) return ERR;

              break;

    case 'y': if( !check_addr_range2( addr_cnt ) ||

                  !get_command_suffix( ibufpp, &pflags, 0 ) ||

                  !yank_lines( first_addr, second_addr ) ) return ERR;

              break;

    case 'z': if( !check_second_addr( current_addr() + !isglobal, addr_cnt ) )

                return ERR;

              if( **ibufpp > '0' && **ibufpp <= '9' )

                { if( parse_int( &n, *ibufpp, ibufpp ) ) set_window_lines( n );

                  else return ERR; }

              if( !get_command_suffix( ibufpp, &pflags, 0 ) ||

                  !print_lines( second_addr,

                    min( last_addr(), second_addr + window_lines() - 1 ),

                    pflags ) )

                return ERR;

              pflags = 0;

              break;

    case '=': if( !get_command_suffix( ibufpp, &pflags, 0 ) ) return ERR;

              printf( "%d\n", addr_cnt ? second_addr : last_addr() );

              break;

    case '!': if( unexpected_address( addr_cnt ) ) return ERR;

              fnp = get_shell_command( ibufpp );

              if( !fnp ) return ERR;

              if( system( fnp + 1 ) < 0 )

                { set_error_msg( "Can't create shell process" ); return ERR; }

              if( !scripted() ) fputs( "!\n", stdout );

              break;

    case '\n': if( !check_second_addr( current_addr() +

                     ( traditional() || !isglobal ), addr_cnt ) ||

                   !print_lines( second_addr, second_addr, 0 ) )

                return ERR;

              break;

    case '#': while( *(*ibufpp)++ != '\n' ) {} ;

              break;

    default : set_error_msg( "Unknown command" ); return ERR;

    }

  if( pflags && !print_lines( current_addr(), current_addr(), pflags ) )

    return ERR;

  return 0;

  }

/* apply command list in the command buffer to the active lines in a

   range; return false if error */

static bool exec_global( const char ** const ibufpp, const int pflags,

                         const bool interactive )

  {

  static char * buf = 0;

  static int bufsz = 0;

  const char * cmd = 0;

  if( !interactive )

    {

    if( traditional() && strcmp( *ibufpp, "\n" ) == 0 )

      cmd = "p\n";			/* null cmd_list == 'p' */

    else

      {

      if( !get_extended_line( ibufpp, 0, false ) ) return false;

      cmd = *ibufpp;

      }

    }

  clear_undo_stack();

  while( true )

    {

    const line_t * const lp = next_active_node();

    if( !lp ) break;

    set_current_addr( get_line_node_addr( lp ) );

    if( current_addr() < 0 ) return false;

    if( interactive )

      {

      /* print current_addr; get a command in global syntax */

      int len = 0;

      if( !print_lines( current_addr(), current_addr(), pflags ) )

        return false;

      *ibufpp = get_stdin_line( &len );

      if( !*ibufpp ) return false;			/* error */

      if( len <= 0 ) return false;			/* EOF */

      if( len == 1 && strcmp( *ibufpp, "\n" ) == 0 ) continue;

      if( len == 2 && strcmp( *ibufpp, "&\n" ) == 0 )

        { if( !cmd ) { set_error_msg( "No previous command" ); return false; } }

      else

        {

        if( !get_extended_line( ibufpp, &len, false ) ||

            !resize_buffer( &buf, &bufsz, len + 1 ) ) return false;

        memcpy( buf, *ibufpp, len + 1 );

        cmd = buf;

        }

      }

    *ibufpp = cmd;

    while( **ibufpp ) if( exec_command( ibufpp, 0, true ) < 0 ) return false;

    }

  return true;

  }

static void script_error( void )

  {

  if( verbose ) fprintf( stderr, "script, line %d: %s\n", linenum(), errmsg );

  }

int main_loop( const bool loose )

  {

  extern jmp_buf jmp_state;

  const char * ibufp;			/* pointer to command buffer */

  volatile int err_status = 0;		/* program exit status */

  int len = 0, status;

  disable_interrupts();

  set_signals();

  status = setjmp( jmp_state );

  if( !status ) enable_interrupts();

  else { status = -1; fputs( "\n?\n", stdout ); set_error_msg( "Interrupt" ); }

  while( true )

    {

    fflush( stdout ); fflush( stderr );

    if( status < 0 && verbose ) { printf( "%s\n", errmsg ); fflush( stdout ); }

    if( prompt_on ) { fputs( prompt_str, stdout ); fflush( stdout ); }

    ibufp = get_stdin_line( &len );

    if( !ibufp ) return 2;			/* an error happened */

    if( len <= 0 )				/* EOF on stdin ('q') */

      {

      if( !modified() || status == EMOD ) status = QUIT;

      else { status = EMOD; if( !loose ) err_status = 2; }

      }

    else status = exec_command( &ibufp, status, false );

    if( status == 0 ) continue;

    if( status == QUIT ) return err_status;

    fputs( "?\n", stdout );			/* give warning */

    if( !loose && err_status == 0 ) err_status = 1;

    if( status == EMOD ) set_error_msg( "Warning: buffer modified" );

    if( is_regular_file( 0 ) )

      { script_error(); return ( ( status == FATAL ) ? 1 : err_status ); }

    if( status == FATAL )

      { if( verbose ) { printf( "%s\n", errmsg ); } return 1; }

    }

  }