path: root/main_loop.c

/*  GNU ed - The GNU line editor.
    Copyright (C) 1993, 1994 Andrew Moore, Talke Studio
    Copyright (C) 2006, 2007, 2008, 2009 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 3 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 { 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-line prompt */
static const char *ibufp = 0;		/* pointer to ed command-line buffer */
static char *shcmd = 0;			/* shell command buffer */
static int shcmdsz = 0;			/* shell command buffer size */
static int shcmdlen = 0;		/* shell command length */
static int first_addr = 0, second_addr = 0;
static char verbose = 0;		/* if set, print all error messages */
static char prompt_on = 0;		/* if set, show command-line prompt */


void set_def_filename( const char *s )
  {
  strncpy( def_filename, s, sizeof( def_filename ) );
  def_filename[sizeof(def_filename)-1] = 0;
  }

void set_prompt( const char *s )
  {
  prompt_on = 1;
  strncpy( prompt_str, s, sizeof( prompt_str ) );
  prompt_str[sizeof(prompt_str)-1] = 0;
  }

void set_verbose( void ) { verbose = 1; }


static const line_t *mark[26];			/* line markers */
static int markno;				/* line marker count */

static char mark_line_node( const line_t *lp, int c )
  {
  c -= 'a';
  if( c < 0 || c >= 26 ) { set_error_msg( "Invalid mark character" ); return 0; }
  if( !mark[c] ) ++markno;
  mark[c] = lp;
  return 1;
  }


void unmark_line_node( const line_t *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]);
  }


/* read a shell command from stdin; return substitution status ( -1, 0, +1 ) */
static int get_shell_command( void )
  {
  static char *buf = 0;
  static int bufsz = 0;
  const char *s;			/* substitution char pointer */
  int i = 0, len;

  if( restricted() ) { set_error_msg( "Shell access restricted" ); return -1; }
  s = ibufp = get_extended_line( ibufp, &len, 1 );
  if( !s ) return -1;
  if( !resize_buffer( &buf, &bufsz, len + 1 ) ) return -1;
  buf[i++] = '!';		/* prefix command w/ bang */
  while( *ibufp != '\n' )
    {
    if( *ibufp == '!' )
      {
      if( s != ibufp )
        {
        if( !resize_buffer( &buf, &bufsz, i + 1 ) ) return -1;
        buf[i++] = *ibufp++;
        }
      else if( !shcmd || ( traditional() && !*( shcmd + 1 ) ) )
        { set_error_msg( "No previous command" ); return -1; }
      else
        {
        if( !resize_buffer( &buf, &bufsz, i + shcmdlen ) ) return -1;
        for( s = shcmd + 1; s < shcmd + shcmdlen; ) buf[i++] = *s++;
        s = ibufp++;
        }
      }
    else if( *ibufp == '%' )
      {
      if( !def_filename[0] )
        { set_error_msg( "No current filename" ); return -1; }
      len = strlen( s = strip_escapes( def_filename ) );
      if( !resize_buffer( &buf, &bufsz, i + len ) ) return -1;
      while( len-- ) buf[i++] = *s++;
      s = ibufp++;
      }
    else
      {
      if( !resize_buffer( &buf, &bufsz, i + 2 ) ) return -1;
      buf[i++] = *ibufp;
      if( *ibufp++ == '\\' ) buf[i++] = *ibufp++;
      }
    }
  if( !resize_buffer( &shcmd, &shcmdsz, i + 1 ) ) return -1;
  memcpy( shcmd, buf, i );
  shcmdlen = i; shcmd[i] = 0;
  return ( *s == '!' || *s == '%' );
  }


static const char *skip_blanks( const char *s )
  {
  while( isspace( (unsigned char)*s ) && *s != '\n' ) ++s;
  return s;
  }


/* return pointer to copy of filename in the command buffer */
static const char *get_filename( void )
  {
  static char *buf = 0;
  static int bufsz = 0;
  int size, n;

  ibufp = skip_blanks( ibufp );
  if( *ibufp != '\n' )
    {
    ibufp = get_extended_line( ibufp, &size, 1 );
    if( !ibufp ) return 0;
    if( *ibufp == '!' )
      {
      ++ibufp;
      n = get_shell_command();
      if( n < 0 ) return 0;
      if( n ) printf( "%s\n", shcmd + 1 );
      return shcmd;
      }
    else if( size > path_max( 0 ) )
      { set_error_msg( "Filename too long" ); return 0; }
    }
  else if( !traditional() && !def_filename[0] )
    { set_error_msg( "No current filename" ); return 0; }
  if( !resize_buffer( &buf, &bufsz, path_max( 0 ) + 1 ) ) return 0;
  for( n = 0; *ibufp != '\n'; ) buf[n++] = *ibufp++;
  buf[n] = 0;
  return ( may_access_filename( buf ) ? buf : 0 );
  }


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


/* return the next line address in the command buffer */
static int next_addr( int *addr_cnt )
  {
  const char *hd = ibufp = skip_blanks( ibufp );
  int addr = current_addr();
  int first = 1;

  while( 1 )
    {
    int n;
    const unsigned char ch = *ibufp;
    if( isdigit( ch ) )
      {
      if( !first ) { invalid_address(); return -2; };
      if( !parse_int( &addr, ibufp, &ibufp ) ) return -2;
      }
    else switch( ch )
      {
      case '+':
      case '\t':
      case ' ':
      case '-': ibufp = skip_blanks( ++ibufp );
                if( isdigit( (unsigned char)*ibufp ) )
                  {
                  if( !parse_int( &n, ibufp, &ibufp ) ) return -2;
                  addr += ( ( ch == '-' ) ? -n : n );
                  }
                else if( ch == '+' ) ++addr;
                else if( ch == '-' ) --addr;
                break;
      case '.':
      case '$': if( !first ) { invalid_address(); return -2; };
                ++ibufp; addr = ( ( ch == '.' ) ? current_addr() : last_addr() );
                break;
      case '/':
      case '?': if( !first ) { invalid_address(); return -2; };
                addr = get_matching_node_addr( &ibufp, ch == '/' );
                if( addr < 0 ) return -2;
                if( ch == *ibufp ) ++ibufp;
                break;
      case '\'':if( !first ) { invalid_address(); return -2; };
                ++ibufp; addr = get_marked_node_addr( *ibufp++ );
                if( addr < 0 ) return -2;
                break;
      case '%':
      case ',':
      case ';': if( first )
                  {
                  ++ibufp; ++*addr_cnt;
                  second_addr = ( ( ch == ';' ) ? current_addr() : 1 );
                  addr = last_addr();
                  break;
                  }				/* FALL THROUGH */
      default:  if( ibufp == hd ) return -1;	/* EOF */
                if( addr < 0 || addr > last_addr() )
                  { invalid_address(); return -2; }
                ++*addr_cnt; return addr;
      }
    first = 0;
    }
  }


/* get line addresses from the command buffer until an invalid address
   is seen. Return number of addresses read */
static int extract_addr_range( void )
  {
  int addr;
  int addr_cnt = 0;

  first_addr = second_addr = current_addr();
  while( ( addr = next_addr( &addr_cnt ) ) >= 0 )
    {
    first_addr = second_addr; second_addr = addr;
    if( *ibufp != ',' && *ibufp != ';' ) break;
    if( *ibufp++ == ';' ) set_current_addr( addr );
    }
  if( addr_cnt == 1 || second_addr != addr ) first_addr = second_addr;
  return ( ( addr != -2 ) ? addr_cnt : -1 );
  }


/* get a valid address from the command buffer */
static char get_third_addr( int *addr )
  {
  int ol1 = first_addr;
  int ol2 = second_addr;

  int addr_cnt = extract_addr_range(); if( addr_cnt < 0 ) return 0;
  if( traditional() && addr_cnt == 0 )
    { set_error_msg( "Destination expected" ); return 0; }
  if( second_addr < 0 || second_addr > last_addr() )
    { invalid_address(); return 0; }
  *addr = second_addr;
  first_addr = ol1; second_addr = ol2;
  return 1;
  }


/* return true if address range is valid */
static char check_addr_range( const int n, const int m, const int addr_cnt )
  {
  if( addr_cnt == 0 )
    {
    first_addr = ( ( n >= 0 ) ? n : current_addr() );
    second_addr = ( ( m >= 0 ) ? m : current_addr() );
    }
  if( first_addr < 1 || first_addr > second_addr || second_addr > last_addr() )
    { invalid_address(); return 0; }
  return 1;
  }


/* verify the command suffix in the command buffer */
static char get_command_suffix( int *gflagsp )
  {
  while( 1 )
    {
    const char ch = *ibufp;
    if( ch == 'l' ) *gflagsp |= GLS;
    else if( ch == 'n' ) *gflagsp |= GNP;
    else if( ch == 'p' ) *gflagsp |= GPR;
    else break;
    ++ibufp;
    }
  if( *ibufp++ != '\n' )
    { set_error_msg( "Invalid command suffix" ); return 0; }
  return 1;
  }


static char unexpected_address( const int addr_cnt )
  {
  if( addr_cnt > 0 ) { set_error_msg( "Unexpected address" ); return 1; }
  return 0;
  }

static char unexpected_command_suffix( const unsigned char ch )
  {
  if( !isspace( ch ) )
    { set_error_msg( "Unexpected command suffix" ); return 1; }
  return 0;
  }


static char command_s( int *gflagsp, const int addr_cnt, const char isglobal )
  {
  static int gflags = 0;
  static int snum = 0;
  enum Sflags {
    SGG = 0x01,		/* complement previous global substitute suffix */
    SGP = 0x02,		/* complement previous print suffix */
    SGR = 0x04,		/* use last regex instead of last pat */
    SGF = 0x08		/* repeat last substitution */
    } sflags = 0;

  do {
    if( isdigit( (unsigned char)*ibufp ) )
      {
      if( !parse_int( &snum, ibufp, &ibufp ) ) return 0;
      sflags |= SGF; gflags &= ~GSG;		/* override GSG */
      }
    else switch( *ibufp )
      {
      case '\n':sflags |= SGF; break;
      case 'g': sflags |= SGG; ++ibufp; break;
      case 'p': sflags |= SGP; ++ibufp; break;
      case 'r': sflags |= SGR; ++ibufp; break;
      default:  if( sflags )
                  { set_error_msg( "Invalid command suffix" ); return 0; }
      }
    }
  while( sflags && *ibufp != '\n' );
  if( sflags && !prev_pattern() )
    { set_error_msg( "No previous substitution" ); return 0; }
  if( sflags & SGG ) snum = 0;			/* override numeric arg */
  if( *ibufp != '\n' && ibufp[1] == '\n' )
    { set_error_msg( "Invalid pattern delimiter" ); return 0; }
  if( ( !sflags || ( sflags & SGR ) ) && !new_compiled_pattern( &ibufp ) )
    return 0;
  if( !sflags && !extract_subst_tail( &ibufp, &gflags, &snum, isglobal ) )
    return 0;
  if( isglobal ) gflags |= GLB;
  else gflags &= ~GLB;
  if( sflags & SGG ) gflags ^= GSG;
  if( sflags & SGP ) { gflags ^= GPR; gflags &= ~( GLS | GNP ); }
  switch( *ibufp )
    {
    case 'l': gflags |= GLS; ++ibufp; break;
    case 'n': gflags |= GNP; ++ibufp; break;
    case 'p': gflags |= GPR; ++ibufp; break;
    }
  if( !check_addr_range( -1, -1, addr_cnt ) ) return 0;
  if( !get_command_suffix( gflagsp ) ) return 0;
  if( !isglobal ) clear_undo_stack();
  if( !search_and_replace( first_addr, second_addr, gflags, snum, isglobal ) )
    return 0;
  if( ( gflags & ( GPR | GLS | GNP ) ) &&
      !display_lines( current_addr(), current_addr(), gflags ) )
    return 0;
  return 1;
  }


static char exec_global( const char *ibufp2, int gflags, const char interact );
/* execute the next command in command buffer; return error status */
static int exec_command( const char isglobal )
  {
  const char *fnp;
  int gflags = 0;
  int addr, c, n;

  const int addr_cnt = extract_addr_range(); if( addr_cnt < 0 ) return ERR;
  ibufp = skip_blanks( ibufp );
  c = *ibufp++;
  switch( c )
    {
    case 'a': if( !get_command_suffix( &gflags ) ) return ERR;
              if( !isglobal ) clear_undo_stack();
              if( !append_lines( ibufp, second_addr, isglobal ) ) return ERR;
              ibufp = "";
              break;
    case 'c': if( first_addr == 0 ) first_addr = 1;
              if( second_addr == 0 ) second_addr = 1;
              if( !check_addr_range( -1, -1, addr_cnt ) ||
                  !get_command_suffix( &gflags ) ) return ERR;
              if( !isglobal ) clear_undo_stack();
              if( !delete_lines( first_addr, second_addr, isglobal ) ||
                  !append_lines( ibufp, current_addr(), isglobal ) ) return ERR;
              ibufp = "";
              break;
    case 'd': if( !check_addr_range( -1, -1, addr_cnt ) ||
                  !get_command_suffix( &gflags ) ) return ERR;
              if( !isglobal ) clear_undo_stack();
              if( !delete_lines( first_addr, second_addr, isglobal ) ) return ERR;
              inc_current_addr();
              break;
    case 'e': if( modified() && !scripted() ) return EMOD;	/* fall through */
    case 'E': if( unexpected_address( addr_cnt ) ||
                  unexpected_command_suffix( *ibufp ) ) return ERR;
              fnp = get_filename();
              if( !fnp || !get_command_suffix( &gflags ) ||
                  !delete_lines( 1, last_addr(), isglobal ) ) return ERR;
              if( !close_sbuf() ) return ERR;
              if( !open_sbuf() ) return FATAL;
              if( fnp[0] && fnp[0] != '!' ) set_def_filename( fnp );
              if( traditional() && !fnp[0] && !def_filename[0] )
                { set_error_msg( "No current filename" ); return ERR; }
              if( read_file( fnp[0] ? fnp : def_filename, 0 ) < 0 )
                return ERR;
              reset_undo_state(); set_modified( 0 );
              break;
    case 'f': if( unexpected_address( addr_cnt ) ||
                  unexpected_command_suffix( *ibufp ) ) return ERR;
              fnp = get_filename();
              if( !fnp ) return ERR;
              if( fnp[0] == '!' )
                { set_error_msg( "Invalid redirection" ); return ERR; }
              if( !get_command_suffix( &gflags ) ) 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( &ibufp, first_addr, second_addr, n ) )
                return ERR;
              n = ( c == 'G' || c == 'V' );	/* interact */
              if( ( n && !get_command_suffix( &gflags ) ) ||
                  !exec_global( ibufp, gflags, n ) )
                return ERR;
              break;
    case 'h':
    case 'H': if( unexpected_address( addr_cnt ) ||
                  !get_command_suffix( &gflags ) ) return ERR;
              if( c == 'H' ) verbose = !verbose;
              if( ( c == 'h' || verbose ) && errmsg[0] )
                fprintf( stderr, "%s\n", errmsg );
              break;
    case 'i': if( second_addr == 0 ) second_addr = 1;
              if( !get_command_suffix( &gflags ) ) return ERR;
              if( !isglobal ) clear_undo_stack();
              if( !append_lines( ibufp, second_addr - 1, isglobal ) ) return ERR;
              ibufp = "";
              break;
    case 'j': if( !check_addr_range( -1, current_addr() + 1, addr_cnt ) ||
                  !get_command_suffix( &gflags ) ) 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 = *ibufp++;
              if( second_addr == 0 ) { invalid_address(); return ERR; }
              if( !get_command_suffix( &gflags ) ||
                  !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_range( -1, -1, addr_cnt ) ||
                  !get_command_suffix( &gflags ) ||
                  !display_lines( first_addr, second_addr, gflags | n ) )
                return ERR;
              gflags = 0;
              break;
    case 'm': if( !check_addr_range( -1, -1, addr_cnt ) ||
                  !get_third_addr( &addr ) ) return ERR;
              if( addr >= first_addr && addr < second_addr )
                { set_error_msg( "Invalid destination" ); return ERR; }
              if( !get_command_suffix( &gflags ) ) 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( &gflags ) ) return ERR;
              if( c == 'P' ) prompt_on = !prompt_on;
              else return ( ( modified() && !scripted() && c == 'q' ) ? EMOD : -1 );
              break;
    case 'r': if( unexpected_command_suffix( *ibufp ) ) return ERR;
              if( addr_cnt == 0 ) second_addr = last_addr();
              fnp = get_filename();
              if( !fnp || !get_command_suffix( &gflags ) ) return ERR;
              if( !isglobal ) clear_undo_stack();
              if( !def_filename[0] && fnp[0] != '!' ) set_def_filename( fnp );
              if( traditional() && !fnp[0] && !def_filename[0] )
                { set_error_msg( "No current filename" ); return ERR; }
              addr = read_file( fnp[0] ? fnp : def_filename, second_addr );
              if( addr < 0 ) return ERR;
              if( addr && addr != last_addr() ) set_modified( 1 );
              break;
    case 's': if( !command_s( &gflags, addr_cnt, isglobal ) ) return ERR;
              break;
    case 't': if( !check_addr_range( -1, -1, addr_cnt ) ||
                  !get_third_addr( &addr ) ||
                  !get_command_suffix( &gflags ) ) 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( &gflags ) ||
                  !undo( isglobal ) ) return ERR;
              break;
    case 'w':
    case 'W': n = *ibufp;
              if( n == 'q' || n == 'Q' ) ++ibufp;
              if( unexpected_command_suffix( *ibufp ) ) return ERR;
              fnp = get_filename();
              if( !fnp ) return ERR;
              if( addr_cnt == 0 && !last_addr() ) first_addr = second_addr = 0;
              else if( !check_addr_range( 1, last_addr(), addr_cnt ) ) return ERR;
              if( !get_command_suffix( &gflags ) ) return ERR;
              if( !def_filename[0] && fnp[0] != '!' ) set_def_filename( fnp );
              if( traditional() && !fnp[0] && !def_filename[0] )
                { set_error_msg( "No current filename" ); return ERR; }
              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() ) set_modified( 0 );
              else if( modified() && !scripted() && n == 'q' ) return EMOD;
              if( n == 'q' || n == 'Q' ) return -1;
              break;
    case 'x': if( second_addr < 0 || last_addr() < second_addr )
                { invalid_address(); return ERR; }
              if( !get_command_suffix( &gflags ) ) return ERR;
              if( !isglobal ) clear_undo_stack();
              if( !put_lines( second_addr ) ) return ERR;
              break;
    case 'y': if( !check_addr_range( -1, -1, addr_cnt ) ||
                  !get_command_suffix( &gflags ) ||
                  !yank_lines( first_addr, second_addr ) ) return ERR;
              break;
    case 'z': first_addr = 1;
              if( !check_addr_range( first_addr, current_addr() +
                                     ( traditional() || !isglobal ), addr_cnt ) )
                return ERR;
              if( *ibufp > '0' && *ibufp <= '9' )
                { if( parse_int( &n, ibufp, &ibufp ) ) set_window_lines( n );
                  else return ERR; }
              if( !get_command_suffix( &gflags ) ||
                  !display_lines( second_addr, min( last_addr(), second_addr + window_lines() ),
                                  gflags ) )
                return ERR;
              gflags = 0;
              break;
    case '=': if( !get_command_suffix( &gflags ) ) return ERR;
              printf( "%d\n", addr_cnt ? second_addr : last_addr() );
              break;
    case '!': if( unexpected_address( addr_cnt ) ) return ERR;
              n = get_shell_command();
              if( n < 0 || !get_command_suffix( &gflags ) ) return ERR;
              if( n ) printf( "%s\n", shcmd + 1 );
              system( shcmd + 1 );
              if( !scripted() ) printf( "!\n" );
              break;
    case '\n': first_addr = 1;
              if( !check_addr_range( first_addr, current_addr() +
                                     ( traditional() || !isglobal ), addr_cnt ) ||
                  !display_lines( second_addr, second_addr, 0 ) )
                return ERR;
              break;
    case '#': while( *ibufp++ != '\n' ) ;
              break;
    default:  set_error_msg( "Unknown command" ); return ERR;
    }
  if( gflags && !display_lines( current_addr(), current_addr(), gflags ) )
    return ERR;
  return 0;
  }


/* apply command list in the command buffer to the active lines in a
   range; return false if error */
static char exec_global( const char *ibufp2, int gflags, const char interact )
  {
  static char *buf = 0;
  static int bufsz = 0;
  const line_t *lp = 0;
  const char *cmd = 0;

  if( !interact )
    {
    if( traditional() && !strcmp( ibufp2, "\n" ) )
      cmd = "p\n";		/* null cmd-list == `p' */
    else if( !( cmd = get_extended_line( ibufp2, 0, 0 ) ) )
      return 0;
    }
  clear_undo_stack();
  while( ( lp = next_active_node() ) )
    {
    set_current_addr( get_line_node_addr( lp ) );
    if( current_addr() < 0 ) return 0;
    if( interact )
      {
      /* print current_addr; get a command in global syntax */
      int len;
      if( !display_lines( current_addr(), current_addr(), gflags ) )
        return 0;
      do { ibufp2 = get_tty_line( &len ); }
      while( ibufp2 && len > 0 && ibufp2[len-1] != '\n' );
      if( !ibufp2 ) return 0;
      if( len == 0 ) { set_error_msg( "Unexpected end-of-file" ); return 0; }
      if( len == 1 && !strcmp( ibufp2, "\n" ) ) continue;
      if( len == 2 && !strcmp( ibufp2, "&\n" ) )
        { if( !cmd ) { set_error_msg( "No previous command" ); return 0; } }
      else if( !( cmd = get_extended_line( ibufp2, &len, 0 ) ) ) return 0;
      else
        {
        if( !resize_buffer( &buf, &bufsz, len + 1 ) ) return 0;
        memcpy( buf, cmd, len + 1 );
        cmd = buf;
        }
      }
    ibufp = cmd;
    while( *ibufp ) if( exec_command( 1 ) < 0 ) return 0;
    }
  return 1;
  }


int main_loop( const char loose )
  {
  extern jmp_buf jmp_state;
  volatile int err_status = 0;			/* program exit status */
  volatile int linenum = 0;			/* script line number */
  int len, status, old_status;

  disable_interrupts();
  set_signals();
  status = setjmp( jmp_state );
  if( !status ) enable_interrupts();
  else { status = -1; fputs( "\n?\n", stderr ); set_error_msg( "Interrupt" ); }

  while( 1 )
    {
    if( status < 0 && verbose ) fprintf( stderr, "%s\n", errmsg );
    if( prompt_on ) { printf( "%s", prompt_str ); fflush( stdout ); }
    ibufp = get_tty_line( &len );
    if( !ibufp ) return err_status;
    if( !len )
      {
      if( !modified() || scripted() ) return err_status;
      fputs( "?\n", stderr ); set_error_msg( "Warning: file modified" );
      if( is_regular_file( 0 ) )
        {
        if( verbose ) fprintf( stderr, "script, line %d: %s\n", linenum, errmsg );
        return 2;
        }
      set_modified( 0 ); status = EMOD; continue;
      }
    else if( ibufp[len-1] != '\n' )	/* discard line */
      { set_error_msg( "Unexpected end-of-file" ); status = ERR; continue; }
    else ++linenum;
    old_status = status;
    status = exec_command( 0 );
    if( status == 0 ) continue;
    if( status == -1 ) return err_status;
    if( status == EMOD )
      {
      if( old_status == EMOD ) return err_status;
      fputs( "?\n", stderr );				/* give warning */
      set_error_msg( "Warning: file modified" );
      if( is_regular_file( 0 ) )
        {
        if( verbose ) fprintf( stderr, "script, line %d: %s\n", linenum, errmsg );
        return 1;
        }
      }
    else if( status == FATAL )
      {
      if( verbose )
        {
        if( is_regular_file( 0 ) )
          fprintf( stderr, "script, line %d: %s\n", linenum, errmsg );
        else fprintf( stderr, "%s\n", errmsg );
        }
      return 1;
      }
    else
      {
      fputs( "?\n", stderr );			/* give warning */
      if( is_regular_file( 0 ) )
        {
        if( verbose ) fprintf( stderr, "script, line %d: %s\n", linenum, errmsg );
        return 1;
        }
      }
    if( !loose ) err_status = 1;
    }
  }


void set_error_msg( const char *msg )
  {
  if( !msg ) msg = "";
  strncpy( errmsg, msg, sizeof( errmsg ) );
  errmsg[sizeof(errmsg)-1] = 0;
  }