yap-6.3/os/pl-file.c

/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@cs.vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (C): 1985-2012, University of Amsterdam
			      VU University Amsterdam

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/


/** @ingroup InputOutput
@{

*/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
This module is far too big.  It defines a layer around open(), etc.   to
get  opening  and  closing  of  files to the symbolic level required for
Prolog.  It also defines basic I/O  predicates,  stream  based  I/O  and
finally  a  bundle  of  operations  on  files,  such  as name expansion,
renaming, deleting, etc.  Most of this module is rather straightforward.

If time is there I will have a look at all this to  clean  it.   Notably
handling times must be cleaned, but that not only holds for this module.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

/*#define O_DEBUG 1*/
/*#define O_DEBUG_MT 1*/

#define NEEDS_SWINSOCK
#include "pl-incl.h"
#include "pl-ctype.h"
#include "pl-utf8.h"
#include <errno.h>

#include <stdlib.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#include <fcntl.h>
#endif
#ifdef HAVE_BSTRING_H
#include <bstring.h>
#endif
#if HAVE_ALLOCA_H
#include <alloca.h>
#endif

#define LOCK()   PL_LOCK(L_FILE)	/* MT locking */
#define UNLOCK() PL_UNLOCK(L_FILE)

#undef LD				/* fetch LD once per function */
#define LD LOCAL_LD

/* there are two types of stream property functions. In the usual case,
   they have an argument, but in a few cases they don't */
typedef int (*property0_t)(IOSTREAM *s ARG_LD);
typedef int (*property_t)(IOSTREAM *s, term_t prop ARG_LD);

static int	bad_encoding(const char *msg, atom_t name);
static int	noprotocol(void);
static PL_blob_t stream_blob;

const atom_t standardStreams[] =
{ ATOM_user_input,			/* 0 */
  ATOM_user_output,			/* 1 */
  ATOM_user_error,			/* 2 */
  ATOM_current_input,			/* 3 */
  ATOM_current_output,			/* 4 */
  ATOM_protocol,			/* 5 */
  NULL_ATOM
};


static int
standardStreamIndexFromName(atom_t name)
{ const atom_t *ap;

  for(ap=standardStreams; *ap; ap++)
  { if ( *ap == name )
      return (int)(ap - standardStreams);
  }

  return -1;
}


static int
standardStreamIndexFromStream(IOSTREAM *s)
{ GET_LD
  IOSTREAM **sp = LD->IO.streams;
  int i = 0;

  for( ; i<6; i++, sp++ )
  { if ( *sp == s )
      return i;
  }

  return -1;
}

		 /*******************************
		 *	   BOOKKEEPING		*
		 *******************************/

/**
 * @defgroup StreamM Stream Manipulation
 * @ingroup InputOutput
 * @{
 */
static void aliasStream(IOSTREAM *s, atom_t alias);
static void unaliasStream(IOSTREAM *s, atom_t name);

static Table streamAliases;		/* alias --> stream */
static Table streamContext;		/* stream --> extra data */

typedef struct _alias
{ struct _alias *next;
  atom_t name;
} alias;


#define IO_TELL	0x001			/* opened by tell/1 */
#define IO_SEE  0x002			/* opened by see/1 */

typedef struct
{ alias *alias_head;
  alias *alias_tail;
  atom_t filename;			/* associated filename */
  unsigned flags;
} stream_context;


static stream_context *
getStreamContext(IOSTREAM *s)
{ if ( !s->context )
  { stream_context *ctx = allocHeapOrHalt(sizeof(*ctx));

    DEBUG(1, Sdprintf("Created ctx=%p for stream %p\n", ctx, s));

    ctx->alias_head = ctx->alias_tail = NULL;
    ctx->filename = NULL_ATOM;
    ctx->flags = 0;
    addHTable(streamContext, s, ctx);
    s->context = ctx;
  }

  return (stream_context*)s->context;
}

static stream_context *
getExistingStreamContext(IOSTREAM *s)
{ return (stream_context*)s->context;
}


/* MT: Must be called locked */

static void
aliasStream(IOSTREAM *s, atom_t name)
{ stream_context *ctx;
  Symbol symb;
  alias *a;

					/* ensure name is free (error?) */
  if ( (symb = lookupHTable(streamAliases, (void *)name)) )
    unaliasStream(symb->value, name);

  ctx = getStreamContext(s);
  addHTable(streamAliases, (void *)name, s);
  PL_register_atom(name);

  a = allocHeapOrHalt(sizeof(*a));
  a->next = NULL;
  a->name = name;

  if ( ctx->alias_tail )
  { ctx->alias_tail->next = a;
    ctx->alias_tail = a;
  } else
  { ctx->alias_head = ctx->alias_tail = a;
  }
}

/* MT: Locked by freeStream()
*/

static void
unaliasStream(IOSTREAM *s, atom_t name)
{ Symbol symb;

  if ( name )
  { if ( (symb = lookupHTable(streamAliases, (void *)name)) )
    { stream_context *ctx;

      deleteSymbolHTable(streamAliases, symb);

      if ( (ctx=getExistingStreamContext(s)) )
      { alias **a;

	for(a = &ctx->alias_head; *a; a = &(*a)->next)
	{ if ( (*a)->name == name )
	  { alias *tmp = *a;

	    *a = tmp->next;
	    freeHeap(tmp, sizeof(*tmp));
	    if ( tmp == ctx->alias_tail )
	      ctx->alias_tail = NULL;

	    break;
	  }
	}
      }

      PL_unregister_atom(name);
    }
  } else				/* delete them all */
  { stream_context *ctx;

    if ( (ctx=getExistingStreamContext(s)) )
    { alias *a, *n;

      for(a = ctx->alias_head; a; a=n)
      { Symbol s2;

	n = a->next;

	if ( (s2 = lookupHTable(streamAliases, (void *)a->name)) )
	{ deleteSymbolHTable(streamAliases, s2);
	  PL_unregister_atom(a->name);
	}

	freeHeap(a, sizeof(*a));
      }

      ctx->alias_head = ctx->alias_tail = NULL;
    }
  }
}


static void
freeStream(IOSTREAM *s)
{ GET_LD
  Symbol symb;
  int i;
  IOSTREAM **sp;

  DEBUG(1, Sdprintf("freeStream(%p)\n", s));

  LOCK();
  unaliasStream(s, NULL_ATOM);
  if ( (symb=lookupHTable(streamContext, s)) )
  { stream_context *ctx = symb->value;

    if ( ctx->filename != NULL_ATOM )
    { PL_unregister_atom(ctx->filename);

      if ( ctx->filename == source_file_name )
      { source_file_name = NULL_ATOM;	/* TBD: pop? */
	source_line_no = -1;
      }
    }

    freeHeap(ctx, sizeof(*ctx));
    deleteSymbolHTable(streamContext, symb);
  }
					/* if we are a standard stream */
					/* reassociate with standard I/O */
					/* NOTE: there may be more! */
  for(i=0, sp = LD->IO.streams; i<6; i++, sp++)
  { if ( *sp == s )
    { if ( s->flags & SIO_INPUT )
	*sp = Sinput;
      else if ( sp == &Suser_error )
	*sp = Serror;
      else if ( sp == &Sprotocol )
	*sp = NULL;
      else
	*sp = Soutput;
    }
  }
  UNLOCK();
}


/* MT: locked by caller (openStream()) */
/* name must be registered by the caller */

static void
setFileNameStream_unlocked(IOSTREAM *s, atom_t name)
{ stream_context *ctx = getStreamContext(s);

  if ( ctx->filename )
  { PL_unregister_atom(ctx->filename);
    ctx->filename = NULL_ATOM;
  }
  if ( !(name == NULL_ATOM || name == ATOM_) )
    ctx->filename = name;
}


int
setFileNameStream(IOSTREAM *s, atom_t name)
{ LOCK();
  setFileNameStream_unlocked(s, name);
  PL_register_atom(name);
  UNLOCK();

  return TRUE;
}


atom_t
fileNameStream(IOSTREAM *s)
{ atom_t name;

  LOCK();
  name = getStreamContext(s)->filename;
  UNLOCK();

  return name;
}

#if __YAP_PROLOG__
static void init_yap(void);
#endif

void
initIO(void)
{ GET_LD
  const atom_t *np;
  int i;

  streamAliases = newHTable(16);
  streamContext = newHTable(16);
  PL_register_blob_type(&stream_blob);

  if ( False(Sinput, SIO_ISATTY) ||
       False(Soutput, SIO_ISATTY) )
  { /* clear PLFLAG_TTY_CONTROL */
    PL_set_prolog_flag("tty_control", PL_BOOL, FALSE);
  }

  ResetTty();
#if __YAP_PROLOG__
  /* needs to be done after tty hacking */
  init_yap();
#endif

  Sclosehook(freeStream);

  Sinput->position  = &Sinput->posbuf;	/* position logging */
  Soutput->position = &Sinput->posbuf;
  Serror->position  = &Sinput->posbuf;

  ttymode = TTY_COOKED;
  PushTty(Sinput, &ttytab, TTY_SAVE);
  LD->prompt.current = ATOM_prompt;
  PL_register_atom(ATOM_prompt);

  Suser_input  = Sinput;
  Suser_output = Soutput;
  Suser_error  = Serror;
  Scurin       = Sinput;		/* see/tell */
  Scurout      = Soutput;
  Sprotocol    = NULL;			/* protocolling */

  getStreamContext(Sinput);		/* add for enumeration */
  getStreamContext(Soutput);
  getStreamContext(Serror);
  for( i=0, np = standardStreams; *np; np++, i++ )
    addHTable(streamAliases, (void *)*np, (void *)(intptr_t)i);

  GD->io_initialised = TRUE;
}


		 /*******************************
		 *	     GET HANDLES	*
		 *******************************/

#ifdef O_PLMT

static inline IOSTREAM *
getStream(IOSTREAM *s)
{ if ( s && s->magic == SIO_MAGIC && Slock(s) == 0 )
  { if ( unlikely(s->magic == SIO_CMAGIC) )
    { Sunlock(s);
      return NULL;
    }
    return s;
  }

  return NULL;
}

static inline IOSTREAM *
tryGetStream(IOSTREAM *s)
{ if ( s && s->magic == SIO_MAGIC && StryLock(s) == 0 )
  { if ( unlikely(s->magic == SIO_CMAGIC) )
    { Sunlock(s);
      return NULL;
    }
    return s;
  }

  return NULL;
}

static inline void
releaseStream(IOSTREAM *s)
{ if ( s->magic == SIO_MAGIC )
    Sunlock(s);
}

#else /*O_PLMT*/

#define getStream(s)	(s)
#define tryGetStream(s) (s)
#define releaseStream(s)

#endif /*O_PLMT*/

int
PL_release_stream(IOSTREAM *s)
{ if ( Sferror(s) )
    return streamStatus(s);

  releaseStream(s);
  return TRUE;
}


		 /*******************************
		 *	      ERRORS		*
		 *******************************/

static int symbol_no_stream(atom_t symbol);

static int
no_stream(term_t t, atom_t name)
{ if ( t )
    return PL_error(NULL, 0, NULL, ERR_EXISTENCE, ATOM_stream, t);
  else
    return symbol_no_stream(name);
}

static int
not_a_stream(term_t t)
{ return PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_stream_or_alias, t);
}

static int
symbol_no_stream(atom_t symbol)
{ GET_LD
  term_t t;

  if ( (t = PL_new_term_ref()) )
  { PL_put_atom(t, symbol);
    return no_stream(t, 0);
  } else
    return FALSE;
}

static int
symbol_not_a_stream(atom_t symbol)
{ GET_LD
  term_t t = PL_new_term_ref();
  PL_put_atom(t, symbol);
  return not_a_stream(t);
}



		 /*******************************
		 *	  PROLOG HANDLES	*
		 *******************************/

typedef struct stream_ref
{ IOSTREAM *read;
  IOSTREAM *write;
} stream_ref;


static int
write_stream_ref(IOSTREAM *s, atom_t aref, int flags)
{ stream_ref *ref = PL_blob_data(aref, NULL, NULL);
  (void)flags;

  if ( ref->read && ref->write )
    Sfprintf(s, "<stream>(%p,%p)", ref->read, ref->write);
  else if ( ref->read )
    Sfprintf(s, "<stream>(%p)", ref->read);
  else
    Sfprintf(s, "<stream>(%p)", ref->write);

  return TRUE;
}


static void
acquire_stream_ref(atom_t aref)
{ stream_ref *ref = PL_blob_data(aref, NULL, NULL);

  if ( ref->read )
    ref->read->references++;
  if ( ref->write )
    ref->write->references++;
}


static int
release_stream_ref(atom_t aref)
{ stream_ref *ref = PL_blob_data(aref, NULL, NULL);

  if ( ref->read )
  { if ( --ref->read->references == 0 && ref->read->erased )
      unallocStream(ref->read);
  }
  if ( ref->write )
  { if ( --ref->write->references == 0 && ref->write->erased )
      unallocStream(ref->write);
  }

  return TRUE;
}


static int
save_stream_ref(atom_t aref, IOSTREAM *fd)
{ stream_ref *ref = PL_blob_data(aref, NULL, NULL);
  (void)fd;

  return PL_warning("Cannot save reference to <stream>(%p,%p)",
		    ref->read, ref->write);
}


static atom_t
load_stream_ref(IOSTREAM *fd)
{ (void)fd;

  return PL_new_atom("<saved-stream-ref>");
}


static PL_blob_t stream_blob =
{ PL_BLOB_MAGIC,
  PL_BLOB_UNIQUE,
  "stream",
  release_stream_ref,
  NULL,
  write_stream_ref,
  acquire_stream_ref,
  save_stream_ref,
  load_stream_ref
};


#define SH_ERRORS   0x01		/* generate errors */
#define SH_ALIAS    0x02		/* allow alias */
#define SH_UNLOCKED 0x04		/* don't lock the stream */
#define SH_OUTPUT   0x08		/* We want an output stream */
#define SH_INPUT    0x10		/* We want an input stream */

static int
get_stream_handle__LD(atom_t a, IOSTREAM **sp, int flags ARG_LD)
{ stream_ref *ref;
  PL_blob_t *type;
  IOSTREAM *s;

  ref = PL_blob_data(a, NULL, &type);
  if ( type == &stream_blob )
  { if ( ref->read )
    { if ( ref->write && (flags&SH_OUTPUT) )
	s = ref->write;
      else
	s = ref->read;
    } else
      s = ref->write;

    if ( s->erased )
       goto noent;

    if ( flags & SH_UNLOCKED )
    { assert( s->magic == SIO_MAGIC || s->magic == SIO_CMAGIC );
      *sp = s;
      return TRUE;
    } else if ( (s=getStream(s)) )
    { *sp = s;
      return TRUE;
    }

    return symbol_no_stream(a);
  } else
  { Symbol symb;

    if ( !(flags & SH_UNLOCKED) )
      LOCK();
    if ( (symb=lookupHTable(streamAliases, (void *)a)) )
    { IOSTREAM *stream;
      uintptr_t n = (uintptr_t)symb->value;

      if ( n < 6 )			/* standard stream! */
      { stream = LD->IO.streams[n];	/* TBD: No need to lock for std-streams */
      } else
	stream = symb->value;

      if ( !(flags & SH_UNLOCKED) )
	UNLOCK();

      if ( stream )
      { if ( (flags & SH_UNLOCKED) )
	{ if ( stream->magic == SIO_MAGIC )
	  { *sp = stream;
	    return TRUE;
	  }
	} else if ( (*sp = getStream(stream)) )
	  return TRUE;
	goto noent;
      }
    }
    if ( !(flags & SH_UNLOCKED) )
      UNLOCK();

    goto noent;
  }

  if ( flags & SH_ERRORS )
    symbol_not_a_stream(a);

  return FALSE;

noent:
  if ( flags & SH_ERRORS )
    symbol_no_stream(a);

  return FALSE;
}

#define get_stream_handle(t, sp, flags) \
	get_stream_handle__LD(t, sp, flags PASS_LD)


static int
term_stream_handle(term_t t, IOSTREAM **s, int flags ARG_LD)
{ atom_t a;

  if ( !PL_get_atom(t, &a) )
    return not_a_stream(t);

  return get_stream_handle(a, s, flags);
}


int
PL_get_stream_handle(term_t t, IOSTREAM **s)
{ GET_LD

  return term_stream_handle(t, s, SH_ERRORS|SH_ALIAS PASS_LD);
}


static int
unify_stream_ref(term_t t, IOSTREAM *s)
{ GET_LD
  stream_ref ref;
  int rval;

  memset(&ref, 0, sizeof(ref));
  if ( s->flags & SIO_INPUT )
    ref.read = s;
  else
    ref.write = s;

  rval = PL_unify_blob(t, &ref, sizeof(ref), &stream_blob);

  if ( !rval && !PL_is_variable(t) )
    return PL_error(NULL, 0, "stream-argument", ERR_UNINSTANTIATION, 0, t);

  return rval;
}


int
PL_unify_stream_or_alias(term_t t, IOSTREAM *s)
{ GET_LD
  int rval;
  stream_context *ctx;
  int i;

  if ( (i=standardStreamIndexFromStream(s)) >= 0 && i < 3 )
    return PL_unify_atom(t, standardStreams[i]);

  LOCK();
  ctx = getStreamContext(s);
  if ( ctx->alias_head )
    rval = PL_unify_atom(t, ctx->alias_head->name);
  else
    rval = unify_stream_ref(t, s);
  UNLOCK();


  return rval;
}


int
PL_unify_stream(term_t t, IOSTREAM *s)
{ LOCK();
  (void)getStreamContext(s);		/* get stream known to Prolog */
  UNLOCK();

  return unify_stream_ref(t, s);
}


IOSTREAM **				/* provide access to Suser_input, */
_PL_streams(void)			/* Suser_output and Suser_error */
{ GET_LD
  return &Suser_input;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
getInputStream(term_t t, IOSTREAM **s)
getOutputStream(term_t t, IOSTREAM **s)
    These functions are the basis used by all Prolog predicates to get
    a input or output stream handle.  If t = 0, current input/output is
    returned.  This allows us to define the standard-stream based version
    simply by calling the explicit stream-based version with 0 for the
    stream argument.

    MT: The returned stream is always locked and should be returned
    using releaseStream() or streamStatus().
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef enum
{ S_DONTCARE = 0,
  S_TEXT,
  S_BINARY
} s_type;


static int
checkStreamType(s_type text, IOSTREAM *s, atom_t *error ARG_LD)
{ if ( text == S_DONTCARE || LD->IO.stream_type_check == ST_FALSE )
    return TRUE;			/* no checking */

					/* ok? */
  if ( text == S_TEXT && (s->flags&SIO_TEXT) )
    return TRUE;
  if ( text == S_BINARY && !(s->flags&SIO_TEXT) )
    return TRUE;
					/* no */
  if ( LD->IO.stream_type_check == ST_LOOSE )
  { if ( text == S_TEXT )
      return TRUE;
    if ( s->encoding == ENC_ISO_LATIN_1 ||
	 s->encoding == ENC_OCTET )
      return TRUE;
  }

  *error = (text == S_TEXT ? ATOM_binary_stream : ATOM_text_stream);
  return FALSE;
}


static int
getOutputStream__LD(term_t t, s_type text, IOSTREAM **stream ARG_LD)
{ atom_t a;
  IOSTREAM *s;
  atom_t tp;

  if ( t == 0 )
  { if ( (s = getStream(Scurout)) )
      goto ok;
    return no_stream(t, ATOM_current_output);
  }

  if ( !PL_get_atom(t, &a) )
    return not_a_stream(t);

  if ( a == ATOM_user )
  { if ( (s = getStream(Suser_output)) )
      goto ok;
    return no_stream(t, ATOM_user);
  }

  if ( !get_stream_handle(a, &s, SH_ERRORS|SH_ALIAS|SH_OUTPUT) )
    return FALSE;

ok:
  if ( !(s->flags&SIO_OUTPUT) )
  { tp = ATOM_stream;
  } else if ( checkStreamType(text, s, &tp PASS_LD) )
  { *stream = s;
    return TRUE;
  }

  releaseStream(s);
  if ( t == 0 )
  { if ( (t = PL_new_term_ref()) )
      PL_put_atom(t, ATOM_current_output);
    else
      return FALSE;				/* resource error */
  }
  return PL_error(NULL, 0, NULL, ERR_PERMISSION,
		  ATOM_output, tp, t);
}


int
getTextOutputStream__LD(term_t t, IOSTREAM **stream ARG_LD)
{ return getOutputStream(t, S_TEXT, stream);
}


int
getBinaryOutputStream__LD(term_t t, IOSTREAM **stream ARG_LD)
{ return getOutputStream(t, S_BINARY, stream);
}


static int
getInputStream__LD(term_t t, s_type text, IOSTREAM **stream ARG_LD)
{ atom_t a;
  IOSTREAM *s;
  atom_t tp;

  if ( t == 0 )
  { if ( (s = getStream(Scurin)) )
      goto ok;
    return no_stream(t, ATOM_current_input);
  }

  if ( !PL_get_atom(t, &a) )
    return not_a_stream(t);

  if ( a == ATOM_user )
  { if ( (s = getStream(Suser_input)) )
      goto ok;
    return no_stream(t, ATOM_user);
  }

  if ( !get_stream_handle(a, &s, SH_ERRORS|SH_ALIAS|SH_INPUT) )
    return FALSE;

ok:
  if ( !(s->flags&SIO_INPUT) )
  { tp = ATOM_stream;
  } else if ( checkStreamType(text, s, &tp PASS_LD) )
  { *stream = s;
    return TRUE;
  }

  releaseStream(s);
  if ( t == 0 )
  { if ( (t = PL_new_term_ref()) )
      PL_put_atom(t, ATOM_current_input);
    else
      return FALSE;				/* resource error */
  }
  return PL_error(NULL, 0, NULL, ERR_PERMISSION,
		  ATOM_input, tp, t);
}

int
getTextInputStream__LD(term_t t, IOSTREAM **stream ARG_LD)
{ return getInputStream__LD(t, S_TEXT, stream PASS_LD);
}

int
getBinaryInputStream__LD(term_t t, IOSTREAM **stream ARG_LD)
{ return getInputStream__LD(t, S_BINARY, stream PASS_LD);
}


/** stream_pairs(-Pair, +Read, +Write)
 * stream_pairs(+Pair, -Read, -Write)
 *
 * This SWI Built-in can be used in two ways: if the second argument is an input stream
 *  and the third sn output stresm, Prolog createes a new _Pair_. A stream pair can be
 * used in any operation, with the Prolog chosing the appropriate stream to the operation.
 *
 * If _Pair_ is bound, the predicate can be used to access the two streams in the pair.
*/

static
PRED_IMPL("stream_pair", 3, stream_pair, 0)
{ PRED_LD
  IOSTREAM *in = NULL, *out = NULL;
  int rc = FALSE;

  if ( !PL_is_variable(A1) )
  { stream_ref *ref;
    atom_t a;
    PL_blob_t *type;

    if ( !PL_get_atom(A1, &a) ||
	 !(ref=PL_blob_data(a, NULL, &type)) ||
	 type != &stream_blob ||
	 !ref->read ||
	 !ref->write )
      return PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_stream_pair, A1);

    return ( PL_unify_stream_or_alias(A2, ref->read) &&
	     PL_unify_stream_or_alias(A3, ref->write) );
  }

  if ( getInputStream(A2, S_DONTCARE, &in) &&
       getOutputStream(A3, S_DONTCARE, &out) )
  { stream_ref ref;

    ref.read = in;
    ref.write = out;

    rc = PL_unify_blob(A1, &ref, sizeof(ref), &stream_blob);
  }

  if ( in )
    releaseStream(in);
  if ( out )
    releaseStream(out);

  return rc;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
In windows GUI applications, the IO-streams  are   not  bound. We do not
wish to generate an error on the  stream   errors  that may be caused by
this. It is a bit of a hack, but   the alternative is to define a stream
that ignores the error. This might get hairy if the user is playing with
these streams too.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifdef __WINDOWS__
static int
isConsoleStream(IOSTREAM *s)
{ int i = standardStreamIndexFromStream(s);

  return i >= 1 && i < 3;			/* only output streams */
}
#else
#define isConsoleStream(s) FALSE
#endif


int
reportStreamError(IOSTREAM *s)
{ if ( GD->cleaning == CLN_NORMAL &&
       !isConsoleStream(s) &&
       (s->flags & (SIO_FERR|SIO_WARN)) )
  { GET_LD
    atom_t op;
    term_t stream = PL_new_term_ref();
    char *msg;

    PL_unify_stream_or_alias(stream, s);

    if ( (s->flags & SIO_FERR) )
    { if ( s->exception )
      { fid_t fid;
	term_t ex;
	int rc;

	LD->exception.processing = TRUE;	/* allow using spare stack */
	if ( !(fid = PL_open_foreign_frame()) )
	  return FALSE;
	ex = PL_new_term_ref();
	rc = PL_recorded(s->exception, ex);
	PL_erase(s->exception);
	s->exception = NULL;
	if ( rc )
	  rc = PL_raise_exception(ex);
	PL_close_foreign_frame(fid);
	return rc;
      }

      if ( s->flags & SIO_INPUT )
      { if ( Sfpasteof(s) )
	{ return PL_error(NULL, 0, NULL, ERR_PERMISSION,
			  ATOM_input, ATOM_past_end_of_stream, stream);
	} else if ( (s->flags & SIO_TIMEOUT) )
	{ PL_error(NULL, 0, NULL, ERR_TIMEOUT,
		   ATOM_read, stream);
	  Sclearerr(s);
	  return FALSE;
	} else
	  op = ATOM_read;
      } else
      { if ( (s->flags & SIO_TIMEOUT) )
	{ PL_error(NULL, 0, NULL, ERR_TIMEOUT,
		   ATOM_write, stream);
	  return FALSE;
	} else
	  op = ATOM_write;
      }

      if ( s->message )
      { msg = s->message;
      } else
      { msg = MSG_ERRNO;
	if ( s->io_errno )
	  errno = s->io_errno;
      }

      PL_error(NULL, 0, msg, ERR_STREAM_OP, op, stream);

      if ( (s->flags & SIO_CLEARERR) )
	Sseterr(s, SIO_FERR, NULL);

      return FALSE;
    } else
    { printMessage(ATOM_warning,
		   PL_FUNCTOR_CHARS, "io_warning", 2,
		   PL_TERM, stream,
		   PL_CHARS, s->message);

      Sseterr(s, SIO_WARN, NULL);
    }
  }

  return TRUE;
}


int
streamStatus(IOSTREAM *s)
{ if ( (s->flags & (SIO_FERR|SIO_WARN)) )
  { int ret = reportStreamError(s);
    releaseStream(s);
    return ret;
  }

  releaseStream(s);
  return TRUE;
}


		 /*******************************
		 *	     TTY MODES		*
		 *******************************/

ttybuf	ttytab;				/* saved terminal status on entry */
int	ttymode;			/* Current tty mode */

typedef struct input_context * InputContext;
typedef struct output_context * OutputContext;

struct input_context
{ IOSTREAM *    stream;                 /* pushed input */
  atom_t	type;			/* Type of input */
  atom_t        term_file;              /* old term_position file */
  int           term_line;              /* old term_position line */
  InputContext  previous;               /* previous context */
};


struct output_context
{ IOSTREAM *    stream;                 /* pushed output */
  OutputContext previous;               /* previous context */
};

#define input_context_stack  (LD->IO.input_stack)
#define output_context_stack (LD->IO.output_stack)

static IOSTREAM *openStream(term_t file, term_t mode, term_t options);

void
dieIO()
{ if ( GD->io_initialised )
  { noprotocol();
    closeFiles(TRUE);
    PopTty(Sinput, &ttytab, TRUE);
  }
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
closeStream() performs Prolog-level closing. Most important right now is
to to avoid closing the user-streams. If a stream cannot be flushed (due
to a write-error), an exception is  generated.

MT: We assume the stream is locked and will unlock it here.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static int
closeStream(IOSTREAM *s)
{ if ( s == Sinput )
  { Sclearerr(s);
    releaseStream(s);
  } else if ( s == Soutput || s == Serror )
  { if ( Sflush(s) < 0 )
      return streamStatus(s);
    releaseStream(s);
  } else
  { if ( !Sferror(s) && Sflush(s) < 0 )
    { streamStatus(s);
      Sclose(s);
      return FALSE;
    }
    if ( Sclose(s) < 0 )		/* will unlock as well */
      return FALSE;
  }

  return TRUE;
}


void
closeFiles(int all)
{ GET_LD
  TableEnum e;
  Symbol symb;

  e = newTableEnum(streamContext);
  while( (symb=advanceTableEnum(e)) )
  { IOSTREAM *s = symb->name;

    if ( all || !(s->flags & SIO_NOCLOSE) )
    { IOSTREAM *s2 = tryGetStream(s);

      if ( s2 )
      { if ( !all )
	{ term_t t = PL_new_term_ref();

	  PL_unify_stream_or_alias(t, s2);
	  printMessage(ATOM_informational,
		       PL_FUNCTOR, FUNCTOR_close_on_abort1,
		         PL_TERM, t);
	  PL_reset_term_refs(t);
	}

	closeStream(s2);
      }
    }
  }
  freeTableEnum(e);
}


void
protocol(const char *str, size_t n)
{ GET_LD
  IOSTREAM *s;

  if ( LD && Sprotocol && (s = getStream(Sprotocol)) )
  { while( n-- > 0 )
      Sputcode(*str++&0xff, s);
    Sflush(s);
    releaseStream(s);			/* we don not check errors */
  }
}


		 /*******************************
		 *	  TEMPORARY I/O		*
		 *******************************/


int
push_input_context(atom_t type)
{ GET_LD
  InputContext c = allocHeapOrHalt(sizeof(struct input_context));

  PL_register_atom(type);

  c->stream           = Scurin;
  c->type	      = type;
  c->term_file        = source_file_name;
  c->term_line        = source_line_no;
  c->previous         = input_context_stack;
  input_context_stack = c;

  return TRUE;
}


int
pop_input_context(void)
{ GET_LD
  InputContext c = input_context_stack;

  if ( c )
  { Scurin              = c->stream;
    source_file_name    = c->term_file;
    source_line_no      = c->term_line;
    input_context_stack = c->previous;
    PL_unregister_atom(c->type);
    freeHeap(c, sizeof(struct input_context));

    return TRUE;
  } else
  { Scurin		= Sinput;
    return FALSE;
  }
}


static
PRED_IMPL("$push_input_context", 1, push_input_context, 0)
{ PRED_LD
  atom_t type;

  if ( PL_get_atom_ex(A1, &type) )
    return push_input_context(type);

  return FALSE;
}


static
PRED_IMPL("$pop_input_context", 0, pop_input_context, 0)
{ return pop_input_context();
}


/** '$input_context'(-List) is det.

True if List is a  list   of  input(Type,File,Line) terms describing the
current input context.
*/

static
PRED_IMPL("$input_context", 1, input_context, 0)
{ PRED_LD
  term_t tail   = PL_copy_term_ref(A1);
  term_t head   = PL_new_term_ref();
  term_t stream = PL_new_term_ref();
  InputContext c = input_context_stack;

  for(c=input_context_stack; c; c=c->previous)
  { atom_t file = c->term_file ? c->term_file : ATOM_minus;
    int line = c->term_file ? c->term_line : 0;

    PL_put_variable(stream);

    if ( !PL_unify_stream_or_alias(stream, c->stream) ||
	 !PL_unify_list(tail, head, tail) ||
	 !PL_unify_term(head, PL_FUNCTOR, FUNCTOR_input4,
			PL_ATOM, c->type,
			PL_ATOM, file,
			PL_INT,  line,
			PL_TERM, stream) )
      return FALSE;
  }

  return PL_unify_nil(tail);
}


void
pushOutputContext(void)
{ GET_LD
  OutputContext c = allocHeapOrHalt(sizeof(struct output_context));

  c->stream            = Scurout;
  c->previous          = output_context_stack;
  output_context_stack = c;
}


void
popOutputContext(void)
{ GET_LD
  OutputContext c = output_context_stack;

  if ( c )
  { if ( c->stream->magic == SIO_MAGIC )
      Scurout = c->stream;
    else
    { Sdprintf("Oops, current stream closed?");
      Scurout = Soutput;
    }
    output_context_stack = c->previous;
    freeHeap(c, sizeof(struct output_context));
  } else
    Scurout = Soutput;
}


int
setupOutputRedirect(term_t to, redir_context *ctx, int redir)
{ GET_LD
  atom_t a;

  ctx->term = to;
  ctx->redirected = redir;

  if ( to == 0 )
  { if ( !(ctx->stream = getStream(Scurout)) )
      return no_stream(to, ATOM_current_output);
    ctx->is_stream = TRUE;
  } else if ( PL_get_atom(to, &a) )
  { if ( a == ATOM_user )
    { if ( !(ctx->stream = getStream(Suser_output)) )
	return no_stream(to, ATOM_user);
      ctx->is_stream = TRUE;
    } else if ( get_stream_handle(a, &ctx->stream, SH_OUTPUT|SH_ERRORS) )
    { if ( !(ctx->stream->flags &SIO_OUTPUT) )
      { releaseStream(ctx->stream);
	return PL_error(NULL, 0, NULL, ERR_PERMISSION,
			ATOM_output, ATOM_stream, to);
      }

      ctx->is_stream = TRUE;
    } else
      return FALSE;
  } else
  { if ( PL_is_functor(to, FUNCTOR_codes2) )
    { ctx->out_format = PL_CODE_LIST;
      ctx->out_arity = 2;
    } else if ( PL_is_functor(to, FUNCTOR_codes1) )
    { ctx->out_format = PL_CODE_LIST;
      ctx->out_arity = 1;
    } else if ( PL_is_functor(to, FUNCTOR_chars2) )
    { ctx->out_format = PL_CHAR_LIST;
      ctx->out_arity = 2;
    } else if ( PL_is_functor(to, FUNCTOR_chars1) )
    { ctx->out_format = PL_CHAR_LIST;
      ctx->out_arity = 1;
    } else if ( PL_is_functor(to, FUNCTOR_string1) )
    { ctx->out_format = PL_STRING;
      ctx->out_arity = 1;
    } else if ( PL_is_functor(to, FUNCTOR_atom1) )
    { ctx->out_format = PL_ATOM;
      ctx->out_arity = 1;
    } else
    { return PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_output, to);
    }

    ctx->is_stream = FALSE;
    ctx->data = ctx->buffer;
    ctx->size = sizeof(ctx->buffer);
    ctx->stream = Sopenmem(&ctx->data, &ctx->size, "w");
    ctx->stream->encoding = ENC_WCHAR;
  }

  ctx->magic = REDIR_MAGIC;

  if ( redir )
  { pushOutputContext();
    Scurout = ctx->stream;
  }

  return TRUE;
}


int
closeOutputRedirect(redir_context *ctx)
{ int rval = TRUE;

  if ( ctx->magic != REDIR_MAGIC )
    return rval;			/* already done */
  ctx->magic = 0;

  if ( ctx->redirected )
    popOutputContext();

  if ( ctx->is_stream )
  { rval = streamStatus(ctx->stream);
  } else
  { GET_LD
    term_t out  = PL_new_term_ref();
    term_t diff, tail;

    if ( Sclose(ctx->stream) == 0 )
    { _PL_get_arg(1, ctx->term, out);
      if ( ctx->out_arity == 2 )
      { diff = PL_new_term_ref();
	_PL_get_arg(2, ctx->term, diff);
	tail = PL_new_term_ref();
      } else
      { diff = tail = 0;
      }

      rval = PL_unify_wchars_diff(out, tail, ctx->out_format,
				  ctx->size/sizeof(wchar_t),
				  (wchar_t*)ctx->data);
      if ( rval && tail )
	rval = PL_unify(tail, diff);
    } else
      rval = FALSE;

    if ( ctx->data != ctx->buffer )
      Sfree(ctx->data);
  }

  return rval;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
discardOutputRedirect() is called if the `implementation' failed. One of
the reasons for failure  can  be   that  the  implementation  detected a
pending I/O stream error, in which case continuation is meaningless.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

void
discardOutputRedirect(redir_context *ctx)
{ if ( ctx->magic != REDIR_MAGIC )
    return;				/* already done */

  ctx->magic = 0;

  if ( ctx->redirected )
    popOutputContext();

  if ( ctx->is_stream )
  { streamStatus(ctx->stream);
  } else
  { closeStream(ctx->stream);
    if ( ctx->data != ctx->buffer )
      Sfree(ctx->data);
  }
}

/** @pred  with_output_to(+ _Ouput_,: _Goal_)


This SWI-Prolog predicate runs  _Goal_ as once/1, while characters written to the current
output are sent to  _Output_.

This predicate supports creating
difference-lists from character data efficiently. The example below
defines the DCG rule `term/3` to insert a term in the output:

~~~~~
 term(Term, In, Tail) :-
        with_output_to(codes(In, Tail), write(Term)).

?- phrase(term(hello), X).

X = [104, 101, 108, 108, 111]
~~~~~

+ A Stream handle or alias
Temporary switch current output to the given stream. Redirection using with_output_to/2 guarantees the original output is restored, also if Goal fails or raises an exception. See also call_cleanup/2.
+ atom(- _Atom_)
Create an atom from the emitted characters. Please note that there is a cost in creating atoms.
+ string(- _String_)
Create a string-object.
+ codes(- _Codes_)
Create a list of character codes from the emitted characters, similar to atom_codes/2.
+ codes(- _Codes_, - _Tail_)
Create a list of character codes as a difference-list.
+ chars(- _Chars_)
Create a list of one-character-atoms codes from the emitted characters, similar to atom_chars/2.
+ chars(- _Chars_, - _Tail_)
Create a list of one-character-atoms as a difference-list.
 */
static
PRED_IMPL("with_output_to", 2, with_output_to, PL_FA_TRANSPARENT)
{ redir_context outctx;
  outctx.magic = 0;

  if ( setupOutputRedirect(A1, &outctx, TRUE) )
  { term_t ex = 0;
    int rval;

    if ( (rval = callProlog(NULL, A2, PL_Q_CATCH_EXCEPTION, &ex)) )
      return closeOutputRedirect(&outctx);
    discardOutputRedirect(&outctx);
    if ( ex )
      return PL_raise_exception(ex);
  }

  return FALSE;
}



void
PL_write_prompt(int dowrite)
{ GET_LD
#if __YAP_PROLOG__
  IOSTREAM *s = getStream(Suser_error);
#else
  IOSTREAM *s = getStream(Suser_output);
#endif

  if ( s )
  { if ( dowrite )
    { atom_t a = PrologPrompt();

      if ( a )
	writeAtomToStream(s, a);
    }
    Sflush(s);
    releaseStream(s);
  }

  LD->prompt.next = FALSE;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Get a single character from Sinput  without   waiting  for a return. The
character should not be echoed.  If   PLFLAG_TTY_CONTROL  is false this
function will read the first character and  then skip all character upto
and including the newline.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static int
Sgetcode_intr(IOSTREAM *s, int signals)
{ int c;

#ifdef __WINDOWS__
  int newline = s->newline;
  s->newline = SIO_NL_POSIX;		/* avoid blocking \r */
#endif
  do
  { Sclearerr(s);
    c = Sgetcode(s);
  } while ( c == -1 &&
	    errno == EINTR &&
	    (!signals || PL_handle_signals() >= 0)
	  );
#ifdef __WINDOWS__
  s->newline = newline;
#endif

  return c;
}


int
getSingleChar(IOSTREAM *stream, int signals)
{ GET_LD
  int c;
  ttybuf buf;

  suspendTrace(TRUE);
  Slock(stream);
  Sflush(stream);
  PushTty(stream, &buf, TTY_RAW);	/* just donot prompt */

  if ( !truePrologFlag(PLFLAG_TTY_CONTROL) )
  { int c2;

    c2 = Sgetcode_intr(stream, signals);
    while( c2 == ' ' || c2 == '\t' )	/* skip blanks */
      c2 = Sgetcode_intr(stream, signals);
    c = c2;
    while( c2 != EOF && c2 != '\n' )	/* read upto newline */
      c2 = Sgetcode_intr(stream, signals);
  } else
  { if ( stream->position )
    { IOPOS oldpos = *stream->position;
      c = Sgetcode_intr(stream, signals);
      *stream->position = oldpos;
    } else
      c = Sgetcode_intr(stream, signals);
  }

  if ( c == 4 || c == 26 )		/* should ask the terminal! */
    c = -1;

  PopTty(stream, &buf, TRUE);
  suspendTrace(FALSE);
  Sunlock(stream);

  return c;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
readLine() reads a line from the terminal.  It is used only by the tracer.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifndef DEL
#define DEL 127
#endif

bool
readLine(IOSTREAM *in, IOSTREAM *out, char *buffer)
{ GET_LD
  int c;
  char *buf = &buffer[strlen(buffer)];
  ttybuf tbuf;

  Slock(in);
  Slock(out);

  PushTty(in, &tbuf, TTY_RAW);		/* just donot prompt */

  for(;;)
  { Sflush(out);

    switch( (c=Sgetcode_intr(in, FALSE)) )
    { case '\n':
      case '\r':
      case EOF:
        *buf++ = EOS;
        PopTty(in, &tbuf, TRUE);
	Sunlock(in);
	Sunlock(out);

	return c == EOF ? FALSE : TRUE;
      case '\b':
      case DEL:
	if ( truePrologFlag(PLFLAG_TTY_CONTROL) && buf > buffer )
	{ Sfputs("\b \b", out);
	  buf--;
	  continue;
	}
        /*FALLTHROUGH*/
      default:
	if ( truePrologFlag(PLFLAG_TTY_CONTROL) )
	  Sputcode(c, out);
	*buf++ = c;
    }
  }
  return FALSE; /* make eclipse happy */
}


IOSTREAM *
PL_current_input()
{ GET_LD
  return getStream(Scurin);
}


IOSTREAM *
PL_current_output()
{ GET_LD
  return getStream(Scurout);
}


static int
openProtocol(term_t f, int appnd)
{ GET_LD
  IOSTREAM *s;
  term_t mode = PL_new_term_ref();

  noprotocol();

  PL_put_atom(mode, appnd ? ATOM_append : ATOM_write);
  if ( (s = openStream(f, mode, 0)) )
  { s->flags |= SIO_NOCLOSE;		/* do not close on abort */

    Sprotocol = s;
    Suser_input->tee = s;
    Suser_output->tee = s;
    Suser_error->tee = s;

    return TRUE;
  }

  return FALSE;
}

static int
noprotocol(void)
{ GET_LD
  IOSTREAM *s;

  if ( Sprotocol && (s = getStream(Sprotocol)) )
  { TableEnum e;
    Symbol symb;

    e = newTableEnum(streamContext);
    while( (symb=advanceTableEnum(e)) )
    { IOSTREAM *p = symb->name;

      if ( p->tee == s )
	p->tee = NULL;
    }
    freeTableEnum(e);

    closeStream(s);
    Sprotocol = NULL;
  }

  return TRUE;
}

/** @pred noprotocol

Stop protocolling user interaction.
*/
static
PRED_IMPL("noprotocol", 0, noprotocol, 0)
{ return noprotocol();
}

//! @}

//  @{
//


		 /*******************************
		 *	 STREAM ATTRIBUTES	*
		 *******************************/

static int
setCloseOnExec(IOSTREAM *s, int val)
{ int fd;

  if ( (fd = Sfileno(s)) < 0)
    return FALSE;

#if defined(F_SETFD) && defined(FD_CLOEXEC)
  { int fd_flags = fcntl(fd, F_GETFD);

    if ( fd_flags == -1 )
      return FALSE;
    if ( val )
      fd_flags |= FD_CLOEXEC;
    else
      fd_flags &= ~FD_CLOEXEC;

    if ( fcntl(fd, F_SETFD, fd_flags) == -1 )
      return FALSE;
  }
#elif defined __WINDOWS__
  { if ( !SetHandleInformation((HANDLE)_get_osfhandle(fd),
			       HANDLE_FLAG_INHERIT, !val) )
      return FALSE;
  }
#else
  return -1;
#endif

  return TRUE;
}

/* returns TRUE: ok, FALSE: error, -1: not available
*/

static int
set_stream(IOSTREAM *s, term_t stream, atom_t aname, term_t a ARG_LD)
{ if ( aname == ATOM_alias )	/* alias(name) */
  { atom_t alias;
    int i;

    if ( !PL_get_atom_ex(a, &alias) )
      return FALSE;

    if ( (i=standardStreamIndexFromName(alias)) >= 0 )
    { LD->IO.streams[i] = s;
      if ( i == 0 )
	LD->prompt.next = TRUE;	/* changed standard input: prompt! */
      return TRUE;
    }

    LOCK();
    aliasStream(s, alias);
    UNLOCK();
    return TRUE;
  } else if ( aname == ATOM_buffer ) /* buffer(Buffering) */
  { atom_t b;

#define SIO_ABUF (SIO_FBUF|SIO_LBUF|SIO_NBUF)
    if ( !PL_get_atom_ex(a, &b) )
      return FALSE;
    if ( b == ATOM_full )
    { s->flags &= ~SIO_ABUF;
      s->flags |= SIO_FBUF;
    } else if ( b == ATOM_line )
    { s->flags &= ~SIO_ABUF;
      s->flags |= SIO_LBUF;
    } else if ( b == ATOM_false )
    { Sflush(s);
      s->flags &= ~SIO_ABUF;
      s->flags |= SIO_NBUF;
    } else
    { return PL_error("set_stream", 2, NULL, ERR_DOMAIN,
		      ATOM_buffer, a);
    }
    return TRUE;
  } else if ( aname == ATOM_buffer_size )
  { int size;

    if ( !PL_get_integer_ex(a, &size) )
      return FALSE;
    if ( size < 1 )
      return PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_not_less_than_one, a);
    Ssetbuffer(s, NULL, size);
    return TRUE;
  } else if ( aname == ATOM_eof_action ) /* eof_action(Action) */
  { atom_t action;

    if ( !PL_get_atom_ex(a, &action) )
      return FALSE;
    if ( action == ATOM_eof_code )
    { s->flags &= ~(SIO_NOFEOF|SIO_FEOF2ERR);
    } else if ( action == ATOM_reset )
    { s->flags &= ~SIO_FEOF2ERR;
      s->flags |= SIO_NOFEOF;
    } else if ( action == ATOM_error )
    { s->flags &= ~SIO_NOFEOF;
      s->flags |= SIO_FEOF2ERR;
    } else
    { PL_error("set_stream", 2, NULL, ERR_DOMAIN,
	       ATOM_eof_action, a);
      return FALSE;
    }

    return TRUE;
  } else if ( aname == ATOM_type ) /* type(Type) */
  { atom_t type;

    if ( !PL_get_atom_ex(a, &type) )
      return FALSE;
    if ( type == ATOM_text )
    { if ( False(s, SIO_TEXT) && Ssetenc(s, LD->encoding, NULL) != 0 )
	return PL_error(NULL, 0, NULL, ERR_PERMISSION,
			ATOM_encoding, ATOM_stream, stream);
      s->flags |= SIO_TEXT;
    } else if ( type == ATOM_binary )
    { if ( True(s, SIO_TEXT) && Ssetenc(s, ENC_OCTET, NULL) != 0 )
	return PL_error(NULL, 0, NULL, ERR_PERMISSION,
			ATOM_encoding, ATOM_stream, stream);

      s->flags &= ~SIO_TEXT;
    } else
    { return PL_error("set_stream", 2, NULL, ERR_DOMAIN,
		      ATOM_type, a);
    }

    return TRUE;
  } else if ( aname == ATOM_close_on_abort ) /* close_on_abort(Bool) */
  { int close;

    if ( !PL_get_bool_ex(a, &close) )
      return FALSE;

    if ( close )
      s->flags &= ~SIO_NOCLOSE;
    else
      s->flags |= SIO_NOCLOSE;

    return TRUE;
  } else if ( aname == ATOM_record_position )
  { int rec;

    if ( !PL_get_bool_ex(a, &rec) )
      return FALSE;

    if ( rec )
      s->position = &s->posbuf;
    else
      s->position = NULL;

    return TRUE;
  } else if ( aname == ATOM_line_position )
  { int lpos;

    if ( !PL_get_integer_ex(a, &lpos) )
      return FALSE;

    if ( s->position )
      s->position->linepos = lpos;
    else
      return PL_error(NULL, 0, NULL, ERR_PERMISSION,
		      ATOM_line_position, ATOM_stream, stream);

    return TRUE;
  } else if ( aname == ATOM_file_name ) /* file_name(Atom) */
  {	atom_t fn;

    if ( !PL_get_atom_ex(a, &fn) )
      return FALSE;

    setFileNameStream(s, fn);

    return TRUE;
  } else if ( aname == ATOM_timeout )
  { double f;
    atom_t v;

    if ( PL_get_atom(a, &v) && v == ATOM_infinite )
    { s->timeout = -1;
      return TRUE;
    }
    if ( !PL_get_float_ex(a, &f) )
      return FALSE;

    s->timeout = (int)(f*1000.0);
    if ( s->timeout < 0 )
      s->timeout = 0;
    return TRUE;
  } else if ( aname == ATOM_tty )	/* tty(bool) */
  {	int val;

    if ( !PL_get_bool_ex(a, &val) )
      return FALSE;

    if ( val )
      set(s, SIO_ISATTY);
    else
      clear(s, SIO_ISATTY);

    return TRUE;
  } else if ( aname == ATOM_encoding )	/* encoding(atom) */
  {	atom_t val;
    IOENC enc;

    if ( !PL_get_atom_ex(a, &val) )
      return FALSE;
    if ( (enc = atom_to_encoding(val)) == ENC_UNKNOWN )
    { bad_encoding(NULL, val);
      return FALSE;
    }

    if ( Ssetenc(s, enc, NULL) == 0 )
      return TRUE;

    return PL_error(NULL, 0, NULL, ERR_PERMISSION,
		    ATOM_encoding, ATOM_stream, stream);
#ifdef O_LOCALE
  } else if ( aname == ATOM_locale )	/* locale(Locale) */
  {	PL_locale *val;

    if ( !getLocaleEx(a, &val) )
      return FALSE;
    if ( Ssetlocale(s, val, NULL) == 0 )
      return TRUE;

    return PL_error(NULL, 0, NULL, ERR_PERMISSION,
		    ATOM_locale, ATOM_stream, stream);
#endif
  } else if ( aname == ATOM_representation_errors )
  { atom_t val;

    if ( !PL_get_atom_ex(a, &val) )
      return FALSE;

    clear(s, SIO_REPXML|SIO_REPPL);

    if ( val == ATOM_error ) {
      ;
    } else if ( val == ATOM_xml )
      set(s, SIO_REPXML);
    else if ( val == ATOM_prolog )
      set(s, SIO_REPPL);
    else
      return PL_error(NULL, 0, NULL, ERR_DOMAIN,
		      ATOM_representation_errors, a);

    return TRUE;
  } else if ( aname == ATOM_newline )
  { atom_t val;

    if ( !PL_get_atom_ex(a, &val) )
      return FALSE;
    if ( val == ATOM_posix )
      s->newline = SIO_NL_POSIX;
    else if ( val == ATOM_dos )
      s->newline = SIO_NL_DOS;
    else if ( val == ATOM_detect )
    { if ( False(s, SIO_INPUT) )
	return PL_error(NULL, 0, "detect only allowed for input streams",
			ERR_DOMAIN, ATOM_newline, a);
      s->newline = SIO_NL_DETECT;
    } else
      return PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_newline, a);

    return TRUE;
  } else if ( aname == ATOM_close_on_exec ) /* close_on_exec(bool) */
  { int val;

    if ( !PL_get_bool_ex(a, &val) )
      return FALSE;

    return setCloseOnExec(s, val);
  } else
  { assert(0);
    return FALSE;
  }
}


typedef struct set_stream_info
{ atom_t name;
  int    flags;
} set_stream_info;

#define SS_READ		0x01
#define SS_WRITE	0x02
#define SS_BOTH		(SS_READ|SS_WRITE)
#define SS_NOPAIR	(0x4|SS_BOTH)

#define SS_INFO(name, flags) { name, flags }

static const set_stream_info ss_info[] =
{ SS_INFO(ATOM_alias,		      SS_NOPAIR),
  SS_INFO(ATOM_buffer,		      SS_BOTH),
  SS_INFO(ATOM_buffer_size,	      SS_BOTH),
  SS_INFO(ATOM_eof_action,	      SS_READ),
  SS_INFO(ATOM_type,		      SS_BOTH),
  SS_INFO(ATOM_close_on_abort,	      SS_BOTH),
  SS_INFO(ATOM_record_position,	      SS_BOTH),
  SS_INFO(ATOM_line_position,	      SS_NOPAIR),
  SS_INFO(ATOM_file_name,	      SS_BOTH),
  SS_INFO(ATOM_timeout,		      SS_BOTH),
  SS_INFO(ATOM_tty,		      SS_BOTH),
  SS_INFO(ATOM_encoding,	      SS_BOTH),
  SS_INFO(ATOM_locale,		      SS_BOTH),
  SS_INFO(ATOM_representation_errors, SS_WRITE),
  SS_INFO(ATOM_newline,		      SS_BOTH),
  SS_INFO(ATOM_close_on_exec,	      SS_BOTH),
  SS_INFO((atom_t)0,		      0)
};

/** @pred  set_stream(+ _S_, + _Prop_) is iso


Set a property _Prop_ for a stream  _S_.

*/
static
PRED_IMPL("set_stream", 2, set_stream, 0)
{ PRED_LD
  IOSTREAM *s;
  atom_t sblob, aname;
  stream_ref *ref;
  PL_blob_t *type;
  int rc, arity;
  const set_stream_info *info;
  term_t aval = PL_new_term_ref();

  term_t stream = A1;
  term_t attr = A2;

  if ( PL_get_name_arity(attr, &aname, &arity) && arity == 1 )
  { for(info = ss_info; info->name; info++)
    { if ( info->name == aname )
	goto found;
    }
    return PL_domain_error("stream_attribute", attr);
  } else
    return PL_type_error("stream_attribute", attr);

found:
  _PL_get_arg(1, attr, aval);

  if ( !PL_get_atom(stream, &sblob) )
    return not_a_stream(stream);

  ref = PL_blob_data(sblob, NULL, &type);
  if ( type == &stream_blob )		/* got a stream handle */
  { if ( ref->read && ref->write &&	/* stream pair */
	 (info->flags & SS_NOPAIR) )
      return PL_error("set_stream", 2, NULL, ERR_PERMISSION,
		      aname, ATOM_stream_pair, stream);

    rc = TRUE;
    if ( ref->read && (info->flags&SS_READ))
    { if ( !(s = getStream(ref->read)) )
        return symbol_no_stream(sblob);
      rc = set_stream(s, stream, aname, aval PASS_LD);
      releaseStream(ref->read);
    }
    if ( rc && ref->write && (info->flags&SS_WRITE) )
    { if ( !(s = getStream(ref->write)) )
        return symbol_no_stream(sblob);
      rc = set_stream(s, stream, aname, aval PASS_LD);
      releaseStream(ref->write);
    }
  } else if ( PL_get_stream_handle(stream, &s) )
  { rc = set_stream(s, stream, aname, aval PASS_LD);
    releaseStream(s);
  } else
    rc = FALSE;

  if ( rc < 0 )				/* not on this OS */
    return PL_domain_error("stream_attribute", attr);

  return rc;
}


#ifdef _MSC_VER					/* defined in pl-nt.c */
extern int ftruncate(int fileno, int64_t length);
#define HAVE_FTRUNCATE
#endif

/** @pred  set_end_of_stream(+ _S_ ) is iso

Set stream position  to be the end of stream.

*/
static
PRED_IMPL("set_end_of_stream", 1, set_end_of_stream, 0)
{ IOSTREAM *s;
  int rc;

  if ( (rc=PL_get_stream_handle(A1, &s)) )
  {
#ifdef HAVE_FTRUNCATE
    int fileno = Sfileno(s);

    if ( fileno >= 0 )
    { if ( ftruncate(fileno, Stell64(s)) != 0 )
	rc = PL_error(NULL, 0, MSG_ERRNO, ERR_FILE_OPERATION,
		      ATOM_set_end_of_stream, ATOM_stream,
		      A1);
    } else
    { rc = PL_error(NULL, 0, "not a file", ERR_PERMISSION,
		    ATOM_set_end_of_stream, ATOM_stream, A1);
    }
#else
    rc = notImplemented("set_end_of_stream", 1);
#endif

    releaseStream(s);
  }

  return rc;
}



		/********************************
		*          STRING I/O           *
		*********************************/

extern IOFUNCTIONS Smemfunctions;

bool
tellString(char **s, size_t *size, IOENC enc)
{ GET_LD
  IOSTREAM *stream;

  stream = Sopenmem(s, size, "w");
  stream->encoding = enc;
  pushOutputContext();
  Scurout = stream;

  return TRUE;
}


bool
toldString(void)
{ GET_LD
  IOSTREAM *s = getStream(Scurout);

  if ( !s )
    return TRUE;

  if ( s->functions == &Smemfunctions )
  { closeStream(s);
    popOutputContext();
  } else
    releaseStream(s);

  return TRUE;
}


		/********************************
		*       WAITING FOR INPUT	*
		********************************/

#ifndef HAVE_SELECT

/** @pred  wait_for_input(+ _Streams_, -_Available_, - _Timeout_) is iso
 *
 *  Implement the select operation over a set of stream _Streams, with
 *  _Available_ unified with all ready streams. The operation can last at most
 *  _Timeout_ seconds.
 *
 *
*/
static
PRED_IMPL("wait_for_input", 3, wait_for_input, 0)
{ return notImplemented("wait_for_input", 3);
}

#else

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Windows<->Unix note. This function uses the   Windows socket API for its
implementation and defines the Unix API  in   terms  of the Windows API.
This approach allows full support  of   the  restrictions of the Windows
implementation. Because the Unix emulation is   more generic, this still
supports  the  generic  facilities  of  Unix  select()  that  make  this
predicate work on pipes, serial devices, etc.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifndef __WINDOWS__
typedef int SOCKET;
#define INVALID_SOCKET -1
#define Swinsock(s) Sfileno(s)
#define NFDS(max) (max+1)			/* see also S__wait() */
#else
#define NFDS(n) 0
#endif

typedef struct fdentry
{ SOCKET fd;
  term_t stream;
  struct fdentry *next;
} fdentry;


static
PRED_IMPL("wait_for_input", 3, wait_for_input, 0)
{ PRED_LD
  fd_set fds;
  struct timeval t, *to;
  double time;
  int rc;
#ifndef __WINDOWS__
  SOCKET max = 0, min = INT_MAX;
#endif
  fdentry *map     = NULL;
  term_t head      = PL_new_term_ref();
  term_t streams   = PL_copy_term_ref(A1);
  term_t available = PL_copy_term_ref(A2);
  term_t ahead     = PL_new_term_ref();
  int from_buffer  = 0;
  atom_t a;

  term_t timeout = A3;

  FD_ZERO(&fds);
  while( PL_get_list(streams, head, streams) )
  { IOSTREAM *s;
    SOCKET fd;
    fdentry *e;

    if ( !PL_get_stream_handle(head, &s) )
      return FALSE;
    if ( (fd=Swinsock(s)) < 0 )
    { releaseStream(s);
      return PL_error("wait_for_input", 3, NULL, ERR_DOMAIN,
		      PL_new_atom("file_stream"), head);
    }
    releaseStream(s);
					/* check for input in buffer */
    if ( s->bufp < s->limitp )
    { if ( !PL_unify_list(available, ahead, available) ||
	   !PL_unify(ahead, head) )
	return FALSE;
      from_buffer++;
    }

    e         = alloca(sizeof(*e));
    e->fd     = fd;
    e->stream = PL_copy_term_ref(head);
    e->next   = map;
    map       = e;

    FD_SET(fd, &fds);
#ifndef __WINDOWS__
    if ( fd > max )
      max = fd;
    if( fd < min )
      min = fd;
#endif
  }
  if ( !PL_get_nil(streams) )
    return PL_error("wait_for_input", 3, NULL, ERR_TYPE, ATOM_list, A1);

  if ( from_buffer > 0 )
    return PL_unify_nil(available);

  if ( PL_get_atom(timeout, &a) && a == ATOM_infinite )
  { to = NULL;
  } else if ( PL_is_integer(timeout) )
  { long v;

    PL_get_long(timeout, &v);
    if ( v > 0L )
    { t.tv_sec = v;
      t.tv_usec = 0;
      to = &t;
    } else if ( v == 0 )
    { to = NULL;
    } else
    { t.tv_sec  = 0;
      t.tv_usec = 0;
      to = &t;
    }
  } else
  { if ( !PL_get_float(timeout, &time) )
      return PL_error("wait_for_input", 3, NULL,
		      ERR_TYPE, ATOM_float, timeout);

    if ( time >= 0.0 )
    { t.tv_sec  = (int)time;
      t.tv_usec = ((int)(time * 1000000) % 1000000);
    } else
    { t.tv_sec  = 0;
      t.tv_usec = 0;
    }
    to = &t;
  }

  while( (rc=select(NFDS(max), &fds, NULL, NULL, to)) == -1 &&
	 errno == EINTR )
  { fdentry *e;

    if ( PL_handle_signals() < 0 )
      return FALSE;				/* exception */

    FD_ZERO(&fds);			/* EINTR may leave fds undefined */
    for(e=map; e; e=e->next)		/* so we rebuild it to be safe */
      FD_SET(e->fd, &fds);
  }

  switch(rc)
  { case -1:
      return PL_error("wait_for_input", 3, MSG_ERRNO, ERR_FILE_OPERATION,
		      ATOM_select, ATOM_stream, A1);

    case 0: /* Timeout */
      break;

    default: /* Something happend -> check fds */
    { fdentry *mp;

      for(mp=map; mp; mp=mp->next)
      { if ( FD_ISSET(mp->fd, &fds) )
	{ if ( !PL_unify_list(available, ahead, available) ||
	       !PL_unify(ahead, mp->stream) )
	    return FALSE;
	}
      }
      break;
    }
  }

  return PL_unify_nil(available);
}

#endif /* HAVE_SELECT */


		/********************************
		*      PROLOG CONNECTION        *
		*********************************/

#define MAX_PENDING SIO_BUFSIZE		/* 4096 */

static void
re_buffer(IOSTREAM *s, const char *from, size_t len)
{ if ( s->bufp < s->limitp )
  { size_t size = s->limitp - s->bufp;

    memmove(s->buffer, s->bufp, size);
    s->bufp = s->buffer;
    s->limitp = &s->bufp[size];
  } else
  { s->bufp = s->limitp = s->buffer;
  }

  memcpy(s->bufp, from, len);
  s->bufp += len;
}


#ifndef HAVE_MBSNRTOWCS
static size_t
mbsnrtowcs(wchar_t *dest, const char **src,
	   size_t nms, size_t len, mbstate_t *ps)
{ wchar_t c;
  const char *us = *src;
  const char *es = us+nms;
  size_t count = 0;

  assert(dest == NULL);			/* incomplete implementation */

  while(us<es)
  { size_t skip = mbrtowc(&c, us, es-us, ps);

    if ( skip == (size_t)-1 )		/* error */
    { DEBUG(1, Sdprintf("mbsnrtowcs(): bad multibyte seq\n"));
      return skip;
    }
    if ( skip == (size_t)-2 )		/* incomplete */
    { *src = us;
      return count;
    }

    count++;
    us += skip;
  }

  *src = us;
  return count;
}
#else
#if defined(HAVE_DECL_MBSNRTOWCS) && !HAVE_DECL_MBSNRTOWCS
size_t mbsnrtowcs(wchar_t *dest, const char **src,
		  size_t nms, size_t len, mbstate_t *ps);
#endif
#endif /*HAVE_MBSNRTOWCS*/

static int
skip_cr(IOSTREAM *s)
{ if ( s->flags&SIO_TEXT )
  { switch(s->newline)
    { case SIO_NL_DETECT:
	s->newline = SIO_NL_DOS;
        /*FALLTHROUGH*/
      case SIO_NL_DOS:
	return TRUE;
    }
  }
  return FALSE;
}

/** @pred read_pending_input( _Stream_ , _Codes_, _End_ )
 *
 * Reads all characters or bytes currently available from _Stream_ to the difference
 * list _Codes_ - _End_. This SWI predicate allows cleaning up input from unbuffered
 * streams.
 */
static
PRED_IMPL("read_pending_input", 3, read_pending_input, 0)
{ PRED_LD
  IOSTREAM *s;

  if ( getInputStream(A1, S_DONTCARE, &s) )
  { char buf[MAX_PENDING];
    ssize_t n;
    int64_t off0 = Stell64(s);
    IOPOS pos0;
    list_ctx ctx;

    if ( Sferror(s) )
      return streamStatus(s);

    n = Sread_pending(s, buf, sizeof(buf), 0);
    if ( n < 0 )			/* should not happen */
      return streamStatus(s);
    if ( n == 0 )			/* end-of-file */
    { S__fcheckpasteeof(s, -1);
      return PL_unify(A2, A3);
    }
    if ( s->position )
    { pos0 = *s->position;
    } else
    { memset(&pos0, 0, sizeof(pos0));	/* make compiler happy */
    }

    switch(s->encoding)
    { case ENC_OCTET:
      case ENC_ISO_LATIN_1:
      case ENC_ASCII:
      { ssize_t i;

	if ( !allocList(n, &ctx) )
	  return FALSE;

	for(i=0; i<n; i++)
	{ int c = buf[i]&0xff;

	  if ( c == '\r' && skip_cr(s) )
	    continue;

	  if ( s->position )
	    S__fupdatefilepos_getc(s, c);

	  addSmallIntList(&ctx, c);
	}
	if ( s->position )
	  s->position->byteno = pos0.byteno+n;

	break;
      }
      case ENC_ANSI:
      { size_t count, i;
	mbstate_t s0;
	const char *us = buf;
	const char *es = buf+n;

	if ( !s->mbstate )
	{ if ( !(s->mbstate = malloc(sizeof(*s->mbstate))) )
	  { PL_error(NULL, 0, NULL, ERR_NOMEM);
	    goto failure;
	  }
	  memset(s->mbstate, 0, sizeof(*s->mbstate));
	}
	s0 = *s->mbstate;
	count = mbsnrtowcs(NULL, &us, n, 0, &s0);
	if ( count == (size_t)-1 )
	{ Sseterr(s, SIO_WARN, "Illegal multibyte Sequence");
	  goto failure;
	}

	DEBUG(2, Sdprintf("Got %ld codes from %d bytes; incomplete: %ld\n",
			  count, n, es-us));

	if ( !allocList(count, &ctx) )
	  return FALSE;

	for(us=buf,i=0; i<count; i++)
	{ wchar_t c;

	  us += mbrtowc(&c, us, es-us, s->mbstate);
	  if ( c == '\r' && skip_cr(s) )
	    continue;
	  if ( s->position )
	    S__fupdatefilepos_getc(s, c);

	  addSmallIntList(&ctx, c);
	}
	if ( s->position )
	  s->position->byteno = pos0.byteno+us-buf;

	re_buffer(s, us, es-us);
        break;
      }
      case ENC_UTF8:
      { const char *us = buf;
	const char *es = buf+n;
	size_t count = 0, i;

	while(us<es)
	{ if ( !(us[0]&0x80) )
	  { count++;
	    us++;
	  } else
	  { int ex = UTF8_FBN(us[0]);

	    if ( ex >= 0 )
	    { const char *ec = us + ex + 1;

	      if ( ec <= es )
	      { count++;
		us=ec;
	      } else			/* incomplete multi-byte */
		break;
	    } else
	    { Sseterr(s, SIO_WARN, "Illegal multibyte Sequence");
	      goto failure;
	    }
	  }
	}

	DEBUG(2, Sdprintf("Got %ld codes from %d bytes; incomplete: %ld\n",
			  count, n, es-us));

	if ( !allocList(count, &ctx) )
	  return FALSE;

	for(us=buf,i=0; i<count; i++)
	{ int c;

	  us = utf8_get_char(us, &c);
	  if ( c == '\r' && skip_cr(s) )
	    continue;
	  if ( s->position )
	    S__fupdatefilepos_getc(s, c);

	  addSmallIntList(&ctx, c);
	}
	if ( s->position )
	  s->position->byteno = pos0.byteno+us-buf;

	re_buffer(s, us, es-us);
        break;
      }
      case ENC_UNICODE_BE:
      case ENC_UNICODE_LE:
      { size_t count = (size_t)n/2;
	const char *us = buf;
	size_t done, i;

	if ( !allocList(count, &ctx) )
	  return FALSE;

	for(i=0; i<count; us+=2, i++)
	{ int c;

	  if ( s->encoding == ENC_UNICODE_BE )
	    c = ((us[0]&0xff)<<8)+(us[1]&0xff);
	  else
	    c = ((us[1]&0xff)<<8)+(us[0]&0xff);
	  if ( c == '\r' && skip_cr(s) )
	    continue;

	  if ( s->position )
	    S__fupdatefilepos_getc(s, c);

	  addSmallIntList(&ctx, c);
	}

	done = count*2;
	if ( s->position )
	  s->position->byteno = pos0.byteno+done;
	re_buffer(s, buf+done, n-done);
        break;
      }
      case ENC_WCHAR:
      { const pl_wchar_t *ws = (const pl_wchar_t*)buf;
	size_t count = (size_t)n/sizeof(pl_wchar_t);
	size_t done, i;

	if ( !allocList(count, &ctx) )
	  return FALSE;

	for(i=0; i<count; i++)
	{ int c = ws[i];

	  if ( c == '\r' && skip_cr(s) )
	    continue;
	  if ( s->position )
	    S__fupdatefilepos_getc(s, c);

	  addSmallIntList(&ctx, c);
	}

	done = count*sizeof(pl_wchar_t);
	if ( s->position )
	  s->position->byteno = pos0.byteno+done;
	re_buffer(s, buf+done, n-done);
        break;
      }
      case ENC_UNKNOWN:
      default:
	assert(0);
        return FALSE;
    }

    if ( !unifyDiffList(A2, A3, &ctx) )
      goto failure;

    releaseStream(s);
    return TRUE;

  failure:
    Sseek64(s, off0, SIO_SEEK_SET);	/* TBD: error? */
    if ( s->position )
      *s->position = pos0;
    releaseStream(s);
    return FALSE;
  }

  return FALSE;
}

//! @}

//! @defgroup CharsIO Character Input/Output
//  @ingroup InputOutput
//  @{
//

static foreign_t
put_byte(term_t stream, term_t byte ARG_LD)
{ IOSTREAM *s;
  int c;

  if ( !PL_get_integer(byte, &c) || c < 0 || c > 255 )
    return PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_byte, byte);
  if ( !getBinaryOutputStream(stream, &s) )
    return FALSE;

  Sputc(c, s);

  return streamStatus(s);
}


/** @pred  put_byte(+ _S_,+ _N_) is iso

As `put_byte(N)`, but to binary stream  _S_.
*/
static
PRED_IMPL("put_byte", 2, put_byte2, 0)
{ PRED_LD

  return put_byte(A1, A2 PASS_LD);
}


/** @pred  put_byte(+ _N_) is iso 


Outputs to the current output stream the character whose code is
 _N_. The current output stream must be a binary stream.
*/
static
PRED_IMPL("put_byte", 1, put_byte1, 0)
{ PRED_LD

  return put_byte(0, A1 PASS_LD);
}


static foreign_t
put_code(term_t stream, term_t chr ARG_LD)
{ IOSTREAM *s;
  int c = 0;

  if ( !PL_get_char(chr, &c, FALSE) )
    return FALSE;
  if ( !getTextOutputStream(stream, &s) )
    return FALSE;

  Sputcode(c, s);

  return streamStatus(s);
}


/** @pred  put_code(+ _S_,+ _N_) is iso

As `put_code(N)`, but to text stream  _S_.

 
*/
/** @pred  put_char(+ _S_,+ _A_) is iso

As `put_char(A)`, but to text stream  _S_.


*/
static
PRED_IMPL("put_code", 2, put_code2, 0)
{ PRED_LD

  return put_code(A1, A2 PASS_LD);
}


/** @pred  put_char(+ _N_) is iso


Outputs to the current output stream the character who is used to build
the representation of atom `A`. The current output stream must be a
text stream.


*/
/** @pred  put_code(+ _N_) is iso 


Outputs to the current output stream the character whose ASCII code is
 _N_. The current output stream must be a text stream. The character
 _N_ must be a legal ASCII character code, an expression yielding such
a code, or a list in which case only the first element is used.

 
*/
static
PRED_IMPL("put_code", 1, put_code1, 0)
{ PRED_LD

  return put_code(0, A1 PASS_LD);
}


/** @pred  put(+ _S_,+ _N_)

As `put(N)`, but to stream  _S_.

 
*/
static
PRED_IMPL("put", 2, put2, 0)
{ PRED_LD

  return put_code(A1, A2 PASS_LD);
}


/** @pred  put(+ _N_) 


Outputs to the current output stream the character whose ASCII code is
 _N_. The character  _N_ must be a legal ASCII character code, an
expression yielding such a code, or a list in which case only the first
element is used.

 
*/
static
PRED_IMPL("put", 1, put1, 0)
{ PRED_LD

  return put_code(0, A1 PASS_LD);
}


static foreign_t
get_nonblank(term_t in, term_t chr ARG_LD)
{ IOSTREAM *s;

  if ( getTextInputStream(in, &s) )
  { int c;

    for(;;)
    { c = Sgetcode(s);

      if ( c == EOF )
      { TRY(PL_unify_integer(chr, -1));
	return streamStatus(s);
      }

      if ( !isBlankW(c) )
      { releaseStream(s);
	return PL_unify_integer(chr, c);
      }
    }
  }

  return FALSE;
}


/** @pred  get(- _C_) 


The next non-blank character from the current input stream is unified
with  _C_. Blank characters are the ones whose ASCII codes are not
greater than 32. If there are no more non-blank characters in the
stream,  _C_ is unified with -1. If `end_of_stream` has already
been reached in the previous reading, this call will give an error message.

 
*/
static
PRED_IMPL("get", 1, get1, 0)
{ PRED_LD

  return get_nonblank(0, A1 PASS_LD);
}


/** @pred  get(+ _S_,- _C_)

The same as `get(C)`, but from stream  _S_.

 
*/
static
PRED_IMPL("get", 2, get2, 0)
{ PRED_LD

  return get_nonblank(A1, A2 PASS_LD);
}


static foreign_t
skip(term_t in, term_t chr ARG_LD)
{ int c = -1;
  int r;
  IOSTREAM *s;

  if ( !PL_get_char(chr, &c, FALSE) )
    return FALSE;
  if ( !getTextInputStream(in, &s) )
    return FALSE;

  while((r=Sgetcode(s)) != c && r != EOF )
    ;

  return streamStatus(s);
}


/** @pred  skip(+ _N_) 


Skips input characters until the next occurrence of the character with
ASCII code  _N_. The argument to this predicate can take the same forms
as those for `put` (see 6.11).

 
*/
static
PRED_IMPL("skip", 1, skip1, 0)
{ PRED_LD

  return skip(0, A1 PASS_LD);
}


/** @pred  skip(+ _S_,- _C_)

Like skip/1, but using stream  _S_ instead of the current
input stream.

 
*/
static
PRED_IMPL("skip", 2, skip2, 0)
{ PRED_LD

  return skip(A1, A2 PASS_LD);
}

/** @pred get_single_char( +_Stream_ )
 *
 * SWI-Prolog predicate that reads the first charcter from `user_input`.
 * This operation is unbuffered,
 * and it does not have to wait for n newline. Spaces and tabulation characters are
 * ignored.
 */
static
PRED_IMPL("get_single_char", 1, get_single_char, 0)
{ GET_LD
  IOSTREAM *s = getStream(Suser_input);
  int c;

  if ( !s )
    return symbol_no_stream(ATOM_user_input);

  c = getSingleChar(s, TRUE);
  if ( c == EOF )
  { if ( PL_exception(0) )
    { releaseStream(s);
      return FALSE;
    }

    PL_unify_integer(A1, -1);
    return streamStatus(s);
  }

  releaseStream(s);

  return PL_unify_integer(A1, c);
}


static foreign_t
get_byte2(term_t in, term_t chr ARG_LD)
{ IOSTREAM *s;

  if ( getBinaryInputStream(in, &s) )
  { int c = Sgetc(s);

    if ( PL_unify_integer(chr, c) )
      return streamStatus(s);

    if ( Sferror(s) )
      return streamStatus(s);

    PL_get_char(chr, &c, TRUE);		/* set type-error */
  }

  return FALSE;
}


/** @pred  get_byte(+ _S_,- _C_) is iso

If  _C_ is unbound, or is a character code, and the stream  _S_ is a
binary stream, read the next byte from that stream and unify its
code with  _C_.

 
*/
static
PRED_IMPL("get_byte", 2, get_byte2, 0)
{ PRED_LD

  return get_byte2(A1, A2 PASS_LD);
}


/** @pred  get_byte(- _C_) is iso 


If  _C_ is unbound, or is a character code, and the current stream is a
binary stream, read the next byte from the current stream and unify its
code with  _C_.

 
*/
static
PRED_IMPL("get_byte", 1, get_byte1, 0)
{ PRED_LD

  return get_byte2(0, A1 PASS_LD);
}

/** @pred  get0(+ _S_,- _C_)

The same as `get0(C)`, but from stream  _S_.


*/
static foreign_t
get_code2(term_t in, term_t chr ARG_LD)
{ IOSTREAM *s;

  if ( getTextInputStream(in, &s) )
  { int c = Sgetcode(s);

    if ( PL_unify_integer(chr, c) )
      return streamStatus(s);

    if ( Sferror(s) )
      return streamStatus(s);

    PL_get_char(chr, &c, TRUE);		/* set type-error */
    releaseStream(s);
  }

  return FALSE;
}


/** @pred  get_code(+ _S_,- _C_) is iso

If  _C_ is unbound, or is a character code, and the stream  _S_ is a
text stream, read the next character from that stream and unify its
code with  _C_.

 
*/
static
PRED_IMPL("get_code", 2, get_code2, 0)
{ PRED_LD
  return get_code2(A1, A2 PASS_LD);
}


/** @pred  get_code(- _C_) is iso 


If  _C_ is unbound, or is the code for a character, and
the current stream is a text stream, read the next character from the
current stream and unify its code with  _C_.

 
*/
static
PRED_IMPL("get_code", 1, get_code1, 0)
{ PRED_LD
  return get_code2(0, A1 PASS_LD);
}


static foreign_t
get_char2(term_t in, term_t chr ARG_LD)
{ IOSTREAM *s;

  if ( getTextInputStream(in, &s) )
  { int c = Sgetcode(s);

    if ( PL_unify_atom(chr, c == -1 ? ATOM_end_of_file : codeToAtom(c)) )
      return streamStatus(s);

    if ( Sferror(s) )
      return streamStatus(s);

    PL_get_char(chr, &c, TRUE);		/* set type-error */
    releaseStream(s);
  }

  return FALSE;
}


/** @pred  get_char(+ _S_,- _C_) is iso

If  _C_ is unbound, or is an atom representation of a character, and
the stream  _S_ is a text stream, read the next character from that
stream and unify its representation as an atom with  _C_.

 
*/
static
PRED_IMPL("get_char", 2, get_char2, 0)
{ PRED_LD
  return get_char2(A1, A2 PASS_LD);
}


/** @pred  get_char(- _C_) is iso 


If  _C_ is unbound, or is an atom representation of a character, and
the current stream is a text stream, read the next character from the
current stream and unify its atom representation with  _C_.

 
*/
static
PRED_IMPL("get_char", 1, get_char1, 0)
{ PRED_LD
  return get_char2(0, A1 PASS_LD);
}


/** @pred  ttyflush

Flush the current output stream.
*/

static
PRED_IMPL("ttyflush", 0, ttyflush, 0)
{ PRED_LD
  IOSTREAM *s = getStream(Suser_output);

  if ( s )
  { Sflush(s);

    return streamStatus(s);
  }

  return symbol_no_stream(ATOM_user_output);
}


/** @pred protocol( _File_ )
 *
 * Start protocolling user interaction to _File_, closing any previous protocolling
 * file and truncating it.
 *
*/
static
PRED_IMPL("protocol", 1, protocol, 0)
{ return openProtocol(A1, FALSE);
}


/** @pred protocola( _File_ )
 *
 * Start protocolling user interaction to _File_, closing any previous protocolling
 * file and then appending it.
 *
*/
static
PRED_IMPL("protocola", 1, protocola, 0)
{ return openProtocol(A1, TRUE);
}

/** @pred protocolling( -_File_ )
 *
 * Report whether we are protocolling and to which _File_.
 *
*/
static
PRED_IMPL("protocolling", 1, protocolling, 0)
{ PRED_LD
  IOSTREAM *s;

  if ( (s = Sprotocol) )
  { atom_t a;

    if ( (a = fileNameStream(s)) )
      return PL_unify_atom(A1, a);
    else
      return PL_unify_stream_or_alias(A1, s);
  }

  return FALSE;
}


/** @pred prompt(- _A_,+ _B_) 

Changes YAP input prompt from  _A_ to  _B_.
*/
static
PRED_IMPL("prompt", 2, prompt, 0)
{ PRED_LD
  atom_t a;

  term_t old = A1;
  term_t new = A2;

  if ( PL_unify_atom(old, LD->prompt.current) &&
       PL_get_atom_ex(new, &a) )
  { if ( LD->prompt.current )
      PL_unregister_atom(LD->prompt.current);
    LD->prompt.current = a;
    PL_register_atom(a);
    return TRUE;
  }

  return FALSE;
}

/** @pred prompt1(+ _Prompt_)

Set the YAP input prompt for the next line.
*/
void
prompt1(atom_t prompt)
{ GET_LD
  if ( LD->prompt.first != prompt )
  { if ( LD->prompt.first )
      PL_unregister_atom(LD->prompt.first);
    LD->prompt.first = prompt;
    PL_register_atom(LD->prompt.first);
  }

  LD->prompt.first_used = FALSE;
}


static
PRED_IMPL("prompt1", 1, prompt1, 0)
{ GET_LD
  atom_t a;
  PL_chars_t txt;

  if ( PL_get_atom(A1, &a) )
  { prompt1(a);
  } else if ( PL_get_text(A1, &txt,  CVT_ALL|CVT_EXCEPTION) )
    { prompt1(YAP_SWIAtomFromAtom(textToAtom(&txt)));
  } else
    return FALSE;

  return TRUE;
}


atom_t
PrologPrompt()
{ GET_LD

  if ( !LD->prompt.first_used && LD->prompt.first )
  { LD->prompt.first_used = TRUE;

    return LD->prompt.first;
  }

  if ( Sinput->position && Sinput->position->linepos == 0 )
    return LD->prompt.current;
  else
    return 0;				/* "" */
}


static int
tab(term_t out, term_t spaces ARG_LD)
{ int64_t count;
  IOSTREAM *s;

  if ( !getTextOutputStream(out, &s) )
    return FALSE;
  if ( !PL_eval_expression_to_int64_ex(spaces, &count) )
    return FALSE;

  while(count-- > 0)
  { if ( Sputcode(' ', s) < 0 )
      break;
  }

  return streamStatus(s);
}


/** @pred  tab(+ _S_,+ _N_)

The same as tab/1, but using stream  _S_.

 
*/
static
PRED_IMPL("tab", 2, tab2, 0)
{ PRED_LD

  return tab(A1, A2 PASS_LD);
}

/** @pred  tab(+ _N_) 


Outputs  _N_ spaces to the current output stream.

 
*/
static
PRED_IMPL("tab", 1, tab1, 0)
{ PRED_LD

  return tab(0, A1 PASS_LD);
}


		 /*******************************
		 *	      ENCODING		*
		 *******************************/

static struct encname
{ IOENC  code;
  atom_t name;
} encoding_names[] =
{ { ENC_UNKNOWN,     ATOM_unknown },
  { ENC_OCTET,       ATOM_octet },
  { ENC_ASCII,       ATOM_ascii },
  { ENC_ISO_LATIN_1, ATOM_iso_latin_1 },
  { ENC_ANSI,	     ATOM_text },
  { ENC_UTF8,        ATOM_utf8 },
  { ENC_UNICODE_BE,  ATOM_unicode_be },
  { ENC_UNICODE_LE,  ATOM_unicode_le },
  { ENC_WCHAR,	     ATOM_wchar_t },
  { ENC_UNKNOWN,     0 },
};


IOENC
atom_to_encoding(atom_t a)
{ struct encname *en;

  for(en=encoding_names; en->name; en++)
  { if ( en->name == a )
      return en->code;
  }

  return ENC_UNKNOWN;
}


atom_t
encoding_to_atom(IOENC enc)
{ return encoding_names[enc].name;
}


static int
bad_encoding(const char *msg, atom_t name)
{ GET_LD
  term_t t = PL_new_term_ref();

  PL_put_atom(t, name);
  return PL_error(NULL, 0, msg, ERR_DOMAIN, ATOM_encoding, t);
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
fn_to_atom() translates a 8-bit  filename  into   a  unicode  atom.  The
encoding is generic `multibyte' on Unix systems   and  fixed to UTF-8 on
Windows, where the uxnt layer  translates   the  UTF-8  sequences to the
Windows *W() functions.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static atom_t
fn_to_atom(const char *fn)
{ PL_chars_t text;
  atom_t a;

  text.text.t    = (char *)fn;
  text.encoding  = ((REP_FN&REP_UTF8) ? ENC_UTF8 :
		    (REP_FN&REP_MB)   ? ENC_ANSI : ENC_ISO_LATIN_1);
  text.storage   = PL_CHARS_HEAP;
  text.length    = strlen(fn);
  text.canonical = FALSE;

  a =  YAP_SWIAtomFromAtom(textToAtom(&text));
  PL_free_text(&text);

  return a;
}


		/********************************
		*       STREAM BASED I/O        *
		*********************************/

static const opt_spec open4_options[] =
{ { ATOM_type,		 OPT_ATOM },
  { ATOM_reposition,     OPT_BOOL },
  { ATOM_alias,	         OPT_ATOM },
  { ATOM_eof_action,     OPT_ATOM },
  { ATOM_close_on_abort, OPT_BOOL },
  { ATOM_buffer,	 OPT_ATOM },
  { ATOM_lock,		 OPT_ATOM },
  { ATOM_wait,		 OPT_BOOL },
  { ATOM_encoding,	 OPT_ATOM },
  { ATOM_bom,		 OPT_BOOL },
  { ATOM_scripting,	 OPT_BOOL },
#ifdef O_LOCALE
  { ATOM_locale,	 OPT_LOCALE },
#endif
  { NULL_ATOM,	         0 }
};


/* MT: openStream() must be called unlocked */

IOSTREAM *
openStream(term_t file, term_t mode, term_t options)
{ GET_LD
  atom_t mname;
  atom_t type           = ATOM_text;
  int    reposition     = TRUE;
  atom_t alias	        = NULL_ATOM;
  atom_t eof_action     = ATOM_eof_code;
  atom_t buffer         = ATOM_full;
  atom_t lock		= ATOM_none;
  int	 wait		= TRUE;
  atom_t encoding	= NULL_ATOM;
#ifdef O_LOCALE
  PL_locale *locale	= NULL;
#endif
  int    close_on_abort = TRUE;
  int	 bom		= -1;
  int	 scripting	= FALSE;
  char   how[10];
  char  *h		= how;
  char *path;
  IOSTREAM *s;
  IOENC enc;

  if ( options )
  { if ( !scan_options(options, 0, ATOM_stream_option, open4_options,
		       &type, &reposition, &alias, &eof_action,
		       &close_on_abort, &buffer, &lock, &wait,
  &encoding, &bom, &scripting
#ifdef O_LOCALE
		       , &locale
#endif
		      ) )
      return FALSE;
  }

					/* MODE */
  if ( PL_get_atom(mode, &mname) )
  { if ( mname == ATOM_write )
    { *h++ = 'w';
    } else if ( mname == ATOM_append )
    { *h++ = 'a';
    } else if ( mname == ATOM_update )
    { *h++ = 'u';
    } else if ( mname == ATOM_read )
    { *h++ = 'r';
    } else
    { PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_io_mode, mode);
      return NULL;
    }
  } else
  { PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_atom, mode);
    return NULL;
  }

					/* ENCODING */
  if ( encoding != NULL_ATOM )
  { enc = atom_to_encoding(encoding);
    if ( enc == ENC_UNKNOWN )
    { bad_encoding(NULL, encoding);
      return NULL;
    }
    if ( type == ATOM_binary && enc != ENC_OCTET )
    { bad_encoding("type(binary) implies encoding(octet)", encoding);
      return NULL;
    }
    switch(enc)				/* explicitely specified: do not */
    { case ENC_OCTET:			/* switch to Unicode.  For implicit */
      case ENC_ASCII:			/* and unicode types we must detect */
      case ENC_ISO_LATIN_1:		/* and skip the BOM */
      case ENC_WCHAR:
	bom = FALSE;
        break;
      default:
	;
    }
  } else if ( type == ATOM_binary )
  { enc = ENC_OCTET;
    bom = FALSE;
  } else
  { enc = LD->encoding;
  }

  if ( bom == -1 )
    bom = (mname == ATOM_read ? TRUE : FALSE);
  if ( type == ATOM_binary )
    *h++ = 'b';

					/* LOCK */
  if ( lock != ATOM_none )
  { *h++ = (wait ? 'l' : 'L');
    if ( lock == ATOM_read || lock == ATOM_shared )
      *h++ = 'r';
    else if ( lock == ATOM_write || lock == ATOM_exclusive )
      *h++ = 'w';
    else
    { term_t l = PL_new_term_ref();
      PL_put_atom(l, lock);
      PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_lock, l);
      return NULL;
    }
  }

  *h = EOS;

					/* FILE */
#ifdef HAVE_POPEN
  if ( PL_is_functor(file, FUNCTOR_pipe1) )
  { term_t a;
    char *cmd;

    PL_clear_exception();
    a = PL_new_term_ref();
    _PL_get_arg(1, file, a);
    if ( !PL_get_chars(a, &cmd, CVT_ATOM|CVT_STRING|REP_FN) )
    { PL_error(NULL, 0, NULL, ERR_TYPE, ATOM_atom, a);
      return NULL;
    }

    if ( !(s = Sopen_pipe(cmd, how)) )
    { PL_error(NULL, 0, OsError(), ERR_FILE_OPERATION,
	       ATOM_open, ATOM_source_sink, file);
      return NULL;
    }
  } else
#endif /*HAVE_POPEN*/
  if ( PL_get_file_name(file, &path, 0) )
  {
#if __ANDROID__
      if (strstr(path,"/assets/")) {
	  if (!(s=Sopen_asset(path+8, "r", GLOBAL_assetManager)))
	    { PL_error(NULL, 0, OsError(), ERR_FILE_OPERATION,
	    	       ATOM_open, ATOM_source_sink, file);
	      return NULL;
	    }
      } else
#endif
    if ( !(s = Sopen_file(path, how)) )
    { PL_error(NULL, 0, OsError(), ERR_FILE_OPERATION,
	       ATOM_open, ATOM_source_sink, file);
      return NULL;
    }
    setFileNameStream_unlocked(s, fn_to_atom(path));
  } else
  { return NULL;
  }

  s->encoding = enc;
#ifdef O_LOCALE
  if ( locale )
  { Ssetlocale(s, locale, NULL);
    releaseLocale(locale);			/* acquired by scan_options() */
  }
#endif
  if ( !close_on_abort )
    s->flags |= SIO_NOCLOSE;

  if ( how[0] == 'r' )
  { if ( eof_action != ATOM_eof_code )
    { if ( eof_action == ATOM_reset )
	s->flags |= SIO_NOFEOF;
      else if ( eof_action == ATOM_error )
	s->flags |= SIO_FEOF2ERR;
      else
      { term_t ex = PL_new_term_ref();
	PL_put_atom(ex, eof_action);
	PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_eof_action, ex);
	return NULL;
      }
    }
  } else
  { if ( buffer != ATOM_full )
    { s->flags &= ~SIO_FBUF;
      if ( buffer == ATOM_line )
	s->flags |= SIO_LBUF;
      else if ( buffer == ATOM_false )
	s->flags |= SIO_NBUF;
      else
      { term_t ex = PL_new_term_ref();
	PL_put_atom(ex, buffer);
	PL_error(NULL, 0, NULL, ERR_DOMAIN, ATOM_buffer, ex);
	return NULL;
      }
    }
  }

  if ( alias != NULL_ATOM )
  { LOCK();
    aliasStream(s, alias);
    UNLOCK();
  }
  if ( !reposition )
    s->position = NULL;

  if ( bom )
  { if ( mname == ATOM_read )
    { if ( ScheckBOM(s) < 0 )
      { bom_error:

	streamStatus(getStream(s));
	return NULL;
      }
      if ( scripting) {
	int c;
	while (( c = Sgetc(s)) == '#') {
	  while( (c = Sgetc(s)) != EOF && c != 10);
	}
	if ( c != EOF )
	  Sungetc(c, s);
	else goto bom_error;
      }
    } else
    { if ( mname == ATOM_write ||
	   ( (mname == ATOM_append || mname == ATOM_update) &&
	     Ssize(s) == 0 ) )
      { if ( SwriteBOM(s) < 0 )
	  goto bom_error;
      }
    }
  }

  return s;
}


/** @pred open(+ _F_,+ _M_,- _S_,+ _Opts_) is iso

Opens the file with name  _F_ in mode  _M_ (`read`,  `write` or
`append`), returning  _S_ unified with the stream name, and following
these options:

+ `type(+ _T_)` is iso

  Specify whether the stream is a `text` stream (default), or a
`binary` stream.

+ `reposition(+ _Bool_)` is iso
  Specify whether it is possible to reposition the stream (`true`), or
not (`false`). By default, YAP enables repositioning for all
files, except terminal files and sockets.

+ `eof(+ _Action_)` is iso

  Specify the action to take if attempting to input characters from a
stream where we have previously found an `end_of_file`. The possible
actions are `error`, that raises an error, `reset`, that tries to
reset the stream and is used for `tty` type files, and `eof_code`,
which generates a new `end_of_file` (default for non-tty files).

+ `alias(+ _Name_)` is iso

  Specify an alias to the stream. The alias <tt>Name</tt> must be an atom. The
alias can be used instead of the stream descriptor for every operation
concerning the stream.

    The operation will fail and give an error if the alias name is already
in use. YAP allows several aliases for the same file, but only
one is returned by stream_property/2

+ `bom(+ _Bool_)`

  If present and `true`, a BOM (<em>Byte Order Mark</em>) was
detected while opening the file for reading or a BOM was written while
opening the stream. See BOM for details.

+ `encoding(+ _Encoding_)`

Set the encoding used for text.  See Encoding for an overview of
wide character and encoding issues.

+ `representation_errors(+ _Mode_)`

  Change the behaviour when writing characters to the stream that cannot
be represented by the encoding.  The behaviour is one of `error`
(throw and Input/Output error exception), `prolog` (write `\u...\`
escape code or `xml` (write `\&#...;` XML character entity).
The initial mode is `prolog` for the user streams and
`error` for all other streams. See also Encoding.

+ `expand_filename(+ _Mode_)`

  If  _Mode_ is `true` then do filename expansion, then ask Prolog
to do file name expansion before actually trying to opening the file:
this includes processing `~` characters and processing `$`
environment variables at the beginning of the file. Otherwise, just try
to open the file using the given name.

  The default behavior is given by the Prolog flag
open_expands_filename.



 
*/
static
PRED_IMPL("open", 4, open4, PL_FA_ISO)
{ IOSTREAM *s = openStream(A1, A2, A4);

  if ( s )
    return PL_unify_stream_or_alias(A3, s);

  return FALSE;
}


/** @pred  open(+ _F_,+ _M_,- _S_) is iso 


Opens the file with name  _F_ in mode  _M_ (`read`, `write` or
`append`), returning  _S_ unified with the stream name.

At most, there are 17 streams  opened at the same time. Each stream is
either an input or an output stream but not both. There are always 3
open streams:  user_input for reading, user_output for writing
and user_error for writing. If there is no  ambiguity, the atoms
user_input and user_output may be referred to as  `user`.

The `file_errors` flag controls whether errors are reported when in
mode `read` or `append` the file  _F_ does not exist or is not
readable, and whether in mode `write` or `append` the file is not
writable.

*/
static
PRED_IMPL("open", 3, open3, PL_FA_ISO)
{ IOSTREAM *s = openStream(A1, A2, 0);

  if ( s )
    return PL_unify_stream_or_alias(A3, s);

  return FALSE;
}

//! @}

/** @defgroup DEC10_IO DEC-10/C-Prolog Compatible File Handling
 *
 * @ingroup InputOutput
 * @{
 */
		 /*******************************
		 *	  EDINBURGH I/O		*
		 *******************************/

static IOSTREAM *
findStreamFromFile(atom_t name, unsigned int flags)
{ TableEnum e;
  Symbol symb;
  IOSTREAM *s = NULL;

  e = newTableEnum(streamContext);
  while( (symb=advanceTableEnum(e)) )
  { stream_context *ctx = symb->value;

    if ( ctx->filename == name &&
	 True(ctx, flags) )
    { s = symb->name;
      break;
    }
  }
  freeTableEnum(e);

  return s;
}


int
pl_see(term_t f)
{ GET_LD
  IOSTREAM *s;
  atom_t a;
  term_t mode;

  if ( !PL_get_atom_ex(f, &a) )
    return FALSE;

  PL_LOCK(L_SEETELL);
  if ( get_stream_handle(a, &s, SH_ALIAS|SH_UNLOCKED) )
  { Scurin = s;
    goto ok;
  }
  if ( a == ATOM_user )
  { Scurin = Suser_input;
    goto ok;
  }
  if ( (s = findStreamFromFile(a, IO_SEE)) )
  { Scurin = s;
    goto ok;
  }

  mode = PL_new_term_ref();
  PL_put_atom(mode, ATOM_read);
  if ( !(s = openStream(f, mode, 0)) )
  { PL_UNLOCK(L_SEETELL);
    return FALSE;
  }

  set(getStreamContext(s), IO_SEE);
  push_input_context(ATOM_see);
  Scurin = s;

ok:
  PL_UNLOCK(L_SEETELL);

  return TRUE;
}

int
pl_seen(void)
{ GET_LD
  IOSTREAM *s = getStream(Scurin);

  pop_input_context();

  if ( s && (s->flags & SIO_NOFEOF) )
    return TRUE;

  if ( s )
    return closeStream(s);

  return symbol_no_stream(ATOM_current_input);
}

/** @pred  see(+ _S_) 


If  _S_ is a currently opened input stream then it is assumed to be
the current input stream. If  _S_ is an atom it is taken as a
filename. If there is no input stream currently associated with it, then
it is opened for input, and the new input stream thus created becomes
the current input stream. If it is not possible to open the file, an
error occurs.  If there is a single opened input stream currently
associated with the file, it becomes the current input stream; if there
are more than one in that condition, then one of them is chosen.

When  _S_ is a stream not currently opened for input, an error may be
reported, depending on the state of the `file_errors` flag. If
 _S_ is neither a stream nor an atom the predicates just fails.

 
*/
static
PRED_IMPL("see", 1, see, 0)
{ return pl_see(A1);
}


/** @pred  seen 


Closes the current input stream (see 6.7.).

 */
static
PRED_IMPL("seen", 0, seen, 0)
{ return pl_seen();
}


/** @pred  seeing(- _S_) 


The current input stream is unified with  _S_.

 
*/
static
PRED_IMPL("seeing", 1, seeing, 0)
{ PRED_LD

  if ( Scurin == Suser_input )
    return PL_unify_atom(A1, ATOM_user);

  return PL_unify_stream(A1, Scurin);
}


/* MT: Does not create a lock on the stream
*/

static int
do_tell(term_t f, atom_t m)
{ GET_LD
  IOSTREAM *s;
  atom_t a;
  term_t mode;

  if ( !PL_get_atom_ex(f, &a) )
    return FALSE;

  PL_LOCK(L_SEETELL);
  if ( get_stream_handle(a, &s, SH_UNLOCKED) )
  { Scurout = s;
    goto ok;
  }
  if ( a == ATOM_user )
  { Scurout = Suser_output;
    goto ok;
  }
  if ( (s = findStreamFromFile(a, IO_TELL)) )
  { Scurout = s;
    goto ok;
  }

  mode = PL_new_term_ref();
  PL_put_atom(mode, m);
  if ( !(s = openStream(f, mode, 0)) )
  { PL_UNLOCK(L_SEETELL);
    return FALSE;
  }

  set(getStreamContext(s), IO_TELL);
  pushOutputContext();
  Scurout = s;

ok:
  PL_UNLOCK(L_SEETELL);
  return TRUE;
}

/** @pred  tell(+ _S_) 


If  _S_ is a currently opened stream for output, it becomes the
current output stream. If  _S_ is an atom it is taken to be a
filename.  If there is no output stream currently associated with it,
then it is opened for output, and the new output stream created becomes
the current output stream. If it is not possible to open the file, an
error occurs.  If there is a single opened output stream currently
associated with the file, then it becomes the current output stream; if
there are more than one in that condition, one of them is chosen.

Whenever  _S_ is a stream not currently opened for output, an error
may be reported, depending on the state of the file_errors flag. The
predicate just fails, if  _S_ is neither a stream nor an atom.

 
*/
static
PRED_IMPL("tell", 1, tell, 0)
{ return do_tell(A1, ATOM_write);
}

static
PRED_IMPL("append", 1, append, 0)
{ return do_tell(A1, ATOM_append);
}

/** @pred  telling(- _S_) 


The current output stream is unified with  _S_.

 
*/
static
PRED_IMPL("telling", 1, telling, 0)
{ PRED_LD

  if ( Scurout == Suser_output )
    return PL_unify_atom(A1, ATOM_user);

  return PL_unify_stream(A1, Scurout);
}

/** @pred  told 


Closes the current output stream, and the user's terminal becomes again
the current output stream. It is important to remember to close streams
after having finished using them, as the maximum number of
simultaneously opened streams is 17.

 
*/
static
PRED_IMPL("told", 0, told, 0)
{ PRED_LD
  IOSTREAM *s = getStream(Scurout);

  popOutputContext();

  if ( s && (s->flags & SIO_NOFEOF) )
    return TRUE;

  if ( s )
    return closeStream(s);

  return symbol_no_stream(ATOM_current_output);
}

/**
 * @}
 */

//! @defgroup Stream Opening and Closing Streams
//  @ingroup InputOutput
//  @{
//


		 /*******************************
		 *	   NULL-STREAM		*
		 *******************************/

static ssize_t
Swrite_null(void *handle, char *buf, size_t size)
{ (void)handle;
  (void)buf;

  return size;
}


static ssize_t
Sread_null(void *handle, char *buf, size_t size)
{ (void)handle;
  (void)buf;
  (void)size;

  return 0;
}


static long
Sseek_null(void *handle, long offset, int whence)
{ (void)handle;

  switch(whence)
  { case SIO_SEEK_SET:
	return offset;
    case SIO_SEEK_CUR:
    case SIO_SEEK_END:
    default:
        return -1;
  }
}


static int
Sclose_null(void *handle)
{ (void)handle;

  return 0;
}


static const IOFUNCTIONS nullFunctions =
{ Sread_null,
  Swrite_null,
  Sseek_null,
  Sclose_null
};


static
PRED_IMPL("open_null_stream", 1, open_null_stream, 0)
{ int sflags = SIO_NBUF|SIO_RECORDPOS|SIO_OUTPUT|SIO_TEXT;
  IOSTREAM *s = Snew((void *)NULL, sflags, (IOFUNCTIONS *)&nullFunctions);

  if ( s )
  { s->encoding = ENC_UTF8;
    return PL_unify_stream_or_alias(A1, s);
  }

  return FALSE;
}


static int
do_close(IOSTREAM *s, int force)
{ if ( force )
  { if ( !s )
      return TRUE;
    if ( s == Sinput )
      Sclearerr(s);
    else if ( s == Soutput || s == Serror )
    { Sflush(s);
      Sclearerr(s);
    } else
    { Sflush(s);
      if ( Sclose(s) < 0 )
	PL_clear_exception();
    }

    return TRUE;
  } else if ( s )
  { return closeStream(s);
  } else
  { return FALSE;
  }
}


static int
pl_close(term_t stream, int force ARG_LD)
{ IOSTREAM *s;
  atom_t a;
  stream_ref *ref;
  PL_blob_t *type;

  if ( !PL_get_atom(stream, &a) )
    return not_a_stream(stream);

  ref = PL_blob_data(a, NULL, &type);
  if ( type == &stream_blob )
  { int rc = TRUE;

    if ( ref->read )
      rc = do_close(getStream(ref->read), force);
    if ( ref->write )
      rc = rc && do_close(getStream(ref->write), force);

    return rc;
  }

  if ( get_stream_handle(a, &s, SH_ERRORS|SH_ALIAS) )
    return do_close(s, force);

  return FALSE;
}


/** @pred  close(+ _S_) is iso 


Closes the stream  _S_. If  _S_ does not stand for a stream
currently opened an error is reported. The streams user_input,
user_output, and user_error can never be closed.

 
*/
static
PRED_IMPL("close", 1, close, PL_FA_ISO)
{ PRED_LD

  return pl_close(A1, FALSE PASS_LD);
}


static const opt_spec close2_options[] =
{ { ATOM_force,		 OPT_BOOL },
  { NULL_ATOM,		 0 }
};


/** @pred  close(+ _S_,+ _O_) is iso

Closes the stream  _S_, following options  _O_. 

The only valid options are `force(true)` and `force(false)`.
YAP currently ignores these options.

 
*/
static
PRED_IMPL("close", 2, close2, PL_FA_ISO)
{ PRED_LD
  int force = FALSE;

  if ( !scan_options(A2, 0, ATOM_close_option, close2_options, &force) )
    return FALSE;

  return pl_close(A1, force PASS_LD);
}


		 /*******************************
		 *	 STREAM-PROPERTY	*
		 *******************************/

static int
stream_file_name_propery(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t name;

  for(; s; s=s->downstream)
  { if ( (name = getStreamContext(s)->filename) )
    { return PL_unify_atom(prop, name);
    }
  }

  return FALSE;
}


static int
stream_mode_property(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t mode;

  if ( s->flags & SIO_INPUT )
    mode = ATOM_read;
  else
  { assert(s->flags & SIO_OUTPUT);

    if ( s->flags & SIO_APPEND )
      mode = ATOM_append;
    else if ( s->flags & SIO_UPDATE )
      mode = ATOM_update;
    else
      mode = ATOM_write;
  }

  return PL_unify_atom(prop, mode);
}


static int
stream_input_prop(IOSTREAM *s ARG_LD)
{ IGNORE_LD

  return (s->flags & SIO_INPUT) ? TRUE : FALSE;
}


static int
stream_output_prop(IOSTREAM *s ARG_LD)
{ IGNORE_LD

  return (s->flags & SIO_OUTPUT) ? TRUE : FALSE;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Incomplete: should be non-deterministic if the stream has multiple aliases!
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static int
stream_alias_prop(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t name;
  stream_context *ctx = getStreamContext(s);
  int i;

  if ( PL_get_atom(prop, &name) )
  { alias *a;

    for( a = ctx->alias_head; a; a = a->next )
    { if ( a->name == name )
	return TRUE;
    }

    if ( (i=standardStreamIndexFromName(name)) >= 0 &&
	 i < 6 &&
	 s == LD->IO.streams[i] )
      return TRUE;

    return FALSE;
  }

  if ( (i=standardStreamIndexFromStream(s)) >= 0 && i < 3 )
    return PL_unify_atom(prop, standardStreams[i]);
  if ( ctx->alias_head )
    return PL_unify_atom(prop, ctx->alias_head->name);

  return FALSE;
}


static int
stream_position_prop(IOSTREAM *s, term_t prop ARG_LD)
{ IGNORE_LD

  if ( s->position )
  { return PL_unify_term(prop,
			 PL_FUNCTOR, FUNCTOR_stream_position4,
			   PL_INT64, s->position->charno,
			   PL_INT, s->position->lineno,
			   PL_INT, s->position->linepos,
			   PL_INT64, s->position->byteno);
  }

  return FALSE;
}


static int
stream_end_of_stream_prop(IOSTREAM *s, term_t prop ARG_LD)
{ if ( s->flags & SIO_INPUT )
  { atom_t val;

    if ( s->flags & SIO_FEOF2 )
      val = ATOM_past;
    else if ( s->flags & SIO_FEOF )
      val = ATOM_at;
    else
      val = ATOM_not;

    return PL_unify_atom(prop, val);
  }

  return FALSE;
}


static int
stream_eof_action_prop(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t val;

  if ( s->flags & SIO_NOFEOF )
    val = ATOM_reset;
  else if ( s->flags & SIO_FEOF2ERR )
    val = ATOM_error;
  else
    val = ATOM_eof_code;

  return PL_unify_atom(prop, val);
}


#ifdef HAVE_FSTAT
#include <sys/stat.h>
#endif

#if !defined(S_ISREG) && defined(S_IFREG)
#define S_ISREG(m) ((m&S_IFMT) == S_IFREG)
#endif

static int
stream_reposition_prop(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t val;

  if ( s->functions->seek )
  {
#ifdef HAVE_FSTAT
    int fd = Sfileno(s);
    struct stat buf;

    if ( fd != -1 && fstat(fd, &buf) == 0 && S_ISREG(buf.st_mode) )
      val = ATOM_true;
    else
      val = ATOM_false;
#else
    val = ATOM_true;
#endif
  } else
    val = ATOM_false;

  return PL_unify_atom(prop, val);
}


static int
stream_close_on_abort_prop(IOSTREAM *s, term_t prop ARG_LD)
{ IGNORE_LD

  return PL_unify_bool_ex(prop, !(s->flags & SIO_NOCLOSE));
}


static int
stream_type_prop(IOSTREAM *s, term_t prop ARG_LD)
{ return PL_unify_atom(prop, s->flags & SIO_TEXT ? ATOM_text : ATOM_binary);
}


static int
stream_file_no_prop(IOSTREAM *s, term_t prop ARG_LD)
{ int fd;

  if ( (fd = Sfileno(s)) >= 0 )
    return PL_unify_integer(prop, fd);

  return FALSE;
}


static int
stream_tty_prop(IOSTREAM *s, term_t prop ARG_LD)
{ IGNORE_LD

  if ( (s->flags & SIO_ISATTY) )
    return PL_unify_bool_ex(prop, TRUE);

  return FALSE;
}


static int
stream_bom_prop(IOSTREAM *s, term_t prop ARG_LD)
{ IGNORE_LD

  if ( (s->flags & SIO_BOM) )
    return PL_unify_bool_ex(prop, TRUE);

  return FALSE;
}


static int
stream_newline_prop(IOSTREAM *s, term_t prop ARG_LD)
{ switch ( s->newline )
  { case SIO_NL_POSIX:
    case SIO_NL_DETECT:
      return PL_unify_atom(prop, ATOM_posix);
    case SIO_NL_DOS:
      return PL_unify_atom(prop, ATOM_dos);
  }

  return FALSE;
}


static int
stream_encoding_prop(IOSTREAM *s, term_t prop ARG_LD)
{ return PL_unify_atom(prop, encoding_to_atom(s->encoding));
}


#ifdef O_LOCALE
static int
stream_locale_prop(IOSTREAM *s, term_t prop ARG_LD)
{ if ( s->locale )
    return unifyLocale(prop, s->locale, TRUE);
  return FALSE;
}
#endif

static int
stream_reperror_prop(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t a;

  if ( (s->flags & SIO_REPXML) )
    a = ATOM_xml;
  else if ( (s->flags & SIO_REPPL) )
    a = ATOM_prolog;
  else
    a = ATOM_error;

  return PL_unify_atom(prop, a);
}


static int
stream_buffer_prop(IOSTREAM *s, term_t prop ARG_LD)
{ atom_t b;

  if ( s->flags & SIO_FBUF )
    b = ATOM_full;
  else if ( s->flags & SIO_LBUF )
    b = ATOM_line;
  else /*if ( s->flags & SIO_NBUF )*/
    b = ATOM_false;

  return PL_unify_atom(prop, b);
}


static int
stream_buffer_size_prop(IOSTREAM *s, term_t prop ARG_LD)
{ if ( (s->flags & SIO_NBUF) )
    return FALSE;

  return PL_unify_integer(prop, s->bufsize);
}


static int
stream_timeout_prop(IOSTREAM *s, term_t prop ARG_LD)
{ if ( s->timeout == -1 )
    return PL_unify_atom(prop, ATOM_infinite);

  return PL_unify_float(prop, (double)s->timeout/1000.0);
}


static int
stream_nlink_prop(IOSTREAM *s, term_t prop ARG_LD)
{ int fd;

  if ( (fd = Sfileno(s)) >= 0 )
  { struct stat buf;

    if ( fstat(fd, &buf) == 0 )
    { return PL_unify_integer(prop, buf.st_nlink);
    }
  }

  return FALSE;
}

static int
stream_close_on_exec_prop(IOSTREAM *s, term_t prop ARG_LD)
{  int fd;
#ifdef __WINDOWS__
   DWORD Flags;
#else
   int fd_flags;
#endif
   IGNORE_LD

   if ( (fd = Sfileno(s)) < 0)
     return FALSE;

#if defined(F_GETFD) && defined(FD_CLOEXEC)

   if ( (fd_flags = fcntl(fd, F_GETFD)) == -1)
     return FALSE;

   return PL_unify_bool_ex(prop, (fd_flags&FD_CLOEXEC) != 0 );

#elif defined __WINDOWS__

   if ( GetHandleInformation((HANDLE)_get_osfhandle(fd), &Flags) == 0 )
     return FALSE;

   return PL_unify_bool_ex(prop, (Flags & HANDLE_FLAG_INHERIT) == 0);

#endif

   return FALSE;
}

typedef struct
{ functor_t functor;			/* functor of property */
  property_t function; /* function to generate */
} sprop;


static const sprop sprop_list [] =
{ { FUNCTOR_file_name1,	    stream_file_name_propery },
  { FUNCTOR_mode1,	    stream_mode_property },
  { FUNCTOR_input0,	    (property_t)stream_input_prop },
  { FUNCTOR_output0,	    (property_t)stream_output_prop },
  { FUNCTOR_alias1,	    stream_alias_prop },
  { FUNCTOR_position1,	    stream_position_prop },
  { FUNCTOR_end_of_stream1, stream_end_of_stream_prop },
  { FUNCTOR_eof_action1,    stream_eof_action_prop },
  { FUNCTOR_reposition1,    stream_reposition_prop },
  { FUNCTOR_type1,	    stream_type_prop },
  { FUNCTOR_file_no1,	    stream_file_no_prop },
  { FUNCTOR_buffer1,	    stream_buffer_prop },
  { FUNCTOR_buffer_size1,   stream_buffer_size_prop },
  { FUNCTOR_close_on_abort1,stream_close_on_abort_prop },
  { FUNCTOR_tty1,	    stream_tty_prop },
  { FUNCTOR_encoding1,	    stream_encoding_prop },
#ifdef O_LOCALE
  { FUNCTOR_locale1,	    stream_locale_prop },
#endif
  { FUNCTOR_bom1,	    stream_bom_prop },
  { FUNCTOR_newline1,	    stream_newline_prop },
  { FUNCTOR_representation_errors1, stream_reperror_prop },
  { FUNCTOR_timeout1,       stream_timeout_prop },
  { FUNCTOR_nlink1,         stream_nlink_prop },
  { FUNCTOR_close_on_exec1, stream_close_on_exec_prop },
  { 0,			    NULL }
};


typedef struct
{ TableEnum e;				/* Enumerator on stream-table */
  IOSTREAM *s;				/* Stream we are enumerating */
  const sprop *p;			/* Pointer in properties */
  int fixed_p;				/* Propety is given */
} prop_enum;


/** @pred  stream_property(? _Stream_,? _Prop_) is iso 



Obtain the properties for the open streams. If the first argument is
unbound, the procedure will backtrack through all open
streams. Otherwise, the first argument must be a stream term (you may
use `current_stream` to obtain a current stream given a file name).

The following properties are recognized:



+ file_name( _P_)
An atom giving the file name for the current stream. The file names are
user_input, user_output, and user_error for the
standard streams.

+ mode( _P_)
The mode used to open the file. It may be one of `append`,
`read`, or `write`.

+ input
The stream is readable.

+ output
The stream is writable.

+ alias( _A_)
ISO-Prolog primitive for stream aliases. <tt>YAP</tt> returns one of the
existing aliases for the stream.

+ position( _P_)
A term describing the position in the stream.

+ end_of_stream( _E_)
Whether the stream is `at` the end of stream, or it has found the
end of stream and is `past`, or whether it has `not` yet
reached the end of stream.

+ eof_action( _A_)
The action to take when trying to read after reaching the end of
stream. The action may be one of `error`, generate an error,
`eof_code`, return character code `-1`, or `reset` the
stream.

+ reposition( _B_)
Whether the stream can be repositioned or not, that is, whether it is
seekable.

+ type( _T_)
Whether the stream is a `text` stream or a `binary` stream.

+ bom(+ _Bool_)
If present and `true`, a BOM (<em>Byte Order Mark</em>) was
detected while opening the file for reading or a BOM was written while
opening the stream. See BOM for details.

+ encoding(+ _Encoding_)
Query the encoding used for text.  See Encoding for an
overview of wide character and encoding issues in YAP.

+ representation_errors(+ _Mode_)
Behaviour when writing characters to the stream that cannot be
represented by the encoding.  The behaviour is one of `error`
(throw and Input/Output error exception), `prolog` (write `\u...\`
escape code or `xml` (write `\&#...;` XML character entity).
The initial mode is `prolog` for the user streams and
`error` for all other streams. See also Encoding and
`open/4`.



+ current_line_number(- _LineNumber_) 


Unify  _LineNumber_ with the line number for the current stream.

 
*/
static
PRED_IMPL("stream_property", 2, stream_property,
	  PL_FA_ISO|PL_FA_NONDETERMINISTIC)
{ PRED_LD
  IOSTREAM *s;
  prop_enum *pe;
  fid_t fid;
  term_t a1;
  atom_t a;

  term_t stream = A1;
  term_t property = A2;

  switch( CTX_CNTRL )
  { case FRG_FIRST_CALL:
      a1 = PL_new_term_ref();

      if ( PL_is_variable(stream) )	/* generate */
      {	const sprop *p = sprop_list;
	int fixed = FALSE;
	functor_t f;

	if ( PL_get_functor(property, &f) ) /* test for defined property */
	{ for( ; p->functor; p++ )
	  { if ( f == p->functor )
	    { fixed = TRUE;
	      break;
	    }
	  }
	  if ( !p->functor )
	    return PL_error(NULL, 0, NULL, ERR_DOMAIN,
			    ATOM_stream_property, property);
	}

	pe = allocForeignState(sizeof(*pe));

	pe->e = newTableEnum(streamContext);
	pe->s = NULL;
	pe->p = p;
	pe->fixed_p = fixed;

	break;
      }

      if ( !PL_get_atom(stream, &a) )
	return not_a_stream(stream);

      LOCK();				/* given stream */
      if ( get_stream_handle(a, &s, SH_ERRORS|SH_UNLOCKED) )
      { functor_t f;

	if ( PL_is_variable(property) )	/* generate properties */
	{ pe = allocForeignState(sizeof(*pe));

	  pe->e = NULL;
	  pe->s = s;
	  pe->p = sprop_list;
	  pe->fixed_p = FALSE;
	  UNLOCK();

	  break;
	}

	if ( PL_get_functor(property, &f) )
	{ const sprop *p = sprop_list;

	  for( ; p->functor; p++ )
	  { if ( f == p->functor )
	    { int rval;

	      switch(arityFunctor(f))
	      { case 0:
		  rval = (*(property0_t)p->function)(s PASS_LD);
		  break;
		case 1:
		{ term_t a1 = PL_new_term_ref();

		  _PL_get_arg(1, property, a1);
		  rval = (*p->function)(s, a1 PASS_LD);
		  break;
		}
		default:
		  assert(0);
		  rval = FALSE;
	      }
	      UNLOCK();
	      return rval;
	    }
	  }
	} else
	{ UNLOCK();
	  return PL_error(NULL, 0, NULL, ERR_DOMAIN,
			  ATOM_stream_property, property);
	}
      }
      UNLOCK();
      return FALSE;				/* bad stream handle */
    case FRG_REDO:
    { pe = CTX_PTR;
      a1 = PL_new_term_ref();

      break;
    }
    case FRG_CUTTED:
    { pe = CTX_PTR;

      if ( pe )				/* 0 if exception on FRG_FIRST_CALL */
      { if ( pe->e )
	  freeTableEnum(pe->e);

	freeForeignState(pe, sizeof(*pe));
      }
      return TRUE;
    }
    default:
      assert(0);
      return FALSE;
  }


  if ( !(fid = PL_open_foreign_frame()) )
  { error:

    if ( pe->e )
      freeTableEnum(pe->e);

    freeForeignState(pe, sizeof(*pe));
    return FALSE;
  }

  for(;;)
  { if ( pe->s )				/* given stream */
    { fid_t fid2;

      if ( PL_is_variable(stream) )
      { if ( !PL_unify_stream(stream, pe->s) )
	  goto enum_e;
      }

      if ( !(fid2 = PL_open_foreign_frame()) )
	goto error;
      for( ; pe->p->functor ; pe->p++ )
      { if ( PL_unify_functor(property, pe->p->functor) )
	{ int rval;

	  switch(arityFunctor(pe->p->functor))
	  { case 0:
	      rval = (*(property0_t)pe->p->function)(pe->s PASS_LD);
	      break;
	    case 1:
	    { _PL_get_arg(1, property, a1);

	      rval = (*pe->p->function)(pe->s, a1 PASS_LD);
	      break;
	    }
	    default:
	      assert(0);
	      rval = FALSE;
	  }
	  if ( rval )
	  { if ( pe->fixed_p )
	      pe->s = NULL;
	    else
	      pe->p++;
	    ForeignRedoPtr(pe);
	  }
	}

	if ( exception_term )
	  goto error;

	if ( pe->fixed_p )
	  break;
	PL_rewind_foreign_frame(fid2);
      }
      PL_close_foreign_frame(fid2);
      pe->s = NULL;
    }

  enum_e:
    if ( pe->e )
    { Symbol symb;

      while ( (symb=advanceTableEnum(pe->e)) )
      { PL_rewind_foreign_frame(fid);
	if ( PL_unify_stream(stream, symb->name) )
	{ pe->s = symb->name;
	  if ( !pe->fixed_p )
	    pe->p = sprop_list;
	  break;
	}
	if ( exception_term )
	  goto error;
      }
    }

    if ( !pe->s )
    { if ( pe->e )
	freeTableEnum(pe->e);

      freeForeignState(pe, sizeof(*pe));
      return FALSE;
    }
  }
  return FALSE;
}


/** @pred  is_stream( _S_) 


Succeeds if  _S_ is a currently open stream.
*/
static
PRED_IMPL("is_stream", 1, is_stream, 0)
{ GET_LD
  IOSTREAM *s;
  atom_t a;

  if ( PL_get_atom(A1, &a) &&
       get_stream_handle(a, &s, SH_UNLOCKED) )
    return TRUE;

  return FALSE;
}

		 /*******************************
		 *	      FLUSH		*
		 *******************************/
/**
 * @}
 */

/**
 * @ingroup StreamM
 * @{
 */


static int
flush_output(term_t out ARG_LD)
{ IOSTREAM *s;

  if ( getOutputStream(out, S_DONTCARE, &s) )
  { Sflush(s);
    return streamStatus(s);
  }

  return FALSE;
}

/** @pred  flush_output is iso 


Send out all data in the output buffer of the current output stream.

 
*/
static
PRED_IMPL("flush_output", 0, flush_output, PL_FA_ISO)
{ PRED_LD

  return flush_output(0 PASS_LD);
}

/** @pred  flush_output(+ _S_) is iso

Send all data in the output buffer for stream  _S_.

 
*/
static
PRED_IMPL("flush_output", 1, flush_output1, PL_FA_ISO)
{ PRED_LD

  return flush_output(A1 PASS_LD);
}

/**
 * @}
 */

/**
 * @ingroup Stream
 * @{
 */


static int
getStreamWithPosition(term_t stream, IOSTREAM **sp)
{ IOSTREAM *s;

  if ( PL_get_stream_handle(stream, &s) )
  { if ( !s->position )
    { PL_error(NULL, 0, NULL, ERR_PERMISSION, /* non-ISO */
	       ATOM_property, ATOM_position, stream);
      releaseStream(s);
      return FALSE;
    }

    *sp = s;
    return TRUE;
  }

  return FALSE;
}


static int
getRepositionableStream(term_t stream, IOSTREAM **sp)
{ GET_LD
  IOSTREAM *s;
  atom_t a;

  if ( !PL_get_atom(stream, &a) )
    return not_a_stream(stream);

  if ( get_stream_handle(a, &s, SH_ERRORS) )
  { if ( !s->position || !s->functions || !s->functions->seek )
    { PL_error(NULL, 0, NULL, ERR_PERMISSION,
	       ATOM_reposition, ATOM_stream, stream);
      releaseStream(s);
      return FALSE;
    }

    *sp = s;
    return TRUE;
  }

  return FALSE;
}


/** @pred  set_stream_position(+ _S_, + _POS_) is iso 


Given a stream position  _POS_ for a stream  _S_, set the current
stream position for  _S_ to be  _POS_.

 
*/
static
PRED_IMPL("set_stream_position", 2, set_stream_position, PL_FA_ISO)
{ PRED_LD
  IOSTREAM *s = NULL;			/* make compiler happy */
  int64_t charno, byteno;
  long linepos, lineno;
  term_t a = PL_new_term_ref();

  term_t stream = A1;
  term_t pos = A2;

  if ( !(getRepositionableStream(stream, &s)) )
    return FALSE;

  if ( !PL_is_functor(pos, FUNCTOR_stream_position4) ||
       !PL_get_arg(1, pos, a) ||
       !PL_get_int64(a, &charno) ||
       !PL_get_arg(2, pos, a) ||
       !PL_get_long(a, &lineno) ||
       !PL_get_arg(3, pos, a) ||
       !PL_get_long(a, &linepos) ||
       !PL_get_arg(4, pos, a) ||
       !PL_get_int64(a, &byteno) )
  { releaseStream(s);
    return PL_error("stream_position", 3, NULL,
		    ERR_DOMAIN, ATOM_stream_position, pos);
  }

  if ( Sseek64(s, byteno, SIO_SEEK_SET) != 0 )
    return PL_error(NULL, 0, MSG_ERRNO, ERR_FILE_OPERATION,
		    ATOM_reposition, ATOM_stream, stream);

  s->position->byteno  = byteno;
  s->position->charno  = charno;
  s->position->lineno  = (int)lineno;
  s->position->linepos = (int)linepos;

  releaseStream(s);

  return TRUE;
}


static
PRED_IMPL("seek", 4, seek, 0)
{ PRED_LD
  atom_t m;
  int whence = -1;
  int64_t off, new;
  IOSTREAM *s;

  term_t stream = A1;
  term_t offset = A2;
  term_t method = A3;
  term_t newloc = A4;

  if ( !(PL_get_atom_ex(method, &m)) )
    return FALSE;

  if ( m == ATOM_bof )
    whence = SIO_SEEK_SET;
  else if ( m == ATOM_current )
    whence = SIO_SEEK_CUR;
  else if ( m == ATOM_eof )
    whence = SIO_SEEK_END;
  else
    return PL_error("seek", 4, NULL, ERR_DOMAIN, ATOM_seek_method, method);

  if ( !PL_get_int64(offset, &off) )
    return PL_error("seek", 4, NULL, ERR_DOMAIN, ATOM_integer, offset);

  if ( PL_get_stream_handle(stream, &s) )
  { int unit = Sunit_size(s);

    off *= unit;
    if ( Sseek64(s, off, whence) < 0 )
    { if ( errno == EINVAL )
	PL_error("seek", 4, "offset out of range", ERR_DOMAIN,
		 ATOM_position, offset);
      else
	PL_error("seek", 4, OsError(), ERR_PERMISSION,
		 ATOM_reposition, ATOM_stream, stream);
      Sclearerr(s);
      releaseStream(s);
      return FALSE;
    }

    new = Stell64(s);
    releaseStream(s);
    new /= unit;

    return PL_unify_int64(newloc, new);
  }

  return FALSE;
}


/** @pred  set_input(+ _S_) is iso 


Set stream  _S_ as the current input stream. Predicates like read/1
and get/1 will start using stream  _S_.

 
*/
static
PRED_IMPL("set_input", 1, set_input, PL_FA_ISO)
{ PRED_LD
  IOSTREAM *s;

  if ( getInputStream(A1, S_DONTCARE, &s) )
  { Scurin = s;
    releaseStream(s);
    return TRUE;
  }

  return FALSE;
}


/** @pred  set_output(+ _S_) is iso


Set stream  _S_ as the current output stream. Predicates like
write/1 and put/1 will start using stream  _S_.

 
*/
static
PRED_IMPL("set_output", 1, set_output, PL_FA_ISO)
{ PRED_LD
  IOSTREAM *s;

  if ( getOutputStream(A1, S_DONTCARE, &s) )
  { Scurout = s;
    releaseStream(s);
    return TRUE;
  }

  return FALSE;
}


/** @pred  current_input(- _S_) is iso 


Unify  _S_ with the current input stream.

 
*/
static
PRED_IMPL("current_input", 1, current_input, PL_FA_ISO)
{ PRED_LD
  return PL_unify_stream(A1, Scurin);
}


/** @pred  current_output(- _S_) is iso 


Unify  _S_ with the current output stream.

 
*/
static
PRED_IMPL("current_output", 1, current_output, PL_FA_ISO)
{ PRED_LD
  return PL_unify_stream(A1, Scurout);
}


/** @pred  character_count(+ _Stream_,- _ByteCount_)


Unify  _CharacterCount_ with the number of bytes written to or
read from  _Stream_.


*/
static
PRED_IMPL("byte_count", 2, byte_count, 0)
{ PRED_LD
  IOSTREAM *s;

  if ( getStreamWithPosition(A1, &s) )
  { int64_t n = s->position->byteno;

    releaseStream(s);
    return PL_unify_int64(A2, n);
  }

  return FALSE;
}


/** @pred  character_count(+ _Stream_,- _CharacterCount_) 


Unify  _CharacterCount_ with the number of characters written to or
read from  _Stream_.

 
*/
static
PRED_IMPL("character_count", 2, character_count, 0)
{ PRED_LD
  IOSTREAM *s;

  if ( getStreamWithPosition(A1, &s) )
  { int64_t n = s->position->charno;

    releaseStream(s);
    return PL_unify_int64(A2, n);
  }

  return FALSE;
}


/** @pred  line_count(+ _Stream_,- _LineNumber_) 


Unify  _LineNumber_ with the line number for the  _Stream_.

 
*/
static
PRED_IMPL("line_count", 2, line_count, 0)
{ GET_LD
  IOSTREAM *s;

  if ( getStreamWithPosition(A1, &s) )
  { intptr_t n = s->position->lineno;

    releaseStream(s);
    return PL_unify_integer(A2, n);
  }

  return FALSE;
}


/** @pred  line_position(+ _Stream_,- _LinePosition_) 


Unify  _LinePosition_ with the position on current text stream
 _Stream_.

 
*/
static
PRED_IMPL("line_position", 2, line_position, 0)
{ GET_LD
  IOSTREAM *s;

  if ( getStreamWithPosition(A1, &s) )
  { intptr_t n = s->position->linepos;

    releaseStream(s);
    return PL_unify_integer(A2, n);
  }

  return FALSE;
}


static
PRED_IMPL("source_location", 2, source_location, 0)
{ PRED_LD
  if ( ReadingSource &&
       PL_unify_atom(A1, source_file_name) &&
       PL_unify_integer(A2, source_line_no) )
    return TRUE;

  return FALSE;
}


static int
at_end_of_stream(term_t stream ARG_LD)
{ IOSTREAM *s;

  if ( getInputStream(stream, S_DONTCARE, &s) )
  { int rval = Sfeof(s);

    if ( rval < 0 )
    { PL_error(NULL, 0, "not-buffered stream", ERR_PERMISSION,
	       ATOM_end_of_stream, ATOM_stream, stream);
      rval = FALSE;
    }

    if ( rval && Sferror(s) )		/* due to error */
      return streamStatus(s);
    else
      releaseStream(s);

    return rval;
  }

  return FALSE;				/* exception */
}

/** @pred  at_end_of_stream(+ _S_) is iso

Succeed if the stream  _S_ has stream position end-of-stream or
past-end-of-stream. Note that  _S_ must be a readable stream.

 
*/
static
PRED_IMPL("at_end_of_stream", 1, at_end_of_stream, PL_FA_ISO)
{ PRED_LD
  return at_end_of_stream(A1 PASS_LD);
}

/** @pred  at_end_of_stream is iso 


Succeed if the current stream has stream position end-of-stream or
past-end-of-stream.

 
*/
static
PRED_IMPL("at_end_of_stream", 0, at_end_of_stream0, PL_FA_ISO)
{ PRED_LD
  return at_end_of_stream(0 PASS_LD);
}


static foreign_t
peek(term_t stream, term_t chr, int how ARG_LD)
{ IOSTREAM *s;
  int c;

  if ( !getInputStream(stream, how == PL_BYTE ? S_BINARY : S_TEXT, &s) )
    return FALSE;
  if ( True(s, SIO_NBUF) || (s->bufsize && s->bufsize < PL_MB_LEN_MAX) )
  { releaseStream(s);
    return PL_error(NULL, 0, "stream is unbuffered", ERR_PERMISSION,
		    ATOM_peek, ATOM_stream, stream);
  }

  if ( how == PL_BYTE )
  { IOPOS pos = s->posbuf;

    c = Sgetc(s);
    if ( c != EOF )
      Sungetc(c, s);
    s->posbuf = pos;
  } else
  { c = Speekcode(s);
  }
  if ( Sferror(s) )
    return streamStatus(s);
  releaseStream(s);

  return PL_unify_char(chr, c, how);
}

/**
 * @}
 */

/**
 * @ingroup CharsIO
 * @{
 */



/** @pred  peek_byte(+ _S_,- _C_) is iso

If  _C_ is unbound, or is a character code, and  _S_ is a binary
stream, read the next byte from the current stream and unify its code
with  _C_, while leaving the current stream position unaltered.

 
*/
static
PRED_IMPL("peek_byte", 2, peek_byte2, 0)
{ PRED_LD
  return peek(A1, A2, PL_BYTE PASS_LD);
}


/** @pred  peek_byte(- _C_) is iso 


If  _C_ is unbound, or is a character code, and the current stream is a
binary stream, read the next byte from the current stream and unify its
code with  _C_, while leaving the current stream position unaltered.

 
*/
static
PRED_IMPL("peek_byte", 1, peek_byte1, 0)
{ PRED_LD
  return peek(0, A1, PL_BYTE PASS_LD);
}


/** @pred  peek_code(+ _S_,- _C_) is iso

If  _C_ is unbound, or is an atom representation of a character, and
the stream  _S_ is a text stream, read the next character from that
stream and unify its representation as an atom with  _C_, while leaving
the current stream position unaltered.

 
*/
static
PRED_IMPL("peek_code", 2, peek_code2, 0)
{ PRED_LD
  return peek(A1, A2, PL_CODE PASS_LD);
}


/** @pred  peek_code(+ _S_,- _C_) is iso

If  _C_ is unbound, or is an atom representation of a character, and
the stream  _S_ is a text stream, read the next character from that
stream and unify its representation as an atom with  _C_, while leaving
the current stream position unaltered.

 
*/
static
PRED_IMPL("peek_code", 1, peek_code1, 0)
{ PRED_LD
  return peek(0, A1, PL_CODE PASS_LD);
}


/** @pred  peek_char(+ _S_,- _C_) is iso

If  _C_ is unbound, or is an atom representation of a character, and
the stream  _S_ is a text stream, read the next character from that
stream and unify its representation as an atom with  _C_, while leaving
the current stream position unaltered.

 
*/
static
PRED_IMPL("peek_char", 2, peek_char2, 0)
{ PRED_LD
  return peek(A1, A2, PL_CHAR PASS_LD);
}

/** @pred  peek_char(- _C_) is iso 


If  _C_ is unbound, or is an atom representation of a character, and
the current stream is a text stream, read the next character from the
current stream and unify its atom representation with  _C_, while
leaving the current stream position unaltered.

 
*/
static
PRED_IMPL("peek_char", 1, peek_char1, 0)
{ PRED_LD
  return peek(0, A1, PL_CHAR PASS_LD);
}

/**
 * @}
 */

/**
 * @ingroup StreamM
 * @{
 */


		 /*******************************
		 *	    INTERACTION		*
		 *******************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
set_prolog_IO(+In, +Out, +Error)

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef struct wrappedIO
{ void		   *wrapped_handle;	/* original handle */
  IOFUNCTIONS      *wrapped_functions;	/* original functions */
  IOSTREAM	   *wrapped_stream;	/* stream we wrapped */
  IOFUNCTIONS       functions;		/* new function block */
} wrappedIO;


ssize_t
Sread_user(void *handle, char *buf, size_t size)
{ GET_LD
  wrappedIO *wio = handle;
  ssize_t rc;

  if ( LD->prompt.next && ttymode != TTY_RAW )
    PL_write_prompt(TRUE);
  else
    Sflush(Suser_output);

  rc = (*wio->wrapped_functions->read)(wio->wrapped_handle, buf, size);
  if ( rc == 0 )			/* end-of-file */
  { Sclearerr(Suser_input);
    LD->prompt.next = TRUE;
  } else if ( rc == 1 && buf[0] == 04 )
  { rc = 0;				/* Map ^D to end-of-file */
  } else if ( rc > 0 && buf[rc-1] == '\n' )
    LD->prompt.next = TRUE;

  return rc;
}


static int
closeWrappedIO(void *handle)
{ wrappedIO *wio = handle;
  int rval;

  if ( wio->wrapped_functions->close )
    rval = (*wio->wrapped_functions->close)(wio->wrapped_handle);
  else
    rval = 0;

  wio->wrapped_stream->functions = wio->wrapped_functions;
  wio->wrapped_stream->handle = wio->wrapped_handle;
  PL_free(wio);

  return rval;
}


static void
wrapIO(IOSTREAM *s,
       ssize_t (*read)(void *, char *, size_t),
       ssize_t (*write)(void *, char *, size_t))
{ wrappedIO *wio = PL_malloc(sizeof(*wio));

  wio->wrapped_functions = s->functions;
  wio->wrapped_handle =	s->handle;
  wio->wrapped_stream = s;

  wio->functions = *s->functions;
  if ( read  ) wio->functions.read  = read;
  if ( write ) wio->functions.write = write;
  wio->functions.close = closeWrappedIO;

  s->functions = &wio->functions;
  s->handle = wio;
}


static
PRED_IMPL("set_prolog_IO", 3, set_prolog_IO, 0)
{ PRED_LD
  IOSTREAM *in = NULL, *out = NULL, *error = NULL;
  int rval = FALSE;
  int wrapin = FALSE;
  int i;

  if ( !term_stream_handle(A1, &in, SH_ERRORS|SH_ALIAS|SH_UNLOCKED PASS_LD) )
    goto out;

  wrapin = (LD->IO.streams[0] != in);
  if ( wrapin )
  { if ( !(in = getStream(in)) )	/* lock it */
      goto out;
  }

  if ( !term_stream_handle(A2, &out, SH_ERRORS|SH_ALIAS PASS_LD) )
    goto out;

  if ( PL_compare(A2, A3) == 0 )	/* == */
  { error = getStream(Snew(out->handle, out->flags, out->functions));
    if ( !error )
      goto out;
    error->flags &= ~SIO_ABUF;		/* disable buffering */
    error->flags |= SIO_NBUF;
  } else
  { if ( !PL_get_stream_handle(A3, &error) )
      goto out;
  }

  LOCK();
  out->flags &= ~SIO_ABUF;		/* output: line buffered */
  out->flags |= SIO_LBUF;

  LD->IO.streams[1] = out;		/* user_output */
  LD->IO.streams[2] = error;		/* user_error */
  LD->IO.streams[4] = out;		/* current_output */

  if ( wrapin )
  { LD->IO.streams[3] = in;		/* current_input */
    LD->IO.streams[0] = in;		/* user_input */
    wrapIO(in, Sread_user, NULL);
    LD->prompt.next = TRUE;
  }

  for(i=0; i<3; i++)
  { LD->IO.streams[i]->position = &LD->IO.streams[0]->posbuf;
    LD->IO.streams[i]->flags |= SIO_RECORDPOS;
  }

  UNLOCK();
  rval = TRUE;

out:
  if ( wrapin && in )
    releaseStream(in);
  if ( out )
    releaseStream(out);
  if ( error && error != out )
    releaseStream(error);

  return rval;
}


static
PRED_IMPL("$size_stream", 2, size_stream, 0)
{ GET_LD
  IOSTREAM *s;
  int rval;

  if ( !PL_get_stream_handle(A1, &s) )
    return FALSE;

  rval = PL_unify_int64(A2, Ssize(s));
  PL_release_stream(s);

  return rval;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
copy_stream_data(+StreamIn, +StreamOut, [Len])
	Copy all data from StreamIn to StreamOut.  Should be somewhere else,
	and maybe we need something else to copy resources.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static int
copy_stream_data(term_t in, term_t out, term_t len ARG_LD)
{ IOSTREAM *i, *o;
  int c;
  int count = 0;

  if ( !getInputStream(in, S_DONTCARE, &i) )
    return FALSE;
  if ( !getOutputStream(out, S_DONTCARE, &o) )
  { releaseStream(i);
    return FALSE;
  }

  if ( !len )
  { while ( (c = Sgetcode(i)) != EOF )
    { if ( (++count % 4096) == 0 && PL_handle_signals() < 0 )
      { releaseStream(i);
	releaseStream(o);
	return FALSE;
      }
      if ( Sputcode(c, o) < 0 )
      { releaseStream(i);
	return streamStatus(o);
      }
    }
  } else
  { int64_t n;

    if ( !PL_get_int64_ex(len, &n) )
      return FALSE;

    while ( n-- > 0 && (c = Sgetcode(i)) != EOF )
    { if ( (++count % 4096) == 0 && PL_handle_signals() < 0 )
      { releaseStream(i);
	releaseStream(o);
	return FALSE;
      }
      if ( Sputcode(c, o) < 0 )
      { releaseStream(i);
	return streamStatus(o);
      }
    }
  }

  releaseStream(o);
  return streamStatus(i);
}

/** @pred copy_stream_data( +_Source_, +_Output_, +_Len_)
 *
 * Copy at most _Len_ characters from stream _Source_ to stream _Output_.
 */
static
PRED_IMPL("copy_stream_data", 3, copy_stream_data3, 0)
{ PRED_LD
  return copy_stream_data(A1, A2, A3 PASS_LD);
}

/** @pred copy_stream_data( +_Source_, +_Output_)
 *
 * Copy all the data left in _Source_ to stream _Output_.
 */
static
PRED_IMPL("copy_stream_data", 2, copy_stream_data2, 0)
{ PRED_LD
  return copy_stream_data(A1, A2, 0 PASS_LD);
}

/**
 * @}
 */


		 /*******************************
		 *      PUBLISH PREDICATES	*
		 *******************************/

BeginPredDefs(file)
					/* ISO IO */
  PRED_DEF("open", 4, open4, PL_FA_ISO)
  PRED_DEF("open", 3, open3, PL_FA_ISO)
  PRED_DEF("close", 1, close, PL_FA_ISO)
  PRED_DEF("close", 2, close2, PL_FA_ISO)
  PRED_DEF("set_input", 1, set_input, PL_FA_ISO)
  PRED_DEF("set_output", 1, set_output, PL_FA_ISO)
  PRED_DEF("current_input", 1, current_input, PL_FA_ISO)
  PRED_DEF("current_output", 1, current_output, PL_FA_ISO)
  PRED_DEF("get_code", 2, get_code2, PL_FA_ISO)
  PRED_DEF("get_code", 1, get_code1, PL_FA_ISO)
  PRED_DEF("get_char", 2, get_char2, PL_FA_ISO)
  PRED_DEF("get_char", 1, get_char1, PL_FA_ISO)
  PRED_DEF("get_byte", 2, get_byte2, PL_FA_ISO)
  PRED_DEF("get_byte", 1, get_byte1, PL_FA_ISO)
  PRED_DEF("peek_code", 2, peek_code2, PL_FA_ISO)
  PRED_DEF("peek_code", 1, peek_code1, PL_FA_ISO)
  PRED_DEF("peek_char", 2, peek_char2, PL_FA_ISO)
  PRED_DEF("peek_char", 1, peek_char1, PL_FA_ISO)
  PRED_DEF("peek_byte", 2, peek_byte2, PL_FA_ISO)
  PRED_DEF("peek_byte", 1, peek_byte1, PL_FA_ISO)
  PRED_DEF("put_byte", 2, put_byte2, PL_FA_ISO)
  PRED_DEF("put_byte", 1, put_byte1, PL_FA_ISO)
  PRED_DEF("put_code", 2, put_code2, PL_FA_ISO)
  PRED_DEF("put_code", 1, put_code1, PL_FA_ISO)
  PRED_DEF("put_char", 2, put_code2, PL_FA_ISO)
  PRED_DEF("put_char", 1, put_code1, PL_FA_ISO)
  PRED_DEF("flush_output", 0, flush_output, PL_FA_ISO)
  PRED_DEF("flush_output", 1, flush_output1, PL_FA_ISO)
  PRED_DEF("at_end_of_stream", 1, at_end_of_stream, PL_FA_ISO)
  PRED_DEF("at_end_of_stream", 0, at_end_of_stream0, PL_FA_ISO)
  PRED_DEF("stream_property", 2, stream_property,
	   PL_FA_ISO|PL_FA_NONDETERMINISTIC)
  PRED_DEF("set_stream_position", 2, set_stream_position, PL_FA_ISO)

					/* edinburgh IO */
  PRED_DEF("see", 1, see, 0)
  PRED_DEF("seen", 0, seen, 0)
  PRED_DEF("seeing", 1, seeing, 0)
  PRED_DEF("tell", 1, tell, 0)
  PRED_DEF("append", 1, append, 0)
  PRED_DEF("told", 0, told, 0)
  PRED_DEF("telling", 1, telling, 0)
  PRED_DEF("put", 2, put2, 0)
  PRED_DEF("put", 1, put1, 0)
  PRED_DEF("skip", 1, skip1, 0)
  PRED_DEF("skip", 2, skip2, 0)
  PRED_DEF("get", 1, get1, 0)
  PRED_DEF("get", 2, get2, 0)
  PRED_DEF("get0", 2, get_code2, 0)
  PRED_DEF("get0", 1, get_code1, 0)
  PRED_DEF("ttyflush", 0, ttyflush, 0)
  PRED_DEF("prompt", 2, prompt, 0)
  PRED_DEF("tab", 2, tab2, 0)
  PRED_DEF("tab", 1, tab1, 0)
					/* Quintus IO */
  PRED_DEF("byte_count", 2, byte_count, 0)
  PRED_DEF("character_count", 2, character_count, 0)
  PRED_DEF("line_count", 2, line_count, 0)
  PRED_DEF("line_position", 2, line_position, 0)
  PRED_DEF("open_null_stream", 1, open_null_stream, 0)

					/* SWI specific */
  PRED_DEF("is_stream", 1, is_stream, 0)
  PRED_DEF("set_stream", 2, set_stream, 0)
  PRED_DEF("with_output_to", 2, with_output_to, PL_FA_TRANSPARENT)
  PRED_DEF("set_prolog_IO", 3, set_prolog_IO, 0)
  PRED_DEF("protocol", 1, protocol, 0)
  PRED_DEF("protocola", 1, protocola, 0)
  PRED_DEF("noprotocol", 0, noprotocol, 0)
  PRED_DEF("protocolling", 1, protocolling, 0)
  PRED_DEF("prompt1", 1, prompt1, 0)
  PRED_DEF("seek", 4, seek, 0)
  PRED_DEF("wait_for_input", 3, wait_for_input, 0)
  PRED_DEF("get_single_char", 1, get_single_char, 0)
  PRED_DEF("read_pending_input", 3, read_pending_input, 0)
  PRED_DEF("source_location", 2, source_location, 0)
  PRED_DEF("copy_stream_data", 3, copy_stream_data3, 0)
  PRED_DEF("copy_stream_data", 2, copy_stream_data2, 0)
  PRED_DEF("stream_pair", 3, stream_pair, 0)
  PRED_DEF("set_end_of_stream", 1, set_end_of_stream, 0)

					/* SWI internal */
  PRED_DEF("$push_input_context", 1, push_input_context, 0)
  PRED_DEF("$pop_input_context", 0, pop_input_context, 0)
  PRED_DEF("$input_context", 1, input_context, 0)
  PRED_DEF("$size_stream", 2, size_stream, 0)
EndPredDefs

#if __YAP_PROLOG__

void Yap_flush(void)
{
 GET_LD
  flush_output(0 PASS_LD);
}

void *
Yap_GetStreamHandle(Atom at)
{ GET_LD
  atom_t a;
  IOSTREAM *s;

  a = YAP_SWIAtomFromAtom(at);
  if (!get_stream_handle(a, &s, SH_ERRORS|SH_ALIAS))
    return NULL;
  return s;
}

void *Yap_GetInputStream(Atom at)
{ GET_LD
  atom_t a;
  IOSTREAM *s;
  if ( at == AtomUser ) {
    if ( (s = getStream(Suser_input)) )
      return s;
    return NULL;
  }

  a = YAP_SWIAtomFromAtom(at);
  if ( !get_stream_handle(a, &s, SH_ERRORS|SH_ALIAS|SH_INPUT) )
    return NULL;

  if ( !(s->flags &SIO_INPUT) )
  { releaseStream(s);
    return Yap_Error(PERMISSION_ERROR_INPUT_STREAM, MkAtomTerm(at),
		     "read or ql");
    return NULL;
  }
  return s;
}

void *Yap_GetOutputStream(Atom at)
{ GET_LD
  atom_t a;
  IOSTREAM *s;
  if ( at == AtomUser ) {
    if ( (s = getStream(Suser_output)) )
      return s;
    return NULL;
  }

  a = YAP_SWIAtomFromAtom(at);
  if ( !get_stream_handle(a, &s, SH_ERRORS|SH_ALIAS|SH_OUTPUT) )
    return NULL;

  if ( !(s->flags &SIO_OUTPUT) )
  { releaseStream(s);
    return Yap_Error(PERMISSION_ERROR_OUTPUT_STREAM, MkAtomTerm(at),
		     "write or ql");
    return NULL;
  }
  return s;
}

static int
pl_get_time(term_t t)
{ return PL_unify_float(t, WallTime());
}

static word
pl_sleep(term_t time)
{ double t;

  if ( PL_get_float_ex(time, &t) )
    return Pause(t);

  fail;
}


static const PL_extension foreigns[] = {
  FRG("nl",			0, pl_nl,			ISO),
  FRG("write_canonical",	1, pl_write_canonical,	      ISO),
  FRG("write_term",		2, pl_write_term,	      ISO),
  FRG("write_term",		3, pl_write_term3,	      ISO),
  FRG("write",			1, pl_write,		      ISO),
  FRG("writeq",			1, pl_writeq,		      ISO),
  FRG("print",			1, pl_print,			0),
  FRG("writeln",		1, pl_writeln,			0),
  FRG("nl",			1, pl_nl1,		      ISO),
  FRG("format",			2, pl_format,		     META),

  FRG("write",			2, pl_write2,		      ISO),
  FRG("writeq",			2, pl_writeq2,		      ISO),
  FRG("print",			2, pl_print2,			0),
  FRG("write_canonical",	2, pl_write_canonical2,	      ISO),
  FRG("format",			3, pl_format3,		     META),
  FRG("sleep",			1, pl_sleep,			0),
  FRG("get_time",		1, pl_get_time,			0),

  // vsc
  FRG("format_predicate",	2, pl_format_predicate,	     META),
  FRG("current_format_predicate", 2, pl_current_format_predicate,
						        META|NDET),
  FRG("$raw_read",		1, pl_raw_read,			0),
  FRG("$raw_read",		2, pl_raw_read2,		0),

  FRG("$swi_current_prolog_flag",	5, pl_prolog_flag5,	     NDET),
  FRG("$swi_current_prolog_flag",	2, pl_prolog_flag,	 NDET|ISO),
  /* DO NOT ADD ENTRIES BELOW THIS ONE */
  LFRG((char *)NULL,		0, NULL,			0)
};

#if __ANDROID__
JNIEnv *Yap_jenv;

void Java_pt_up_fc_dcc_yap_JavaYap_load(JNIEnv *env0, jobject obj, jobject mgr);

void Java_pt_up_fc_dcc_yap_JavaYap_load
     (JNIEnv *env0, jobject obj, jobject mgr0)
{
  AAssetManager *mgr = AAssetManager_fromJava(env0, mgr0);
  Yap_jenv = env0;
  if (mgr == NULL) {
  } else {
      GLOBAL_assetManager = mgr;
  }
}

AAssetManager *Yap_assetManager( void );

AAssetManager *Yap_assetManager( void )
{
  return GLOBAL_assetManager;
}
#endif


struct PL_local_data *Yap_InitThreadIO(int wid)
{
  struct PL_local_data *p;
  if (wid) 
    p = (struct PL_local_data *)malloc(sizeof(struct PL_local_data));
  else
    return &lds;
  if (!p) {
    Yap_Error(OUT_OF_HEAP_ERROR, 0L, "Creating thread %d\n", wid);
    return p;
  }
#if THREADS
  memcpy(p, Yap_local[0]->PL_local_data_p_, sizeof(struct PL_local_data));
#endif
  return p;
}

#ifdef THREADS

#define COUNT_MUTEX_INITIALIZER(name) \
 { PTHREAD_MUTEX_INITIALIZER, \
   name, \
   0L \
 }


counting_mutex _PL_mutexes[] =
{ COUNT_MUTEX_INITIALIZER("L_MISC"),
  COUNT_MUTEX_INITIALIZER("L_ALLOC"),
  COUNT_MUTEX_INITIALIZER("L_ATOM"),
  COUNT_MUTEX_INITIALIZER("L_FLAG"),
  COUNT_MUTEX_INITIALIZER("L_FUNCTOR"),
  COUNT_MUTEX_INITIALIZER("L_RECORD"),
  COUNT_MUTEX_INITIALIZER("L_THREAD"),
  COUNT_MUTEX_INITIALIZER("L_PREDICATE"),
  COUNT_MUTEX_INITIALIZER("L_MODULE"),
  COUNT_MUTEX_INITIALIZER("L_TABLE"),
  COUNT_MUTEX_INITIALIZER("L_BREAK"),
  COUNT_MUTEX_INITIALIZER("L_FILE"),
  COUNT_MUTEX_INITIALIZER("L_PLFLAG"),
  COUNT_MUTEX_INITIALIZER("L_OP"),
  COUNT_MUTEX_INITIALIZER("L_INIT"),
  COUNT_MUTEX_INITIALIZER("L_TERM"),
  COUNT_MUTEX_INITIALIZER("L_GC"),
  COUNT_MUTEX_INITIALIZER("L_AGC"),
  COUNT_MUTEX_INITIALIZER("L_STOPTHEWORLD"),
  COUNT_MUTEX_INITIALIZER("L_FOREIGN"),
  COUNT_MUTEX_INITIALIZER("L_OS"),
  COUNT_MUTEX_INITIALIZER("L_LOCALE")
#ifdef __WINDOWS__
, COUNT_MUTEX_INITIALIZER("L_DDE")
, COUNT_MUTEX_INITIALIZER("L_CSTACK")
#endif

};

static void
initMutexes( void )
{ counting_mutex *m;
  int n = sizeof(_PL_mutexes)/sizeof(*m);
  int i;

  for(i=0, m=_PL_mutexes; i<n; i++, m++)
    simpleMutexInit(&m->mutex);
}


#endif


static void
init_yap(void)
{
  GET_LD
#ifdef THREADS
  initMutexes();
#endif
  /* we need encodings first */
#ifdef O_LOCALE
  initLocale();
#endif
  initCharTypes();
  debugstatus.styleCheck = LONGATOM_CHECK|MULTITON_CHECK|DISCONTIGUOUS_STYLE|MULTIPLE_CHECK|SINGLETON_CHECK;
  initPrologFlags();
  clearPrologFlagMask(PLFLAG_DEBUGINFO);
  setPrologFlagMask(PLFLAG_TTY_CONTROL);
  initFiles();
  PL_register_extensions(PL_predicates_from_ctype);
  PL_register_extensions(PL_predicates_from_file);
  PL_register_extensions(PL_predicates_from_files);
  PL_register_extensions(PL_predicates_from_glob);
  PL_register_extensions(PL_predicates_from_write);
  PL_register_extensions(PL_predicates_from_read);
  PL_register_extensions(PL_predicates_from_tai);
  PL_register_extensions(PL_predicates_from_prologflag);
  //PL_register_extensions(PL_predicates_from_system);
#ifdef O_LOCALE
  PL_register_extensions(PL_predicates_from_locale);
#endif
#ifdef __WINDOWS__
  PL_register_extensions(PL_predicates_from_win);
#endif
  PL_register_extensions(foreigns);
  fileerrors = TRUE;
  SinitStreams();
  initOs();
  PL_install_readline();
}
#endif

/**
@}
*/