/* file stdio intrinsics for S-Lang */
/*
Copyright (C) 2004-2017,2018 John E. Davis

This file is part of the S-Lang Library.

The S-Lang Library is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The S-Lang 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
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.
*/

#include "slinclud.h"

#if defined(__unix__) || (defined (__os2__) && defined (__EMX__))
# include <sys/types.h>
#endif

#ifdef HAVE_FCNTL_H
# include <fcntl.h>
#else
# ifdef HAVE_SYS_FCNTL_H
#  include <sys/fcntl.h>
# endif
#endif

#ifdef __unix__
# include <sys/file.h>
#endif

#if defined(__BORLANDC__)
# include <io.h>
# include <dir.h>
#endif

#if defined(__DECC) && defined(VMS)
# include <unixio.h>
# include <unixlib.h>
#endif

#ifdef VMS
# include <stat.h>
#else
# include <sys/stat.h>
#endif

#include <errno.h>

#include <ctype.h>

/* #define SL_APP_WANTS_FOREACH */
#include "slang.h"
#include "_slang.h"

#ifdef HAVE_FSEEKO
# define FSEEK(a,b,c) fseeko(a,b,c)
# define FTELL(a) ftello(a)
#else
# define FSEEK(a,b,c) fseek(a,b,c)
# define FTELL(a) ftell(a)
#endif

typedef struct
{
   FILE *fp;			       /* kind of obvious */
   char *file;			       /* file name associated with pointer */

   unsigned int flags;		       /* modes, etc... */
#define SL_READ		0x0001
#define SL_WRITE	0x0002
#define SL_BINARY	0x0004
#define SL_FDOPEN	0x2000
#define SL_PIPE		0x4000
#define SL_INUSE	0x8000

   char *buf;
   unsigned int buflen;
}
SL_File_Table_Type;

static SL_File_Table_Type *SL_File_Table;

static SL_File_Table_Type *get_free_file_table_entry (void)
{
   SL_File_Table_Type *t = SL_File_Table, *tmax;

   tmax = t + SL_MAX_FILES;
   while (t < tmax)
     {
	if (t->flags == 0)
	  {
	     memset ((char *) t, 0, sizeof (SL_File_Table_Type));
	     return t;
	  }
	t++;
     }

   return NULL;
}

/* This function returns 1 if a system call should be restarted, otherwise 0 */
static int handle_errno (int e)
{
#ifdef EINTR
   if (e == EINTR)
     {
	if (0 == SLang_handle_interrupt ())
	  {
	     errno = 0;
	     return 1;
	  }
     }
#endif
   _pSLerrno_errno = e;
   return 0;
}

/* The man page for fputs indicates that it returns a non-negative integer, or
 * EOF.  It says nothing about how many bytes were sucessfully written.  Sigh.
 * So, use fwrite instead.
 */
static ssize_t signal_safe_fputs (char *buf, FILE *fp)
{
   size_t len;
   size_t num_written;

   len = strlen (buf);
   num_written = 0;
   while (num_written < len)
     {
	unsigned int n = len - num_written;
	unsigned int dn;

	clearerr (fp);
	errno = 0;
	dn = fwrite (buf + num_written, 1, n, fp);

	num_written += dn;
	if (dn < n)
	  {
	     int e = errno;

	     /* The idea is that since some of the bytes were written
	      * (dn != 0), trying it again would not hurt.  The reason for this
	      * is that sometimes glibc's fwrite would get interrupted by a
	      * signal, but return with errno==0 (not EINTR), which resulted
	      * in data being lost.  So it seemed that as long as something was
	      * being written, things would work out ok.
	      *
	      * However, it was discovered that this work-around would fail
	      * when writing to a stream buffered pipe that was closed.  In
	      * such a case, glibc was returning a short non-zero item count
	      * even though the underlying stream was closed.  For this reason
	      * I recommend that one should turn off stdio buffering when
	      * writing to pipes.  Here, a special check is added for EPIPE.
	      */
	     _pSLerrno_errno = e;
	     if ((dn == 0)
#ifdef EPIPE
		 || (e == EPIPE)
#endif
		)
	       {
		  if (0 == handle_errno (e))
		    break;
	       }
	  }
     }
   return num_written;
}

static int signal_safe_fgets (char *buf, unsigned int buflen, FILE *fp)
{
   errno = 0;

   while (NULL == fgets (buf, buflen, fp))
     {
	if (0 == handle_errno (errno))
	  return -1;
     }
   return 0;
}

static unsigned int file_process_flags (char *mode)
{
   char ch;
   unsigned int flags = 0;

   while (1)
     {
	ch = *mode++;
	switch (ch)
	  {
	   case 'r': flags |= SL_READ;
	     break;
	   case 'w':
	   case 'a':
	   case 'A':
	     flags |= SL_WRITE;
	     break;
	   case '+': flags |= SL_WRITE | SL_READ;
	     break;
	   case 'b': flags |= SL_BINARY;
	     break;
	   case 0:
	     return flags;

	   default:
	     _pSLang_verror (SL_INVALID_PARM, "File flag %c is not supported", ch);
	     return 0;
	  }
     }
}

static int open_file_type (char *file, int fd, char *mode,
			   FILE *(*open_fun)(char *, char *),
			   int (*close_fun)(FILE *),
			   unsigned int xflags)
{
   FILE *fp;
   SL_File_Table_Type *t;
   unsigned int flags;
   SLang_MMT_Type *mmt;

   fp = NULL;
   /* t = NULL; */
   mmt = NULL;

   if ((NULL == (t = get_free_file_table_entry ()))
       || (0 == (flags = file_process_flags(mode))))
     goto return_error;

   while (1)
     {
	errno = 0;
	if (fd != -1)
	  fp = fdopen (fd, mode);
	else
	  fp = open_fun (file, mode);

	if (fp != NULL)
	  break;

	if (0 == handle_errno (errno))
	  goto return_error;
     }

   if (NULL == (mmt = SLang_create_mmt (SLANG_FILE_PTR_TYPE, (VOID_STAR) t)))
     goto return_error;

   t->fp = fp;
   t->flags = flags | xflags;
   fp = NULL;			       /* allow free_mmt to close fp */

   if ((NULL != (t->file = SLang_create_slstring (file)))
       && (0 == SLang_push_mmt (mmt)))
     return 0;

   /* drop */

   return_error:
   if (fp != NULL) (*close_fun) (fp);
   if (mmt != NULL) SLang_free_mmt (mmt);
   (void) SLang_push_null ();
   return -1;
}

/* Since some compilers do not have popen/pclose prototyped and in scope,
 * and pc compilers sometimes have silly prototypes involving PASCAL, etc.
 * use wrappers around the function to avoid compilation errors.
 */

static FILE *fopen_fun (char *f, char *m)
{
   FILE *fp;

   errno = 0;
   while (NULL == (fp = fopen (f, m)))
     {
	if (0 == handle_errno (errno))
	  return NULL;
     }
   return fp;
}

/* This function is used only the open_file_type function */
static int fclose_fun (FILE *fp)
{
   if (EOF == fclose (fp))
     {
	(void) handle_errno (errno);
	return -1;
     }
   return 0;
}

static void stdio_fopen (char *file, char *mode)
{
   (void) open_file_type (file, -1, mode, fopen_fun, fclose_fun, 0);
}

int _pSLstdio_fdopen (char *file, int fd, char *mode)
{
   if (fd == -1)
     {
	_pSLerrno_errno = EBADF;
	(void) SLang_push_null ();
	return -1;
     }

   return open_file_type (file, fd, mode, NULL, fclose_fun, SL_FDOPEN);
}

#ifdef HAVE_POPEN
static int pclose_fun (FILE *fp)
{
   int status;

   errno = 0;
   status = pclose (fp);
   if (status != 0)
     _pSLerrno_errno = errno;
   return status;
}

static FILE *popen_fun (char *file, char *mode)
{
   return popen (file, mode);
}

static void stdio_popen (char *file, char *mode)
{
   (void) open_file_type (file, -1, mode, popen_fun, pclose_fun, SL_PIPE);
}
#endif

/* returns pointer to file entry if it is open and consistent with
   flags.  Returns NULL otherwise */
static SLang_MMT_Type *pop_fp (unsigned int flags, FILE **fp_ptr)
{
   SL_File_Table_Type *t;
   SLang_MMT_Type *mmt;

   *fp_ptr = NULL;

   if (NULL == (mmt = SLang_pop_mmt (SLANG_FILE_PTR_TYPE)))
     return NULL;

   t = (SL_File_Table_Type *) SLang_object_from_mmt (mmt);
   if ((t->flags & flags)
       && (NULL != (*fp_ptr = t->fp)))
     return mmt;

#ifdef EBADF
   _pSLerrno_errno = EBADF;
#endif
   SLang_free_mmt (mmt);
   return NULL;
}

static FILE *check_fp (SL_File_Table_Type *t, unsigned flags)
{
   if ((t != NULL) && (t->flags & flags))
     return t->fp;

   return NULL;
}

SLFUTURE_CONST char *SLang_get_name_from_fileptr (SLang_MMT_Type *mmt)
{
   SL_File_Table_Type *ft;

   ft = (SL_File_Table_Type *) SLang_object_from_mmt (mmt);
   if (ft == NULL)
     return NULL;
   return ft->file;
}

int SLang_pop_fileptr (SLang_MMT_Type **mmt, FILE **fp)
{
   if (NULL == (*mmt = pop_fp (0xFFFF, fp)))
     return -1;

   return 0;
}

int SLang_get_fileptr (SLang_MMT_Type *mmt, FILE **fpp)
{
   SL_File_Table_Type *t;

   *fpp = NULL;
   if (mmt == NULL)
     return -1;

   t = (SL_File_Table_Type *) SLang_object_from_mmt (mmt);
   if (t == NULL)
     return -1;

   *fpp = t->fp;
   return 0;
}

static int close_file_type (SL_File_Table_Type *t)
{
   int ret = 0;
   FILE *fp;

   if (t == NULL)
     return -1;

   fp = t->fp;

   /* fclose should not be restarted upon EINTR.  So, flush the stream
    * and then close it.  Assume the same for pclose.
    */
   if (NULL == fp) ret = -1;
#if HAVE_POPEN
   else if (t->flags & SL_PIPE)
     ret = pclose (fp);
#endif
   else
     {
	if (t->flags & SL_WRITE)
	  {
	     errno = 0;
	     while ((-1 == fflush (fp))
		    && (1 == handle_errno (errno)))
	       errno = 0;
	  }
	if (EOF == fclose (fp))
	  ret = -1;
     }

   if (t->buf != NULL) SLfree (t->buf);
   if (t->file != NULL) SLang_free_slstring (t->file);
   memset ((char *) t, 0, sizeof (SL_File_Table_Type));
   return ret;
}

static int stdio_fclose (void)
{
   int ret;
   SLang_MMT_Type *mmt;
   SL_File_Table_Type *t;

   if (NULL == (mmt = SLang_pop_mmt (SLANG_FILE_PTR_TYPE)))
     return -1;

   t = (SL_File_Table_Type *) SLang_object_from_mmt (mmt);
   if (NULL == check_fp (t, 0xFFFF))
     {
	SLang_free_mmt (mmt);
	return -1;
     }

   if (t->flags & SL_FDOPEN)
     _pSLfclose_fdopen_fp (mmt);

   ret = close_file_type (t);

   t->flags = SL_INUSE;
   SLang_free_mmt (mmt);
   return ret;
}

static int read_one_line (FILE *fp, char **strp, SLstrlen_Type *lenp, int trim_trailing)
{
   char buf[512];
   char *str;
   size_t len;

   *strp = NULL;
   len = 0;
   str = NULL;

   while (-1 != signal_safe_fgets (buf, sizeof (buf), fp))
     {
	size_t dlen;
	char *new_str;
	int done_flag;

	dlen = strlen (buf);
	/* Note: If the file contains embedded \0 characters, then this
	 * fails to work properly since dlen will not be correct.
	 */
	done_flag = ((dlen + 1 < sizeof (buf))
		     || (buf[dlen - 1] == '\n'));

	if (done_flag && (str == NULL))
	  {
	     /* Avoid the malloc */
	     str = buf;
	     len = dlen;
	     break;
	  }

	if (NULL == (new_str = (char *)SLrealloc (str, len + dlen + 1)))
	  {
	     SLfree (str);
	     return -1;
	  }

	str = new_str;
	strcpy (str + len, buf);
	len += dlen;

	if (done_flag) break;
     }

   if (str == NULL)
     return 0;

   if (trim_trailing)
     {
	unsigned int len1 = len;
	while (len1)
	  {
	     len1--;
	     if (0 == isspace ((unsigned char)str[len1]))
	       {
		  len1++;
		  break;
	       }
	  }
	len = len1;
     }

   *strp = SLang_create_nslstring (str, len);
   if (str != buf) SLfree (str);

   if (*strp == NULL) return -1;

   *lenp = len;
   return 1;
}

/* returns number of characters read and pushes the string to the stack.
   If it fails, it returns -1 */
static int stdio_fgets (SLang_Ref_Type *ref, SL_File_Table_Type *t)
{
   char *s;
   SLstrlen_Type len;
   FILE *fp;
   int status;

   if (NULL == (fp = check_fp (t, SL_READ)))
     return -1;

   status = read_one_line (fp, &s, &len, 0);
   if (status <= 0)
     return -1;

   status = SLang_assign_to_ref (ref, SLANG_STRING_TYPE, (VOID_STAR)&s);
   _pSLang_free_slstring (s);

   if (status == -1)
     return -1;

   return (int) len;
}

static void stdio_fgetslines_internal (FILE *fp, unsigned int n)
{
   unsigned int num_lines, max_num_lines;
   char **list;
   SLang_Array_Type *at;
   SLindex_Type inum_lines;

   if (n > 1024)
     max_num_lines = 1024;
   else
     {
	max_num_lines = n;
	if (max_num_lines == 0)
	  max_num_lines++;
     }

   list = (char **) _SLcalloc (max_num_lines, sizeof (char *));
   if (list == NULL)
     return;

   num_lines = 0;
   while (num_lines < n)
     {
	int status;
	char *line;
	SLstrlen_Type len;

	status = read_one_line (fp, &line, &len, 0);
	if (status == -1)
	  goto return_error;

	if (status == 0)
	  break;

	if (max_num_lines == num_lines)
	  {
	     char **new_list;

	     if (max_num_lines + 4096 > n)
	       max_num_lines = n;
	     else
	       max_num_lines += 4096;

	     new_list = (char **) SLrealloc ((char *)list, sizeof (char *) * max_num_lines);
	     if (new_list == NULL)
	       {
		  _pSLang_free_slstring (line);
		  goto return_error;
	       }
	     list = new_list;
	  }

	list[num_lines] = line;
	num_lines++;
     }

   if (num_lines != max_num_lines)
     {
	char **new_list;

	new_list = (char **)SLrealloc ((char *)list, sizeof (char *) * (num_lines + 1));
	if (new_list == NULL)
	  goto return_error;

	list = new_list;
     }

   inum_lines = (SLindex_Type) num_lines;
   if (NULL == (at = SLang_create_array (SLANG_STRING_TYPE, 0, (VOID_STAR) list, &inum_lines, 1)))
     goto return_error;

   if (-1 == SLang_push_array (at, 1))
     SLang_push_null ();
   return;

return_error:
   while (num_lines > 0)
     {
	num_lines--;
	SLang_free_slstring (list[num_lines]);
     }
   SLfree ((char *)list);
   SLang_push_null ();
}

static void stdio_fgetslines (void)
{
   unsigned int n;
   FILE *fp;
   SLang_MMT_Type *mmt;

   n = (unsigned int)-1;

   if (SLang_Num_Function_Args == 2)
     {
	if (-1 == SLang_pop_uinteger (&n))
	  return;
     }

   if (NULL == (mmt = pop_fp (SL_READ, &fp)))
     {
	SLang_push_null ();
	return;
     }

   stdio_fgetslines_internal (fp, n);
   SLang_free_mmt (mmt);
}

static int stdio_fputslines (void)
{
   char **lines, **lines_max;
   int num;
   FILE *fp;
   SLang_MMT_Type *mmt;
   SLang_Array_Type *at;

   if (NULL == (mmt = pop_fp (SL_WRITE, &fp)))
     return -1;

   if (-1 == SLang_pop_array_of_type (&at, SLANG_STRING_TYPE))
     {
	SLang_free_mmt (mmt);
	return -1;
     }
   lines = (char **)at->data;
   lines_max = lines + at->num_elements;

   while (lines < lines_max)
     {
	if ((*lines != NULL)
	    && (-1 == signal_safe_fputs (*lines, fp)))
	  break;

	lines++;
     }
   SLang_free_mmt (mmt);
   num = (int) (lines - (char **)at->data);
   SLang_free_array (at);
   return num;
}

static int stdio_fputs (char *s, SL_File_Table_Type *t)
{
   FILE *fp;

   if (NULL == (fp = check_fp (t, SL_WRITE)))
     return -1;

   return signal_safe_fputs (s, fp);
}

static int stdio_fflush (SL_File_Table_Type *t)
{
   FILE *fp;

   if (NULL == (fp = check_fp (t, SL_WRITE)))
     return -1;

   errno = 0;
   clearerr (fp);
   while ((EOF == fflush (fp)) || ferror (fp))
     {
	if (0 == handle_errno (errno))
	  return -1;
	clearerr (fp);
     }

   return 0;
}

/* Helper function */
static int check_ferror_and_realloc (FILE *fp, int ret, char **strp, unsigned int num_wanted,
				     unsigned int num_read, unsigned int sizeof_type)
{
   if ((num_read == 0)
       && (num_read != num_wanted))
     ret = -1;

   if ((ret == -1) && ferror (fp))
     _pSLerrno_errno = errno;

   if ((ret == 0)
       && (num_read != num_wanted))
     {
	char *new_s;
	unsigned int nbytes = num_read * sizeof_type;
	new_s = (char *)SLrealloc (*strp, nbytes + 1);
	if (new_s == NULL)
	  ret = -1;
	else
	  *strp = new_s;
     }
   return ret;
}

static void stdio_fread_bytes (SLang_Ref_Type *ref, unsigned int *num_wantedp, SL_File_Table_Type *t)
{
   FILE *fp;
   size_t num_read = 0, num_wanted = *num_wantedp;
   int ret = -1;
   char *buf = NULL;
   SLstrlen_Type nwp1;
   SLang_BString_Type *bs;
   if (NULL == (fp = check_fp (t, SL_READ)))
     goto the_return;

   /* FIXME: until SLstrlen_Type == size_t, add this check */
   nwp1 = num_wanted + 1;
   if ((size_t)nwp1 != num_wanted+1)
     {
	SLang_set_error (SL_MALLOC_ERROR);
	return;
     }

   if (NULL == (buf = (char *)SLmalloc (num_wanted + 1)))
     goto the_return;

   while (num_read < num_wanted)
     {
	size_t dnum;

	dnum = fread (buf + num_read, sizeof(char), num_wanted-num_read, fp);
	num_read += dnum;
	if (num_read == num_wanted)
	  break;

	if (0 == handle_errno (errno))
	  break;
     }

   ret = check_ferror_and_realloc (fp, 0, &buf, num_wanted, num_read, sizeof (char));
   if (ret == -1)
     goto the_return;

   bs = SLbstring_create_malloced ((unsigned char *)buf, num_read, 1);
   ret = SLang_assign_to_ref (ref, SLANG_BSTRING_TYPE, (VOID_STAR)&bs);
   SLbstring_free (bs);
   buf = NULL;

   the_return:

   if (buf != NULL) SLfree (buf);
   if (ret == -1)
     (void) SLang_push_integer (ret);
   else
     (void) SLang_push_uinteger (num_read);
}

/* Usage: n = fread (&str, data-type, nelems, fp); */
static void stdio_fread (SLang_Ref_Type *ref, int *data_typep, unsigned int *num_elemns, SL_File_Table_Type *t)
{
   char *s;
   FILE *fp;
   int ret;
   SLstrlen_Type num_read, num_to_read;
   SLstrlen_Type nbytes;
   SLang_Class_Type *cl;
   size_t sizeof_type;
   int data_type;

   /* FIXME: priority = low : I should add some mechanism to support
    * other types.
    */
   data_type = *data_typep;
   if ((data_type == SLANG_BSTRING_TYPE) || (data_type == SLANG_STRING_TYPE))
     {
	stdio_fread_bytes (ref, num_elemns, t);
	return;
     }

   ret = -1;
   s = NULL;
   /* cl = NULL; */

   if (NULL == (fp = check_fp (t, SL_READ)))
     goto the_return;

   cl = _pSLclass_get_class ((SLtype) data_type);

   if (cl->cl_fread == NULL)
     {
	_pSLang_verror (SL_NOT_IMPLEMENTED,
		      "fread does not support %s objects",
		      cl->cl_name);
	goto the_return;
     }

   sizeof_type = cl->cl_sizeof_type;

   num_to_read = *num_elemns;
   nbytes = num_to_read * sizeof_type;

   s = (char *)SLmalloc (nbytes + 1);
   if (s == NULL)
     goto the_return;

   ret = cl->cl_fread (data_type, fp, (VOID_STAR)s, num_to_read, &num_read);

   ret = check_ferror_and_realloc (fp, ret, &s, num_to_read, num_read, sizeof_type);
   if (ret == -1)
     goto the_return;

   if (num_read == 1)
     {
	ret = SLang_assign_to_ref (ref, data_type, (VOID_STAR)s);
	SLfree (s);
     }
   else
     {
	SLang_Array_Type *at;
	SLindex_Type inum_read = (SLindex_Type) num_read;
	at = SLang_create_array (data_type, 0, (VOID_STAR)s, &inum_read, 1);
	if (at == NULL)
	  goto the_return;

	ret = SLang_assign_to_ref (ref, SLANG_ARRAY_TYPE, (VOID_STAR)&at);
	SLang_free_array (at);
     }
   s = NULL;
   /* drop */
the_return:
   if (s != NULL)
     SLfree (s);

   if (ret == -1)
     SLang_push_integer (ret);
   else
     SLang_push_uinteger (num_read);
}

/* Usage: n = fwrite (str, fp); */
static void stdio_fwrite (SL_File_Table_Type *t)
{
   FILE *fp;
   unsigned char *s;
   SLstrlen_Type num_to_write, num_write;
   int ret;
   SLang_BString_Type *b;
   SLang_Array_Type *at;
   SLang_Class_Type *cl;

   ret = -1;
   b = NULL;
   at = NULL;

   switch (SLang_peek_at_stack ())
     {
      case SLANG_BSTRING_TYPE:
      case SLANG_STRING_TYPE:
	if (-1 == SLang_pop_bstring (&b))
	  goto the_return;

	if (NULL == (s = SLbstring_get_pointer (b, &num_to_write)))
	  goto the_return;

	cl = _pSLclass_get_class (SLANG_UCHAR_TYPE);
	break;

      default:
	if (-1 == SLang_pop_array (&at, 1))
	  goto the_return;

	cl = at->cl;
	num_to_write = at->num_elements;
	s = (unsigned char *) at->data;
     }

   if (NULL == (fp = check_fp (t, SL_WRITE)))
     goto the_return;

   if (cl->cl_fwrite == NULL)
     {
	_pSLang_verror (SL_NOT_IMPLEMENTED,
		      "fwrite does not support %s objects", cl->cl_name);
	goto the_return;
     }

   /* The cl_fwrite method should handle EINTR */
   ret = cl->cl_fwrite (cl->cl_data_type, fp, s, num_to_write, &num_write);

   if ((ret == -1) && ferror (fp))
     _pSLerrno_errno = errno;

   /* drop */
   the_return:
   if (b != NULL)
     SLbstring_free (b);
   if (at != NULL)
     SLang_free_array (at);

   if (ret == -1)
     SLang_push_integer (ret);
   else
     SLang_push_uinteger (num_write);
}

static int stdio_fseek (SL_File_Table_Type *t, _pSLc_off_t_Type *ofs, int *whence)
{
   FILE *fp;

   if (NULL == (fp = check_fp (t, 0xFFFF)))
     return -1;

   errno = 0;
   while (-1 == FSEEK (fp, *ofs, *whence))
     {
	if (0 == handle_errno (errno))
	  return -1;
     }
   return 0;
}

static void stdio_ftell (SL_File_Table_Type *t)
{
   FILE *fp;
   _pSLc_off_t_Type ofs;

   if (NULL == (fp = check_fp (t, 0xFFFF)))
     {
	(void) SLang_push_int (-1);
	return;
     }

   errno = 0;
   while (-1L == (ofs = FTELL (fp)))
     {
	if (0 == handle_errno (errno))
	  {
	     (void) SLang_push_int (-1);
	     return;
	  }
     }
   (void) SLANG_PUSH_OFF_T (ofs);
}

static int stdio_feof (SL_File_Table_Type *t)
{
   FILE *fp;

   if (NULL == (fp = check_fp (t, 0xFFFF)))
     return -1;

   return feof (fp);
}

static int stdio_ferror (SL_File_Table_Type *t)
{
   FILE *fp;

   if (NULL == (fp = check_fp (t, 0xFFFF)))
     return -1;

   return ferror (fp);
}

static void stdio_clearerr (SL_File_Table_Type *t)
{
   FILE *fp;

   if (NULL != (fp = check_fp (t, 0xFFFF)))
     clearerr (fp);
}

/* () = fprintf (fp, "FORMAT", arg...); */
static int stdio_fprintf (void)
{
   char *s;
   FILE *fp;
   SLang_MMT_Type *mmt;
   int status;

   if (-1 == _pSLstrops_do_sprintf_n (SLang_Num_Function_Args - 2))
     return -1;

   if (-1 == SLang_pop_slstring (&s))
     return -1;

   if (NULL == (mmt = pop_fp (SL_WRITE, &fp)))
     {
	_pSLang_free_slstring (s);
	return -1;
     }

   status = signal_safe_fputs (s, fp);

   SLang_free_mmt (mmt);
   _pSLang_free_slstring (s);
   return status;
}

static int stdio_printf (void)
{
   char *s;
   int status;

   if (-1 == _pSLstrops_do_sprintf_n (SLang_Num_Function_Args - 1))
     return -1;

   if (-1 == SLang_pop_slstring (&s))
     return -1;

   status = signal_safe_fputs (s, stdout);

   _pSLang_free_slstring (s);
   return status;
}

#ifdef HAVE_SETVBUF
static int stdio_setvbuf (SL_File_Table_Type *t, int *modep, int *sizep)
{
   FILE *fp;
   int status;
   char *newbuf;
   unsigned int size;

   if (NULL == (fp = check_fp (t, 0xFFFF)))
     return -1;

   if (*sizep < 0)
     {
	SLang_verror (SL_InvalidParm_Error, "setvbuf: Expecting a positive integer for the size parameter");
	return -1;
     }

   size = (unsigned int) *sizep;
   newbuf = NULL;

   errno = 0;
   if (*modep == _IONBF)
     status = setvbuf (fp, NULL, _IONBF, 0);
   else if (*sizep == 0)
     status = setvbuf (fp, NULL, *modep, 0);
   else
     {
	if (size == 0) size = BUFSIZ;

	if (NULL == (newbuf = (char *)SLmalloc (size)))
	  return -1;
	errno = 0;
	status = setvbuf (fp, newbuf, *modep, size);
     }

   if (status != 0)
     {
	_pSLerrno_errno = errno;
	if (newbuf != NULL)
	  SLfree (newbuf);
	return -1;
     }

   if (newbuf != NULL)
     {
	if (t->buf != NULL)
	  SLfree (t->buf);
	t->buf = newbuf;
	t->buflen = size;
     }
   return status;
}
#endif

#define F SLANG_FILE_PTR_TYPE
#define R SLANG_REF_TYPE
#define I SLANG_INT_TYPE
#define V SLANG_VOID_TYPE
#define S SLANG_STRING_TYPE
#define B SLANG_BSTRING_TYPE
#define U SLANG_UINT_TYPE
#define D SLANG_DATATYPE_TYPE
static SLang_Intrin_Fun_Type Stdio_Name_Table[] =
{
   MAKE_INTRINSIC_0("fgetslines", stdio_fgetslines, V),
   MAKE_INTRINSIC_0("fputslines", stdio_fputslines, I),
   MAKE_INTRINSIC_SS("fopen", stdio_fopen, V),
   MAKE_INTRINSIC_1("feof", stdio_feof, I, F),
   MAKE_INTRINSIC_1("ferror", stdio_ferror, I, F),
   MAKE_INTRINSIC_0("fclose", stdio_fclose, I),
   MAKE_INTRINSIC_2("fgets", stdio_fgets, I, R, F),
   MAKE_INTRINSIC_1("fflush", stdio_fflush, I, F),
   MAKE_INTRINSIC_2("fputs", stdio_fputs, I, S, F),
   MAKE_INTRINSIC_0("fprintf", stdio_fprintf, I),
   MAKE_INTRINSIC_0("printf", stdio_printf, I),
   MAKE_INTRINSIC_3("fseek", stdio_fseek, I, F, SLANG_C_OFF_T_TYPE, I),
   MAKE_INTRINSIC_1("ftell", stdio_ftell, V, F),
   MAKE_INTRINSIC_1("clearerr", stdio_clearerr, V, F),
   MAKE_INTRINSIC_4("fread", stdio_fread, V, R, D, U, F),
   MAKE_INTRINSIC_3("fread_bytes", stdio_fread_bytes, V, R, U, F),
   MAKE_INTRINSIC_1("fwrite", stdio_fwrite, V, F),
#ifdef HAVE_POPEN
   MAKE_INTRINSIC_SS("popen", stdio_popen, V),
   MAKE_INTRINSIC_0("pclose", stdio_fclose, I),
#endif
#ifdef HAVE_SETVBUF
   MAKE_INTRINSIC_3("setvbuf", stdio_setvbuf, I, F, I, I),
#endif
   SLANG_END_INTRIN_FUN_TABLE
};
#undef F
#undef I
#undef R
#undef V
#undef S
#undef B
#undef U
#undef D

#ifndef SEEK_SET
# define SEEK_SET 0
#endif
#ifndef SEEK_CUR
# define SEEK_CUR 1
#endif
#ifndef SEEK_END
# define SEEK_END 2
#endif

static SLang_IConstant_Type Stdio_Consts [] =
{
   MAKE_ICONSTANT("SEEK_SET", SEEK_SET),
   MAKE_ICONSTANT("SEEK_END", SEEK_END),
   MAKE_ICONSTANT("SEEK_CUR", SEEK_CUR),
#ifdef _IONBF
   MAKE_ICONSTANT("_IONBF", _IONBF),
#endif
#ifdef _IOLBF
   MAKE_ICONSTANT("_IOLBF", _IOLBF),
#endif
#ifdef _IOFBF
   MAKE_ICONSTANT("_IOFBF", _IOFBF),
#endif
   SLANG_END_ICONST_TABLE
};

static void destroy_file_type (SLtype type, VOID_STAR ptr)
{
   /* Do not change errno when a variable goes out of scope */
   int e = _pSLerrno_errno;

   (void) type;
   (void) close_file_type ((SL_File_Table_Type *) ptr);

   _pSLerrno_errno = e;
}

struct _pSLang_Foreach_Context_Type
{
   SLang_MMT_Type *mmt;
   FILE *fp;
#define CTX_USE_LINE		1
#define CTX_USE_CHAR		2
#define CTX_USE_LINE_WS		3
   unsigned char type;
};

static SLang_Foreach_Context_Type *
cl_foreach_open (SLtype type, unsigned int num)
{
   SLang_Foreach_Context_Type *c;
   SLang_MMT_Type *mmt;
   FILE *fp;

   if (NULL == (mmt = pop_fp (SL_READ, &fp)))
     return NULL;

   /* type = CTX_USE_LINE; */

   switch (num)
     {
	char *s;

      case 0:
	type = CTX_USE_LINE;
	break;

      case 1:
	if (-1 == SLang_pop_slstring (&s))
	  {
	     SLang_free_mmt (mmt);
	     return NULL;
	  }
	if (0 == strcmp (s, "char"))
	  type = CTX_USE_CHAR;
	else if (0 == strcmp (s, "line"))
	  type = CTX_USE_LINE;
	else if (0 == strcmp (s, "wsline"))
	  type = CTX_USE_LINE_WS;
	else
	  {
	     _pSLang_verror (SL_NOT_IMPLEMENTED,
			   "using '%s' not supported by File_Type",
			   s);
	     _pSLang_free_slstring (s);
	     SLang_free_mmt (mmt);
	     return NULL;
	  }
	_pSLang_free_slstring (s);
	break;

      default:
	SLdo_pop_n (num);
	_pSLang_verror (SL_NOT_IMPLEMENTED,
		      "Usage: foreach (File_Type) using ([line|wsline|char])");
	SLang_free_mmt (mmt);
	return NULL;
     }

   if (NULL == (c = (SLang_Foreach_Context_Type *) SLmalloc (sizeof (SLang_Foreach_Context_Type))))
     {
	SLang_free_mmt (mmt);
	return NULL;
     }
   memset ((char *) c, 0, sizeof (SLang_Foreach_Context_Type));

   c->type = type;
   c->mmt = mmt;
   c->fp = fp;

   return c;
}

static void cl_foreach_close (SLtype type, SLang_Foreach_Context_Type *c)
{
   (void) type;
   if (c == NULL) return;
   SLang_free_mmt (c->mmt);
   SLfree ((char *) c);
}

static int cl_foreach (SLtype type, SLang_Foreach_Context_Type *c)
{
   int status;
   int ch;
   SLuindex_Type len;
   char *s;

   (void) type;

   if (c == NULL)
     return -1;

   switch (c->type)
     {
      case CTX_USE_CHAR:
	if (EOF == (ch = getc (c->fp)))
	  return 0;
	if (-1 == SLang_push_uchar ((unsigned char) ch))
	  return -1;
	return 1;

      case CTX_USE_LINE:
      case CTX_USE_LINE_WS:
	status = read_one_line (c->fp, &s, &len, (c->type==CTX_USE_LINE_WS));
	if (status <= 0)
	  return status;
	if (0 == _pSLang_push_slstring (s))
	  return 1;
	return -1;
     }

   return -1;
}

static int Stdio_Initialized;
static SLang_MMT_Type *Stdio_Mmts[3];

int SLang_init_stdio (void)
{
   unsigned int i;
   SL_File_Table_Type *s;
   SLang_Class_Type *cl;
   SLFUTURE_CONST char *names[3];

   if (Stdio_Initialized)
     return 0;

   SL_File_Table = (SL_File_Table_Type *)SLcalloc(sizeof (SL_File_Table_Type), SL_MAX_FILES);
   if (SL_File_Table == NULL)
     return -1;

   if (NULL == (cl = SLclass_allocate_class ("File_Type")))
     return -1;

   (void) SLclass_set_destroy_function (cl, destroy_file_type);
   (void) SLclass_set_foreach_functions (cl, cl_foreach_open, cl_foreach, cl_foreach_close);

   if (-1 == SLclass_register_class (cl, SLANG_FILE_PTR_TYPE, sizeof (SL_File_Table_Type), SLANG_CLASS_TYPE_MMT))
     return -1;

   if ((-1 == SLadd_intrin_fun_table(Stdio_Name_Table, "__STDIO__"))
       || (-1 == SLadd_iconstant_table (Stdio_Consts, NULL))
       || (-1 == _pSLerrno_init ()))
     return -1;

   names[0] = "stdin";
   names[1] = "stdout";
   names[2] = "stderr";

   s = SL_File_Table;
   s->fp = stdin;  s->flags = SL_READ;

   s++;
   s->fp = stdout;  s->flags = SL_WRITE;

   s++;
   s->fp = stderr;  s->flags = SL_WRITE|SL_READ;

   s = SL_File_Table;
   for (i = 0; i < 3; i++)
     {
	if (NULL == (s->file = SLang_create_slstring (names[i])))
	  return -1;

	if (NULL == (Stdio_Mmts[i] = SLang_create_mmt (SLANG_FILE_PTR_TYPE, (VOID_STAR) s)))
	  return -1;
	SLang_inc_mmt (Stdio_Mmts[i]);

	if (-1 == SLadd_intrinsic_variable (s->file, (VOID_STAR)&Stdio_Mmts[i], SLANG_FILE_PTR_TYPE, 1))
	  return -1;
	s++;
     }

   Stdio_Initialized = 1;
   return 0;
}

