/* -*- mode: C; mode: fold; -*- */
/* Copyright (c) 1992, 1998, 2000, 2007-2009 John E. Davis
 * This file is part of JED editor library source.
 *
 * You may distribute this file under the terms the GNU General Public
 * License.  See the file COPYING for more information.
 */
#include "config.h"
#ifdef JED
# include "jed-feat.h"
#endif
/*{{{ Include Files */

#include <stdio.h>
#include <slang.h>

#include "jdmacros.h"
#include "util.h"

#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif

#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif

#include <string.h>
#include <limits.h>

#include <errno.h>

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

#ifdef VMS
# include <file.h>
#endif

#ifdef __unix__
# include <sys/types.h>
# include <sys/stat.h>
# include <sys/file.h>
# ifdef HAVE_FCNTL_H
#  include <fcntl.h>
# endif
# ifdef HAVE_SYS_FCNTL_H
#  include <sys/fcntl.h>
# endif
#endif

#if defined(__BORLANDC__) || defined(_MSC_VER)
# include <fcntl.h>
# include <io.h>
# include <sys/stat.h>
#endif

#ifdef __os2__
# include <fcntl.h>
# include <io.h>
# include <sys/types.h>
# include <sys/stat.h>
#endif
 
#ifndef O_RDONLY
# ifdef VMS
#  include <file.h>
# else
#  include <fcntl.h>
# endif
#endif

#include "vfile.h"

/*}}}*/

unsigned int VFile_Mode = VFILE_TEXT;


struct VFILE
{
   /* If has_unget is set, then next call to vgets will return with
    * ungetbuf and unget_len.
    */
   int has_unget;
   char *unget_buf;
   unsigned int unget_len;

   char *buf;			       /* buffer for stream */
   char *bmax;			       /* pointer to end buffer */
   char *bp;			       /* current pointer in stream */
   char *eof;			       /* pointer to EOF if non NULL */
   int fd;			       /* file descrip for stream */
   unsigned int size;		       /* default buffer size */
   unsigned int mode;
   unsigned int cr_flag;	       /* true if lines end in cr */
};


VFILE *vopen(char *file, unsigned int size, unsigned int fmode) /*{{{*/
{
   int fd;
   unsigned int mode;

#ifdef O_BINARY
   mode = O_BINARY;
#else 
   mode = 0;
#endif
      
   if ((fd = open(file, mode | O_RDONLY, 0)) < 0) return(NULL);
   return vstream(fd, size, fmode);
}

/*}}}*/

void vclose(VFILE *v) /*{{{*/
{
   (void) close(v->fd);
   SLfree(v->buf);
   SLfree ((char *)v);
}

/*}}}*/

VFILE *vstream(int fd, unsigned int size, unsigned int mode) /*{{{*/
{
   VFILE *v;
   
   if (NULL == (v = (VFILE *) SLmalloc(sizeof(VFILE)))) return(NULL);
   v->has_unget = 0;
   v->bmax = v->bp = v->buf = NULL;
   v->fd = fd;
   v->eof = NULL;
   v->size = size;
   if (mode == 0) mode = VFile_Mode;
   v->mode = mode;
   v->cr_flag = 0;
   return v;
}

/*}}}*/

/* Here is how vgets appears to work (disclaimer: it came without developer
 * documentation and I did not analyse it completely):
 * If you want to nul-terminate the returned string, check if position num-1
 * contains the '\n' character. If so, overwrite it with nul; otherwise, write
 * nul at position num.
 * Do _not_ write at position num when there is a '\n' at num-1, or you will
 * corrupt the line obtained by the next call to vgets! (Actually, you _can_
 * write there, but make sure you save and restore the character.)
 */
/* I malloc one extra so that I can always add a null character to last line */
static char *vgets_internal(VFILE *vp, unsigned int *num) /*{{{*/
{
   register char *bp, *bp1;
   register char *bmax, *bpmax;
   char *neew;
   int fd;
   unsigned int n, max, fmode;
   int doread = 0;

   if (vp == NULL)
     {
	*num = 0;
	return NULL;
     }

   fd = vp->fd;
   n = vp->size;
   fmode = vp->mode;

   *num = 0;
   if (NULL == vp->buf)
     {
#if defined (__MSDOS_16BIT__)
	if (!n) n = 512;
#else
	if (!n) n = 64 * 1024;
#endif
	
	if (NULL == (neew = SLmalloc(n + 1)))
	  return NULL;

	vp->bp = vp->buf = neew;
	vp->bmax = neew + n;
	doread = 1;
     }

   bp = vp->bp;
   if ((vp->eof != NULL) && (bp >= vp->eof)) return (NULL);
   bp1 = vp->buf;
   bmax = vp->bmax;
   
   while (1)
     {	
	if (doread)
	  {
	     max = (int) (vp->bmax - bp);
	     while (max > 0)
	       {
		  int nread;

		  nread = read(fd, bp, max);
		  if (nread == 0)
		    break;

		  if (nread == -1)
		    {
#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__BORLANDC__))
# ifdef EPIPE
		       if (errno == EPIPE)
			 break;
# endif
#endif
#ifndef IBMPC_SYSTEM
# ifdef EINTR
		       if (errno == EINTR)
			 continue;
# endif
# ifdef EAGAIN
		       if (errno == EAGAIN)
			 {
			    slrn_sleep (1);
			    continue;
			 }
# endif
#endif
		       return NULL;
		    }
		  
		  max -= nread;
		  bp += nread;
	       }
	     if (max) vp->eof = bp;
	     if (bp == bp1)
	       {
		  return(NULL);
	       }
	     bp = bp1;
	  }
	else bp1 = bp;
	   
	/* extract a line */
	if (vp->eof != NULL) bmax = vp->eof;
	
	n = (unsigned int) (bmax - bp);
#if defined(__MSDOS__)
	if (n)
	  {
	     bpmax = bp;
#if defined(__BORLANDC__) && !defined(__WIN32__)
	     asm  {
		mov bx, di
		mov al, 10
		mov cx, n
		les di, bpmax
		cld
		repne scasb
		inc cx
		sub n, cx
		mov di, bx
	     }
	     bp += n;
#else
 	     if (NULL == (bpmax = SLMEMCHR(bp, '\n', n)))
 	       bp += n;
 	     else
 	       bp = bpmax;
#endif /* __WIN32__ */
	     if (*bp != '\n') bp++;
	  }
	
	if (bp < bmax)
	  {
	     vp->bp = ++bp;
	     *num = (unsigned int) (bp - bp1);
	     
	     /* if it is text, replace the carriage return by a newline
	        and adjust the number read by 1 */
	     bp -= 2;
	     if ((fmode == VFILE_TEXT) && (*num > 1) && (*bp == '\r'))
	       {
		  *bp = '\n';
		  *num -= 1;
		  vp->cr_flag = 1;
	       }
	     return bp1;
	  }
#else
	if (NULL != (bpmax = SLMEMCHR(bp, '\n', n)))
	  {
	     bpmax++;
	     vp->bp = bpmax;
	     *num = (unsigned int) (bpmax - bp1);
	     
	     if ((fmode == VFILE_TEXT) && (*num > 1))
	       {
		  bpmax -= 2;
		  if (*bpmax == '\r') 
		    {
		       vp->cr_flag = 1;
		       *bpmax = '\n'; (*num)--;
		    }
	       }
	     return bp1;
	  }
	bp = bp + n;
#endif	/* __MSDOS__ */
	if (vp->eof != NULL)
	  {
	     *num = (unsigned int) (bp - bp1);
	     vp->bp = bp;
	     
	     
#if defined(IBMPC_SYSTEM)
	     /* kill ^Z at EOF if present */
	     if ((fmode == VFILE_TEXT) && (*num) && (26 == *(bp - 1))) 
	       {
		  *num -= 1;
		  if (!*num) bp1 = NULL;
	       }
#endif
	     return(bp1);
	  }
	
	doread = 1;

	bp = bp1;
	bp1 = vp->buf;
	if (bp != bp1)
	  {
	     /* shift to beginning */
	     while (bp < bmax) *bp1++ = *bp++;
	     bp = bp1;
	     bp1 = vp->buf;
	  }
	else 
	  {
	     bp = bmax;
	     vp->bmax += 2 * (int) (vp->bmax - vp->buf);
	     neew = SLrealloc (vp->buf, 1 + (unsigned int) (vp->bmax - vp->buf));
	     if (neew == NULL) 
	       return NULL;
	     
	     bp = neew + (int) (bmax - vp->buf);
	     bmax = vp->bmax = neew + (int) (vp->bmax - vp->buf);
	     bp1 = vp->buf = neew;
	  }
     }
}

/*}}}*/


char *vgets (VFILE *vp, unsigned int *nump)
{
   if (vp == NULL)
     {
	*nump = (unsigned int)-1;
	return NULL;
     }

   if (vp->has_unget)
     {
	vp->has_unget = 0;
	*nump = vp->unget_len;
	return vp->unget_buf;
     }
   
   vp->unget_buf = vgets_internal (vp, &vp->unget_len);
   *nump = vp->unget_len;
   return vp->unget_buf;
}


int vungets (VFILE *v)
{
   if (v == NULL)
     return -1;

   if (v->has_unget)
     return -1;

   v->has_unget = 1;
   return 0;
}