/*
 * compfile.c - File I/O and ZLIB compression
 *
 * Copyright (C) 1995-1998 David Firth
 * Copyright (C) 1998-2003 Atari800 development team (see DOC/CREDITS)
 *
 * This file is part of the Atari800 emulator project which emulates
 * the Atari 400, 800, 800XL, 130XE, and 5200 8-bit computers.
 *
 * Atari800 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.
 *
 * Atari800 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 Atari800; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "atari.h"
#include "config.h"
#include "log.h"
#ifdef HAVE_LIBZ
#include <zlib.h>
#endif
#include <fcntl.h>
#ifndef HAVE_MKSTEMP
# ifndef O_BINARY
#  define O_BINARY	0
# endif
# define mkstemp(a) open(mktemp(a),O_RDWR|O_CREAT|O_BINARY,0600)
#endif
/* Size of memory buffer ZLIB should use when decompressing files */
#define ZLIB_BUFFER_SIZE	32767

/* prototypes */
static int decode_C1(void);
static int decode_C3(void);
static int decode_C4(void);
static int decode_C6(void);
static int decode_C7(void);
static int decode_FA(void);
static int read_atari16(FILE *);
static int write_atari16(FILE *,int);
static int read_offset(FILE *);
static int read_sector(FILE *);
static int write_sector(FILE *);
static long soffset(void);

/* Global variables */
static unsigned int	secsize;
static unsigned short	cursec ,maxsec;
static unsigned char	createdisk ,working ,last ,density, buf[256], atr;
static FILE *fin = NULL, *fout = NULL;

#ifdef HAVE_LIBZ
#define GZOPEN( X, Y ) gzopen( X, Y )
#define GZCLOSE( X ) gzclose( X )
#define GZREAD( X, Y, Z ) gzread( X, Y, Z )
#else	/* HAVE_LIBZ */
#define GZOPEN( X, Y ) (-1)
#define GZCLOSE( X ) (-1)
#define GZREAD( X, Y, Z ) (-1)
#endif	/* HAVE_LIBZ */

/* This is a port-specific function that should return -1 if the port is unable to
   use zlib, any other value if it can. For instance, Windows might return -1 if the
   zlib DLL cannot be loaded. If you are not zlib capable you should macro out the
   gz???? functions to avoid linkage problems */
extern int zlib_capable( void );

/* prepend_tmpfile_path is a port-specific function that should insert into the supplied
   buffer pointer any path name the port wants before the filename created by mkstemp().
   This function should return the number of bytes that the prepended path represents */
extern int prepend_tmpfile_path( char *buffer );

/* This function was added because unlike DOS, the Windows version might visit this
   module many times, not a run-once occurence. Everything needs to be reset per file,
   so that is what init_globals does */
static void init_globals( FILE *input, FILE *output )
{
	secsize = 0;
	cursec = maxsec = 0;
	createdisk = working = last = density = 0;
	atr = 16;
	memset( buf, 0, 256 );
	fin = input;
	fout = output;
}

static void show_file_error( FILE *stream )
{
	if( feof( stream ) )
		Aprint( "Unexpected end of file during I/O operation, file is probably corrupt" );
	else
		Aprint( "I/O error reading or writing a character" );
}

/* Opens a ZLIB compressed (gzip) file, creates a temporary filename, and decompresses
   the contents of the .gz file to the temporary file name. Note that *outfilename is
   actually blank coming in and is filled by mkstemp */
FILE * openzlib(int diskno, const char *infilename, char *outfilename )
{
#ifndef HAVE_LIBZ
	Aprint( "This executable cannot decompress ZLIB files" );
	return NULL;
#else
	gzFile	gzSource;
	FILE	*file = NULL, *outfile = NULL;
	char	*curptr = outfilename;
	char	*zlib_buffer = NULL;

	if( zlib_capable() == -1 )
	{
		Aprint( "This executable cannot decompress ZLIB files" );
		return NULL;
	}

	zlib_buffer = malloc( ZLIB_BUFFER_SIZE + 1 );
	if( !zlib_buffer )
	{
		Aprint( "Could not obtain memory for zlib decompression" );
		return NULL;
	}

	curptr += prepend_tmpfile_path( outfilename );
    strcpy(curptr,"TMP_XXXXXX\0");
	outfile = fdopen(mkstemp(curptr), "wb");
	if (!outfile)
	{
		Aprint( "Could not open temporary file" );
		free( zlib_buffer );
		return NULL;
	}

	gzSource = GZOPEN( infilename, "rb" );
	if( !gzSource )
	{
		Aprint( "ZLIB could not open file %s", infilename );
		fclose( outfile );
	}
	else	/* Convert the gzip file to the temporary file */
	{
		int	result, temp;

		Aprint( "Converting %s to %s", infilename, outfilename );
		do
		{
			result = GZREAD( gzSource, &zlib_buffer[0], ZLIB_BUFFER_SIZE );
			if( result > 0 )
			{
				if( fwrite(zlib_buffer, 1, result, outfile) != result )
				{
					Aprint( "Error writing to temporary file %s, disk may be full", outfilename );
					result = -1;
				}
			}
		} while( result == ZLIB_BUFFER_SIZE );
		temp = GZCLOSE( gzSource );
		fclose( outfile );
		if( result > -1 )
			file = fopen(outfilename, "rb");
		else
		{
			Aprint( "Error while parsing gzip file" );
			file = NULL;
		}
	}

	if(!file)
	{
		if( zlib_buffer )
			free( zlib_buffer );
		Aprint( "Removing temporary file %s", outfilename );
		remove( outfilename );
	}

	return file;
#endif	/* HAVE_LIBZ */
}

int dcmtoatr(FILE *fin, FILE *fout, const char *input, char *output )
{
	int archivetype;	/* Block type for first block */
	int blocktype;		/* Current block type */
	int tmp;			/* Temporary for read without clobber on eof */

	init_globals( fin, fout );
	Aprint( "Converting %s to %s", input, output );
	if( !fin || !fout )
	{
		Aprint( "Programming error - NULL file specified for conversion" );
		return 0;
	}
	archivetype = blocktype = fgetc(fin);

	if( archivetype == EOF )
	{
		show_file_error( fin );
		return 0;
	}

	switch(blocktype) 
	{
		case 0xF9:
		case 0xFA:
			break;
		default:
			Aprint("0x%02X is not a known header block at start of input file",blocktype);
			return 0;
	}
	
	rewind(fin);
	
	while( 1 )
	{
		if (feof(fin)) 
		{
			fflush(stdout); /* Possible buffered I/O confusion fix */
			if ((!last) && (blocktype == 0x45) && (archivetype == 0xF9)) {
				Aprint("Multi-part archive error.");
				Aprint("To process these files, you must first combine the files into a single file.");
				Aprint("COPY /B file1.dcm+file2.dcm+file3.dcm newfile.dcm from the DOS prompt");
			}
			else 
			{
				Aprint("EOF before end block, input file likely corrupt");
			}
			return 0;
		}
		
		if (working) {
			if (soffset() != ftell(fout)) 
			{
				Aprint("Output desyncronized, possibly corrupt dcm file. fin=%lu fout=%lu != %lu cursec=%u secsize=%u", 
					ftell(fin),ftell(fout),soffset(),cursec,secsize);
				return 0;
			}
		}
		
		tmp = fgetc(fin); /* blocktype is needed on EOF error--don't corrupt it */
		if( tmp == EOF )
		{
			show_file_error( fin );
			return 0;
		}

		blocktype = tmp;
		switch(blocktype) 
		{
		      case 0xF9:
			  case 0xFA:
				  /* New block */
				  if( decode_FA() == 0 )
					  return 0;
				  break;
			  case 0x45:
				  /* End block */
				  working=0;
				  if (last)
					  return 1;	/* Normal exit */
				  break;
			  case 0x41:
			  case 0xC1:
				  if( decode_C1() == 0 )
					  return 0;
				  break;
			  case 0x43:
			  case 0xC3:
				  if( decode_C3() == 0 )
					  return 0;
				  break;
			  case 0x44:
			  case 0xC4:
				  if( decode_C4() == 0 )
					  return 0;
				  break;
			  case 0x46:
			  case 0xC6:
				  if( decode_C6() == 0 )
					  return 0;
				  break;
			  case 0x47:
			  case 0xC7:
				  if( decode_C7() == 0 )
					  return 0;
				  break;
			  default:
				  Aprint("0x%02X is not a known block type.  File may be corrupt.",blocktype);
				  return 0;
		} /* end case */
		
		if ((blocktype != 0x45) && (blocktype != 0xFA) && (blocktype != 0xF9)) 
		{
			if (!(blocktype & 0x80)) 
			{
				cursec=read_atari16(fin);
				if( fseek(fout, soffset(), SEEK_SET) != 0 )
				{
					Aprint( "Failed a seek in output file, cannot continue" );
					return 0;
				}
			} 
			else 
			{
				cursec++;
				if(cursec==4 && secsize!=128)
					fseek(fout,(secsize-128)*3,SEEK_CUR);
			}
		}
	} 	
	return 0; /* Should never be executed */
}

/* Opens a DCM file and decodes it to a temporary file, then returns the
   file handle for the temporary file and its name. */
FILE *opendcm( int diskno, const char *infilename, char *outfilename )
{
	FILE	*infile, *outfile;
	FILE	*file = NULL;
	char	*curptr = outfilename;

    strcpy(curptr,"TMP_XXXXXX\0");
	outfile = fdopen(mkstemp(curptr), "wb");
	if( !outfile ){
		Aprint("mkstemp failed\n");
		return NULL;
	}	
	infile = fopen( infilename, "rb" );
	if( !infile )
	{
		fclose( outfile );
	}
	else
	{
		if( dcmtoatr( infile, outfile, infilename, outfilename ) != 0 )
		{
			fflush( outfile );
			fclose( outfile );
			file = fopen(outfilename, "rb");
		}
	}

	if(!file)
	{
		Aprint( "Removing temporary file %s", outfilename );
		remove( outfilename );
	}

	return file;
}

static int decode_C1(void)
{
	int	secoff,tmpoff,c;

	tmpoff = fgetc(fin);
	if( tmpoff == EOF)
	{
		show_file_error( fin );
		return 0;
	}

	c=tmpoff;
	for (secoff=0; secoff<=tmpoff; secoff++) 
	{
		buf[c]=fgetc(fin);
		c--;
		if( feof(fin) )
		{
			show_file_error( fin );
			return 0;
		}
	}
	if( !write_sector(fout) )
		return 0;
	return 1;
}

static int decode_C3(void)
{
	int	secoff,tmpoff,c;
	
	secoff=0;
	do 
	{
		if (secoff)
			tmpoff = read_offset(fin);
		else
			tmpoff = fgetc(fin);

		if( tmpoff == EOF )
		{
			show_file_error( fin );
			return 0;
		}

		for (; secoff<tmpoff; secoff++) 
		{
			buf[secoff] = fgetc(fin);
			if( feof(fin) )
			{
				show_file_error( fin );
				return 0;
			}

		}
		if (secoff == (int)secsize)
			break;

		tmpoff = read_offset(fin);
		c = fgetc(fin);
		if( tmpoff == EOF || c == EOF )
		{
			show_file_error( fin );
			return 0;
		}

		for (; secoff<tmpoff; secoff++) 
		{
			buf[secoff] = c;
		}
	} while(secoff < (int)secsize);

	if( !write_sector(fout) )
		return 0;
	return 1;
}

static int decode_C4(void)
{
	int	secoff,tmpoff;

	tmpoff = read_offset(fin);
	if( tmpoff == EOF )
	{
		show_file_error( fin );
		return 0;
	}

	for (secoff=tmpoff; secoff<(int)secsize; secoff++) {
		buf[secoff]=fgetc(fin);
		if( feof(fin) )
		{
			show_file_error( fin );
			return 0;
		}
	}
	if( !write_sector(fout) )
		return 0;
	return 1;
}

static int decode_C6(void)
{
	if( !write_sector(fout) )
		return 0;
	return 1;
}

static int decode_C7(void)
{
	if( !read_sector(fin) )
		return 0;
	if( !write_sector(fout) )
		return 0;
	
	return 1;
}

static int decode_FA(void)
{
	unsigned char c;

	if (working) 
	{
		Aprint("Trying to start section but last section never had an end section block.");
		return 0;
	}
	c=fgetc(fin);
	if( feof(fin) )
	{
		show_file_error( fin );
		return 0;
	}
	density=((c & 0x70) >> 4);
	last=((c & 0x80) >> 7);
	switch(density) 
	{
		case 0:
			maxsec=720;
			secsize=128;
			break;
		case 2:
			maxsec=720;
			secsize=256;
			break;
		case 4:
			maxsec=1040;
			secsize=128;
			break;
		default:
			Aprint( "Density type is unknown, density type=%u",density);
			return 0;
	}

	if (createdisk == 0) {
		createdisk = 1;
		/* write out atr header */
		/* special code, 0x0296 */
		if( write_atari16(fout,0x296) == 0 )
			return 0;
		/* image size (low) */
		if( write_atari16(fout,(short)(((long)maxsec * secsize) >> 4)) == 0 )
			return 0;
		/* sector size */
		if( write_atari16(fout,secsize) == 0 )
			return 0;
		/* image size (high) */
		if( write_atari16(fout,(short)(((long)maxsec * secsize) >> 20)) == 0 )
			return 0;
		/* 8 bytes unused */
		if( write_atari16(fout,0) == 0 )
			return 0;
		if( write_atari16(fout,0) == 0 )
			return 0;
		if( write_atari16(fout,0) == 0 )
			return 0;
		if( write_atari16(fout,0) == 0 )
			return 0;
		memset(buf,0,256);
		for (cursec=0; cursec<maxsec; cursec++) {
			if( fwrite(buf,secsize,1,fout) != 1 )
			{
				Aprint( "Error writing to output file" );
				return 0;
			}
		}
	}
	cursec=read_atari16(fin);
	if( fseek( fout, soffset(), SEEK_SET) != 0 )
	{
		Aprint( "Failed a seek in output file, cannot continue" );
		return 0;
	}
	working=1;
	return 1;
}

/*
** read_atari16()
** Read a 16-bit integer with Atari byte-ordering.
** 1  Jun 95  crow@cs.dartmouth.edu (Preston Crow)
*/
static int read_atari16(FILE *fin)
{
	int ch_low,ch_high; /* fgetc() is type int, not char */

	ch_low = fgetc(fin);
	ch_high = fgetc(fin);
	if( ch_low == EOF || ch_high == EOF )
	{
		show_file_error( fin );
		return 0;
	}
	return(ch_low + 256*ch_high);
}

static int write_atari16(FILE *fout,int n)
{
	unsigned char ch_low,ch_high;

	ch_low = (unsigned char)(n&0xff);
	ch_high = (unsigned char)(n/256);
	if( fputc(ch_low,fout) == EOF || fputc(ch_high,fout) == EOF )
	{
		show_file_error( fout );
		return 0;
	}
	return 1;
}

/*
** read_offset()
** Simple routine that 'reads' the offset from an RLE encoded block, if the
**   offset is 0, then it returns it as 256.
** 5  Jun 95  cmwagner@gate.net (Chad Wagner)
*/
static int read_offset(FILE *fin)
{
	int ch; /* fgetc() is type int, not char */

	ch = fgetc(fin);
	if( ch == EOF )
	{
		show_file_error( fin );
		return EOF;
	}
	if (ch == 0)
		ch = 256;

	return(ch);
}

/*
** read_sector()
** Simple routine that reads in a sector, based on it's location, and the
**  sector size.  Sectors 1-3, are 128 bytes, all other sectors are secsize.
** 5  Jun 95  cmwagner@gate.net (Chad Wagner)
*/
static int read_sector(FILE *fin)
{
	if( fread(buf,(cursec < 4 ? 128 : secsize),1,fin) != 1 )
	{
		Aprint( "A sector read operation failed from the source file" );
		return 0;
	}
	return 1;
}

/*
** write_sector()
** Simple routine that writes in a sector, based on it's location, and the
**  sector size.  Sectors 1-3, are 128 bytes, all other sectors are secsize.
** 5  Jun 95  cmwagner@gate.net (Chad Wagner)
*/
static int write_sector(FILE *fout)
{
	if( fwrite(buf,(cursec < 4 ? 128 : secsize),1,fout) != 1 )
	{
		Aprint( "A sector write operation failed to the destination file" );
		return 0;
	}
	return 1;
}

/*
** soffset()
** calculates offsets within ATR or XFD images, for seeking.
** 28 Sep 95  lovegrov@student.umass.edu (Mike White)
*/
static long soffset()
{
	return (long)atr + (cursec < 4 ? ((long)cursec - 1) * 128 :
			 ((long)cursec - 1) * secsize);
}

/*
$Log: compfile.c,v $
Revision 1.14  2003/12/17 07:01:18  markgrebe
Fixed serious bug in Type 41 decoding

Revision 1.13  2003/09/14 20:07:28  joy
O_BINARY defined

Revision 1.12  2003/09/14 19:30:31  joy
mkstemp emulated if unavailable

Revision 1.11  2003/06/15 07:32:35  joy
GZOPEN for non HAVE_LIBZ platforms

Revision 1.10  2003/03/03 09:57:32  joy
Ed improved autoconf again plus fixed some little things

Revision 1.9  2003/02/24 09:32:50  joy
header cleanup

Revision 1.8  2001/12/04 13:05:16  joy
include zlib.h from the system include path and not from local directory (suggested by Nathan)

Revision 1.7  2001/09/08 07:49:33  knik
unused definitions and inclusions removed

Revision 1.6  2001/07/25 13:03:35  fox
removed unused declarations

Revision 1.5  2001/04/15 09:14:33  knik
zlib_capable -> have_libz (autoconf compatibility)

Revision 1.4  2001/03/25 06:57:35  knik
open() replaced by fopen()

Revision 1.3  2001/03/18 06:34:58  knik
WIN32 conditionals removed

*/
