
/*
 *     xDMS  v1.3  -  Portable DMS archive unpacker  -  Public Domain
 *     Written by     Andre Rodrigues de la Rocha  <adlroc@usa.net>
 *
 *     Handles the processing of a single DMS archive
 *
 */


#define HEADLEN 56
#define THLEN 20
#define TRACK_BUFFER_LEN 32000
#define TEMP_BUFFER_LEN 32000


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "cdata.h"
#include "u_init.h"
#include "u_rle.h"
#include "u_quick.h"
#include "u_medium.h"
#include "u_deep.h"
#include "u_heavy.h"
#include "crc_csum.h"
#include "pfile.h"



static USHORT Process_Track(FILE *, FILE *, UCHAR *, UCHAR *, USHORT, USHORT, USHORT);
static USHORT Unpack_Track(UCHAR *, UCHAR *, USHORT, USHORT, UCHAR, UCHAR);
static void printbandiz(UCHAR *, USHORT);
static void dms_decrypt(UCHAR *, USHORT);


static char modes[7][7]={"NOCOMP","SIMPLE","QUICK ","MEDIUM","DEEP  ","HEAVY1","HEAVY2"};
static USHORT PWDCRC;

UCHAR *text;

int OverrideErrors;


USHORT Process_File(char *iname, char *oname, USHORT cmd, USHORT opt, USHORT PCRC, USHORT pwd){
	FILE *fi, *fo=NULL;
	USHORT from, to, geninfo, c_version, cmode, hcrc, disktype, pv, ret;
	ULONG pkfsize, unpkfsize;
	UCHAR *b1, *b2;
	time_t date;


	b1 = (UCHAR *)calloc((size_t)TRACK_BUFFER_LEN,1);
	if (!b1) return ERR_NOMEMORY;
	b2 = (UCHAR *)calloc((size_t)TRACK_BUFFER_LEN,1);
	if (!b2) {
		free(b1);
		return ERR_NOMEMORY;
	}
	text = (UCHAR *)calloc((size_t)TEMP_BUFFER_LEN,1);
	if (!text) {
		free(b1);
		free(b2);
		return ERR_NOMEMORY;
	}

	/* if iname is NULL, input is stdin;   if oname is NULL, output is stdout */

	if (iname){
		fi = fopen(iname,"rb");
		if (!fi) {
			free(b1);
			free(b2);
			free(text);
			return ERR_CANTOPENIN;
		}
	} else {
		fi = stdin;
	}

	if (fread(b1,1,HEADLEN,fi) != HEADLEN) {
		if (iname) fclose(fi);
		free(b1);
		free(b2);
		free(text);
		return ERR_SREAD;
	}

	if ( (b1[0] != 'D') || (b1[1] != 'M') || (b1[2] != 'S') || (b1[3] != '!') ) {
		/*  Check the first 4 bytes of file to see if it is "DMS!"  */
		if (iname) fclose(fi);
		free(b1);
		free(b2);
		free(text);
		return ERR_NOTDMS;
	}

	hcrc = (USHORT)((b1[HEADLEN-2]<<8) | b1[HEADLEN-1]);
	/* Header CRC */

	if (hcrc != CreateCRC(b1+4,(ULONG)(HEADLEN-6))) {
		if (iname) fclose(fi);
		free(b1);
		free(b2);
		free(text);
		return ERR_HCRC;
	}
	
	geninfo = (USHORT) ((b1[10]<<8) | b1[11]);	/* General info about archive */
	date = (time_t) ((((ULONG)b1[12])<<24) | (((ULONG)b1[13])<<16) | (((ULONG)b1[14])<<8) | (ULONG)b1[15]);	/* date in standard UNIX/ANSI format */
	from = (USHORT) ((b1[16]<<8) | b1[17]);		/*  Lowest track in archive. May be incorrect if archive is "appended" */
	to = (USHORT) ((b1[18]<<8) | b1[19]);		/*  Highest track in archive. May be incorrect if archive is "appended" */

	pkfsize = (ULONG) ((((ULONG)b1[21])<<16) | (((ULONG)b1[22])<<8) | (ULONG)b1[23]);	/*  Length of total packed data as in archive   */
	unpkfsize = (ULONG) ((((ULONG)b1[25])<<16) | (((ULONG)b1[26])<<8) | (ULONG)b1[27]);	/*  Length of unpacked data. Usually 901120 bytes  */

	c_version = (USHORT) ((b1[46]<<8) | b1[47]);	/*  version of DMS used to generate it  */
	disktype = (USHORT) ((b1[50]<<8) | b1[51]);		/*  Type of compressed disk  */
	cmode = (USHORT) ((b1[52]<<8) | b1[53]);        /*  Compression mode mostly used in this archive  */

	PWDCRC = PCRC;

	if ( (cmd == CMD_VIEW) || (cmd == CMD_VIEWFULL) ) {

		if (iname)
			printf("\n File : %s\n",iname);
		else
			printf("\n Data from stdin\n");


		pv = (USHORT)(c_version/100);
		printf(" Created with DMS version %d.%02d ",pv,c_version-pv*100);
		if (geninfo & 0x80)
			printf("Registered\n");
		else
			printf("Evaluation\n");

		printf(" Creation date : %s",ctime(&date));
		printf(" Lowest track in archive : %d\n",from);
		printf(" Highest track in archive : %d\n",to);
		printf(" Packed data size : %u\n",pkfsize);
		printf(" Unpacked data size : %u\n",unpkfsize);
		printf(" Disk type of archive : ");

		/*  The original DMS from SDS software (DMS up to 1.11) used other values    */
		/*  in disk type to indicate formats as MS-DOS, AMax and Mac, but it was     */
		/*  not suported for compression. It was for future expansion and was never  */
		/*  used. The newer versions of DMS made by ParCon Software changed it to    */
		/*  add support for new Amiga disk types.                                    */
		switch (disktype) {
			case 0:
			case 1:
				/* Can also be a non-dos disk */
				printf("AmigaOS 1.0 OFS\n");
				break;
			case 2:
				printf("AmigaOS 2.0 FFS\n");
				break;
			case 3:
				printf("AmigaOS 3.0 OFS / International\n");
				break;
			case 4:
				printf("AmigaOS 3.0 FFS / International\n");
				break;
			case 5:
				printf("AmigaOS 3.0 OFS / Dir Cache\n");
				break;
			case 6:
				printf("AmigaOS 3.0 FFS / Dir Cache\n");
				break;
			case 7:
				printf("FMS Amiga System File\n");
				break;
			default:
				printf("Unknown\n");
		}

		printf(" Compression mode used : ");
		if (cmode>6)
			printf("Unknown !\n");
		else
			printf("%s\n",modes[cmode]);

		printf(" General info : ");
		if ((geninfo==0)||(geninfo==0x80)) printf("None");
		if (geninfo & 1) printf("NoZero ");
		if (geninfo & 2) printf("Encrypted ");
		if (geninfo & 4) printf("Appends ");
		if (geninfo & 8) printf("Banner ");
		if (geninfo & 16) printf("HD ");
		if (geninfo & 32) printf("MS-DOS ");
		if (geninfo & 64) printf("DMS_DEV_Fixed ");
		if (geninfo & 256) printf("FILEID.DIZ");
		printf("\n");

		printf(" Info Header CRC : %04X\n\n",hcrc);

	}

	if (disktype == 7) {
		/*  It's not a DMS compressed disk image, but a FMS archive  */
		if (iname) fclose(fi);
		free(b1);
		free(b2);
		free(text);
		return ERR_FMS;
	}


	if (cmd == CMD_VIEWFULL)	{
		printf(" Track   Plength  Ulength  Cmode   USUM  HCRC  DCRC Cflag\n");
		printf(" ------  -------  -------  ------  ----  ----  ---- -----\n");
	}

	if (((cmd==CMD_UNPACK) || (cmd==CMD_SHOWBANNER)) && (geninfo & 2) && (!pwd))
		return ERR_NOPASSWD;

	if (cmd == CMD_UNPACK) {
		if (oname){
			fo = fopen(oname,"wb");
			if (!fo) {
				if (iname) fclose(fi);
				free(b1);
				free(b2);
				free(text);
				return ERR_CANTOPENOUT;
			}
		} else {
			fo = stdout;
		}
	}

	ret=NO_PROBLEM;

	Init_Decrunchers();

	if (cmd != CMD_VIEW) {
		if (cmd == CMD_SHOWBANNER) /*  Banner is in the first track  */
			ret = Process_Track(fi,NULL,b1,b2,cmd,opt,(geninfo & 2)?pwd:0);
		else {
			while ( (ret=Process_Track(fi,fo,b1,b2,cmd,opt,(geninfo & 2)?pwd:0)) == NO_PROBLEM ) ;
			if ((cmd == CMD_UNPACK) && (opt == OPT_VERBOSE)) fprintf(stderr,"\n");
		}
	}

	if ((cmd == CMD_VIEWFULL) || (cmd == CMD_SHOWDIZ) || (cmd == CMD_SHOWBANNER)) printf("\n");

	if (ret == FILE_END) ret = NO_PROBLEM;


	/*  Used to give an error message, but I have seen some DMS  */
	/*  files with texts or zeros at the end of the valid data   */
	/*  So, when we find something that is not a track header,   */
	/*  we suppose that the valid data is over. And say it's ok. */
	if (ret == ERR_NOTTRACK) ret = NO_PROBLEM;


	if (iname) fclose(fi);
	if ((cmd == CMD_UNPACK) && oname) fclose(fo);

	free(b1);
	free(b2);
	free(text);

	return ret;
}



static USHORT Process_Track(FILE *fi, FILE *fo, UCHAR *b1, UCHAR *b2,
			    USHORT cmd, USHORT opt, USHORT pwd)
{
	USHORT hcrc, dcrc, usum, number, pklen1, pklen2, unpklen, l, r;
	UCHAR cmode, flags;


	l = (USHORT)fread(b1,1,THLEN,fi);

	if (l != THLEN) {
		if (l==0)
			return FILE_END;
		else
			return ERR_SREAD;
	}

	/*  "TR" identifies a Track Header  */
	if ((b1[0] != 'T')||(b1[1] != 'R')) return ERR_NOTTRACK;

	/*  Track Header CRC  */
	hcrc = (USHORT)((b1[THLEN-2] << 8) | b1[THLEN-1]);

	if (CreateCRC(b1,(ULONG)(THLEN-2)) != hcrc)
		return ERR_THCRC;

	number = (USHORT)((b1[2] << 8) | b1[3]);	/*  Number of track  */
	pklen1 = (USHORT)((b1[6] << 8) | b1[7]);	/*  Length of packed track data as in archive  */
	pklen2 = (USHORT)((b1[8] << 8) | b1[9]);	/*  Length of data after first unpacking  */
	unpklen = (USHORT)((b1[10] << 8) | b1[11]);	/*  Length of data after subsequent rle unpacking */
	flags = b1[12];		/*  control flags  */
	cmode = b1[13];		/*  compression mode used  */
	usum = (USHORT)((b1[14] << 8) | b1[15]);	/*  Track Data CheckSum AFTER unpacking  */
	dcrc = (USHORT)((b1[16] << 8) | b1[17]);	/*  Track Data CRC BEFORE unpacking  */

	if (cmd == CMD_VIEWFULL) {
		if (number==80)
			printf(" FileID   ");
		else if (number==0xffff)
			printf(" Banner   ");
		else if ((number==0) && (unpklen==1024))
			printf(" FakeBB   ");
		else
			printf("   %2d     ",(short)number);

	    printf("%5d    %5d   %s  %04X  %04X  %04X    %0d\n", pklen1, unpklen, modes[cmode], usum, hcrc, dcrc, flags);
	}

	if ((pklen1 > TRACK_BUFFER_LEN) || (pklen2 >TRACK_BUFFER_LEN) || (unpklen > TRACK_BUFFER_LEN)) return ERR_BIGTRACK;

	if (fread(b1,1,(size_t)pklen1,fi) != pklen1) return ERR_SREAD;

	if (CreateCRC(b1,(ULONG)pklen1) != dcrc) {
		if (OverrideErrors) {
			fprintf(stderr, "Detected a CRC error on "
				"track %d, but overriding.\n", number);
		} else {
			return ERR_TDCRC;
		}
	}

	/*  track 80 is FILEID.DIZ, track 0xffff (-1) is Banner  */
	/*  and track 0 with 1024 bytes only is a fake boot block with more advertising */
	/*  FILE_ID.DIZ is never encrypted  */

	if (pwd && (number != 80))
		dms_decrypt(b1,pklen1);

	if ((cmd == CMD_UNPACK) && (number<80) && (unpklen>2048)) {

		memset(b2, 0, unpklen);

		r = Unpack_Track(b1, b2, pklen2, unpklen, cmode, flags);
		if (r != NO_PROBLEM) {
			if (OverrideErrors) {
				fprintf(stderr, "Detected an error while "
					"unpacking track %d, but "
					"overriding.\n", number);
			} else {
				if (pwd)
					return ERR_BADPASSWD;
				else
					return r;
			}
		}
		if (usum != Calc_CheckSum(b2,(ULONG)unpklen)) {
			if (OverrideErrors) {
				fprintf(stderr, "Detected an error after "
					"unpacking track %d, but "
					"overriding.\n", number);
			} else {
				if (pwd)
					return ERR_BADPASSWD;
				else
					return ERR_CSUM;
			}
		}

		if (fwrite(b2, 1, (size_t) unpklen, fo) != unpklen)
			return ERR_CANTWRITE;

		if (opt == OPT_VERBOSE) {
			fprintf(stderr,"#");
			fflush(stderr);
		}
	}

	if ((cmd == CMD_SHOWBANNER) && (number == 0xffff)){
		r = Unpack_Track(b1, b2, pklen2, unpklen, cmode, flags);
		if (r != NO_PROBLEM) {
			if (OverrideErrors) {
				fprintf(stderr, "Detected an error while "
					"unpacking bannder, but overriding.\n");
			} else {
				if (pwd)
					return ERR_BADPASSWD;
				else
					return r;
			}
		}
		if (usum != Calc_CheckSum(b2,(ULONG)unpklen)) {
			if (OverrideErrors) {
				fprintf(stderr, "Detected an error after "
					"unpacking banner, but overriding.\n");
			} else {
				if (pwd)
					return ERR_BADPASSWD;
				else
					return ERR_CSUM;
			}
		}
		printbandiz(b2,unpklen);
	}

	if ((cmd == CMD_SHOWDIZ) && (number == 80)) {
		r = Unpack_Track(b1, b2, pklen2, unpklen, cmode, flags);
		if (r != NO_PROBLEM) {
			if (OverrideErrors) {
				fprintf(stderr, "Detected an error while "
					"unpacking showdiz, but overriding.\n");
			} else {
				return r;
			}
		}
		if (usum != Calc_CheckSum(b2,(ULONG)unpklen)) {
			if (OverrideErrors) {
				fprintf(stderr, "Detected an error after "
					"unpacking showdiz, but overriding.\n");
			} else {
				return ERR_CSUM;
			}
		}
		printbandiz(b2,unpklen);
	}

	return NO_PROBLEM;

}



static USHORT Unpack_Track(UCHAR *b1, UCHAR *b2, USHORT pklen2, USHORT unpklen,
			   UCHAR cmode, UCHAR flags)
{
	switch (cmode){
		case 0:
			/*   No Compression   */
			memcpy(b2,b1,(size_t)unpklen);
			break;
		case 1:
			/*   Simple Compression   */
			if (Unpack_RLE(b1,b2,unpklen)) return ERR_BADDECR;
			break;
		case 2:
			/*   Quick Compression   */
			if (Unpack_QUICK(b1,b2,pklen2)) return ERR_BADDECR;
			if (Unpack_RLE(b2,b1,unpklen)) return ERR_BADDECR;
			memcpy(b2,b1,(size_t)unpklen);
			break;
		case 3:
			/*   Medium Compression   */
			if (Unpack_MEDIUM(b1,b2,pklen2)) return ERR_BADDECR;
			if (Unpack_RLE(b2,b1,unpklen)) return ERR_BADDECR;
			memcpy(b2,b1,(size_t)unpklen);
			break;
		case 4:
			/*   Deep Compression   */
			if (Unpack_DEEP(b1,b2,pklen2)) return ERR_BADDECR;
			if (Unpack_RLE(b2,b1,unpklen)) return ERR_BADDECR;
			memcpy(b2,b1,(size_t)unpklen);
			break;
		case 5:
		case 6:
			/*   Heavy Compression   */
			if (cmode==5) {
				/*   Heavy 1   */
				if (Unpack_HEAVY(b1,b2,flags & 7,pklen2)) return ERR_BADDECR;
			} else {
				/*   Heavy 2   */
				if (Unpack_HEAVY(b1,b2,flags | 8,pklen2)) return ERR_BADDECR;
			}
			if (flags & 4) {
				/*  Unpack with RLE only if this flag is set  */
				if (Unpack_RLE(b2,b1,unpklen)) return ERR_BADDECR;
				memcpy(b2,b1,(size_t)unpklen);
			}
			break;
		default:
			return ERR_UNKNMODE;
	}

	if (!(flags & 1)) Init_Decrunchers();

	return NO_PROBLEM;
}


/*  DMS uses a lame encryption  */
static void dms_decrypt(UCHAR *p, USHORT len){
	USHORT t;

	while (len--){
		t = (USHORT) *p;
		*p++ ^= (UCHAR)PWDCRC;
		PWDCRC = (USHORT)((PWDCRC >> 1) + t);
	}
}



static void printbandiz(UCHAR *m, USHORT len){
	UCHAR *i,*j;

	i=j=m;
	while (i<m+len) {
		if (*i == 10) {
			*i=0;
			printf("%s\n",j);
			j=i+1;
		}
		i++;
	}

}


