/* mas.c                                                   vi:se ts=8 sw=8: */

/* mas--A disk image archiver
 * Copyright (C) 2001  Peter Backes
 *
 * This program 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>    /* fopen(), ... */
#include <string.h>   /* memcpy(), memset() */
#include <stdlib.h>   /* EXIT_FAILURE, EXIT_SUCCESS */

/* Disk parameter block */
struct diskpb {
	/* Archive info */
	char name[8];     
	char padding[24]; /* Null bytes */
	short recs;       /* Count of tracks actually saved */
	char resvd[8];    /* Null bytes */
	/* Disk format */
	short nsid;       /* Sides */
	short nsecpt;     /* Sectors per track */
	short ntrkps;     /* Tracks per side */
};

#define DPBSIZE  48   /* Size of disk parameter block on disk */
#define SECSIZE 512   /* Sector size */

const char *prgnam;                    unsigned char buffer[SECSIZE];
static void (*action)(FILE *af, const char *bn, int cks, struct diskpb *hdr);

int getdpb(struct diskpb *dstdpb, unsigned char *srcbuf)
{
	unsigned char *src, *dst, *bot;    int cks = 0; /* Padding checksum */

	memcpy(dstdpb->name, srcbuf, 8);

	for (src = bot = srcbuf +  8, bot += 24, dst = dstdpb->padding;
	     src < bot; cks += (*dst++ = *src++) != 0x00);

	for (src = bot = srcbuf + 34, bot +=  8, dst = dstdpb->resvd;
	     src < bot; cks += (*dst++ = *src++) != 0x00);

	dstdpb->recs   = srcbuf[32] << 8;  dstdpb->recs   |= srcbuf[33];
	dstdpb->nsid   = srcbuf[42] << 8;  dstdpb->nsid   |= srcbuf[43];
	dstdpb->nsecpt = srcbuf[44] << 8;  dstdpb->nsecpt |= srcbuf[45];
	dstdpb->ntrkps = srcbuf[46] << 8;  dstdpb->ntrkps |= srcbuf[47];

	return cks;
}

static void extract(FILE *af, const char *bn, int cks, struct diskpb *hdr)
{
	FILE *of; /* Output file */    char filename[13]; /* FILENAME.EXT\0*/
	/* count of specified and unspecified tracks */
	int nst = hdr->recs * hdr->nsecpt, nut = hdr->nsid 
		* hdr->ntrkps * hdr->nsecpt - nst;

	sprintf(filename, "%.8s.IMG", hdr->name);

	if ((of = fopen(filename, "wb")) == NULL) {
		fprintf(stderr, "%s: Unable to open %s for output\n",
			prgnam, filename);
		return;
	}

	printf("x %s %d+%d\n", filename, nst, nut);

	while (nst-- > 0)
		fwrite(buffer, SECSIZE, fread(buffer, SECSIZE, 1, af), of);

	if (nut > 0)
		memset(buffer, 0x00, SECSIZE);

	while (nut-- > 0)
		fwrite(buffer, SECSIZE, 1, of);

	fclose(of);
}

static void list1(FILE *af, const char *bn, int cks, struct diskpb *hdr)
{
	int nst = hdr->recs * hdr->nsecpt;
	printf("%16s  %-8.8s /%02X/  %-5d     %-5d %-5d %-5d    \n",
	       bn, hdr->name, cks, hdr->recs, hdr->nsid, 
	       hdr->nsecpt, hdr->ntrkps);
	/* If you know only one file is in the archive then the 
	 * header integrity can be verified as follows.
	 * (long) nst * SECSIZE + DPBSIZE == st.st_size
	 */
	fseek(af, (long) nst * SECSIZE, SEEK_CUR);

	/* See NINJA.DRAFT.NOTE1 for the casting style used here. */
}

static void list0(FILE *af, const char *bn, int cks, struct diskpb *hdr)
{
	printf("        filename  ident    ERR   Len       Sides Sect  "
		"Tps      \n");
	action = list1;
	list1(af, bn, cks, hdr);
}

int main(int argc, char *argv[])
{
	FILE *af; /* Archive file */   int i;
	struct diskpb hdr;             const char *basename;

	prgnam = *argv;

	if (argc < 2) {
		fprintf(stderr, "%s: not enough arguments\n", prgnam);
		return EXIT_FAILURE;
	} else if (!strcmp(argv[1], "-x"))
		action = extract;
	else if (!strcmp(argv[1], "-l"))
		action = list0;
	else {
		fprintf(stderr, "Usage: %s -xl file [...]\n", prgnam);
		return EXIT_FAILURE;
	}

 	for (i = 2; i < argc; i++) {
		if ((af = fopen(argv[i], "rb")) == NULL) {
			fprintf(stderr, "%s: Could not open %s for input\n", 
				prgnam, argv[i]);
			continue;
		}

		if ((basename = strrchr(argv[i], '/')) == 0)
			basename = argv[i];
		else
			basename++;

		while (fread(buffer, DPBSIZE, 1, af) == 1)
			action(af, basename, getdpb(&hdr, buffer), &hdr);

		fclose(af);
	}
	return EXIT_SUCCESS;
}