/*

 * CPI.C: A program to examine MSDOS codepage files (*.cpi)

 * and extract specific codepages.

 * Compiles under Linux & DOS (using BC++ 3.1).

 *

 * Compile: gcc -o cpi cpi.c

 * Call: codepage [-a|-l|nnn] file.cpi

 *

 * Author: Ahmed M. Naas (ahmed@oea.xs4all.nl)

 * Many changes: aeb@cwi.nl  [changed until it would handle all

 *	*.cpi files people have sent me; I have no documentation,

 *	so all this is experimental]

 * Remains to do: DRDOS fonts.

 *

 * Copyright: Public domain.

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

int handle_codepage(int);

void handle_fontfile(void);

#define PACKED __attribute__((packed))

/* Use this (instead of the above) to compile under MSDOS */

/*#define PACKED  */

struct {

	unsigned char id0 PACKED;

	unsigned char id[7] PACKED;

	unsigned char res[8] PACKED;

	unsigned short pnum PACKED;      /* number of pointers */

	unsigned char ptyp PACKED;       /* type of pointers */

	unsigned long fih_offset PACKED; /* FontInfoHeader offset */

} FontFileHeader;

int drfont = 0;

#define N 4

struct {

	unsigned char num_fonts PACKED; /* N = 4 fonts per code page*/

	unsigned char font_height[N] PACKED;

	unsigned long dfd_offset[N] PACKED; /* DisplayFontData offset */

} DRDOS_ExtendedFontFileHeader;

struct {

	unsigned short num_codepages PACKED;

} FontInfoHeader;

struct {

	unsigned short size PACKED;

	unsigned long off_nexthdr PACKED;

	unsigned short device_type PACKED; /* screen=1; printer=2 */

	unsigned char device_name[8] PACKED;

	unsigned short codepage PACKED;

	unsigned char res[6] PACKED;

	unsigned long off_font PACKED;

} CPEntryHeader;

struct {

	unsigned short reserved PACKED;

	unsigned short num_fonts PACKED;

	unsigned short size PACKED;

} CPInfoHeader;

struct {

	unsigned char height PACKED;

	unsigned char width PACKED;

	unsigned short reserved PACKED;

	unsigned short num_chars PACKED;

} ScreenFontHeader;

struct {

	unsigned short printer_type PACKED;

	unsigned short seqlength PACKED;

} PrinterFontHeader;

FILE *in, *out;

void usage(void);

int opta, optc, optl, optL, optx;

extern int optind;

extern char *optarg;

unsigned short codepage;

int main(int argc, char *argv[])

{

	if (argc < 2)

		usage();

	opta = optc = optl = optL = optx = 0;

	if (argc == 2)

		optl = 1;

	else

		while (1) {

			switch (getopt(argc, argv, "alLc")) {

				case 'a':

					opta = 1;

					continue;

				case 'c':

					optc = 1;

					continue;

				case 'L':

					optL = 1;

					continue;

				case 'l':

					optl = 1;

					continue;

				case '?':

				default:

					usage();

				case -1:

					break;

			}

			break;

		}

	if (optind < argc) {

		if ((in = fopen(argv[optind], "r")) == NULL) {

			printf("\nUnable to open file %s.\n", argv[optind]);

			exit(0);

		}

		optind++;

	} else

		usage();

	if (optind != argc) {

		if (optind != argc - 1 || opta)

			usage();

		codepage = atoi(argv[optind]);

		optx     = 1;

	}

	if (optc)

		handle_codepage(0);

	else

		handle_fontfile();

	if (optx) {

		printf("no page %d found\n", codepage);

		exit(1);

	}

	fclose(in);

	return (0);

}

void handle_fontfile()

{

	int i, j;

	j = fread(&FontFileHeader, 1, sizeof(FontFileHeader), in);

	if (j != sizeof(FontFileHeader)) {

		printf("error reading FontFileHeader - got %d chars\n", j);

		exit(1);

	}

	if (optL)

		printf("FontFileHeader: id=0x%x \"%7.7s\" res=%8.8s "

		       "num=%d typ=%d fih_offset=%ld\n\n",

		       FontFileHeader.id0, FontFileHeader.id, FontFileHeader.res,

		       FontFileHeader.pnum, FontFileHeader.ptyp,

		       FontFileHeader.fih_offset);

	if (!strcmp(FontFileHeader.id, "DRFONT ")) {

		drfont = 1;

		j      = fread(&DRDOS_ExtendedFontFileHeader, 1,

		          sizeof(DRDOS_ExtendedFontFileHeader), in);

		if (j != sizeof(DRDOS_ExtendedFontFileHeader)) {

			printf("error reading ExtendedFontFileHeader - "

			       "got %d chars\n",

			       j);

			exit(1);

		}

		if (DRDOS_ExtendedFontFileHeader.num_fonts != N) {

			printf("found %d instead of 4 fonts in drfont\n",

			       DRDOS_ExtendedFontFileHeader.num_fonts);

			exit(1);

		}

		if (optL) {

			printf("ExtendedFontFileHeader:\n");

			for (j = 0; j < N; j++) {

				printf("font%d: height %d dfd_offset %d\n", j,

				       DRDOS_ExtendedFontFileHeader.font_height[j],

				       DRDOS_ExtendedFontFileHeader.dfd_offset[j]);

			}

			printf("\n");

		}

	}

	j = fread(&FontInfoHeader, 1, sizeof(FontInfoHeader), in);

	if (j != sizeof(FontInfoHeader)) {

		printf("error reading FontInfoHeader - got %d chars\n", j);

		exit(1);

	}

	if (optL)

		printf("FontInfoHeader: num_codepages=%d\n\n",

		       FontInfoHeader.num_codepages);

#if 1

	if (drfont) {

		printf("this program cannot handle DRDOS font files\n");

		exit(1);

	}

#endif

	for (i = FontInfoHeader.num_codepages; i; i--)

		if (handle_codepage(i - 1))

			break;

}

int handle_codepage(int more_to_come)

{

	int j;

	char outfile[20];

	unsigned char *fonts;

	long inpos, nexthdr;

	j = fread(&CPEntryHeader, 1, sizeof(CPEntryHeader), in);

	if (j != sizeof(CPEntryHeader)) {

		printf("error reading CPEntryHeader - got %d chars\n", j);

		exit(1);

	}

	if (optL) {

		int t = CPEntryHeader.device_type;

		printf("CPEntryHeader: size=%d dev=%d [%s] name=%8.8s "

		       "codepage=%d\n\t\tres=%6.6s nxt=%ld off_font=%ld\n\n",

		       CPEntryHeader.size,

		       t, (t == 1) ? "screen" : (t == 2) ? "printer" : "?",

		       CPEntryHeader.device_name,

		       CPEntryHeader.codepage,

		       CPEntryHeader.res,

		       CPEntryHeader.off_nexthdr, CPEntryHeader.off_font);

	} else if (optl) {

		printf("\nCodepage = %d\n", CPEntryHeader.codepage);

		printf("Device = %.8s\n", CPEntryHeader.device_name);

	}

#if 0

	if (CPEntryHeader.size != sizeof(CPEntryHeader)) {

	    /* seen 26 and 28, so that the difference below is -2 or 0 */

	    if (optl)

	      printf("Skipping %d bytes of garbage\n",

		     CPEntryHeader.size - sizeof(CPEntryHeader));

	    fseek(in, CPEntryHeader.size - sizeof(CPEntryHeader),

		  SEEK_CUR);

	}

#endif

	if (!opta && (!optx || CPEntryHeader.codepage != codepage) && !optc)

		goto next;

	inpos = ftell(in);

	if (inpos != CPEntryHeader.off_font && !optc) {

		if (optL)

			printf("pos=%ld font at %ld\n", inpos, CPEntryHeader.off_font);

		fseek(in, CPEntryHeader.off_font, SEEK_SET);

	}

	j = fread(&CPInfoHeader, 1, sizeof(CPInfoHeader), in);

	if (j != sizeof(CPInfoHeader)) {

		printf("error reading CPInfoHeader - got %d chars\n", j);

		exit(1);

	}

	if (optl) {

		printf("Number of Fonts = %d\n", CPInfoHeader.num_fonts);

		printf("Size of Bitmap = %d\n", CPInfoHeader.size);

	}

	if (CPInfoHeader.num_fonts == 0)

		goto next;

	if (optc)

		return 0;

	sprintf(outfile, "%d.cp", CPEntryHeader.codepage);

	if ((out = fopen(outfile, "w")) == NULL) {

		printf("\nUnable to open file %s.\n", outfile);

		exit(1);

	} else

		printf("\nWriting %s\n", outfile);

	fonts = (unsigned char *)malloc(CPInfoHeader.size);

	fread(fonts, CPInfoHeader.size, 1, in);

	fwrite(&CPEntryHeader, sizeof(CPEntryHeader), 1, out);

	fwrite(&CPInfoHeader, sizeof(CPInfoHeader), 1, out);

	j = fwrite(fonts, 1, CPInfoHeader.size, out);

	if (j != CPInfoHeader.size) {

		printf("error writing %s - wrote %d chars\n", outfile, j);

		exit(1);

	}

	fclose(out);

	free(fonts);

	if (optx)

		exit(0);

next:

	/*

	 * It seems that if entry headers and fonts are interspersed,

	 * then nexthdr will point past the font, regardless of

	 * whether more entries follow.

	 * Otherwise, first all entry headers are given, and then

	 * all fonts; in this case nexthdr will be 0 in the last entry.

	 */

	nexthdr = CPEntryHeader.off_nexthdr;

	if (nexthdr == 0 || nexthdr == -1) {

		if (more_to_come) {

			printf("more codepages expected, but nexthdr=%ld\n",

			       nexthdr);

			exit(1);

		} else

			return 1;

	}

	inpos = ftell(in);

	if (inpos != CPEntryHeader.off_nexthdr) {

		if (optL)

			printf("pos=%ld nexthdr at %ld\n", inpos, nexthdr);

		if (opta && !more_to_come) {

			printf("no more code pages, but nexthdr != 0\n");

			return 1;

		}

		fseek(in, CPEntryHeader.off_nexthdr, SEEK_SET);

	}

	return 0;

}

void usage(void)

{

	printf("\nUsage: cpi code_page_file [-c] [-L] [-l] [-a|nnn]\n");

	printf(" -c: input file is a single codepage\n");

	printf(" -L: print header info (you don't want to see this)\n");

	printf(" -l or no option: list all codepages contained in the file\n");

	printf(" -a: extract all codepages from the file\n");

	printf(" nnn (3 digits): extract codepage nnn from the file\n");

	printf("Example: cpi ega.cpi 850 \n");

	printf(" will create a file 850.cp containing the requested codepage.\n\n");

	exit(1);

}