Convert text file formats between mac/dos/unix

I seriously doubt anybody would use this nowadays since OSX, dos2unix, and unix2dos have been around for a while. However, I still put this on since someone asked me to write this little utility and it might still be useful for somebody.

/*
	convert.c -- convert text file formats between mac/dos/unix

	by Tsan-Kuang Lee (2002/06/03)

	Install:
		Compile it and give it a common converter name, e.g. "convert".
			gcc -o convert convert.c

		soft link the three versions of the converter to it, i.e.

			ln -s ~/bin/convert makedos
			ln -s ~/bin/convert makemac
			ln -s ~/bin/convert makeunix
		Make sure they are in the path

	Usage:
		 makedos file1 >target
			this will convert file1 into dos format and pipe into target
			If >target is omit, it prints out the file in dos format.
			(In sum, if no options are given, stdin and stdout are assumed.)

		 similar for makeunix and makemac

	Copyleft:
		Do whatever you want.  I wrote it in 15 minutes for my immediate need,
		so it's very messy.  Many quick and dirty (and ugly) lines.  If you can
		clean it up, I'd appreciate that.


	=======================================================================

	Explaination:

		DOS, UNIX, MAC text files use different line break marker.

			Line break:

				mac : 0d        (CR)
				dos : 0d 0a     (CR LF)
				unix : 0a       (LF)

		Besides, DOS files end with CTRL_Z

			dos: with ^z (0x22) at the end

			(PS: this program omits the CTRL_Z because WINDOWS discards that)
 */

#define MAKEUNIX    "makeunix"
#define MAKEDOS     "makedos"
#define MAKEMAC     "makemac"

#define FILETYPE_UNKNOWN    (0)
#define FILETYPE_UNIX   (1)
#define FILETYPE_DOS    (2)
#define FILETYPE_MAC    (3)
#define FILETYPE_BINARY (4)

#define CTRL_Z                  0x1a

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

static void err_report();       /* error reporting function */
static int ChkFileType(FILE *pFile);
char* printtype (int filetype);
static FILE *Fpi;           /* input file pointer */



static char program_path[127];

static int              nCharLimit     = 127;

extern int main(argc, argv)
int argc;
char    **argv;
{
	register int data;
	int leng;
	int from_filetype, to_filetype;

	from_filetype = to_filetype = FILETYPE_UNKNOWN;

	strcpy (program_path, argv[0]);
	leng = strlen (program_path);

	if (leng >= strlen (MAKEUNIX))
	{
		if (!strcmp(&(program_path[leng-8]),MAKEUNIX))
			to_filetype = FILETYPE_UNIX;
	}
	if (leng >= strlen (MAKEDOS)) /* or MAKEMAC */
	{
		if (!strcmp(&(program_path[leng-strlen(MAKEDOS)]),MAKEDOS))
			to_filetype = FILETYPE_DOS;
		else if (!strcmp(&(program_path[leng-strlen(MAKEMAC)]),MAKEMAC))
			to_filetype = FILETYPE_MAC;
	}

	if (to_filetype == FILETYPE_UNKNOWN)
		err_report(2);

	/* parse command line, open input file if needed */
	switch (argc) {
	case 1: {
			Fpi = stdin;
			break;
		}
	case 2: {
			if ((Fpi = fopen(*++argv, "r ")) == NULL)
				err_report(1);
			break;
		}
	default:
		err_report(0);      /* emit usage message */
	}

	from_filetype = ChkFileType(Fpi);

	// (void) fprintf(stderr,"Convert from %s to %s.\n", printtype(from_filetype), printtype(to_filetype));

	fseek (Fpi, 0L, SEEK_SET);

	while ( ! feof(Fpi)) {
		data = fgetc(Fpi);
		if (data == EOF) break;     /* screen out nasty EOF */

		if (data == 0x0a || data == 0x0d)
		{
			switch (from_filetype)
			{
				case FILETYPE_MAC: /* from MAC */
					switch (to_filetype)
					{
						case FILETYPE_MAC:
							fputc(0x0d,stdout);
							break;
						case FILETYPE_UNIX:
							fputc(0x0a,stdout);
							break;
						case FILETYPE_DOS:
							fputc(0x0d,stdout);
							fputc(0x0a,stdout);
							break;
						default:
							break;
					}
					break;
				case FILETYPE_UNIX: /* from UNIX (already has 0x0a) */
					switch (to_filetype)
					{
						case FILETYPE_MAC:
							fputc(0x0d,stdout);
							break;
						case FILETYPE_UNIX:
							fputc(0x0a,stdout);
							break;
						case FILETYPE_DOS:
							fputc(0x0d,stdout);
							fputc(0x0a,stdout);
							break;
						default:
							break;
					}
					break;
				case FILETYPE_DOS: /*from DOS (has 0x0d 0x0a) */
					switch (to_filetype)
					{
						case FILETYPE_MAC:
							if (data == 0x0d)
								fputc(0x0d,stdout);
							break;
						case FILETYPE_UNIX:
							if (data == 0x0a)
								fputc(0x0a,stdout);
							break;
						case FILETYPE_DOS:
							fputc(data,stdout);
							break;
						default:
							break;
					}
					break;
				default:
					break;
			} /* end switch */
		}
		else if (data != '\026') /* a control-Z */
			(void) fputc(data,stdout);
	}

/*  this is taken away since my Windows doesn't seem to follow this rule */

//  if (to_filetype == FILETYPE_DOS)
//      (void) fputc('\026',stdout);        /* a control-Z */

	(void) fclose(Fpi);
	exit(0);


}


static void err_report(n)
int n;
{
	switch (n)  {
	case 0:
		(void) fprintf(stderr,"Usage: %s <file>  \n",program_path);
		break;
	case 1:
		(void) fprintf(stderr,"%s: Can't open input file.\n",program_path);
		break;
	case 2:
		(void) fprintf(stderr,"%s: Program filename must be MAKEUNIX, MAKEDOS, or MAKEMAC\n",program_path);
		break;
	}

	exit(1);
}




static int ChkFileType(FILE *pFile)
{
	auto     size_t             i;
	auto     size_t             siz;
	auto     int                nCR = 0;
	auto     int                nLF = 0;
	static   unsigned char      buf[1024];

	siz = fread(buf, 1, sizeof(buf), pFile);
	fseek(pFile, 0L, SEEK_SET);
	if (0 == siz)
		return(FILETYPE_BINARY);

	for (i = 0; i <  siz; ++i)
	{
		switch (buf[i])
		{
			case '\r':  /* 0x0d */
				++nCR;
				break;

			case '\n':  /* 0x0a */
				++nLF;
				break;

			case '\t':
			case 11:
			case 12:
			case CTRL_Z:
				break;

			default:
				if (buf[i] < ' ' ||  (int) buf[i] > nCharLimit)
					return(FILETYPE_BINARY);

				break;
		}
	}

	// printf ("0d = %d, 0a = %d\n", nCR, nLF);

	if (0 == nCR && nLF)
		return(FILETYPE_UNIX);

	if (0 == nLF && nCR)
		return(FILETYPE_MAC);

	return(FILETYPE_DOS);
}


char* printtype (int filetype)
{
	switch (filetype)
	{
		case FILETYPE_MAC:
			return("MAC");
			break;
		case FILETYPE_DOS:
			return("DOS");
			break;
		case FILETYPE_UNIX:
			return("UNIX");
			break;
		default:
			return("ERROR");
	}
}