/*  retconv.c  -  convert return code from/to DOS/Mac/UNIX  */

#include <stdio.h>

#define LF	0
#define CR	1
#define CRLF	2

int main(int argc, char *argv[])
{
	int c, i;
	int convmode = LF, prevchar = 0;

	for (i = 1; i < argc; i++) {
		if (*argv[i] == '-') {
			switch (c = *(argv[i] + 1)) {
			case 'd':	/* to DOS */
				convmode = CRLF;
				break;
			case 'm':	/* to Mac */
				convmode = CR;
				break;
			case 'u':	/* to UNIX */
				convmode = LF;
				break;
			case 'h':
				fprintf(stderr, "Usage: %s [-dmu] < infile > outfile\n", argv[0]);
				exit(1);
			default:
				fprintf(stderr, "invalid option -- %c\n", c);
				exit(1);
			}
		}
	}

	while ((c = fgetc(stdin)) != EOF) {
		switch (c) {
		case '\r':
		case '\n':
			/* return code from DOS */
			if (prevchar == '\r' && c == '\n')
				break;
			switch (convmode) {
			case LF:
				fputc('\n', stdout);
				break;
			case CR:
				fputc('\r', stdout);
				break;
			case CRLF:
				fputc('\r', stdout);
				fputc('\n', stdout);
				break;
			}
			break;
		default:
			fputc(c, stdout);
		}
		prevchar = c;
	}
	return 0;
}