bin

bin.c (1801B)

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

#define ISFLAG(str, fshort, flong) (!strcmp(str, fshort) || !strcmp(str, flong))

const char *usage = "USAGE: bin [-r] [-s SKIP] [-n COUNT] [FILE]\n";

void
die(const char *fmtstr, ...)
{
	va_list ap;

	va_start(ap, fmtstr);
	vfprintf(stderr, fmtstr, ap);
	va_end(ap);

	exit(EXIT_FAILURE);
}

int
main(int argc, const char **argv)
{
	unsigned char byte, bit;
	size_t skip, cnt, pos;
	const char *filepath;
	int i, revbyte, cntset;
	char *end;
	FILE *f;

	filepath = NULL;
	cnt = skip = 0;
	revbyte = 0;
	cntset = 0;

	for (i = 1; i < argc; i++) {
		if (ISFLAG(argv[i], "-s", "--skip")) {
			if (i++ >= argc - 1) goto missing_arg;
			skip = strtoul(argv[i], &end, 0);
			if (end && *end) goto bad_arg;
		} else if (ISFLAG(argv[i], "-n", "--count")) {
			if (i++ >= argc - 1) goto missing_arg;
			cnt = strtoul(argv[i], &end, 0);
			cntset = 1;
			if (end && *end) goto bad_arg;
		} else if (ISFLAG(argv[i], "-r", "--revb")) {
			revbyte = 1;
		} else if (ISFLAG(argv[i], "-h", "--help")) {
			die(usage);
		} else if (*argv[i] == '-') {
			die("Unknown flag: %s\n", argv[i]);
		} else if (filepath) {
			die("Too many files specified\n");
		} else {
			filepath = argv[i];
		}
	}

	if (!filepath)
		f = stdin;
	else if (!(f = fopen(filepath, "r")))
		die("Failed to open file\n");

	pos = 0;
	while (!cntset || pos < skip + cnt) {
		if (pos % 8 == 0) byte = fgetc(f);
		if (feof(f)) break;
		if (pos >= skip) {
			if (revbyte)
				bit = (byte >> (pos % 8)) & 1;
			else
				bit = (byte >> (7 - pos % 8)) & 1;
			putchar(bit ? '1' : '0');
		}
		pos += 1;
	}

	fclose(f);

	return EXIT_SUCCESS;

missing_arg:
	die("Flag %s expects an argument\n", argv[i]);

bad_arg:
	die("Argument has unexpected value: %s\n", argv[i]);
}