harakit/src/scrut.c

/*
 * Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero 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 Affero General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see https://www.gnu.org/licenses/.
 */

#include <stdio.h> /* fprintf(3), stderr, NULL */
#include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
#include <string.h> /* memset(3), strchr(3) */
#include <sysexits.h> /* EX_USAGE */
#include <unistd.h> /* access(3), getopt(3), F_OK, R_OK, W_OK, X_OK */
#include <sys/stat.h> /* lstat(3), stat struct, S_ISBLK, S_ISCHR, S_ISDIR,
                       * S_ISFIFO, S_ISGID, S_ISREG, S_ISLNK, S_ISSOCK,
                       * S_ISUID, S_ISVTX */

static char args[] = "bcdefghkprsuwxLS";
static char ops[(sizeof args) / (sizeof *args)];
static char *program_name = "scrut";

int usage(char *s) {
	fprintf(
		stderr,
		"Usage: %s [-%s] file...\n",
		s == NULL ? program_name : s, args
	);

	return EX_USAGE;
}

int main(int argc, char *argv[]) {
	struct stat buf;
	int c;
	size_t i;
	char *p;

	if (argc < 2) { return usage(argv[0]); }

	memset(ops, '\0', sizeof ops);
	while ((c = getopt(argc, argv, args)) != -1) {
		if ((p = strchr(args, c)) == NULL) {
			return usage(argv[0]);
		} else {
			ops[p - args] = c;
		}
	}

	/* straighten out ops */
	for (i = 0, p = ops; i < (sizeof ops) / (sizeof *ops); ++i) {
		if (ops[i] != '\0') {
			*p = ops[i];
			if (&ops[i] != p++) { ops[i] = '\0'; }
		}
	}

	if (optind == argc) { return usage(argv[0]); }

	argv += optind;
	do { /* while(*++argv != NULL); */
		if(access(*argv, F_OK) != 0 || lstat(*argv, &buf) == -1) {
			return EXIT_FAILURE; /* doesn't exist or isn't stattable */
		}

		for (i = 0; ops[i] != '\0'; ++i)
			if (ops[i] == 'e') {
				continue;
			} else if (ops[i] == 'h') {
				return usage(argv[0]);
			} else if (
					(ops[i] == 'b'
						&& !S_ISBLK(buf.st_mode))
					|| (ops[i] == 'c'
						&& !S_ISCHR(buf.st_mode))
					|| (ops[i] == 'd'
						&& !S_ISDIR(buf.st_mode))
					|| (ops[i] == 'f'
						&& !S_ISREG(buf.st_mode))
					|| (ops[i] == 'g'
						&& !(buf.st_mode & S_ISGID))
					|| (ops[i] == 'k'
						&& !(buf.st_mode & S_ISVTX))
					|| (ops[i] == 'p'
						&& !S_ISFIFO(buf.st_mode))
					|| (ops[i] == 'r'
						&& access(*argv, R_OK) != 0)
					|| (ops[i] == 'u'
						&& !(buf.st_mode & S_ISUID))
					|| (ops[i] == 'w'
						&& access(*argv, W_OK) != 0)
					|| (ops[i] == 'x'
						&& access(*argv, X_OK) != 0)
					|| (ops[i] == 'L'
						&& !S_ISLNK(buf.st_mode))
					|| (ops[i] == 'S'
						&& !S_ISSOCK(buf.st_mode))
			) { return EXIT_FAILURE; }
	} while(*++argv != NULL);

	return EXIT_SUCCESS;
}