/*-
 * Copyright (c) 1998 Dag-Erling Coïdan Smørgrav
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD: src/usr.sbin/chkgrp/chkgrp.c,v 1.3.2.2 2001/07/12 22:57:35 mjacob Exp $
 * $DragonFly: src/usr.sbin/chkgrp/chkgrp.c,v 1.6 2005/08/25 17:09:32 liamfoy Exp $
 */
#include <sys/types.h>

#include <ctype.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>

#define DEFAULTGFILE "/etc/group"

static void     usage(void);
static char empty[] = { 0 };

static void
usage(void)
{
	fprintf(stderr, "usage: chkgrp [groupfile]\n");
	exit(EX_USAGE);
}

int
main(int argc, char *argv[])
{
	size_t len;
	int n = 0, i, k, e = 0;
	char *line, *f[4], *p;
	const char *cp, *gfn;
	FILE *gf;

	/* check arguments */
	switch (argc) {
	case 1:
		gfn = DEFAULTGFILE;
		break;
	case 2:
		gfn = argv[1];
		break;
	default:
		gfn = NULL;	/* silence compiler */
		usage();
	}

	/* open group file */
	if ((gf = fopen(gfn, "r")) == NULL)
		err(EX_IOERR, "%s", gfn);

	/* check line by line */
	while (++n) {
		if ((line = fgetln(gf, &len)) == NULL)
			break;
		if (len > 0 && line[len - 1] != '\n') {
			warnx("%s: line %d: no newline character", gfn, n);
			e++;
		}
		while (len && isspace(line[len - 1]))
			len--;

		/* ignore blank lines and comments */
		for (p = line; p < (line + len); p++)
			if (!isspace(*p))
				break;
		if (!len || (*p == '#')) {
#if 0
			/* entry is correct, so print it */
			printf("%*.*s\n", len, len, line);
#endif
			continue;
		}
		/*
		 * A correct group entry has four colon-separated fields, the
		 * third of which must be entirely numeric and the fourth of
		 * which may be empty. We also check for any incorrect characters.
		 */
		for (i = k = 0; k < 4; k++) {
			for (f[k] = line + i; (i < (int)len) && (line[i] != ':'); i++)
				 /* nothing */ ;
			if ((k < 3) && (line[i] != ':'))
				break;
			line[i++] = 0;
		}

                if (k < 4) {
                        warnx("%s: line %d: missing field(s)", gfn, n);
			for ( ; k < 4; k++)
				f[k] = empty; 
                        e++;
                }

		for (cp = f[0] ; *cp ; cp++) {
			if (!isalnum(*cp) && *cp != '.' && *cp != '_' && *cp != '-' &&
			        (cp > f[0] || *cp != '+')) {
				warnx("%s: line %d: '%c' invalid character", gfn, n, *cp);
				e++;
			}
		}

		for (cp = f[3] ; *cp ; cp++) {
			if (!isalnum(*cp) && *cp != ',' && *cp != '.' && *cp != '_' && *cp != '-') {
				warnx("%s: line %d: '%c' invalid character", gfn, n, *cp);
				e++;
			}
		}

		/* check if fourth field ended with a colon */
		if (i < (int)len) {
			warnx("%s: line %d: too many fields", gfn, n);
			e++;
		}
		/* check that none of the fields contain whitespace */
		for (k = 0; k < 4; k++) {
			if (strcspn(f[k], " \t") != strlen(f[k])) {
				warnx("%s: line %d: field %d contains whitespace",
				      gfn, n, k + 1);
				e++;
			}
		}

		/* check that the GID is numeric */
		if (strspn(f[2], "0123456789") != strlen(f[2])) {
			warnx("%s: line %d: GID is not numeric", gfn, n);
			e++;
		}
#if 0
		/* entry is correct, so print it */
		printf("%s:%s:%s:%s\n", f[0], f[1], f[2], f[3]);
#endif
	}

	/* check what broke the loop */
	if (ferror(gf))
		err(EX_IOERR, "%s: line %d", gfn, n);

	/* done */
	fclose(gf);
	if (e == 0)
		printf("%s is fine\n", gfn);
	exit(e ? EX_DATAERR : EX_OK);
}