/*-
 * 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);
}