/*      $NetBSD: getgrent.c,v 1.12 2005/09/14 15:54:53 drochner Exp $   */

/*
 * Copyright (c) 1989, 1991, 1993
 *      The Regents of the University of California.  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.
 * 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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

/*
 * Portions Copyright (c) 1994, Jason Downs. 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.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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(S) 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.
 */

/*
 * Copied from:  lib/libc/gen/getgrent.c
 *     NetBSD: getgrent.c,v 1.46 2003/02/17 00:11:54 simonb Exp
 * and then gutted, leaving only /etc/group support.
 */

#include <sys/cdefs.h>

#ifdef __weak_alias
#define endgrent                _endgrent
#define getgrent                _getgrent
#define getgrgid                _getgrgid
#define getgrnam                _getgrnam
#define getgrnam_r              _getgrnam_r
#define setgrent                _setgrent
#define setgroupent             _setgroupent
#define getgrouplist            _getgrouplist

__weak_alias(endgrent,_endgrent)
__weak_alias(getgrent,_getgrent)
__weak_alias(getgrgid,_getgrgid)
__weak_alias(getgrnam,_getgrnam)
__weak_alias(getgrnam_r,_getgrnam_r)
__weak_alias(setgrent,_setgrent)
__weak_alias(setgroupent,_setgroupent)
__weak_alias(getgrouplist,_getgrouplist)
#endif

#include <sys/param.h>

#include <grp.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

static FILE             *_gr_fp;
static struct group     _gr_group;
static int              _gr_stayopen;
static int              _gr_filesdone;

static int grscan(int, gid_t, const char *, const char *);
static int grstart(void);
static int grmatchline(int, gid_t, const char *, const char *);

#define MAXGRP          200
#define MAXLINELENGTH   1024

static __aconst char    *members[MAXGRP];
static char             grline[MAXLINELENGTH];

struct group *
getgrent(void)
{

        if ((!_gr_fp && !grstart()) || !grscan(0, 0, NULL, NULL))
                return (NULL);
        return &_gr_group;
}

int
getgrnam_r(const char *name, struct group *grp, char *buffer,
        size_t buflen, struct group **result)
{
        struct group *gp, *bgp;

        /* 
         * We blatantly cheat (don't provide reentrancy) 
         * and hope to get away with it
         */

        *result = NULL;
        bgp = (struct group*)buffer;
        if (buflen < sizeof(struct group))
                return ENOMEM;

        gp = getgrnam(name);
        if (gp) {
                *bgp = *gp;
                *result = bgp;
        }

        return (gp) ? ENOENT : 0;
}

struct group *
getgrnam(const char *name)
{
        int rval;

        if (!grstart())
                return NULL;
        rval = grscan(1, 0, name, NULL);
        if (!_gr_stayopen)
                endgrent();
        return (rval) ? &_gr_group : NULL;
}

struct group *
getgrgid(gid_t gid)
{
        int rval;

        if (!grstart())
                return NULL;
        rval = grscan(1, gid, NULL, NULL);
        if (!_gr_stayopen)
                endgrent();
        return (rval) ? &_gr_group : NULL;
}

static int
grstart(void)
{

        _gr_filesdone = 0;
        if (_gr_fp) {
                rewind(_gr_fp);
                return 1;
        }
        return (_gr_fp = fopen(_PATH_GROUP, "r")) ? 1 : 0;
}

void
setgrent(void)
{

        (void) setgroupent(0);
}

int
setgroupent(int stayopen)
{

        if (!grstart())
                return 0;
        _gr_stayopen = stayopen;
        return 1;
}

void
endgrent(void)
{

        _gr_filesdone = 0;
        if (_gr_fp) {
                (void)fclose(_gr_fp);
                _gr_fp = NULL;
        }
}

int
getgrouplist(const char *uname, gid_t agroup,
    gid_t *groups, int *grpcnt)
{
        struct group *grp;
        int maxgroups, i, ngroups, ret;

        maxgroups = *grpcnt;
        ret = 0;
        ngroups = 0;

        /*
         * install primary group
         */
        if (ngroups < maxgroups)
                groups[ngroups] = agroup;
        else
                ret = -1;
        ngroups++;

        /*
         * Scan the group file to find additional groups.
         */
        setgrent();
 nextgroup:
        while ((grp = getgrent()) != NULL) {
                if (grp->gr_gid == agroup)
                        continue;
                for (i = 0; grp->gr_mem[i]; i++) {
                        if (strcmp(grp->gr_mem[i], uname) != 0)
                                continue;
                        for (i = 0; i < MIN(ngroups, maxgroups); i++) {
                                if (grp->gr_gid == groups[i])
                                        goto nextgroup;
                        }
                        if (ngroups < maxgroups)
                                groups[ngroups] = grp->gr_gid;
                        else
                                ret = -1;
                        ngroups++;
                        break;
                }
        }
        endgrent();
        *grpcnt = ngroups;
        return ret;
}

static int
grscan(int search, gid_t gid, const char *name, const char *user)
{

        if (_gr_filesdone)
                return 0;
        for (;;) {
                if (!fgets(grline, sizeof(grline), _gr_fp)) {
                        if (!search)
                                _gr_filesdone = 1;
                        return 0;
                }
                /* skip lines that are too big */
                if (!strchr(grline, '\n')) {
                        int ch;

                        while ((ch = getc(_gr_fp)) != '\n' && ch != EOF)
                                ;
                        continue;
                }
                if (grmatchline(search, gid, name, user))
                        return 1;
        }
        /* NOTREACHED */
}

static int
grmatchline(int search, gid_t gid, const char *name, const char *user)
{
        unsigned long   id;
        __aconst char   **m;
        char            *cp, *bp, *ep;

        /* name may be NULL if search is nonzero */

        bp = grline;
        _gr_group.gr_name = strsep(&bp, ":\n");
        if (search && name && strcmp(_gr_group.gr_name, name))
                return 0;
        _gr_group.gr_passwd = strsep(&bp, ":\n");
        if (!(cp = strsep(&bp, ":\n")))
                return 0;
        id = strtoul(cp, &ep, 10);
        if (id > GID_MAX || *ep != '\0')
                return 0;
        _gr_group.gr_gid = (gid_t)id;
        if (search && name == NULL && _gr_group.gr_gid != gid)
                return 0;
        cp = NULL;
        if (bp == NULL)
                return 0;
        for (_gr_group.gr_mem = m = members;; bp++) {
                if (m == &members[MAXGRP - 1])
                        break;
                if (*bp == ',') {
                        if (cp) {
                                *bp = '\0';
                                *m++ = cp;
                                cp = NULL;
                        }
                } else if (*bp == '\0' || *bp == '\n' || *bp == ' ') {
                        if (cp) {
                                *bp = '\0';
                                *m++ = cp;
                        }
                        break;
                } else if (cp == NULL)
                        cp = bp;
        }
        *m = NULL;
        if (user) {
                for (m = members; *m; m++)
                        if (!strcmp(user, *m))
                                return 1;
                return 0;
        }
        return 1;
}