/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1985, 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.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: getusershell.c,v 1.17 1999/01/25 01:09:34 lukem Exp $");

#include "namespace.h"
#include <sys/param.h>
#include <sys/file.h>

#include <ctype.h>
#include <errno.h>
#include <nsswitch.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stringlist.h>
#include <unistd.h>

#ifdef HESIOD
#include <hesiod.h>
#endif
#ifdef YP
#include <rpc/rpc.h>
#include <rpcsvc/ypclnt.h>
#include <rpcsvc/yp_prot.h>
#endif
#include "un-namespace.h"

static const char *const *curshell;
static StringList        *sl;

static const char *const *initshells(void);

/*
 * Get a list of shells from "shells" nsswitch database
 */
char *
getusershell(void)
{
        char *ret;

        if (curshell == NULL)
                curshell = initshells();
        /*LINTED*/
        ret = (char *)*curshell;
        if (ret != NULL)
                curshell++;
        return (ret);
}

void
endusershell(void)
{
        if (sl) {
                sl_free(sl, 1);
                sl = NULL;
        }
        curshell = NULL;
}

void
setusershell(void)
{

        curshell = initshells();
}


static int      _local_initshells(void *, void *, va_list);

/*ARGSUSED*/
static int
_local_initshells(void  *rv, void *cb_data, va_list ap)
{
        char    *sp, *cp;
        FILE    *fp;
        char     line[MAXPATHLEN + 2];

        if (sl)
                sl_free(sl, 1);
        sl = sl_init();

        if ((fp = fopen(_PATH_SHELLS, "re")) == NULL)
                return NS_UNAVAIL;

        while (fgets(line, MAXPATHLEN + 1, fp) != NULL) {
                cp = line;
                while (*cp != '#' && *cp != '/' && *cp != '\0')
                        cp++;
                if (*cp == '#' || *cp == '\0')
                        continue;
                sp = cp;
                while (!isspace(*cp) && *cp != '#' && *cp != '\0')
                        cp++;
                *cp = '\0';
                sl_add(sl, strdup(sp));
        }
        (void)fclose(fp);
        return NS_SUCCESS;
}

#ifdef HESIOD
static int      _dns_initshells(void *, void *, va_list);

/*ARGSUSED*/
static int
_dns_initshells(void *rv, void *cb_data, va_list ap)
{
        char      shellname[] = "shells-XXXXX";
        int       hsindex, hpi, r;
        char    **hp;
        void     *context;

        if (sl)
                sl_free(sl, 1);
        sl = sl_init();
        r = NS_UNAVAIL;
        if (hesiod_init(&context) == -1)
                return (r);

        for (hsindex = 0; ; hsindex++) {
                snprintf(shellname, sizeof(shellname)-1, "shells-%d", hsindex);
                hp = hesiod_resolve(context, shellname, "shells");
                if (hp == NULL) {
                        if (errno == ENOENT) {
                                if (hsindex == 0)
                                        r = NS_NOTFOUND;
                                else
                                        r = NS_SUCCESS;
                        }
                        break;
                } else {
                        for (hpi = 0; hp[hpi]; hpi++)
                                sl_add(sl, hp[hpi]);
                        free(hp);
                }
        }
        hesiod_end(context);
        return (r);
}
#endif /* HESIOD */

#ifdef YP
static int      _nis_initshells(void *, void *, va_list);

/*ARGSUSED*/
static int
_nis_initshells(void *rv, void *cb_data, va_list ap)
{
        static char *ypdomain;
        char    *key, *data;
        char    *lastkey;
        int      keylen, datalen;
        int      r;

        if (sl)
                sl_free(sl, 1);
        sl = sl_init();

        if (ypdomain == NULL) {
                switch (yp_get_default_domain(&ypdomain)) {
                case 0:
                        break;
                case YPERR_RESRC:
                        return NS_TRYAGAIN;
                default:
                        return NS_UNAVAIL;
                }
        }

        /*
         * `key' and `data' point to strings dynamically allocated by
         * the yp_... functions.
         * `data' is directly put into the stringlist of shells.
         */
        key = data = NULL;
        if (yp_first(ypdomain, "shells", &key, &keylen, &data, &datalen))
                return NS_UNAVAIL;
        do {
                data[datalen] = '\0';           /* clear trailing \n */
                sl_add(sl, data);

                lastkey = key;
                r = yp_next(ypdomain, "shells", lastkey, keylen,
                    &key, &keylen, &data, &datalen);
                free(lastkey);
        } while (r == 0);
        
        if (r == YPERR_NOMORE) {
                /*
                 * `data' and `key' ought to be NULL - do not try to free them.
                 */
                return NS_SUCCESS;
        }

        return NS_UNAVAIL;
}
#endif /* YP */

static const char *const *
initshells(void)
{
        static const ns_dtab dtab[] = {
                NS_FILES_CB(_local_initshells, NULL)
                NS_DNS_CB(_dns_initshells, NULL)
                NS_NIS_CB(_nis_initshells, NULL)
                { 0 }
        };
        if (sl)
                sl_free(sl, 1);
        sl = sl_init();

        if (_nsdispatch(NULL, dtab, NSDB_SHELLS, "initshells", __nsdefaultsrc)
            != NS_SUCCESS) {
                if (sl)
                        sl_free(sl, 1);
                sl = sl_init();
                /*
                 * Local shells should NOT be added here.  They should be
                 * added in /etc/shells.
                 */
                sl_add(sl, strdup(_PATH_BSHELL));
                sl_add(sl, strdup(_PATH_CSHELL));
        }
        sl_add(sl, NULL);

        return (const char *const *)(sl->sl_str);
}