/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
 * 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 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 AUTHOR 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 "namespace.h"
#include <sys/endian.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <utmpx.h>
#include "utxdb.h"
#include "un-namespace.h"

static _Thread_local FILE *uf = NULL;
static _Thread_local int udb;

int
setutxdb(int db, const char *file)
{
        struct stat sb;

        switch (db) {
        case UTXDB_ACTIVE:
                if (file == NULL)
                        file = _PATH_UTX_ACTIVE;
                break;
        case UTXDB_LASTLOGIN:
                if (file == NULL)
                        file = _PATH_UTX_LASTLOGIN;
                break;
        case UTXDB_LOG:
                if (file == NULL)
                        file = _PATH_UTX_LOG;
                break;
        default:
                errno = EINVAL;
                return (-1);
        }

        if (uf != NULL)
                fclose(uf);
        uf = fopen(file, "re");
        if (uf == NULL)
                return (-1);

        if (db != UTXDB_LOG) {
                /* Safety check: never use broken files. */
                if (_fstat(fileno(uf), &sb) != -1 &&
                    sb.st_size % sizeof(struct futx) != 0) {
                        fclose(uf);
                        uf = NULL;
                        errno = EFTYPE;
                        return (-1);
                }
                /* Prevent reading of partial records. */
                (void)setvbuf(uf, NULL, _IOFBF,
                    rounddown(BUFSIZ, sizeof(struct futx)));
        }

        udb = db;
        return (0);
}

void
setutxent(void)
{

        setutxdb(UTXDB_ACTIVE, NULL);
}

void
endutxent(void)
{

        if (uf != NULL) {
                fclose(uf);
                uf = NULL;
        }
}

static int
getfutxent(struct futx *fu)
{

        if (uf == NULL)
                setutxent();
        if (uf == NULL)
                return (-1);

        if (udb == UTXDB_LOG) {
                uint16_t len;

retry:
                if (fread(&len, sizeof(len), 1, uf) != 1)
                        return (-1);
                len = be16toh(len);
                if (len == 0) {
                        /*
                         * XXX: Though zero-size records are valid in theory,
                         * they can never occur in practice. Zero-size records
                         * indicate file corruption. Seek one byte forward, to
                         * see if we can find a record there.
                         */
                        ungetc('\0', uf);
                        goto retry;
                }
                if (len > sizeof *fu) {
                        /* Forward compatibility. */
                        if (fread(fu, sizeof(*fu), 1, uf) != 1)
                                return (-1);
                        fseek(uf, len - sizeof(*fu), SEEK_CUR);
                } else {
                        /* Partial record. */
                        memset(fu, 0, sizeof(*fu));
                        if (fread(fu, len, 1, uf) != 1)
                                return (-1);
                }
        } else {
                if (fread(fu, sizeof(*fu), 1, uf) != 1)
                        return (-1);
        }
        return (0);
}

struct utmpx *
getutxent(void)
{
        struct futx fu;

        if (getfutxent(&fu) != 0)
                return (NULL);
        return (futx_to_utx(&fu));
}

struct utmpx *
getutxid(const struct utmpx *id)
{
        struct futx fu;

        for (;;) {
                if (getfutxent(&fu) != 0)
                        return (NULL);

                switch (fu.fu_type) {
                case USER_PROCESS:
                case INIT_PROCESS:
                case LOGIN_PROCESS:
                case DEAD_PROCESS:
                        switch (id->ut_type) {
                        case USER_PROCESS:
                        case INIT_PROCESS:
                        case LOGIN_PROCESS:
                        case DEAD_PROCESS:
                                if (memcmp(fu.fu_id, id->ut_id,
                                    MIN(sizeof(fu.fu_id), sizeof(id->ut_id))) ==
                                    0)
                                        goto found;
                        }
                        break;
                default:
                        if (fu.fu_type == id->ut_type)
                                goto found;
                        break;
                }
        }

found:
        return (futx_to_utx(&fu));
}

struct utmpx *
getutxline(const struct utmpx *line)
{
        struct futx fu;

        for (;;) {
                if (getfutxent(&fu) != 0)
                        return (NULL);

                switch (fu.fu_type) {
                case USER_PROCESS:
                case LOGIN_PROCESS:
                        if (strncmp(fu.fu_line, line->ut_line,
                            MIN(sizeof(fu.fu_line), sizeof(line->ut_line))) ==
                            0)
                                goto found;
                        break;
                }
        }

found:
        return (futx_to_utx(&fu));
}

struct utmpx *
getutxuser(const char *user)
{
        struct futx fu;

        for (;;) {
                if (getfutxent(&fu) != 0)
                        return (NULL);

                switch (fu.fu_type) {
                case USER_PROCESS:
                        if (strncmp(fu.fu_user, user, sizeof(fu.fu_user)) == 0)
                                goto found;
                        break;
                }
        }

found:
        return (futx_to_utx(&fu));
}