/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2001-2002 Chris D. Faulhaber
 * 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 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 <sys/types.h>
#include "namespace.h"
#include <sys/acl.h>
#include "un-namespace.h"

#include <errno.h>
#include <stdio.h>

#include "acl_support.h"

/*
 * acl_calc_mask() (23.4.2): calculate and set the permissions
 * associated with the ACL_MASK ACL entry.  If the ACL already
 * contains an ACL_MASK entry, its permissions shall be
 * overwritten; if not, one shall be added.
 */
int
acl_calc_mask(acl_t *acl_p)
{
        struct acl      *acl_int, *acl_int_new;
        acl_t           acl_new;
        int             i, mask_mode, mask_num;

        /*
         * (23.4.2.4) requires acl_p to point to a pointer to a valid ACL.
         * Since one of the primary reasons to use this function would be
         * to calculate the appropriate mask to obtain a valid ACL, we only
         * perform sanity checks here and validate the ACL prior to
         * returning.
         */
        if (acl_p == NULL || *acl_p == NULL) {
                errno = EINVAL;
                return (-1);
        }

        if (!_acl_brand_may_be(*acl_p, ACL_BRAND_POSIX)) {
                errno = EINVAL;
                return (-1);
        }
        _acl_brand_as(*acl_p, ACL_BRAND_POSIX);

        acl_int = &(*acl_p)->ats_acl;
        if ((acl_int->acl_cnt < 3) || (acl_int->acl_cnt > ACL_MAX_ENTRIES)) {
                errno = EINVAL;
                return (-1);
        }

        acl_new = acl_dup(*acl_p);
        if (acl_new == NULL)
                return (-1);
        acl_int_new = &acl_new->ats_acl;

        mask_mode = 0;
        mask_num = -1;

        /* gather permissions and find a mask entry */
        for (i = 0; i < acl_int_new->acl_cnt; i++) {
                switch(acl_int_new->acl_entry[i].ae_tag) {
                case ACL_USER:
                case ACL_GROUP:
                case ACL_GROUP_OBJ:
                        mask_mode |=
                            acl_int_new->acl_entry[i].ae_perm & ACL_PERM_BITS;
                        break;
                case ACL_MASK:
                        mask_num = i;
                        break;
                }
        }

        /* if a mask entry already exists, overwrite the perms */
        if (mask_num != -1)
                acl_int_new->acl_entry[mask_num].ae_perm = mask_mode;
        else {
                /* if no mask exists, check acl_cnt... */
                if (acl_int_new->acl_cnt == ACL_MAX_ENTRIES) {
                        errno = ENOMEM;
                        acl_free(acl_new);
                        return (-1);
                }
                /* ...and add the mask entry */
                acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_tag = ACL_MASK;
                acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_id =
                    ACL_UNDEFINED_ID;
                acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_perm =
                    mask_mode;
                acl_int_new->acl_cnt++;
        }

        if (acl_valid(acl_new) == -1) {
                errno = EINVAL;
                acl_free(acl_new);
                return (-1);
        }

        **acl_p = *acl_new;
        acl_free(acl_new);

        return (0);
}