/* $OpenBSD: stack.c,v 1.35 2026/01/14 17:43:49 tb Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * 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 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

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

#include <openssl/objects.h>
#include <openssl/stack.h>

#include "stack_local.h"

#undef MIN_NODES
#define MIN_NODES       4

int
(*sk_set_cmp_func(_STACK *sk, int (*c)(const void *, const void *)))(
    const void *, const void *)
{
        int (*old)(const void *, const void *) = sk->comp;

        if (sk->comp != c)
                sk->sorted = 0;
        sk->comp = c;

        return old;
}
LCRYPTO_ALIAS(sk_set_cmp_func);

_STACK *
sk_dup(_STACK *sk)
{
        _STACK *ret;
        void **s;

        if ((ret = sk_new(sk->comp)) == NULL)
                goto err;
        s = reallocarray(ret->data, sk->num_alloc, sizeof(void *));
        if (s == NULL)
                goto err;
        ret->data = s;

        ret->num = sk->num;
        memcpy(ret->data, sk->data, sizeof(void *) * sk->num);
        ret->sorted = sk->sorted;
        ret->num_alloc = sk->num_alloc;
        ret->comp = sk->comp;
        return (ret);

err:
        if (ret)
                sk_free(ret);
        return (NULL);
}
LCRYPTO_ALIAS(sk_dup);

_STACK *
sk_new_null(void)
{
        return sk_new((int (*)(const void *, const void *))0);
}
LCRYPTO_ALIAS(sk_new_null);

_STACK *
sk_new(int (*c)(const void *, const void *))
{
        _STACK *ret;
        int i;

        if ((ret = malloc(sizeof(_STACK))) == NULL)
                goto err;
        if ((ret->data = reallocarray(NULL, MIN_NODES, sizeof(void *))) == NULL)
                goto err;
        for (i = 0; i < MIN_NODES; i++)
                ret->data[i] = NULL;
        ret->comp = c;
        ret->num_alloc = MIN_NODES;
        ret->num = 0;
        ret->sorted = 0;
        return (ret);

err:
        free(ret);
        return (NULL);
}
LCRYPTO_ALIAS(sk_new);

int
sk_insert(_STACK *st, void *data, int loc)
{
        void **s;

        if (st == NULL)
                return 0;
        if (st->num_alloc <= st->num + 1) {
                s = reallocarray(st->data, st->num_alloc, 2 * sizeof(void *));
                if (s == NULL)
                        return (0);
                st->data = s;
                st->num_alloc *= 2;
        }
        if ((loc >= (int)st->num) || (loc < 0))
                st->data[st->num] = data;
        else {
                memmove(&(st->data[loc + 1]), &(st->data[loc]),
                    sizeof(void *) * (st->num - loc));
                st->data[loc] = data;
        }
        st->num++;
        st->sorted = 0;
        return (st->num);
}
LCRYPTO_ALIAS(sk_insert);

void *
sk_delete_ptr(_STACK *st, void *p)
{
        int i;

        for (i = 0; i < st->num; i++)
                if (st->data[i] == p)
                        return (sk_delete(st, i));
        return (NULL);
}
LCRYPTO_ALIAS(sk_delete_ptr);

void *
sk_delete(_STACK *st, int loc)
{
        void *ret;

        if (!st || (loc < 0) || (loc >= st->num))
                return NULL;

        ret = st->data[loc];
        if (loc != st->num - 1) {
                memmove(&(st->data[loc]), &(st->data[loc + 1]),
                    sizeof(void *) * (st->num - 1 - loc));
        }
        st->num--;
        return (ret);
}
LCRYPTO_ALIAS(sk_delete);

static const void *
obj_bsearch_ex(const void *key, const void *base_, int num, int size,
    int (*cmp)(const void *, const void *))
{
        const char *base = base_;
        int l, h, i, c;

        l = 0;
        h = num;
        while (l < h) {
                i = (l + h) / 2;
                if ((c = cmp(key,  &base[i * size])) == 0) {
                        /* Return first match. */
                        while (i > 0 && cmp(key, &base[(i - 1) * size]) == 0)
                                i--;
                        return &base[i * size];
                }
                if (c < 0)
                        h = i;
                else
                        l = i + 1;
        }

        return NULL;
}

int
sk_find(_STACK *st, void *data)
{
        const void * const *r;
        int i;

        if (st == NULL)
                return -1;

        if (st->comp == NULL) {
                for (i = 0; i < st->num; i++)
                        if (st->data[i] == data)
                                return (i);
                return (-1);
        }
        sk_sort(st);
        if (data == NULL)
                return (-1);
        r = obj_bsearch_ex(&data, st->data, st->num, sizeof(void *), st->comp);
        if (r == NULL)
                return (-1);
        return (int)((void **)r - st->data);
}
LCRYPTO_ALIAS(sk_find);

int
sk_push(_STACK *st, void *data)
{
        return (sk_insert(st, data, st->num));
}
LCRYPTO_ALIAS(sk_push);

int
sk_unshift(_STACK *st, void *data)
{
        return (sk_insert(st, data, 0));
}
LCRYPTO_ALIAS(sk_unshift);

void *
sk_shift(_STACK *st)
{
        if (st == NULL)
                return (NULL);
        if (st->num <= 0)
                return (NULL);
        return (sk_delete(st, 0));
}
LCRYPTO_ALIAS(sk_shift);

void *
sk_pop(_STACK *st)
{
        if (st == NULL)
                return (NULL);
        if (st->num <= 0)
                return (NULL);
        return (sk_delete(st, st->num - 1));
}
LCRYPTO_ALIAS(sk_pop);

void
sk_zero(_STACK *st)
{
        if (st == NULL)
                return;
        if (st->num <= 0)
                return;
        memset(st->data, 0, sizeof(st->data)*st->num);
        st->num = 0;
}
LCRYPTO_ALIAS(sk_zero);

void
sk_pop_free(_STACK *st, void (*func)(void *))
{
        int i;

        if (st == NULL)
                return;
        for (i = 0; i < st->num; i++)
                if (st->data[i] != NULL)
                        func(st->data[i]);
        sk_free(st);
}
LCRYPTO_ALIAS(sk_pop_free);

void
sk_free(_STACK *st)
{
        if (st == NULL)
                return;
        free(st->data);
        free(st);
}
LCRYPTO_ALIAS(sk_free);

int
sk_num(const _STACK *st)
{
        if (st == NULL)
                return -1;
        return st->num;
}
LCRYPTO_ALIAS(sk_num);

void *
sk_value(const _STACK *st, int i)
{
        if (!st || (i < 0) || (i >= st->num))
                return NULL;
        return st->data[i];
}
LCRYPTO_ALIAS(sk_value);

void *
sk_set(_STACK *st, int i, void *value)
{
        if (!st || (i < 0) || (i >= st->num))
                return NULL;
        st->sorted = 0;
        return (st->data[i] = value);
}
LCRYPTO_ALIAS(sk_set);

void
sk_sort(_STACK *st)
{
        if (st && !st->sorted) {
                int (*comp_func)(const void *, const void *);

                /* same comment as in sk_find ... previously st->comp was declared
                 * as a (void*,void*) callback type, but this made the population
                 * of the callback pointer illogical - our callbacks compare
                 * type** with type**, so we leave the casting until absolutely
                 * necessary (ie. "now"). */
                comp_func = (int (*)(const void *, const void *))(st->comp);
                qsort(st->data, st->num, sizeof(void *), comp_func);
                st->sorted = 1;
        }
}
LCRYPTO_ALIAS(sk_sort);

int
sk_is_sorted(const _STACK *st)
{
        if (st == NULL)
                return 1;

        if (st->sorted)
                return 1;

        /* If there is no comparison function we cannot sort. */
        if (st->comp == NULL)
                return 0;

        /* Lists with zero or one elements are always sorted. */
        return st->num <= 1;
}
LCRYPTO_ALIAS(sk_is_sorted);