/* Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <stdlib.h>

#include "apr_buckets.h"

#include "apr_allocator.h"

#include "apr_version.h"

#define ALLOC_AMT (8192 - APR_MEMNODE_T_SIZE)

typedef struct node_header_t {

    apr_size_t size;

    apr_bucket_alloc_t *alloc;

    apr_memnode_t *memnode;

    struct node_header_t *next;

} node_header_t;

#define SIZEOF_NODE_HEADER_T  APR_ALIGN_DEFAULT(sizeof(node_header_t))

#define SMALL_NODE_SIZE       (APR_BUCKET_ALLOC_SIZE + SIZEOF_NODE_HEADER_T)

/** A list of free memory from which new buckets or private bucket

 *  structures can be allocated.

 */

struct apr_bucket_alloc_t {

    apr_pool_t *pool;

    apr_allocator_t *allocator;

    node_header_t *freelist;

    apr_memnode_t *blocks;

};

static apr_status_t alloc_cleanup(void *data)

{

    apr_bucket_alloc_t *list = data;

    apr_allocator_free(list->allocator, list->blocks);

#if APR_POOL_DEBUG

    if (list->pool && list->allocator != apr_pool_allocator_get(list->pool)) {

        apr_allocator_destroy(list->allocator);

    }

#endif

    return APR_SUCCESS;

}

APU_DECLARE_NONSTD(apr_bucket_alloc_t *) apr_bucket_alloc_create(apr_pool_t *p)

{

    apr_allocator_t *allocator = apr_pool_allocator_get(p);

    apr_bucket_alloc_t *list;

#if APR_POOL_DEBUG

    /* may be NULL for debug mode. */

    if (allocator == NULL) {

        if (apr_allocator_create(&allocator) != APR_SUCCESS) {

            apr_abortfunc_t fn = apr_pool_abort_get(p);

            if (fn)

                (fn)(APR_ENOMEM);

            abort();

        }

    }

#endif

    list = apr_bucket_alloc_create_ex(allocator);

    if (list == NULL) {

            apr_abortfunc_t fn = apr_pool_abort_get(p);

            if (fn)

                (fn)(APR_ENOMEM);

            abort();

    }

    list->pool = p;

    apr_pool_cleanup_register(list->pool, list, alloc_cleanup,

                              apr_pool_cleanup_null);

    return list;

}

APU_DECLARE_NONSTD(apr_bucket_alloc_t *) apr_bucket_alloc_create_ex(

                                             apr_allocator_t *allocator)

{

    apr_bucket_alloc_t *list;

    apr_memnode_t *block;

    block = apr_allocator_alloc(allocator, ALLOC_AMT);

    if (!block) {

        return NULL;

    }

    list = (apr_bucket_alloc_t *)block->first_avail;

    list->pool = NULL;

    list->allocator = allocator;

    list->freelist = NULL;

    list->blocks = block;

    block->first_avail += APR_ALIGN_DEFAULT(sizeof(*list));

    return list;

}

APU_DECLARE_NONSTD(void) apr_bucket_alloc_destroy(apr_bucket_alloc_t *list)

{

    if (list->pool) {

        apr_pool_cleanup_kill(list->pool, list, alloc_cleanup);

    }

    apr_allocator_free(list->allocator, list->blocks);

#if APR_POOL_DEBUG

    if (list->pool && list->allocator != apr_pool_allocator_get(list->pool)) {

        apr_allocator_destroy(list->allocator);

    }

#endif

}

APU_DECLARE_NONSTD(apr_size_t) apr_bucket_alloc_aligned_floor(apr_bucket_alloc_t *list,

                                                              apr_size_t size)

{

    if (size <= SMALL_NODE_SIZE) {

        size = SMALL_NODE_SIZE;

    }

    else {

#if APR_VERSION_AT_LEAST(1,6,0)

        if (size < APR_MEMNODE_T_SIZE) {

            size = apr_allocator_align(list->allocator, 0);

        }

        else {

            size = apr_allocator_align(list->allocator,

                                       size - APR_MEMNODE_T_SIZE);

        }

#else

        /* Assumes the minimum (default) allocator's boundary of 4K and

         * minimum (immutable before APR-1.6.x) allocation size of 8K,

         * hence possibly (yet unlikely) under-estimating the floor...

         */

        size = APR_ALIGN(size, 4096);

        if (size < 8192) {

            size = 8192;

        }

#endif

        size -= APR_MEMNODE_T_SIZE;

    }

    size -= SIZEOF_NODE_HEADER_T;

    return size;

}

APU_DECLARE_NONSTD(void *) apr_bucket_alloc(apr_size_t size, 

                                            apr_bucket_alloc_t *list)

{

    node_header_t *node;

    apr_memnode_t *active = list->blocks;

    char *endp;

    size += SIZEOF_NODE_HEADER_T;

    if (size <= SMALL_NODE_SIZE) {

        if (list->freelist) {

            node = list->freelist;

            list->freelist = node->next;

        }

        else {

            endp = active->first_avail + SMALL_NODE_SIZE;

            if (endp >= active->endp) {

                list->blocks = apr_allocator_alloc(list->allocator, ALLOC_AMT);

                if (!list->blocks) {

                    list->blocks = active;

                    return NULL;

                }

                list->blocks->next = active;

                active = list->blocks;

                endp = active->first_avail + SMALL_NODE_SIZE;

            }

            node = (node_header_t *)active->first_avail;

            node->alloc = list;

            node->memnode = active;

            node->size = SMALL_NODE_SIZE;

            active->first_avail = endp;

        }

    }

    else {

        apr_memnode_t *memnode = apr_allocator_alloc(list->allocator, size);

        if (!memnode) {

            return NULL;

        }

        node = (node_header_t *)memnode->first_avail;

        node->alloc = list;

        node->memnode = memnode;

        node->size = size;

    }

    return ((char *)node) + SIZEOF_NODE_HEADER_T;

}

#ifdef APR_BUCKET_DEBUG

#if APR_HAVE_STDLIB_H

#include <stdlib.h>

#endif

static void check_not_already_free(node_header_t *node)

{

    apr_bucket_alloc_t *list = node->alloc;

    node_header_t *curr = list->freelist;

    while (curr) {

        if (node == curr) {

            abort();

        }

        curr = curr->next;

    }

}

#else

#define check_not_already_free(node)

#endif

APU_DECLARE_NONSTD(void) apr_bucket_free(void *mem)

{

    node_header_t *node = (node_header_t *)((char *)mem - SIZEOF_NODE_HEADER_T);

    apr_bucket_alloc_t *list = node->alloc;

    if (node->size == SMALL_NODE_SIZE) {

        check_not_already_free(node);

        node->next = list->freelist;

        list->freelist = node;

    }

    else {

        apr_allocator_free(list->allocator, node->memnode);

    }

}