/* Copyright (C) 2001-2023 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
   CA 94129, USA, for further information.
*/


/* Code common to zlib encoding and decoding streams */
#include "std.h"
#include "gserrors.h"
#include "gstypes.h"
#include "gsmemory.h"
#include "gsstruct.h"
#include "strimpl.h"
#include "szlibxx.h"
#include "zconf.h"

private_st_zlib_block();
private_st_zlib_dynamic_state();
public_st_zlib_state();

/* Set defaults for stream parameters. */
void
s_zlib_set_defaults(stream_state * st)
{
    stream_zlib_state *const ss = (stream_zlib_state *)st;

    ss->windowBits = MAX_WBITS;
    ss->no_wrapper = false;
    ss->level = Z_DEFAULT_COMPRESSION;
    ss->method = Z_DEFLATED;
    /* DEF_MEM_LEVEL should be in zlib.h or zconf.h, but it isn't. */
    ss->memLevel = min(MAX_MEM_LEVEL, 8);
    ss->strategy = Z_DEFAULT_STRATEGY;
    /* Clear pointers */
    ss->dynamic = 0;
}

/* Allocate the dynamic state. */
int
s_zlib_alloc_dynamic_state(stream_zlib_state *ss)
{
    gs_memory_t *mem = ss->memory;
    zlib_dynamic_state_t *zds =
        gs_alloc_struct_immovable(mem, zlib_dynamic_state_t,
                                  &st_zlib_dynamic_state,
                                  "s_zlib_alloc_dynamic_state");

    ss->dynamic = zds;
    if (zds == 0)
        return_error(gs_error_VMerror);
    zds->blocks = 0;
    zds->memory = mem;
    zds->zstate.zalloc = (alloc_func)s_zlib_alloc;
    zds->zstate.zfree = (free_func)s_zlib_free;
    zds->zstate.opaque = (voidpf)zds;
    return 0;
}

/* Free the dynamic state. */
void
s_zlib_free_dynamic_state(stream_zlib_state *ss)
{
    if (ss->dynamic)
        gs_free_object(ss->dynamic->memory, ss->dynamic,
                       "s_zlib_free_dynamic_state");
}

/* Provide zlib-compatible allocation and freeing functions. */
void *
s_zlib_alloc(void *zmem, uint items, uint size)
{
    zlib_dynamic_state_t *const zds = zmem;
    gs_memory_t *mem = zds->memory->stable_memory;
    zlib_block_t *block =
        gs_alloc_struct(mem, zlib_block_t, &st_zlib_block,
                        "s_zlib_alloc(block)");
    void *data =
        gs_alloc_byte_array_immovable(mem, items, size, "s_zlib_alloc(data)");

    if (block == 0 || data == 0) {
        gs_free_object(mem, data, "s_zlib_alloc(data)");
        gs_free_object(mem, block, "s_zlib_alloc(block)");
        return Z_NULL;
    }
    block->data = data;
    block->next = zds->blocks;
    block->prev = 0;
    if (zds->blocks)
        zds->blocks->prev = block;
    zds->blocks = block;
    return data;
}
void
s_zlib_free(void *zmem, void *data)
{
    zlib_dynamic_state_t *const zds = zmem;
    gs_memory_t *mem = zds->memory->stable_memory;
    zlib_block_t *block = zds->blocks;

    gs_free_object(mem, data, "s_zlib_free(data)");
    for (; ; block = block->next) {
        if (block == 0) {
            lprintf1("Freeing unrecorded data "PRI_INTPTR"!\n", (intptr_t)data);
            return;
        }
        if (block->data == data)
            break;
    }
    if (block->next)
        block->next->prev = block->prev;
    if (block->prev)
        block->prev->next = block->next;
    else
        zds->blocks = block->next;
    gs_free_object(mem, block, "s_zlib_free(block)");
}