// Copyright (C) 2004-2025 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include <string.h>

#include <stdio.h>

typedef struct fz_pool_node

{

  struct fz_pool_node *next;

  char mem[FZ_FLEXIBLE_ARRAY];

} fz_pool_node;

#define POOL_SIZE (4<<10) /* default size of pool blocks */

#define POOL_SELF (1<<10) /* size where allocs are put into their own blocks */

struct fz_pool

{

  size_t size;

  fz_pool_node *head, *tail;

  char *pos, *end;

};

fz_pool *fz_new_pool(fz_context *ctx)

{

  fz_pool *pool;

  fz_pool_node *node = NULL;

  pool = fz_malloc_struct(ctx, fz_pool);

  fz_try(ctx)

  {

    node = Memento_label(fz_calloc(ctx, offsetof(fz_pool_node, mem) + POOL_SIZE, 1), "fz_pool_block");

    pool->head = pool->tail = node;

    pool->pos = node->mem;

    pool->end = node->mem + POOL_SIZE;

  }

  fz_catch(ctx)

  {

    fz_free(ctx, pool);

    fz_rethrow(ctx);

  }

  return pool;

}

static void *fz_pool_alloc_oversize(fz_context *ctx, fz_pool *pool, size_t size)

{

  fz_pool_node *node;

  /* link in memory at the head of the list */

  node = Memento_label(fz_calloc(ctx, offsetof(fz_pool_node, mem) + size, 1), "fz_pool_oversize");

  node->next = pool->head;

  pool->head = node;

  pool->size += offsetof(fz_pool_node, mem) + size;

  return node->mem;

}

void *fz_pool_alloc(fz_context *ctx, fz_pool *pool, size_t size)

{

  char *ptr;

  if (size >= POOL_SELF)

    return fz_pool_alloc_oversize(ctx, pool, size);

  /* round size to pointer alignment (we don't expect to use doubles) */

  size = (size + FZ_POINTER_ALIGN_MOD - 1) & ~(FZ_POINTER_ALIGN_MOD-1);

  if (pool->pos + size > pool->end)

  {

    fz_pool_node *node = Memento_label(fz_calloc(ctx, offsetof(fz_pool_node, mem) + POOL_SIZE, 1), "fz_pool_block");

    pool->tail = pool->tail->next = node;

    pool->pos = node->mem;

    pool->end = node->mem + POOL_SIZE;

    pool->size += offsetof(fz_pool_node, mem) + POOL_SIZE;

  }

  ptr = pool->pos;

  pool->pos += size;

  return ptr;

}

char *fz_pool_strdup(fz_context *ctx, fz_pool *pool, const char *s)

{

  size_t n = strlen(s) + 1;

  char *p = fz_pool_alloc(ctx, pool, n);

  memcpy(p, s, n);

  return p;

}

size_t fz_pool_size(fz_context *ctx, fz_pool *pool)

{

  return pool ? pool->size : 0;

}

void fz_drop_pool(fz_context *ctx, fz_pool *pool)

{

  fz_pool_node *node;

  if (!pool)

    return;

  node = pool->head;

  while (node)

  {

    fz_pool_node *next = node->next;

    fz_free(ctx, node);

    node = next;

  }

  fz_free(ctx, pool);

}

typedef struct fz_pool_array_section

{

  struct fz_pool_array_section *next;

  size_t len;

  char elements[FZ_FLEXIBLE_ARRAY];

} fz_pool_array_section;

struct fz_pool_array

{

  fz_pool *pool;

  size_t size;

  size_t len;

  fz_pool_array_section head;

};

fz_pool_array *fz_new_pool_array_imp(fz_context *ctx, fz_pool *pool, size_t size, size_t initial)

{

  fz_pool_array *arr;

  if (initial <= 0)

    initial = 4;

  arr = fz_pool_alloc(ctx, pool, sizeof(fz_pool_array) + size * initial);

  arr->pool = pool;

  arr->size = size;

  arr->len = 0;

  arr->head.len = initial;

  return arr;

}

void *fz_pool_array_append(fz_context *ctx, fz_pool_array *arr, size_t *idx)

{

  size_t len = arr->len;

  size_t base = 0;

  fz_pool_array_section *sec = &arr->head;

  while (base + sec->len < len && sec->next != NULL)

    base += sec->len, sec = sec->next;

  if (base + sec->len == len)

  {

    /* We need to allocate a new block */

    size_t newlen = sec->len * 2;

    sec->next = fz_pool_alloc(ctx, arr->pool, sizeof(fz_pool_array_section) + arr->size * newlen);

    base = len;

    sec = sec->next;

    sec->len = newlen;

  }

  /* Now insert */

  arr->len++;

  if (idx)

    *idx = len;

  return (void *)(&sec->elements[0] + arr->size * (len - base));

}

void *fz_pool_array_lookup(fz_context *ctx, fz_pool_array *arr, size_t idx)

{

  size_t base = 0;

  fz_pool_array_section *sec = &arr->head;

  if (idx >= arr->len)

    fz_throw(ctx, FZ_ERROR_ARGUMENT, "array is not that long");

  while (base + sec->len < idx)

    base += sec->len, sec = sec->next;

  return (void *)(&sec->elements[0] + arr->size * (idx - base));

}

size_t fz_pool_array_len(fz_context *ctx, fz_pool_array *arr)

{

  return arr->len;

}