/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#include "pool.h"

#include "posix.h"

#ifndef GIT_WIN32

#include <unistd.h>

#endif

struct git_pool_page {

  git_pool_page *next;

  size_t size;

  size_t avail;

  GIT_ALIGN(char data[GIT_FLEX_ARRAY], 8);

};

static void *pool_alloc_page(git_pool *pool, size_t size);

#ifndef GIT_DEBUG_POOL

static size_t system_page_size = 0;

int git_pool_global_init(void)

{

  if (git__page_size(&system_page_size) < 0)

    system_page_size = 4096;

  /* allow space for malloc overhead */

  system_page_size -= (2 * sizeof(void *)) + sizeof(git_pool_page);

  return 0;

}

int git_pool_init(git_pool *pool, size_t item_size)

{

  GIT_ASSERT_ARG(pool);

  GIT_ASSERT_ARG(item_size >= 1);

  memset(pool, 0, sizeof(git_pool));

  pool->item_size = item_size;

  pool->page_size = system_page_size;

  return 0;

}

void git_pool_clear(git_pool *pool)

{

  git_pool_page *scan, *next;

  for (scan = pool->pages; scan != NULL; scan = next) {

    next = scan->next;

    git__free(scan);

  }

  pool->pages = NULL;

}

static void *pool_alloc_page(git_pool *pool, size_t size)

{

  git_pool_page *page;

  const size_t new_page_size = (size <= pool->page_size) ? pool->page_size : size;

  size_t alloc_size;

  if (GIT_ADD_SIZET_OVERFLOW(&alloc_size, new_page_size, sizeof(git_pool_page)) ||

    !(page = git__malloc(alloc_size)))

    return NULL;

  page->size = new_page_size;

  page->avail = new_page_size - size;

  page->next = pool->pages;

  pool->pages = page;

  return page->data;

}

static void *pool_alloc(git_pool *pool, size_t size)

{

  git_pool_page *page = pool->pages;

  void *ptr = NULL;

  if (!page || page->avail < size)

    return pool_alloc_page(pool, size);

  ptr = &page->data[page->size - page->avail];

  page->avail -= size;

  return ptr;

}

uint32_t git_pool__open_pages(git_pool *pool)

{

  uint32_t ct = 0;

  git_pool_page *scan;

  for (scan = pool->pages; scan != NULL; scan = scan->next) ct++;

  return ct;

}

bool git_pool__ptr_in_pool(git_pool *pool, void *ptr)

{

  git_pool_page *scan;

  for (scan = pool->pages; scan != NULL; scan = scan->next)

    if ((void *)scan->data <= ptr &&

      (void *)(((char *)scan->data) + scan->size) > ptr)

      return true;

  return false;

}

#else

int git_pool_global_init(void)

{

  return 0;

}

static int git_pool__ptr_cmp(const void * a, const void * b)

{

  if(a > b) {

    return 1;

  }

  if(a < b) {

    return -1;

  }

  else {

    return 0;

  }

}

int git_pool_init(git_pool *pool, size_t item_size)

{

  GIT_ASSERT_ARG(pool);

  GIT_ASSERT_ARG(item_size >= 1);

  memset(pool, 0, sizeof(git_pool));

  pool->item_size = item_size;

  pool->page_size = git_pool__system_page_size();

  git_vector_init(&pool->allocations, 100, git_pool__ptr_cmp);

  return 0;

}

void git_pool_clear(git_pool *pool)

{

  git_vector_dispose_deep(&pool->allocations);

}

static void *pool_alloc(git_pool *pool, size_t size) {

  void *ptr = NULL;

  if((ptr = git__malloc(size)) == NULL) {

    return NULL;

  }

  git_vector_insert_sorted(&pool->allocations, ptr, NULL);

  return ptr;

}

bool git_pool__ptr_in_pool(git_pool *pool, void *ptr)

{

  size_t pos;

  return git_vector_bsearch(&pos, &pool->allocations, ptr) != GIT_ENOTFOUND;

}

#endif

void git_pool_swap(git_pool *a, git_pool *b)

{

  git_pool temp;

  if (a == b)

    return;

  memcpy(&temp, a, sizeof(temp));

  memcpy(a, b, sizeof(temp));

  memcpy(b, &temp, sizeof(temp));

}

static size_t alloc_size(git_pool *pool, size_t count)

{

  const size_t align = sizeof(void *) - 1;

  if (pool->item_size > 1) {

    const size_t item_size = (pool->item_size + align) & ~align;

    return item_size * count;

  }

  return (count + align) & ~align;

}

void *git_pool_malloc(git_pool *pool, size_t items)

{

  return pool_alloc(pool, alloc_size(pool, items));

}

void *git_pool_mallocz(git_pool *pool, size_t items)

{

  const size_t size = alloc_size(pool, items);

  void *ptr = pool_alloc(pool, size);

  if (ptr)

    memset(ptr, 0x0, size);

  return ptr;

}

char *git_pool_strndup(git_pool *pool, const char *str, size_t n)

{

  char *ptr = NULL;

  GIT_ASSERT_ARG_WITH_RETVAL(pool, NULL);

  GIT_ASSERT_ARG_WITH_RETVAL(str, NULL);

  GIT_ASSERT_ARG_WITH_RETVAL(pool->item_size == sizeof(char), NULL);

  if (n == SIZE_MAX)

    return NULL;

  if ((ptr = git_pool_malloc(pool, (n + 1))) != NULL) {

    memcpy(ptr, str, n);

    ptr[n] = '\0';

  }

  return ptr;

}

char *git_pool_strdup(git_pool *pool, const char *str)

{

  GIT_ASSERT_ARG_WITH_RETVAL(pool, NULL);

  GIT_ASSERT_ARG_WITH_RETVAL(str, NULL);

  GIT_ASSERT_ARG_WITH_RETVAL(pool->item_size == sizeof(char), NULL);

  return git_pool_strndup(pool, str, strlen(str));

}

char *git_pool_strdup_safe(git_pool *pool, const char *str)

{

  return str ? git_pool_strdup(pool, str) : NULL;

}

char *git_pool_strcat(git_pool *pool, const char *a, const char *b)

{

  void *ptr;

  size_t len_a, len_b, total;

  GIT_ASSERT_ARG_WITH_RETVAL(pool, NULL);

  GIT_ASSERT_ARG_WITH_RETVAL(pool->item_size == sizeof(char), NULL);

  len_a = a ? strlen(a) : 0;

  len_b = b ? strlen(b) : 0;

  if (GIT_ADD_SIZET_OVERFLOW(&total, len_a, len_b) ||

    GIT_ADD_SIZET_OVERFLOW(&total, total, 1))

    return NULL;

  if ((ptr = git_pool_malloc(pool, total)) != NULL) {

    if (len_a)

      memcpy(ptr, a, len_a);

    if (len_b)

      memcpy(((char *)ptr) + len_a, b, len_b);

    *(((char *)ptr) + len_a + len_b) = '\0';

  }

  return ptr;

}