/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

/* @UNSAFE: whole file */

#include "lib.h"

#include "safe-memset.h"

#include "mempool.h"

/*

 * The system pool is a thin wrapper around calloc() and free().  It exists

 * to allow direct heap usage via the pool API.

 *

 * Implementation

 * ==============

 *

 * Creation

 * --------

 *

 * The system pool is created statically and therefore is available at any

 * time.

 *

 * Allocation, Reallocation & Freeing

 * ----------------------------------

 *

 * The p_malloc(), p_realloc(), and p_free() calls get directed to calloc(),

 * realloc(), and free().  There is no additional per-allocation information

 * to track.

 *

 * Clearing

 * --------

 *

 * Not supported.  Attempting to clear the system pool will result in a

 * panic.

 *

 * Destruction

 * -----------

 *

 * It is not possible to destroy the system pool.  Any attempt to unref the

 * pool is a no-op.

 */

#ifndef HAVE_MALLOC_USABLE_SIZE

/* no extra includes needed */

#elif defined (HAVE_MALLOC_NP_H)

#  include <malloc_np.h> /* FreeBSD */

#elif defined (HAVE_MALLOC_H)

#  include <malloc.h> /* Linux */

#endif

#define CLEAR_CHR 0xde

static const char *pool_system_get_name(pool_t pool);

static void pool_system_ref(pool_t pool);

static void pool_system_unref(pool_t *pool);

static void *pool_system_malloc(pool_t pool, size_t size);

static void *pool_system_realloc(pool_t pool, void *mem,

         size_t old_size, size_t new_size);

static void pool_system_clear(pool_t pool);

static size_t pool_system_get_max_easy_alloc_size(pool_t pool);

static struct pool_vfuncs static_system_pool_vfuncs = {

  pool_system_get_name,

  pool_system_ref,

  pool_system_unref,

  pool_system_malloc,

  pool_system_free,

  pool_system_realloc,

  pool_system_clear,

  pool_system_get_max_easy_alloc_size

};

struct pool static_system_pool = {

  .v = &static_system_pool_vfuncs,

  .alloconly_pool = FALSE,

  .datastack_pool = FALSE

};

pool_t system_pool = &static_system_pool;

static const char *pool_system_get_name(pool_t pool ATTR_UNUSED)

{

  return "system";

}

static void pool_system_ref(pool_t pool ATTR_UNUSED)

{

}

static void pool_system_unref(pool_t *pool ATTR_UNUSED)

{

}

static void *pool_system_malloc(pool_t pool ATTR_UNUSED, size_t size)

{

  void *mem;

#ifdef DEBUG

  int old_errno = errno;

#endif

  mem = calloc(size, 1);

  if (unlikely(mem == NULL)) {

    i_fatal_status(FATAL_OUTOFMEM, "pool_system_malloc(%zu): "

             "Out of memory", size);

  }

#ifdef DEBUG

  /* we rely on errno not changing. it shouldn't. */

  i_assert(errno == old_errno);

#endif

  return mem;

}

void pool_system_free(pool_t pool ATTR_UNUSED, void *mem ATTR_UNUSED)

{

#ifdef DEBUG

  int old_errno = errno;

#endif

#if defined(HAVE_MALLOC_USABLE_SIZE) && defined(DEBUG)

  safe_memset(mem, CLEAR_CHR, malloc_usable_size(mem));

#endif

  free(mem);

#ifdef DEBUG

  /* we rely on errno not changing. it shouldn't. */

  i_assert(errno == old_errno);

#endif

}

static void *pool_system_realloc(pool_t pool ATTR_UNUSED, void *mem,

         size_t old_size, size_t new_size)

{

#if defined(HAVE_MALLOC_USABLE_SIZE)

  i_assert(old_size == SIZE_MAX || mem == NULL ||

     old_size <= malloc_usable_size(mem));

#endif

  mem = realloc(mem, new_size);

  if (unlikely(mem == NULL)) {

    i_fatal_status(FATAL_OUTOFMEM, "pool_system_realloc(%zu): "

             "Out of memory", new_size);

  }

  if (old_size < new_size) {

    /* clear new data */

    memset((char *) mem + old_size, 0, new_size - old_size);

  }

  return mem;

}

static void ATTR_NORETURN

pool_system_clear(pool_t pool ATTR_UNUSED)

{

  i_panic("pool_system_clear() must not be called");

}

static size_t pool_system_get_max_easy_alloc_size(pool_t pool ATTR_UNUSED)

{

  return 0;

}