dbus-memory.c

/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-memory.c  D-Bus memory handling
 *
 * Copyright (C) 2002, 2003  Red Hat Inc.
 *
 * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
 *
 * Licensed under the Academic Free License version 2.1
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */
 
#include <config.h>
#include "dbus-memory.h"
#include "dbus-internals.h"
#include "dbus-sysdeps.h"
#include "dbus-list.h"
#include "dbus-threads.h"
#include <dbus/dbus-test-tap.h>
#include <stdlib.h>
 
 
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
/* Test-only, does not need to be thread-safe */
static dbus_bool_t debug_initialized = FALSE;
static int fail_nth = -1;
static size_t fail_size = 0;
static int fail_alloc_counter = -1;
static int n_failures_per_failure = 1;
static int n_failures_this_failure = 0;
static dbus_bool_t guards = FALSE;
static dbus_bool_t disable_mem_pools = FALSE;
static dbus_bool_t backtrace_on_fail_alloc = FALSE;
static dbus_bool_t malloc_cannot_fail = FALSE;
static DBusAtomic n_blocks_outstanding = {0};
 
#define GUARD_VALUE 0xdeadbeef
#define GUARD_INFO_SIZE 8
#define GUARD_START_PAD 16
#define GUARD_END_PAD 16
#define GUARD_START_OFFSET (GUARD_START_PAD + GUARD_INFO_SIZE)
#define GUARD_EXTRA_SIZE (GUARD_START_OFFSET + GUARD_END_PAD)
 
static void
_dbus_initialize_malloc_debug (void)
{
  if (!debug_initialized)
    {
      debug_initialized = TRUE;
      
      if (_dbus_getenv ("DBUS_MALLOC_FAIL_NTH") != NULL)
        {
          fail_nth = atoi (_dbus_getenv ("DBUS_MALLOC_FAIL_NTH"));
          fail_alloc_counter = fail_nth;
          _dbus_verbose ("Will fail dbus_malloc every %d times\n", fail_nth);
        }
      
      if (_dbus_getenv ("DBUS_MALLOC_FAIL_GREATER_THAN") != NULL)
        {
          fail_size = atoi (_dbus_getenv ("DBUS_MALLOC_FAIL_GREATER_THAN"));
          _dbus_verbose ("Will fail mallocs over %ld bytes\n",
                         (long) fail_size);
        }
 
      if (_dbus_getenv ("DBUS_MALLOC_GUARDS") != NULL)
        {
          guards = TRUE;
          _dbus_verbose ("Will use dbus_malloc guards\n");
        }
 
      if (_dbus_getenv ("DBUS_DISABLE_MEM_POOLS") != NULL)
        {
          disable_mem_pools = TRUE;
          _dbus_verbose ("Will disable memory pools\n");
        }
 
      if (_dbus_getenv ("DBUS_MALLOC_BACKTRACES") != NULL)
        {
          backtrace_on_fail_alloc = TRUE;
          _dbus_verbose ("Will backtrace on failing a dbus_malloc\n");
        }
 
      if (_dbus_getenv ("DBUS_MALLOC_CANNOT_FAIL") != NULL)
        {
          malloc_cannot_fail = TRUE;
          _dbus_verbose ("Will abort if system malloc() and friends fail\n");
        }
    }
}
 
dbus_bool_t
_dbus_disable_mem_pools (void)
{
  _dbus_initialize_malloc_debug ();
  return disable_mem_pools;
}
 
void
_dbus_set_fail_alloc_counter (int until_next_fail)
{
  _dbus_initialize_malloc_debug ();
 
  fail_alloc_counter = until_next_fail;
 
#if 0
  _dbus_verbose ("Set fail alloc counter = %d\n", fail_alloc_counter);
#endif
}
 
int
_dbus_get_fail_alloc_counter (void)
{
  _dbus_initialize_malloc_debug ();
 
  return fail_alloc_counter;
}
 
void
_dbus_set_fail_alloc_failures (int failures_per_failure)
{
  n_failures_per_failure = failures_per_failure;
}
 
int
_dbus_get_fail_alloc_failures (void)
{
  return n_failures_per_failure;
}
 
dbus_bool_t
_dbus_decrement_fail_alloc_counter (void)
{
  _dbus_initialize_malloc_debug ();
 
  if (fail_alloc_counter < 0)
    {
      /* We never fail in this case, but we still decrement the counter,
       * so that _dbus_test_oom_handling() can use it to count allocations.
       * Saturate at _DBUS_INT_MIN to avoid undefined integer overflow
       * (or in this case underflow). */
      if (fail_alloc_counter > _DBUS_INT_MIN)
        fail_alloc_counter -= 1;
 
      return FALSE;
    }
  else if (fail_alloc_counter == 0)
    {
      /* It's time to pretend we ran out of memory. */
      if (backtrace_on_fail_alloc)
        _dbus_print_backtrace ();
 
      _dbus_verbose ("failure %d\n", n_failures_this_failure);
      
      n_failures_this_failure += 1;
      if (n_failures_this_failure >= n_failures_per_failure)
        {
          fail_alloc_counter = fail_nth;
          n_failures_this_failure = 0;
 
          _dbus_verbose ("reset fail alloc counter to %d\n", fail_alloc_counter);
        }
      
      return TRUE;
    }
  else
    {
      /* Don't fail this allocation, but count down to the next time we
       * will fail an allocation. */
      fail_alloc_counter -= 1;
      return FALSE;
    }
}
 
int
_dbus_get_malloc_blocks_outstanding (void)
{
  return _dbus_atomic_get (&n_blocks_outstanding);
}
 
typedef enum
{
  SOURCE_UNKNOWN,
  SOURCE_MALLOC,
  SOURCE_REALLOC,
  SOURCE_MALLOC_ZERO,
  SOURCE_REALLOC_NULL
} BlockSource;
 
static const char*
source_string (BlockSource source)
{
  switch (source)
    {
    case SOURCE_UNKNOWN:
      return "unknown";
    case SOURCE_MALLOC:
      return "malloc";
    case SOURCE_REALLOC:
      return "realloc";
    case SOURCE_MALLOC_ZERO:
      return "malloc0";
    case SOURCE_REALLOC_NULL:
      return "realloc(NULL)";
    default:
      _dbus_assert_not_reached ("Invalid malloc block source ID");
      return "invalid!";
    }
}
 
static void
check_guards (void       *free_block,
              dbus_bool_t overwrite)
{
  if (free_block != NULL)
    {
      unsigned char *block = ((unsigned char*)free_block) - GUARD_START_OFFSET;
      size_t requested_bytes = *(dbus_uint32_t *) (void *) block;
      BlockSource source = *(dbus_uint32_t *) (void *) (block + 4);
      unsigned int i;
      dbus_bool_t failed;
 
      failed = FALSE;
 
#if 0
      _dbus_verbose ("Checking %d bytes request from source %s\n",
                     requested_bytes, source_string (source));
#endif
      
      i = GUARD_INFO_SIZE;
      while (i < GUARD_START_OFFSET)
        {
          dbus_uint32_t value = *(dbus_uint32_t *) (void *) &block[i];
          if (value != GUARD_VALUE)
            {
              _dbus_warn ("Block of %lu bytes from %s had start guard value 0x%ux at %d expected 0x%x",
                          (long) requested_bytes, source_string (source),
                          value, i, GUARD_VALUE);
              failed = TRUE;
            }
          
          i += 4;
        }
 
      i = GUARD_START_OFFSET + requested_bytes;
      while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
        {
          dbus_uint32_t value = *(dbus_uint32_t *) (void *) &block[i];
          if (value != GUARD_VALUE)
            {
              _dbus_warn ("Block of %lu bytes from %s had end guard value 0x%ux at %d expected 0x%x",
                          (long) requested_bytes, source_string (source),
                          value, i, GUARD_VALUE);
              failed = TRUE;
            }
          
          i += 4;
        }
 
      /* set memory to anything but nul bytes */
      if (overwrite)
        memset (free_block, 'g', requested_bytes);
      
      if (failed)
        _dbus_assert_not_reached ("guard value corruption");
    }
}
 
static void*
set_guards (void       *real_block,
            size_t      requested_bytes,
            BlockSource source)
{
  unsigned char *block = real_block;
  unsigned int i;
  
  if (block == NULL)
    return NULL;
 
  _dbus_assert (GUARD_START_OFFSET + GUARD_END_PAD == GUARD_EXTRA_SIZE);
 
  *((dbus_uint32_t *) (void *) block) = requested_bytes;
  *((dbus_uint32_t *) (void *) (block + 4)) = source;
 
  i = GUARD_INFO_SIZE;
  while (i < GUARD_START_OFFSET)
    {
      (*(dbus_uint32_t *) (void *) &block[i]) = GUARD_VALUE;
 
      i += 4;
    }
 
  i = GUARD_START_OFFSET + requested_bytes;
  while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
    {
      (*(dbus_uint32_t *) (void *) &block[i]) = GUARD_VALUE;
 
      i += 4;
    }
  
  check_guards (block + GUARD_START_OFFSET, FALSE);
  
  return block + GUARD_START_OFFSET;
}
 
#endif
 
 
 
void*
dbus_malloc (size_t bytes)
{
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  _dbus_initialize_malloc_debug ();
  
  if (_dbus_decrement_fail_alloc_counter ())
    {
      _dbus_verbose (" FAILING malloc of %ld bytes\n", (long) bytes);
      return NULL;
    }
#endif
 
  if (bytes == 0) /* some system mallocs handle this, some don't */
    return NULL;
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  else if (fail_size != 0 && bytes > fail_size)
    return NULL;
  else if (guards)
    {
      void *block;
 
      block = malloc (bytes + GUARD_EXTRA_SIZE);
      if (block)
        {
          _dbus_atomic_inc (&n_blocks_outstanding);
        }
      else if (malloc_cannot_fail)
        {
          _dbus_warn ("out of memory: malloc (%ld + %ld)",
              (long) bytes, (long) GUARD_EXTRA_SIZE);
          _dbus_abort ();
        }
      
      return set_guards (block, bytes, SOURCE_MALLOC);
    }
#endif
  else
    {
      void *mem;
      mem = malloc (bytes);
 
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
      if (mem)
        {
          _dbus_atomic_inc (&n_blocks_outstanding);
        }
      else if (malloc_cannot_fail)
        {
          _dbus_warn ("out of memory: malloc (%ld)", (long) bytes);
          _dbus_abort ();
        }
#endif
 
      return mem;
    }
}
 
void*
dbus_malloc0 (size_t bytes)
{
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  _dbus_initialize_malloc_debug ();
  
  if (_dbus_decrement_fail_alloc_counter ())
    {
      _dbus_verbose (" FAILING malloc0 of %ld bytes\n", (long) bytes);
      
      return NULL;
    }
#endif
  
  if (bytes == 0)
    return NULL;
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  else if (fail_size != 0 && bytes > fail_size)
    return NULL;
  else if (guards)
    {
      void *block;
 
      block = calloc (bytes + GUARD_EXTRA_SIZE, 1);
 
      if (block)
        {
          _dbus_atomic_inc (&n_blocks_outstanding);
        }
      else if (malloc_cannot_fail)
        {
          _dbus_warn ("out of memory: calloc (%ld + %ld, 1)",
              (long) bytes, (long) GUARD_EXTRA_SIZE);
          _dbus_abort ();
        }
 
      return set_guards (block, bytes, SOURCE_MALLOC_ZERO);
    }
#endif
  else
    {
      void *mem;
      mem = calloc (bytes, 1);
 
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
      if (mem)
        {
          _dbus_atomic_inc (&n_blocks_outstanding);
        }
      else if (malloc_cannot_fail)
        {
          _dbus_warn ("out of memory: calloc (%ld)", (long) bytes);
          _dbus_abort ();
        }
#endif
 
      return mem;
    }
}
 
void*
dbus_realloc (void  *memory,
              size_t bytes)
{
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  _dbus_initialize_malloc_debug ();
  
  if (_dbus_decrement_fail_alloc_counter ())
    {
      _dbus_verbose (" FAILING realloc of %ld bytes\n", (long) bytes);
      
      return NULL;
    }
#endif
  
  if (bytes == 0) /* guarantee this is safe */
    {
      dbus_free (memory);
      return NULL;
    }
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  else if (fail_size != 0 && bytes > fail_size)
    return NULL;
  else if (guards)
    {
      if (memory)
        {
          size_t old_bytes;
          void *block;
          
          check_guards (memory, FALSE);
          
          block = realloc (((unsigned char*)memory) - GUARD_START_OFFSET,
                           bytes + GUARD_EXTRA_SIZE);
 
          if (block == NULL)
            {
              if (malloc_cannot_fail)
                {
                  _dbus_warn ("out of memory: realloc (%p, %ld + %ld)",
                      memory, (long) bytes, (long) GUARD_EXTRA_SIZE);
                  _dbus_abort ();
                }
 
              return NULL;
            }
 
          old_bytes = *(dbus_uint32_t*)block;
          if (bytes >= old_bytes)
            /* old guards shouldn't have moved */
            check_guards (((unsigned char*)block) + GUARD_START_OFFSET, FALSE);
          
          return set_guards (block, bytes, SOURCE_REALLOC);
        }
      else
        {
          void *block;
          
          block = malloc (bytes + GUARD_EXTRA_SIZE);
 
          if (block)
            {
              _dbus_atomic_inc (&n_blocks_outstanding);
            }
          else if (malloc_cannot_fail)
            {
              _dbus_warn ("out of memory: malloc (%ld + %ld)",
                  (long) bytes, (long) GUARD_EXTRA_SIZE);
              _dbus_abort ();
            }
 
          return set_guards (block, bytes, SOURCE_REALLOC_NULL);   
        }
    }
#endif
  else
    {
      void *mem;
      mem = realloc (memory, bytes);
 
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
      if (mem == NULL && malloc_cannot_fail)
        {
          _dbus_warn ("out of memory: malloc (%ld)", (long) bytes);
          _dbus_abort ();
        }
 
      if (memory == NULL && mem != NULL)
            _dbus_atomic_inc (&n_blocks_outstanding);
#endif
      return mem;
    }
}
 
void
dbus_free (void  *memory)
{
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
  if (guards)
    {
      check_guards (memory, TRUE);
      if (memory)
        {
#ifdef DBUS_DISABLE_ASSERT
          _dbus_atomic_dec (&n_blocks_outstanding);
#else
          dbus_int32_t old_value;
 
          old_value = _dbus_atomic_dec (&n_blocks_outstanding);
          _dbus_assert (old_value >= 1);
#endif
 
          free (((unsigned char*)memory) - GUARD_START_OFFSET);
        }
      
      return;
    }
#endif
    
  if (memory) /* we guarantee it's safe to free (NULL) */
    {
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
#ifdef DBUS_DISABLE_ASSERT
      _dbus_atomic_dec (&n_blocks_outstanding);
#else
      dbus_int32_t old_value;
 
      old_value = _dbus_atomic_dec (&n_blocks_outstanding);
      _dbus_assert (old_value >= 1);
#endif
#endif
 
      free (memory);
    }
}
 
void
dbus_free_string_array (char **str_array)
{
  if (str_array)
    {
      int i;
 
      i = 0;
      while (str_array[i])
        {
          dbus_free (str_array[i]);
          i++;
        }
 
      dbus_free (str_array);
    }
}
 
 
 
int _dbus_current_generation = 1;
 
typedef struct ShutdownClosure ShutdownClosure;
 
struct ShutdownClosure
{
  ShutdownClosure *next;     
  DBusShutdownFunction func; 
  void *data;                
};
 
/* Protected by _DBUS_LOCK (shutdown_funcs) */
static ShutdownClosure *registered_globals = NULL;
 
dbus_bool_t
_dbus_register_shutdown_func (DBusShutdownFunction  func,
                              void                 *data)
{
  dbus_bool_t ok;
 
  if (!_DBUS_LOCK (shutdown_funcs))
    return FALSE;
 
  ok = _dbus_register_shutdown_func_unlocked (func, data);
  _DBUS_UNLOCK (shutdown_funcs);
  return ok;
}
 
dbus_bool_t
_dbus_register_shutdown_func_unlocked (DBusShutdownFunction  func,
                                       void                 *data)
{
  ShutdownClosure *c;
 
  c = dbus_new (ShutdownClosure, 1);
 
  if (c == NULL)
    return FALSE;
 
  c->func = func;
  c->data = data;
 
  c->next = registered_globals;
  registered_globals = c;
 
  return TRUE;
}
 
 
 
void
dbus_shutdown (void)
{
  while (registered_globals != NULL)
    {
      ShutdownClosure *c;
 
      c = registered_globals;
      registered_globals = c->next;
      
      (* c->func) (c->data);
      
      dbus_free (c);
    }
 
  /* We wrap this in the thread-initialization lock because
   * dbus_threads_init() uses the current generation to tell whether
   * we're initialized, so we need to make sure that un-initializing
   * propagates into all threads. */
  _dbus_threads_lock_platform_specific ();
  _dbus_current_generation += 1;
  _dbus_threads_unlock_platform_specific ();
}
 
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
#include "dbus-test.h"
 
dbus_bool_t
_dbus_memory_test (const char *test_data_dir _DBUS_GNUC_UNUSED)
{
  dbus_bool_t old_guards;
  void *p;
  size_t size;
 
  old_guards = guards;
  guards = TRUE;
  p = dbus_malloc (4);
  if (p == NULL)
    _dbus_test_fatal ("no memory");
  for (size = 4; size < 256; size += 4)
    {
      p = dbus_realloc (p, size);
      if (p == NULL)
        _dbus_test_fatal ("no memory");
    }
  for (size = 256; size != 0; size -= 4)
    {
      p = dbus_realloc (p, size);
      if (p == NULL)
        _dbus_test_fatal ("no memory");
    }
  dbus_free (p);
  guards = old_guards;
  return TRUE;
}
 
#endif