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>
/* end of public API docs */
#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
/* End of internals docs */
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);
}
}
/* End of public API docs block */
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;
}
/* End of private API docs block */
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
_dbus_assert_not_reached
#define _dbus_assert_not_reached(explanation)
Aborts with an error message if called.
Definition dbus-internals.h:164
_dbus_assert
#define _dbus_assert(condition)
Aborts with an error message if the condition is false.
Definition dbus-internals.h:153
_DBUS_UNLOCK
#define _DBUS_UNLOCK(name)
Unlocks a global lock.
Definition dbus-internals.h:438
_DBUS_LOCK
#define _DBUS_LOCK(name)
Locks a global lock, initializing it first if necessary.
Definition dbus-internals.h:437
_DBUS_INT_MIN
#define _DBUS_INT_MIN
Minimum value of type "int".
Definition dbus-internals.h:326
_dbus_warn
void _dbus_warn(const char *format,...)
Prints a warning message to stderr.
Definition dbus-internals.c:278
NULL
#define NULL
A null pointer, defined appropriately for C or C++.
Definition dbus-macros.h:51
TRUE
#define TRUE
Expands to "1".
Definition dbus-macros.h:41
FALSE
#define FALSE
Expands to "0".
Definition dbus-macros.h:44
_dbus_current_generation
int _dbus_current_generation
_dbus_current_generation is used to track each time that dbus_shutdown() is called,...
Definition dbus-memory.c:790
_dbus_register_shutdown_func
dbus_bool_t _dbus_register_shutdown_func(DBusShutdownFunction func, void *data)
Register a cleanup function to be called exactly once the next time dbus_shutdown() is called.
Definition dbus-memory.c:819
dbus_shutdown
void dbus_shutdown(void)
Frees all memory allocated internally by libdbus and reverses the effects of dbus_threads_init().
Definition dbus-memory.c:906
dbus_free
void dbus_free(void *memory)
Frees a block of memory previously allocated by dbus_malloc() or dbus_malloc0().
Definition dbus-memory.c:710
dbus_realloc
void * dbus_realloc(void *memory, size_t bytes)
Resizes a block of memory previously allocated by dbus_malloc() or dbus_malloc0().
Definition dbus-memory.c:610
dbus_new
#define dbus_new(type, count)
Safe macro for using dbus_malloc().
Definition dbus-memory.h:59
dbus_malloc0
void * dbus_malloc0(size_t bytes)
Allocates the given number of bytes, as with standard malloc(), but all bytes are initialized to zero...
Definition dbus-memory.c:540
dbus_free_string_array
void dbus_free_string_array(char **str_array)
Frees a NULL-terminated array of strings.
Definition dbus-memory.c:758
dbus_malloc
void * dbus_malloc(size_t bytes)
Allocates the given number of bytes, as with standard malloc().
Definition dbus-memory.c:470
_dbus_atomic_dec
dbus_int32_t _dbus_atomic_dec(DBusAtomic *atomic)
Atomically decrement an integer.
Definition dbus-sysdeps-unix.c:3205
_dbus_getenv
const char * _dbus_getenv(const char *varname)
Wrapper for getenv().
Definition dbus-sysdeps.c:197
_dbus_atomic_get
dbus_int32_t _dbus_atomic_get(DBusAtomic *atomic)
Atomically get the value of an integer.
Definition dbus-sysdeps-unix.c:3233
_dbus_threads_lock_platform_specific
void _dbus_threads_lock_platform_specific(void)
Lock a static mutex used to protect _dbus_threads_init_platform_specific().
Definition dbus-sysdeps-pthread.c:296
_dbus_threads_unlock_platform_specific
void _dbus_threads_unlock_platform_specific(void)
Undo _dbus_threads_lock_platform_specific().
Definition dbus-sysdeps-pthread.c:302
_dbus_atomic_inc
dbus_int32_t _dbus_atomic_inc(DBusAtomic *atomic)
Atomically increments an integer.
Definition dbus-sysdeps-unix.c:3178
_dbus_abort
void _dbus_abort(void)
Aborts the program with SIGABRT (dumping core).
Definition dbus-sysdeps.c:89
_dbus_print_backtrace
void _dbus_print_backtrace(void)
On GNU libc systems, print a crude backtrace to stderr.
Definition dbus-sysdeps-unix.c:3842
dbus_uint32_t
unsigned int dbus_uint32_t
A 32-bit unsigned integer on all platforms.
Definition dbus-arch-deps.h:45
dbus_int32_t
int dbus_int32_t
A 32-bit signed integer on all platforms.
Definition dbus-arch-deps.h:44
dbus_bool_t
dbus_uint32_t dbus_bool_t
A boolean, valid values are TRUE and FALSE.
Definition dbus-types.h:37
DBusAtomic
An atomic integer safe to increment or decrement from multiple threads.
Definition dbus-sysdeps.h:340
ShutdownClosure
This struct represents a function to be called on shutdown.
Definition dbus-memory.c:801
ShutdownClosure::next
ShutdownClosure * next
Next ShutdownClosure.
Definition dbus-memory.c:802
ShutdownClosure::func
DBusShutdownFunction func
Function to call.
Definition dbus-memory.c:803
ShutdownClosure::data
void * data
Data for function.
Definition dbus-memory.c:804