1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /* dbus-memory.c D-Bus memory handling
4 * Copyright (C) 2002, 2003 Red Hat Inc.
6 * Licensed under the Academic Free License version 2.1
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 #include "dbus-memory.h"
26 #include "dbus-internals.h"
27 #include "dbus-sysdeps.h"
28 #include "dbus-list.h"
32 * @defgroup DBusMemory Memory Allocation
34 * @brief dbus_malloc(), dbus_free(), etc.
36 * Functions and macros related to allocating and releasing
42 * @defgroup DBusMemoryInternals Memory allocation implementation details
43 * @ingroup DBusInternals
44 * @brief internals of dbus_malloc() etc.
46 * Implementation details related to allocating and releasing blocks
51 * @addtogroup DBusMemory
59 * Safe macro for using dbus_malloc(). Accepts the type
60 * to allocate and the number of type instances to
61 * allocate as arguments, and returns a memory block
62 * cast to the desired type, instead of as a void*.
64 * @param type type name to allocate
65 * @param count number of instances in the allocated array
66 * @returns the new memory block or #NULL on failure
72 * Safe macro for using dbus_malloc0(). Accepts the type
73 * to allocate and the number of type instances to
74 * allocate as arguments, and returns a memory block
75 * cast to the desired type, instead of as a void*.
76 * The allocated array is initialized to all-bits-zero.
78 * @param type type name to allocate
79 * @param count number of instances in the allocated array
80 * @returns the new memory block or #NULL on failure
84 * @typedef DBusFreeFunction
86 * The type of a function which frees a block of memory.
88 * @param memory the memory to free
91 /** @} */ /* end of public API docs */
94 * @addtogroup DBusMemoryInternals
99 #ifdef DBUS_BUILD_TESTS
100 static dbus_bool_t debug_initialized = FALSE;
101 static int fail_nth = -1;
102 static size_t fail_size = 0;
103 static int fail_alloc_counter = _DBUS_INT_MAX;
104 static int n_failures_per_failure = 1;
105 static int n_failures_this_failure = 0;
106 static dbus_bool_t guards = FALSE;
107 static dbus_bool_t disable_mem_pools = FALSE;
108 static dbus_bool_t backtrace_on_fail_alloc = FALSE;
109 static DBusAtomic n_blocks_outstanding = {0};
111 /** value stored in guard padding for debugging buffer overrun */
112 #define GUARD_VALUE 0xdeadbeef
113 /** size of the information about the block stored in guard mode */
114 #define GUARD_INFO_SIZE 8
115 /** size of the GUARD_VALUE-filled padding after the header info */
116 #define GUARD_START_PAD 16
117 /** size of the GUARD_VALUE-filled padding at the end of the block */
118 #define GUARD_END_PAD 16
119 /** size of stuff at start of block */
120 #define GUARD_START_OFFSET (GUARD_START_PAD + GUARD_INFO_SIZE)
121 /** total extra size over the requested allocation for guard stuff */
122 #define GUARD_EXTRA_SIZE (GUARD_START_OFFSET + GUARD_END_PAD)
125 _dbus_initialize_malloc_debug (void)
127 if (!debug_initialized)
129 debug_initialized = TRUE;
131 if (_dbus_getenv ("DBUS_MALLOC_FAIL_NTH") != NULL)
133 fail_nth = atoi (_dbus_getenv ("DBUS_MALLOC_FAIL_NTH"));
134 fail_alloc_counter = fail_nth;
135 _dbus_verbose ("Will fail malloc every %d times\n", fail_nth);
138 if (_dbus_getenv ("DBUS_MALLOC_FAIL_GREATER_THAN") != NULL)
140 fail_size = atoi (_dbus_getenv ("DBUS_MALLOC_FAIL_GREATER_THAN"));
141 _dbus_verbose ("Will fail mallocs over %ld bytes\n",
145 if (_dbus_getenv ("DBUS_MALLOC_GUARDS") != NULL)
148 _dbus_verbose ("Will use malloc guards\n");
151 if (_dbus_getenv ("DBUS_DISABLE_MEM_POOLS") != NULL)
153 disable_mem_pools = TRUE;
154 _dbus_verbose ("Will disable memory pools\n");
157 if (_dbus_getenv ("DBUS_MALLOC_BACKTRACES") != NULL)
159 backtrace_on_fail_alloc = TRUE;
160 _dbus_verbose ("Will backtrace on failing a malloc\n");
166 * Whether to turn off mem pools, useful for leak checking.
168 * @returns #TRUE if mempools should not be used.
171 _dbus_disable_mem_pools (void)
173 _dbus_initialize_malloc_debug ();
174 return disable_mem_pools;
178 * Sets the number of allocations until we simulate a failed
179 * allocation. If set to 0, the next allocation to run
180 * fails; if set to 1, one succeeds then the next fails; etc.
181 * Set to _DBUS_INT_MAX to not fail anything.
183 * @param until_next_fail number of successful allocs before one fails
186 _dbus_set_fail_alloc_counter (int until_next_fail)
188 _dbus_initialize_malloc_debug ();
190 fail_alloc_counter = until_next_fail;
193 _dbus_verbose ("Set fail alloc counter = %d\n", fail_alloc_counter);
198 * Gets the number of successful allocs until we'll simulate
201 * @returns current counter value
204 _dbus_get_fail_alloc_counter (void)
206 _dbus_initialize_malloc_debug ();
208 return fail_alloc_counter;
212 * Sets how many mallocs to fail when the fail alloc counter reaches
215 * @param failures_per_failure number to fail
218 _dbus_set_fail_alloc_failures (int failures_per_failure)
220 n_failures_per_failure = failures_per_failure;
224 * Gets the number of failures we'll have when the fail malloc
227 * @returns number of failures planned
230 _dbus_get_fail_alloc_failures (void)
232 return n_failures_per_failure;
235 #ifdef DBUS_BUILD_TESTS
237 * Called when about to alloc some memory; if
238 * it returns #TRUE, then the allocation should
239 * fail. If it returns #FALSE, then the allocation
242 * @returns #TRUE if this alloc should fail
245 _dbus_decrement_fail_alloc_counter (void)
247 _dbus_initialize_malloc_debug ();
248 #ifdef DBUS_WIN_FIXME
249 _dbus_warn("disabled memory allocation errors for now, it makes testing much more complicated");
253 if (fail_alloc_counter <= 0)
255 if (backtrace_on_fail_alloc)
256 _dbus_print_backtrace ();
258 _dbus_verbose ("failure %d\n", n_failures_this_failure);
260 n_failures_this_failure += 1;
261 if (n_failures_this_failure >= n_failures_per_failure)
264 fail_alloc_counter = fail_nth;
266 fail_alloc_counter = _DBUS_INT_MAX;
268 n_failures_this_failure = 0;
270 _dbus_verbose ("reset fail alloc counter to %d\n", fail_alloc_counter);
277 fail_alloc_counter -= 1;
281 #endif /* DBUS_BUILD_TESTS */
284 * Get the number of outstanding malloc()'d blocks.
286 * @returns number of blocks
289 _dbus_get_malloc_blocks_outstanding (void)
291 return n_blocks_outstanding.value;
295 * Where the block came from.
307 source_string (BlockSource source)
317 case SOURCE_MALLOC_ZERO:
319 case SOURCE_REALLOC_NULL:
320 return "realloc(NULL)";
322 _dbus_assert_not_reached ("Invalid malloc block source ID");
327 check_guards (void *free_block,
328 dbus_bool_t overwrite)
330 if (free_block != NULL)
332 unsigned char *block = ((unsigned char*)free_block) - GUARD_START_OFFSET;
333 size_t requested_bytes = *(dbus_uint32_t*)block;
334 BlockSource source = *(dbus_uint32_t*)(block + 4);
341 _dbus_verbose ("Checking %d bytes request from source %s\n",
342 requested_bytes, source_string (source));
346 while (i < GUARD_START_OFFSET)
348 dbus_uint32_t value = *(dbus_uint32_t*) &block[i];
349 if (value != GUARD_VALUE)
351 _dbus_warn ("Block of %lu bytes from %s had start guard value 0x%ux at %d expected 0x%x\n",
352 (long) requested_bytes, source_string (source),
353 value, i, GUARD_VALUE);
360 i = GUARD_START_OFFSET + requested_bytes;
361 while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
363 dbus_uint32_t value = *(dbus_uint32_t*) &block[i];
364 if (value != GUARD_VALUE)
366 _dbus_warn ("Block of %lu bytes from %s had end guard value 0x%ux at %d expected 0x%x\n",
367 (long) requested_bytes, source_string (source),
368 value, i, GUARD_VALUE);
375 /* set memory to anything but nul bytes */
377 memset (free_block, 'g', requested_bytes);
380 _dbus_assert_not_reached ("guard value corruption");
385 set_guards (void *real_block,
386 size_t requested_bytes,
389 unsigned char *block = real_block;
395 _dbus_assert (GUARD_START_OFFSET + GUARD_END_PAD == GUARD_EXTRA_SIZE);
397 *((dbus_uint32_t*)block) = requested_bytes;
398 *((dbus_uint32_t*)(block + 4)) = source;
401 while (i < GUARD_START_OFFSET)
403 (*(dbus_uint32_t*) &block[i]) = GUARD_VALUE;
408 i = GUARD_START_OFFSET + requested_bytes;
409 while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
411 (*(dbus_uint32_t*) &block[i]) = GUARD_VALUE;
416 check_guards (block + GUARD_START_OFFSET, FALSE);
418 return block + GUARD_START_OFFSET;
423 /** @} */ /* End of internals docs */
427 * @addtogroup DBusMemory
433 * Allocates the given number of bytes, as with standard
434 * malloc(). Guaranteed to return #NULL if bytes is zero
435 * on all platforms. Returns #NULL if the allocation fails.
436 * The memory must be released with dbus_free().
438 * dbus_malloc() memory is NOT safe to free with regular free() from
439 * the C library. Free it with dbus_free() only.
441 * @param bytes number of bytes to allocate
442 * @return allocated memory, or #NULL if the allocation fails.
445 dbus_malloc (size_t bytes)
447 #ifdef DBUS_BUILD_TESTS
448 _dbus_initialize_malloc_debug ();
450 if (_dbus_decrement_fail_alloc_counter ())
452 _dbus_verbose (" FAILING malloc of %ld bytes\n", (long) bytes);
457 if (bytes == 0) /* some system mallocs handle this, some don't */
459 #ifdef DBUS_BUILD_TESTS
460 else if (fail_size != 0 && bytes > fail_size)
466 block = malloc (bytes + GUARD_EXTRA_SIZE);
468 _dbus_atomic_inc (&n_blocks_outstanding);
470 return set_guards (block, bytes, SOURCE_MALLOC);
476 mem = malloc (bytes);
477 #ifdef DBUS_BUILD_TESTS
479 _dbus_atomic_inc (&n_blocks_outstanding);
486 * Allocates the given number of bytes, as with standard malloc(), but
487 * all bytes are initialized to zero as with calloc(). Guaranteed to
488 * return #NULL if bytes is zero on all platforms. Returns #NULL if the
489 * allocation fails. The memory must be released with dbus_free().
491 * dbus_malloc0() memory is NOT safe to free with regular free() from
492 * the C library. Free it with dbus_free() only.
494 * @param bytes number of bytes to allocate
495 * @return allocated memory, or #NULL if the allocation fails.
498 dbus_malloc0 (size_t bytes)
500 #ifdef DBUS_BUILD_TESTS
501 _dbus_initialize_malloc_debug ();
503 if (_dbus_decrement_fail_alloc_counter ())
505 _dbus_verbose (" FAILING malloc0 of %ld bytes\n", (long) bytes);
513 #ifdef DBUS_BUILD_TESTS
514 else if (fail_size != 0 && bytes > fail_size)
520 block = calloc (bytes + GUARD_EXTRA_SIZE, 1);
522 _dbus_atomic_inc (&n_blocks_outstanding);
523 return set_guards (block, bytes, SOURCE_MALLOC_ZERO);
529 mem = calloc (bytes, 1);
530 #ifdef DBUS_BUILD_TESTS
532 _dbus_atomic_inc (&n_blocks_outstanding);
539 * Resizes a block of memory previously allocated by dbus_malloc() or
540 * dbus_malloc0(). Guaranteed to free the memory and return #NULL if bytes
541 * is zero on all platforms. Returns #NULL if the resize fails.
542 * If the resize fails, the memory is not freed.
544 * @param memory block to be resized
545 * @param bytes new size of the memory block
546 * @return allocated memory, or #NULL if the resize fails.
549 dbus_realloc (void *memory,
552 #ifdef DBUS_BUILD_TESTS
553 _dbus_initialize_malloc_debug ();
555 if (_dbus_decrement_fail_alloc_counter ())
557 _dbus_verbose (" FAILING realloc of %ld bytes\n", (long) bytes);
563 if (bytes == 0) /* guarantee this is safe */
568 #ifdef DBUS_BUILD_TESTS
569 else if (fail_size != 0 && bytes > fail_size)
578 check_guards (memory, FALSE);
580 block = realloc (((unsigned char*)memory) - GUARD_START_OFFSET,
581 bytes + GUARD_EXTRA_SIZE);
583 old_bytes = *(dbus_uint32_t*)block;
584 if (block && bytes >= old_bytes)
585 /* old guards shouldn't have moved */
586 check_guards (((unsigned char*)block) + GUARD_START_OFFSET, FALSE);
588 return set_guards (block, bytes, SOURCE_REALLOC);
594 block = malloc (bytes + GUARD_EXTRA_SIZE);
597 _dbus_atomic_inc (&n_blocks_outstanding);
599 return set_guards (block, bytes, SOURCE_REALLOC_NULL);
606 mem = realloc (memory, bytes);
607 #ifdef DBUS_BUILD_TESTS
608 if (memory == NULL && mem != NULL)
609 _dbus_atomic_inc (&n_blocks_outstanding);
616 * Frees a block of memory previously allocated by dbus_malloc() or
617 * dbus_malloc0(). If passed #NULL, does nothing.
619 * @param memory block to be freed
622 dbus_free (void *memory)
624 #ifdef DBUS_BUILD_TESTS
627 check_guards (memory, TRUE);
630 _dbus_atomic_dec (&n_blocks_outstanding);
632 _dbus_assert (n_blocks_outstanding.value >= 0);
634 free (((unsigned char*)memory) - GUARD_START_OFFSET);
641 if (memory) /* we guarantee it's safe to free (NULL) */
643 #ifdef DBUS_BUILD_TESTS
644 _dbus_atomic_dec (&n_blocks_outstanding);
646 _dbus_assert (n_blocks_outstanding.value >= 0);
654 * Frees a #NULL-terminated array of strings.
655 * If passed #NULL, does nothing.
657 * @param str_array the array to be freed
660 dbus_free_string_array (char **str_array)
669 dbus_free (str_array[i]);
673 dbus_free (str_array);
677 /** @} */ /* End of public API docs block */
681 * @addtogroup DBusMemoryInternals
687 * _dbus_current_generation is used to track each
688 * time that dbus_shutdown() is called, so we can
689 * reinit things after it's been called. It is simply
690 * incremented each time we shut down.
692 int _dbus_current_generation = 1;
695 * Represents a function to be called on shutdown.
697 typedef struct ShutdownClosure ShutdownClosure;
700 * This struct represents a function to be called on shutdown.
702 struct ShutdownClosure
704 ShutdownClosure *next; /**< Next ShutdownClosure */
705 DBusShutdownFunction func; /**< Function to call */
706 void *data; /**< Data for function */
709 _DBUS_DEFINE_GLOBAL_LOCK (shutdown_funcs);
710 static ShutdownClosure *registered_globals = NULL;
713 * Register a cleanup function to be called exactly once
714 * the next time dbus_shutdown() is called.
716 * @param func the function
717 * @param data data to pass to the function
718 * @returns #FALSE on not enough memory
721 _dbus_register_shutdown_func (DBusShutdownFunction func,
726 c = dbus_new (ShutdownClosure, 1);
734 _DBUS_LOCK (shutdown_funcs);
736 c->next = registered_globals;
737 registered_globals = c;
739 _DBUS_UNLOCK (shutdown_funcs);
744 /** @} */ /* End of private API docs block */
748 * @addtogroup DBusMemory
754 * Frees all memory allocated internally by libdbus and
755 * reverses the effects of dbus_threads_init(). libdbus keeps internal
756 * global variables, for example caches and thread locks, and it
757 * can be useful to free these internal data structures.
759 * dbus_shutdown() does NOT free memory that was returned
760 * to the application. It only returns libdbus-internal
763 * You MUST free all memory and release all reference counts
764 * returned to you by libdbus prior to calling dbus_shutdown().
766 * You can't continue to use any D-Bus objects, such as connections,
767 * that were allocated prior to dbus_shutdown(). You can, however,
768 * start over; call dbus_threads_init() again, create new connections,
771 * WARNING: dbus_shutdown() is NOT thread safe, it must be called
772 * while NO other threads are using D-Bus. (Remember, you have to free
773 * all D-Bus objects and memory before you call dbus_shutdown(), so no
774 * thread can be using libdbus.)
776 * The purpose of dbus_shutdown() is to allow applications to get
777 * clean output from memory leak checkers. dbus_shutdown() may also be
778 * useful if you want to dlopen() libdbus instead of linking to it,
779 * and want to be able to unload the library again.
781 * There is absolutely no requirement to call dbus_shutdown() - in fact,
782 * most applications won't bother and should not feel guilty.
784 * You have to know that nobody is using libdbus in your application's
785 * process before you can call dbus_shutdown(). One implication of this
786 * is that calling dbus_shutdown() from a library is almost certainly
787 * wrong, since you don't know what the rest of the app is up to.
793 while (registered_globals != NULL)
797 c = registered_globals;
798 registered_globals = c->next;
800 (* c->func) (c->data);
805 _dbus_current_generation += 1;
808 /** @} */ /** End of public API docs block */
810 #ifdef DBUS_BUILD_TESTS
811 #include "dbus-test.h"
814 * @ingroup DBusMemoryInternals
815 * Unit test for DBusMemory
816 * @returns #TRUE on success.
819 _dbus_memory_test (void)
821 dbus_bool_t old_guards;
829 _dbus_assert_not_reached ("no memory");
830 for (size = 4; size < 256; size += 4)
832 p = dbus_realloc (p, size);
834 _dbus_assert_not_reached ("no memory");
836 for (size = 256; size != 0; size -= 4)
838 p = dbus_realloc (p, size);
840 _dbus_assert_not_reached ("no memory");