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
24 #include "dbus-memory.h"
25 #include "dbus-internals.h"
26 #include "dbus-sysdeps.h"
27 #include "dbus-list.h"
31 * @defgroup DBusMemory Memory Allocation
33 * @brief dbus_malloc(), dbus_free(), etc.
35 * Functions and macros related to allocating and releasing
41 * @defgroup DBusMemoryInternals Memory allocation implementation details
42 * @ingroup DBusInternals
43 * @brief internals of dbus_malloc() etc.
45 * Implementation details related to allocating and releasing blocks
50 * @addtogroup DBusMemory
58 * Safe macro for using dbus_malloc(). Accepts the type
59 * to allocate and the number of type instances to
60 * allocate as arguments, and returns a memory block
61 * cast to the desired type, instead of as a void*.
63 * @param type type name to allocate
64 * @param count number of instances in the allocated array
65 * @returns the new memory block or #NULL on failure
71 * Safe macro for using dbus_malloc0(). Accepts the type
72 * to allocate and the number of type instances to
73 * allocate as arguments, and returns a memory block
74 * cast to the desired type, instead of as a void*.
75 * The allocated array is initialized to all-bits-zero.
77 * @param type type name to allocate
78 * @param count number of instances in the allocated array
79 * @returns the new memory block or #NULL on failure
83 * @typedef DBusFreeFunction
85 * The type of a function which frees a block of memory.
87 * @param memory the memory to free
90 /** @} */ /* end of public API docs */
93 * @addtogroup DBusMemoryInternals
98 #ifdef DBUS_BUILD_TESTS
99 static dbus_bool_t debug_initialized = FALSE;
100 static int fail_nth = -1;
101 static size_t fail_size = 0;
102 static int fail_alloc_counter = _DBUS_INT_MAX;
103 static int n_failures_per_failure = 1;
104 static int n_failures_this_failure = 0;
105 static dbus_bool_t guards = FALSE;
106 static dbus_bool_t disable_mem_pools = FALSE;
107 static dbus_bool_t backtrace_on_fail_alloc = FALSE;
108 static DBusAtomic n_blocks_outstanding = {0};
110 /** value stored in guard padding for debugging buffer overrun */
111 #define GUARD_VALUE 0xdeadbeef
112 /** size of the information about the block stored in guard mode */
113 #define GUARD_INFO_SIZE 8
114 /** size of the GUARD_VALUE-filled padding after the header info */
115 #define GUARD_START_PAD 16
116 /** size of the GUARD_VALUE-filled padding at the end of the block */
117 #define GUARD_END_PAD 16
118 /** size of stuff at start of block */
119 #define GUARD_START_OFFSET (GUARD_START_PAD + GUARD_INFO_SIZE)
120 /** total extra size over the requested allocation for guard stuff */
121 #define GUARD_EXTRA_SIZE (GUARD_START_OFFSET + GUARD_END_PAD)
124 _dbus_initialize_malloc_debug (void)
126 if (!debug_initialized)
128 debug_initialized = TRUE;
130 if (_dbus_getenv ("DBUS_MALLOC_FAIL_NTH") != NULL)
132 fail_nth = atoi (_dbus_getenv ("DBUS_MALLOC_FAIL_NTH"));
133 fail_alloc_counter = fail_nth;
134 _dbus_verbose ("Will fail malloc every %d times\n", fail_nth);
137 if (_dbus_getenv ("DBUS_MALLOC_FAIL_GREATER_THAN") != NULL)
139 fail_size = atoi (_dbus_getenv ("DBUS_MALLOC_FAIL_GREATER_THAN"));
140 _dbus_verbose ("Will fail mallocs over %ld bytes\n",
144 if (_dbus_getenv ("DBUS_MALLOC_GUARDS") != NULL)
147 _dbus_verbose ("Will use malloc guards\n");
150 if (_dbus_getenv ("DBUS_DISABLE_MEM_POOLS") != NULL)
152 disable_mem_pools = TRUE;
153 _dbus_verbose ("Will disable memory pools\n");
156 if (_dbus_getenv ("DBUS_MALLOC_BACKTRACES") != NULL)
158 backtrace_on_fail_alloc = TRUE;
159 _dbus_verbose ("Will backtrace on failing a malloc\n");
165 * Whether to turn off mem pools, useful for leak checking.
167 * @returns #TRUE if mempools should not be used.
170 _dbus_disable_mem_pools (void)
172 _dbus_initialize_malloc_debug ();
173 return disable_mem_pools;
177 * Sets the number of allocations until we simulate a failed
178 * allocation. If set to 0, the next allocation to run
179 * fails; if set to 1, one succeeds then the next fails; etc.
180 * Set to _DBUS_INT_MAX to not fail anything.
182 * @param until_next_fail number of successful allocs before one fails
185 _dbus_set_fail_alloc_counter (int until_next_fail)
187 _dbus_initialize_malloc_debug ();
189 fail_alloc_counter = until_next_fail;
192 _dbus_verbose ("Set fail alloc counter = %d\n", fail_alloc_counter);
197 * Gets the number of successful allocs until we'll simulate
200 * @returns current counter value
203 _dbus_get_fail_alloc_counter (void)
205 _dbus_initialize_malloc_debug ();
207 return fail_alloc_counter;
211 * Sets how many mallocs to fail when the fail alloc counter reaches
214 * @param failures_per_failure number to fail
217 _dbus_set_fail_alloc_failures (int failures_per_failure)
219 n_failures_per_failure = failures_per_failure;
223 * Gets the number of failures we'll have when the fail malloc
226 * @returns number of failures planned
229 _dbus_get_fail_alloc_failures (void)
231 return n_failures_per_failure;
234 #ifdef DBUS_BUILD_TESTS
236 * Called when about to alloc some memory; if
237 * it returns #TRUE, then the allocation should
238 * fail. If it returns #FALSE, then the allocation
241 * @returns #TRUE if this alloc should fail
244 _dbus_decrement_fail_alloc_counter (void)
246 _dbus_initialize_malloc_debug ();
247 #ifdef DBUS_WIN_FIXME
248 _dbus_warn("disabled memory allocation errors for now, it makes testing much more complicated");
252 if (fail_alloc_counter <= 0)
254 if (backtrace_on_fail_alloc)
255 _dbus_print_backtrace ();
257 _dbus_verbose ("failure %d\n", n_failures_this_failure);
259 n_failures_this_failure += 1;
260 if (n_failures_this_failure >= n_failures_per_failure)
263 fail_alloc_counter = fail_nth;
265 fail_alloc_counter = _DBUS_INT_MAX;
267 n_failures_this_failure = 0;
269 _dbus_verbose ("reset fail alloc counter to %d\n", fail_alloc_counter);
276 fail_alloc_counter -= 1;
280 #endif /* DBUS_BUILD_TESTS */
283 * Get the number of outstanding malloc()'d blocks.
285 * @returns number of blocks
288 _dbus_get_malloc_blocks_outstanding (void)
290 return n_blocks_outstanding.value;
294 * Where the block came from.
306 source_string (BlockSource source)
316 case SOURCE_MALLOC_ZERO:
318 case SOURCE_REALLOC_NULL:
319 return "realloc(NULL)";
321 _dbus_assert_not_reached ("Invalid malloc block source ID");
326 check_guards (void *free_block,
327 dbus_bool_t overwrite)
329 if (free_block != NULL)
331 unsigned char *block = ((unsigned char*)free_block) - GUARD_START_OFFSET;
332 size_t requested_bytes = *(dbus_uint32_t*)block;
333 BlockSource source = *(dbus_uint32_t*)(block + 4);
340 _dbus_verbose ("Checking %d bytes request from source %s\n",
341 requested_bytes, source_string (source));
345 while (i < GUARD_START_OFFSET)
347 dbus_uint32_t value = *(dbus_uint32_t*) &block[i];
348 if (value != GUARD_VALUE)
350 _dbus_warn ("Block of %lu bytes from %s had start guard value 0x%ux at %d expected 0x%x\n",
351 (long) requested_bytes, source_string (source),
352 value, i, GUARD_VALUE);
359 i = GUARD_START_OFFSET + requested_bytes;
360 while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
362 dbus_uint32_t value = *(dbus_uint32_t*) &block[i];
363 if (value != GUARD_VALUE)
365 _dbus_warn ("Block of %lu bytes from %s had end guard value 0x%ux at %d expected 0x%x\n",
366 (long) requested_bytes, source_string (source),
367 value, i, GUARD_VALUE);
374 /* set memory to anything but nul bytes */
376 memset (free_block, 'g', requested_bytes);
379 _dbus_assert_not_reached ("guard value corruption");
384 set_guards (void *real_block,
385 size_t requested_bytes,
388 unsigned char *block = real_block;
394 _dbus_assert (GUARD_START_OFFSET + GUARD_END_PAD == GUARD_EXTRA_SIZE);
396 *((dbus_uint32_t*)block) = requested_bytes;
397 *((dbus_uint32_t*)(block + 4)) = source;
400 while (i < GUARD_START_OFFSET)
402 (*(dbus_uint32_t*) &block[i]) = GUARD_VALUE;
407 i = GUARD_START_OFFSET + requested_bytes;
408 while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
410 (*(dbus_uint32_t*) &block[i]) = GUARD_VALUE;
415 check_guards (block + GUARD_START_OFFSET, FALSE);
417 return block + GUARD_START_OFFSET;
422 /** @} */ /* End of internals docs */
426 * @addtogroup DBusMemory
432 * Allocates the given number of bytes, as with standard
433 * malloc(). Guaranteed to return #NULL if bytes is zero
434 * on all platforms. Returns #NULL if the allocation fails.
435 * The memory must be released with dbus_free().
437 * dbus_malloc() memory is NOT safe to free with regular free() from
438 * the C library. Free it with dbus_free() only.
440 * @param bytes number of bytes to allocate
441 * @return allocated memory, or #NULL if the allocation fails.
444 dbus_malloc (size_t bytes)
446 #ifdef DBUS_BUILD_TESTS
447 _dbus_initialize_malloc_debug ();
449 if (_dbus_decrement_fail_alloc_counter ())
451 _dbus_verbose (" FAILING malloc of %ld bytes\n", (long) bytes);
456 if (bytes == 0) /* some system mallocs handle this, some don't */
458 #ifdef DBUS_BUILD_TESTS
459 else if (fail_size != 0 && bytes > fail_size)
465 block = malloc (bytes + GUARD_EXTRA_SIZE);
467 _dbus_atomic_inc (&n_blocks_outstanding);
469 return set_guards (block, bytes, SOURCE_MALLOC);
475 mem = malloc (bytes);
476 #ifdef DBUS_BUILD_TESTS
478 _dbus_atomic_inc (&n_blocks_outstanding);
485 * Allocates the given number of bytes, as with standard malloc(), but
486 * all bytes are initialized to zero as with calloc(). Guaranteed to
487 * return #NULL if bytes is zero on all platforms. Returns #NULL if the
488 * allocation fails. The memory must be released with dbus_free().
490 * dbus_malloc0() memory is NOT safe to free with regular free() from
491 * the C library. Free it with dbus_free() only.
493 * @param bytes number of bytes to allocate
494 * @return allocated memory, or #NULL if the allocation fails.
497 dbus_malloc0 (size_t bytes)
499 #ifdef DBUS_BUILD_TESTS
500 _dbus_initialize_malloc_debug ();
502 if (_dbus_decrement_fail_alloc_counter ())
504 _dbus_verbose (" FAILING malloc0 of %ld bytes\n", (long) bytes);
512 #ifdef DBUS_BUILD_TESTS
513 else if (fail_size != 0 && bytes > fail_size)
519 block = calloc (bytes + GUARD_EXTRA_SIZE, 1);
521 _dbus_atomic_inc (&n_blocks_outstanding);
522 return set_guards (block, bytes, SOURCE_MALLOC_ZERO);
528 mem = calloc (bytes, 1);
529 #ifdef DBUS_BUILD_TESTS
531 _dbus_atomic_inc (&n_blocks_outstanding);
538 * Resizes a block of memory previously allocated by dbus_malloc() or
539 * dbus_malloc0(). Guaranteed to free the memory and return #NULL if bytes
540 * is zero on all platforms. Returns #NULL if the resize fails.
541 * If the resize fails, the memory is not freed.
543 * @param memory block to be resized
544 * @param bytes new size of the memory block
545 * @return allocated memory, or #NULL if the resize fails.
548 dbus_realloc (void *memory,
551 #ifdef DBUS_BUILD_TESTS
552 _dbus_initialize_malloc_debug ();
554 if (_dbus_decrement_fail_alloc_counter ())
556 _dbus_verbose (" FAILING realloc of %ld bytes\n", (long) bytes);
562 if (bytes == 0) /* guarantee this is safe */
567 #ifdef DBUS_BUILD_TESTS
568 else if (fail_size != 0 && bytes > fail_size)
577 check_guards (memory, FALSE);
579 block = realloc (((unsigned char*)memory) - GUARD_START_OFFSET,
580 bytes + GUARD_EXTRA_SIZE);
582 old_bytes = *(dbus_uint32_t*)block;
583 if (block && bytes >= old_bytes)
584 /* old guards shouldn't have moved */
585 check_guards (((unsigned char*)block) + GUARD_START_OFFSET, FALSE);
587 return set_guards (block, bytes, SOURCE_REALLOC);
593 block = malloc (bytes + GUARD_EXTRA_SIZE);
596 _dbus_atomic_inc (&n_blocks_outstanding);
598 return set_guards (block, bytes, SOURCE_REALLOC_NULL);
605 mem = realloc (memory, bytes);
606 #ifdef DBUS_BUILD_TESTS
607 if (memory == NULL && mem != NULL)
608 _dbus_atomic_inc (&n_blocks_outstanding);
615 * Frees a block of memory previously allocated by dbus_malloc() or
616 * dbus_malloc0(). If passed #NULL, does nothing.
618 * @param memory block to be freed
621 dbus_free (void *memory)
623 #ifdef DBUS_BUILD_TESTS
626 check_guards (memory, TRUE);
629 _dbus_atomic_dec (&n_blocks_outstanding);
631 _dbus_assert (n_blocks_outstanding.value >= 0);
633 free (((unsigned char*)memory) - GUARD_START_OFFSET);
640 if (memory) /* we guarantee it's safe to free (NULL) */
642 #ifdef DBUS_BUILD_TESTS
643 _dbus_atomic_dec (&n_blocks_outstanding);
645 _dbus_assert (n_blocks_outstanding.value >= 0);
653 * Frees a #NULL-terminated array of strings.
654 * If passed #NULL, does nothing.
656 * @param str_array the array to be freed
659 dbus_free_string_array (char **str_array)
668 dbus_free (str_array[i]);
672 dbus_free (str_array);
676 /** @} */ /* End of public API docs block */
680 * @addtogroup DBusMemoryInternals
686 * _dbus_current_generation is used to track each
687 * time that dbus_shutdown() is called, so we can
688 * reinit things after it's been called. It is simply
689 * incremented each time we shut down.
691 int _dbus_current_generation = 1;
694 * Represents a function to be called on shutdown.
696 typedef struct ShutdownClosure ShutdownClosure;
699 * This struct represents a function to be called on shutdown.
701 struct ShutdownClosure
703 ShutdownClosure *next; /**< Next ShutdownClosure */
704 DBusShutdownFunction func; /**< Function to call */
705 void *data; /**< Data for function */
708 _DBUS_DEFINE_GLOBAL_LOCK (shutdown_funcs);
709 static ShutdownClosure *registered_globals = NULL;
712 * Register a cleanup function to be called exactly once
713 * the next time dbus_shutdown() is called.
715 * @param func the function
716 * @param data data to pass to the function
717 * @returns #FALSE on not enough memory
720 _dbus_register_shutdown_func (DBusShutdownFunction func,
725 c = dbus_new (ShutdownClosure, 1);
733 _DBUS_LOCK (shutdown_funcs);
735 c->next = registered_globals;
736 registered_globals = c;
738 _DBUS_UNLOCK (shutdown_funcs);
743 /** @} */ /* End of private API docs block */
747 * @addtogroup DBusMemory
753 * Frees all memory allocated internally by libdbus and
754 * reverses the effects of dbus_threads_init(). libdbus keeps internal
755 * global variables, for example caches and thread locks, and it
756 * can be useful to free these internal data structures.
758 * dbus_shutdown() does NOT free memory that was returned
759 * to the application. It only returns libdbus-internal
762 * You MUST free all memory and release all reference counts
763 * returned to you by libdbus prior to calling dbus_shutdown().
765 * You can't continue to use any D-Bus objects, such as connections,
766 * that were allocated prior to dbus_shutdown(). You can, however,
767 * start over; call dbus_threads_init() again, create new connections,
770 * WARNING: dbus_shutdown() is NOT thread safe, it must be called
771 * while NO other threads are using D-Bus. (Remember, you have to free
772 * all D-Bus objects and memory before you call dbus_shutdown(), so no
773 * thread can be using libdbus.)
775 * The purpose of dbus_shutdown() is to allow applications to get
776 * clean output from memory leak checkers. dbus_shutdown() may also be
777 * useful if you want to dlopen() libdbus instead of linking to it,
778 * and want to be able to unload the library again.
780 * There is absolutely no requirement to call dbus_shutdown() - in fact,
781 * most applications won't bother and should not feel guilty.
783 * You have to know that nobody is using libdbus in your application's
784 * process before you can call dbus_shutdown(). One implication of this
785 * is that calling dbus_shutdown() from a library is almost certainly
786 * wrong, since you don't know what the rest of the app is up to.
792 while (registered_globals != NULL)
796 c = registered_globals;
797 registered_globals = c->next;
799 (* c->func) (c->data);
804 _dbus_current_generation += 1;
807 /** @} */ /** End of public API docs block */
809 #ifdef DBUS_BUILD_TESTS
810 #include "dbus-test.h"
813 * @ingroup DBusMemoryInternals
814 * Unit test for DBusMemory
815 * @returns #TRUE on success.
818 _dbus_memory_test (void)
820 dbus_bool_t old_guards;
828 _dbus_assert_not_reached ("no memory");
829 for (size = 4; size < 256; size += 4)
831 p = dbus_realloc (p, size);
833 _dbus_assert_not_reached ("no memory");
835 for (size = 256; size != 0; size -= 4)
837 p = dbus_realloc (p, size);
839 _dbus_assert_not_reached ("no memory");