1 /* -*- mode: C; c-file-style: "gnu" -*- */
2 /* dbus-memory.c D-BUS memory handling
4 * Copyright (C) 2002, 2003 Red Hat Inc.
6 * Licensed under the Academic Free License version 2.0
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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 int 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 %d 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;
235 * Called when about to alloc some memory; if
236 * it returns #TRUE, then the allocation should
237 * fail. If it returns #FALSE, then the allocation
240 * @returns #TRUE if this alloc should fail
243 _dbus_decrement_fail_alloc_counter (void)
245 _dbus_initialize_malloc_debug ();
247 if (fail_alloc_counter <= 0)
249 if (backtrace_on_fail_alloc)
250 _dbus_print_backtrace ();
252 _dbus_verbose ("failure %d\n", n_failures_this_failure);
254 n_failures_this_failure += 1;
255 if (n_failures_this_failure >= n_failures_per_failure)
258 fail_alloc_counter = fail_nth;
260 fail_alloc_counter = _DBUS_INT_MAX;
262 n_failures_this_failure = 0;
264 _dbus_verbose ("reset fail alloc counter to %d\n", fail_alloc_counter);
271 fail_alloc_counter -= 1;
277 * Get the number of outstanding malloc()'d blocks.
279 * @returns number of blocks
282 _dbus_get_malloc_blocks_outstanding (void)
284 return n_blocks_outstanding;
288 * Where the block came from.
300 source_string (BlockSource source)
310 case SOURCE_MALLOC_ZERO:
312 case SOURCE_REALLOC_NULL:
313 return "realloc(NULL)";
315 _dbus_assert_not_reached ("Invalid malloc block source ID");
320 check_guards (void *free_block)
322 if (free_block != NULL)
324 unsigned char *block = ((unsigned char*)free_block) - GUARD_START_OFFSET;
325 size_t requested_bytes = *(dbus_uint32_t*)block;
326 BlockSource source = *(dbus_uint32_t*)(block + 4);
333 _dbus_verbose ("Checking %d bytes request from source %s\n",
334 requested_bytes, source_string (source));
338 while (i < GUARD_START_OFFSET)
340 dbus_uint32_t value = *(dbus_uint32_t*) &block[i];
341 if (value != GUARD_VALUE)
343 _dbus_warn ("Block of %u bytes from %s had start guard value 0x%x at %d expected 0x%x\n",
344 requested_bytes, source_string (source),
345 value, i, GUARD_VALUE);
352 i = GUARD_START_OFFSET + requested_bytes;
353 while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
355 dbus_uint32_t value = *(dbus_uint32_t*) &block[i];
356 if (value != GUARD_VALUE)
358 _dbus_warn ("Block of %u bytes from %s had end guard value 0x%x at %d expected 0x%x\n",
359 requested_bytes, source_string (source),
360 value, i, GUARD_VALUE);
368 _dbus_assert_not_reached ("guard value corruption");
373 set_guards (void *real_block,
374 size_t requested_bytes,
377 unsigned char *block = real_block;
383 _dbus_assert (GUARD_START_OFFSET + GUARD_END_PAD == GUARD_EXTRA_SIZE);
385 *((dbus_uint32_t*)block) = requested_bytes;
386 *((dbus_uint32_t*)(block + 4)) = source;
389 while (i < GUARD_START_OFFSET)
391 (*(dbus_uint32_t*) &block[i]) = GUARD_VALUE;
396 i = GUARD_START_OFFSET + requested_bytes;
397 while (i < (GUARD_START_OFFSET + requested_bytes + GUARD_END_PAD))
399 (*(dbus_uint32_t*) &block[i]) = GUARD_VALUE;
404 check_guards (block + GUARD_START_OFFSET);
406 return block + GUARD_START_OFFSET;
411 /** @} */ /* End of internals docs */
415 * @addtogroup DBusMemory
421 * Allocates the given number of bytes, as with standard
422 * malloc(). Guaranteed to return #NULL if bytes is zero
423 * on all platforms. Returns #NULL if the allocation fails.
424 * The memory must be released with dbus_free().
426 * @param bytes number of bytes to allocate
427 * @return allocated memory, or #NULL if the allocation fails.
430 dbus_malloc (size_t bytes)
432 #ifdef DBUS_BUILD_TESTS
433 _dbus_initialize_malloc_debug ();
435 if (_dbus_decrement_fail_alloc_counter ())
437 _dbus_verbose (" FAILING malloc of %d bytes\n", bytes);
443 if (bytes == 0) /* some system mallocs handle this, some don't */
445 #ifdef DBUS_BUILD_TESTS
446 else if (fail_size != 0 && bytes > fail_size)
452 block = malloc (bytes + GUARD_EXTRA_SIZE);
454 n_blocks_outstanding += 1;
456 return set_guards (block, bytes, SOURCE_MALLOC);
462 mem = malloc (bytes);
463 #ifdef DBUS_BUILD_TESTS
465 n_blocks_outstanding += 1;
472 * Allocates the given number of bytes, as with standard malloc(), but
473 * all bytes are initialized to zero as with calloc(). Guaranteed to
474 * return #NULL if bytes is zero on all platforms. Returns #NULL if the
475 * allocation fails. The memory must be released with dbus_free().
477 * @param bytes number of bytes to allocate
478 * @return allocated memory, or #NULL if the allocation fails.
481 dbus_malloc0 (size_t bytes)
483 #ifdef DBUS_BUILD_TESTS
484 _dbus_initialize_malloc_debug ();
486 if (_dbus_decrement_fail_alloc_counter ())
488 _dbus_verbose (" FAILING malloc0 of %d bytes\n", bytes);
496 #ifdef DBUS_BUILD_TESTS
497 else if (fail_size != 0 && bytes > fail_size)
503 block = calloc (bytes + GUARD_EXTRA_SIZE, 1);
505 n_blocks_outstanding += 1;
506 return set_guards (block, bytes, SOURCE_MALLOC_ZERO);
512 mem = calloc (bytes, 1);
513 #ifdef DBUS_BUILD_TESTS
515 n_blocks_outstanding += 1;
522 * Resizes a block of memory previously allocated by dbus_malloc() or
523 * dbus_malloc0(). Guaranteed to free the memory and return #NULL if bytes
524 * is zero on all platforms. Returns #NULL if the resize fails.
525 * If the resize fails, the memory is not freed.
527 * @param memory block to be resized
528 * @param bytes new size of the memory block
529 * @return allocated memory, or #NULL if the resize fails.
532 dbus_realloc (void *memory,
535 #ifdef DBUS_BUILD_TESTS
536 _dbus_initialize_malloc_debug ();
538 if (_dbus_decrement_fail_alloc_counter ())
540 _dbus_verbose (" FAILING realloc of %d bytes\n", bytes);
546 if (bytes == 0) /* guarantee this is safe */
551 #ifdef DBUS_BUILD_TESTS
552 else if (fail_size != 0 && bytes > fail_size)
561 check_guards (memory);
563 block = realloc (((unsigned char*)memory) - GUARD_START_OFFSET,
564 bytes + GUARD_EXTRA_SIZE);
566 old_bytes = *(dbus_uint32_t*)block;
567 if (block && bytes >= old_bytes)
568 /* old guards shouldn't have moved */
569 check_guards (((unsigned char*)block) + GUARD_START_OFFSET);
571 return set_guards (block, bytes, SOURCE_REALLOC);
577 block = malloc (bytes + GUARD_EXTRA_SIZE);
580 n_blocks_outstanding += 1;
582 return set_guards (block, bytes, SOURCE_REALLOC_NULL);
589 mem = realloc (memory, bytes);
590 #ifdef DBUS_BUILD_TESTS
591 if (memory == NULL && mem != NULL)
592 n_blocks_outstanding += 1;
599 * Frees a block of memory previously allocated by dbus_malloc() or
600 * dbus_malloc0(). If passed #NULL, does nothing.
602 * @param memory block to be freed
605 dbus_free (void *memory)
607 #ifdef DBUS_BUILD_TESTS
610 check_guards (memory);
613 n_blocks_outstanding -= 1;
615 _dbus_assert (n_blocks_outstanding >= 0);
617 free (((unsigned char*)memory) - GUARD_START_OFFSET);
624 if (memory) /* we guarantee it's safe to free (NULL) */
626 #ifdef DBUS_BUILD_TESTS
627 n_blocks_outstanding -= 1;
629 _dbus_assert (n_blocks_outstanding >= 0);
637 * Frees a #NULL-terminated array of strings.
638 * If passed #NULL, does nothing.
640 * @param str_array the array to be freed
643 dbus_free_string_array (char **str_array)
652 dbus_free (str_array[i]);
656 dbus_free (str_array);
660 /** @} */ /* End of public API docs block */
664 * @addtogroup DBusMemoryInternals
670 * _dbus_current_generation is used to track each
671 * time that dbus_shutdown() is called, so we can
672 * reinit things after it's been called. It is simply
673 * incremented each time we shut down.
675 int _dbus_current_generation = 1;
678 * Represents a function to be called on shutdown.
680 typedef struct ShutdownClosure ShutdownClosure;
683 * This struct represents a function to be called on shutdown.
685 struct ShutdownClosure
687 ShutdownClosure *next; /**< Next ShutdownClosure */
688 DBusShutdownFunction func; /**< Function to call */
689 void *data; /**< Data for function */
692 _DBUS_DEFINE_GLOBAL_LOCK (shutdown_funcs);
693 static ShutdownClosure *registered_globals = NULL;
696 * Register a cleanup function to be called exactly once
697 * the next time dbus_shutdown() is called.
699 * @param func the function
700 * @param data data to pass to the function
701 * @returns #FALSE on not enough memory
704 _dbus_register_shutdown_func (DBusShutdownFunction func,
709 c = dbus_new (ShutdownClosure, 1);
717 _DBUS_LOCK (shutdown_funcs);
719 c->next = registered_globals;
720 registered_globals = c;
722 _DBUS_UNLOCK (shutdown_funcs);
727 /** @} */ /* End of private API docs block */
731 * @addtogroup DBusMemory
737 * The D-BUS library keeps some internal global variables, for example
738 * to cache the username of the current process. This function is
739 * used to free these global variables. It is really useful only for
740 * leak-checking cleanliness and the like. WARNING: this function is
741 * NOT thread safe, it must be called while NO other threads are using
742 * D-BUS. You cannot continue using D-BUS after calling this function,
743 * as it does things like free global mutexes created by
744 * dbus_threads_init(). To use a D-BUS function after calling
745 * dbus_shutdown(), you have to start over from scratch, e.g. calling
746 * dbus_threads_init() again.
751 while (registered_globals != NULL)
755 c = registered_globals;
756 registered_globals = c->next;
758 (* c->func) (c->data);
763 _dbus_current_generation += 1;
766 /** @} */ /** End of public API docs block */
768 #ifdef DBUS_BUILD_TESTS
769 #include "dbus-test.h"
772 * @ingroup DBusMemoryInternals
773 * Unit test for DBusMemory
774 * @returns #TRUE on success.
777 _dbus_memory_test (void)
779 dbus_bool_t old_guards;
787 _dbus_assert_not_reached ("no memory");
788 for (size = 4; size < 256; size += 4)
790 p = dbus_realloc (p, size);
792 _dbus_assert_not_reached ("no memory");
794 for (size = 256; size != 0; size -= 4)
796 p = dbus_realloc (p, size);
798 _dbus_assert_not_reached ("no memory");