PolarSSL v1.3.9
memory_buffer_alloc.c
Go to the documentation of this file.
1/*
2 * Buffer-based memory allocator
3 *
4 * Copyright (C) 2006-2014, Brainspark B.V.
5 *
6 * This file is part of PolarSSL (http://www.polarssl.org)
7 * Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
8 *
9 * All rights reserved.
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License along
22 * with this program; if not, write to the Free Software Foundation, Inc.,
23 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
24 */
25
26#if !defined(POLARSSL_CONFIG_FILE)
27#include "polarssl/config.h"
28#else
29#include POLARSSL_CONFIG_FILE
30#endif
31
32#if defined(POLARSSL_MEMORY_BUFFER_ALLOC_C)
33
34#include "polarssl/memory_buffer_alloc.h"
35
36#include <string.h>
37
38#if defined(POLARSSL_MEMORY_DEBUG)
39#include <stdio.h>
40#endif
41#if defined(POLARSSL_MEMORY_BACKTRACE)
42#include <execinfo.h>
43#endif
44
45#if defined(POLARSSL_THREADING_C)
46#include "polarssl/threading.h"
47#endif
48
49#if defined(POLARSSL_PLATFORM_C)
50#include "polarssl/platform.h"
51#else
52#define polarssl_fprintf fprintf
53#endif
54
55/* Implementation that should never be optimized out by the compiler */
56static void polarssl_zeroize( void *v, size_t n ) {
57 volatile unsigned char *p = v; while( n-- ) *p++ = 0;
58}
59
60#define MAGIC1 0xFF00AA55
61#define MAGIC2 0xEE119966
62#define MAX_BT 20
63
64typedef struct _memory_header memory_header;
65struct _memory_header
66{
67 size_t magic1;
68 size_t size;
69 size_t alloc;
70 memory_header *prev;
71 memory_header *next;
72 memory_header *prev_free;
73 memory_header *next_free;
74#if defined(POLARSSL_MEMORY_BACKTRACE)
75 char **trace;
76 size_t trace_count;
77#endif
78 size_t magic2;
79};
80
81typedef struct
82{
83 unsigned char *buf;
84 size_t len;
85 memory_header *first;
86 memory_header *first_free;
87 size_t current_alloc_size;
88 int verify;
89#if defined(POLARSSL_MEMORY_DEBUG)
90 size_t malloc_count;
91 size_t free_count;
92 size_t total_used;
93 size_t maximum_used;
94 size_t header_count;
95 size_t maximum_header_count;
96#endif
97#if defined(POLARSSL_THREADING_C)
98 threading_mutex_t mutex;
99#endif
100}
101buffer_alloc_ctx;
102
103static buffer_alloc_ctx heap;
104
105#if defined(POLARSSL_MEMORY_DEBUG)
106static void debug_header( memory_header *hdr )
107{
108#if defined(POLARSSL_MEMORY_BACKTRACE)
109 size_t i;
110#endif
111
112 polarssl_fprintf( stderr, "HDR: PTR(%10zu), PREV(%10zu), NEXT(%10zu), "
113 "ALLOC(%zu), SIZE(%10zu)\n",
114 (size_t) hdr, (size_t) hdr->prev, (size_t) hdr->next,
115 hdr->alloc, hdr->size );
116 polarssl_fprintf( stderr, " FPREV(%10zu), FNEXT(%10zu)\n",
117 (size_t) hdr->prev_free, (size_t) hdr->next_free );
118
119#if defined(POLARSSL_MEMORY_BACKTRACE)
120 polarssl_fprintf( stderr, "TRACE: \n" );
121 for( i = 0; i < hdr->trace_count; i++ )
122 polarssl_fprintf( stderr, "%s\n", hdr->trace[i] );
123 polarssl_fprintf( stderr, "\n" );
124#endif
125}
126
127static void debug_chain()
128{
129 memory_header *cur = heap.first;
130
131 polarssl_fprintf( stderr, "\nBlock list\n" );
132 while( cur != NULL )
133 {
134 debug_header( cur );
135 cur = cur->next;
136 }
137
138 polarssl_fprintf( stderr, "Free list\n" );
139 cur = heap.first_free;
140
141 while( cur != NULL )
142 {
143 debug_header( cur );
144 cur = cur->next_free;
145 }
146}
147#endif /* POLARSSL_MEMORY_DEBUG */
148
149static int verify_header( memory_header *hdr )
150{
151 if( hdr->magic1 != MAGIC1 )
152 {
153#if defined(POLARSSL_MEMORY_DEBUG)
154 polarssl_fprintf( stderr, "FATAL: MAGIC1 mismatch\n" );
155#endif
156 return( 1 );
157 }
158
159 if( hdr->magic2 != MAGIC2 )
160 {
161#if defined(POLARSSL_MEMORY_DEBUG)
162 polarssl_fprintf( stderr, "FATAL: MAGIC2 mismatch\n" );
163#endif
164 return( 1 );
165 }
166
167 if( hdr->alloc > 1 )
168 {
169#if defined(POLARSSL_MEMORY_DEBUG)
170 polarssl_fprintf( stderr, "FATAL: alloc has illegal value\n" );
171#endif
172 return( 1 );
173 }
174
175 if( hdr->prev != NULL && hdr->prev == hdr->next )
176 {
177#if defined(POLARSSL_MEMORY_DEBUG)
178 polarssl_fprintf( stderr, "FATAL: prev == next\n" );
179#endif
180 return( 1 );
181 }
182
183 if( hdr->prev_free != NULL && hdr->prev_free == hdr->next_free )
184 {
185#if defined(POLARSSL_MEMORY_DEBUG)
186 polarssl_fprintf( stderr, "FATAL: prev_free == next_free\n" );
187#endif
188 return( 1 );
189 }
190
191 return( 0 );
192}
193
194static int verify_chain()
195{
196 memory_header *prv = heap.first, *cur = heap.first->next;
197
198 if( verify_header( heap.first ) != 0 )
199 {
200#if defined(POLARSSL_MEMORY_DEBUG)
201 polarssl_fprintf( stderr, "FATAL: verification of first header "
202 "failed\n" );
203#endif
204 return( 1 );
205 }
206
207 if( heap.first->prev != NULL )
208 {
209#if defined(POLARSSL_MEMORY_DEBUG)
210 polarssl_fprintf( stderr, "FATAL: verification failed: "
211 "first->prev != NULL\n" );
212#endif
213 return( 1 );
214 }
215
216 while( cur != NULL )
217 {
218 if( verify_header( cur ) != 0 )
219 {
220#if defined(POLARSSL_MEMORY_DEBUG)
221 polarssl_fprintf( stderr, "FATAL: verification of header "
222 "failed\n" );
223#endif
224 return( 1 );
225 }
226
227 if( cur->prev != prv )
228 {
229#if defined(POLARSSL_MEMORY_DEBUG)
230 polarssl_fprintf( stderr, "FATAL: verification failed: "
231 "cur->prev != prv\n" );
232#endif
233 return( 1 );
234 }
235
236 prv = cur;
237 cur = cur->next;
238 }
239
240 return( 0 );
241}
242
243static void *buffer_alloc_malloc( size_t len )
244{
245 memory_header *new, *cur = heap.first_free;
246 unsigned char *p;
247#if defined(POLARSSL_MEMORY_BACKTRACE)
248 void *trace_buffer[MAX_BT];
249 size_t trace_cnt;
250#endif
251
252 if( heap.buf == NULL || heap.first == NULL )
253 return( NULL );
254
255 if( len % POLARSSL_MEMORY_ALIGN_MULTIPLE )
256 {
257 len -= len % POLARSSL_MEMORY_ALIGN_MULTIPLE;
258 len += POLARSSL_MEMORY_ALIGN_MULTIPLE;
259 }
260
261 // Find block that fits
262 //
263 while( cur != NULL )
264 {
265 if( cur->size >= len )
266 break;
267
268 cur = cur->next_free;
269 }
270
271 if( cur == NULL )
272 return( NULL );
273
274 if( cur->alloc != 0 )
275 {
276#if defined(POLARSSL_MEMORY_DEBUG)
277 polarssl_fprintf( stderr, "FATAL: block in free_list but allocated "
278 "data\n" );
279#endif
280 exit( 1 );
281 }
282
283#if defined(POLARSSL_MEMORY_DEBUG)
284 heap.malloc_count++;
285#endif
286
287 // Found location, split block if > memory_header + 4 room left
288 //
289 if( cur->size - len < sizeof(memory_header) +
290 POLARSSL_MEMORY_ALIGN_MULTIPLE )
291 {
292 cur->alloc = 1;
293
294 // Remove from free_list
295 //
296 if( cur->prev_free != NULL )
297 cur->prev_free->next_free = cur->next_free;
298 else
299 heap.first_free = cur->next_free;
300
301 if( cur->next_free != NULL )
302 cur->next_free->prev_free = cur->prev_free;
303
304 cur->prev_free = NULL;
305 cur->next_free = NULL;
306
307#if defined(POLARSSL_MEMORY_DEBUG)
308 heap.total_used += cur->size;
309 if( heap.total_used > heap.maximum_used )
310 heap.maximum_used = heap.total_used;
311#endif
312#if defined(POLARSSL_MEMORY_BACKTRACE)
313 trace_cnt = backtrace( trace_buffer, MAX_BT );
314 cur->trace = backtrace_symbols( trace_buffer, trace_cnt );
315 cur->trace_count = trace_cnt;
316#endif
317
318 if( ( heap.verify & MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 )
319 exit( 1 );
320
321 return( ( (unsigned char *) cur ) + sizeof(memory_header) );
322 }
323
324 p = ( (unsigned char *) cur ) + sizeof(memory_header) + len;
325 new = (memory_header *) p;
326
327 new->size = cur->size - len - sizeof(memory_header);
328 new->alloc = 0;
329 new->prev = cur;
330 new->next = cur->next;
331#if defined(POLARSSL_MEMORY_BACKTRACE)
332 new->trace = NULL;
333 new->trace_count = 0;
334#endif
335 new->magic1 = MAGIC1;
336 new->magic2 = MAGIC2;
337
338 if( new->next != NULL )
339 new->next->prev = new;
340
341 // Replace cur with new in free_list
342 //
343 new->prev_free = cur->prev_free;
344 new->next_free = cur->next_free;
345 if( new->prev_free != NULL )
346 new->prev_free->next_free = new;
347 else
348 heap.first_free = new;
349
350 if( new->next_free != NULL )
351 new->next_free->prev_free = new;
352
353 cur->alloc = 1;
354 cur->size = len;
355 cur->next = new;
356 cur->prev_free = NULL;
357 cur->next_free = NULL;
358
359#if defined(POLARSSL_MEMORY_DEBUG)
360 heap.header_count++;
361 if( heap.header_count > heap.maximum_header_count )
362 heap.maximum_header_count = heap.header_count;
363 heap.total_used += cur->size;
364 if( heap.total_used > heap.maximum_used )
365 heap.maximum_used = heap.total_used;
366#endif
367#if defined(POLARSSL_MEMORY_BACKTRACE)
368 trace_cnt = backtrace( trace_buffer, MAX_BT );
369 cur->trace = backtrace_symbols( trace_buffer, trace_cnt );
370 cur->trace_count = trace_cnt;
371#endif
372
373 if( ( heap.verify & MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 )
374 exit( 1 );
375
376 return( ( (unsigned char *) cur ) + sizeof(memory_header) );
377}
378
379static void buffer_alloc_free( void *ptr )
380{
381 memory_header *hdr, *old = NULL;
382 unsigned char *p = (unsigned char *) ptr;
383
384 if( ptr == NULL || heap.buf == NULL || heap.first == NULL )
385 return;
386
387 if( p < heap.buf || p > heap.buf + heap.len )
388 {
389#if defined(POLARSSL_MEMORY_DEBUG)
390 polarssl_fprintf( stderr, "FATAL: polarssl_free() outside of managed "
391 "space\n" );
392#endif
393 exit( 1 );
394 }
395
396 p -= sizeof(memory_header);
397 hdr = (memory_header *) p;
398
399 if( verify_header( hdr ) != 0 )
400 exit( 1 );
401
402 if( hdr->alloc != 1 )
403 {
404#if defined(POLARSSL_MEMORY_DEBUG)
405 polarssl_fprintf( stderr, "FATAL: polarssl_free() on unallocated "
406 "data\n" );
407#endif
408 exit( 1 );
409 }
410
411 hdr->alloc = 0;
412
413#if defined(POLARSSL_MEMORY_DEBUG)
414 heap.free_count++;
415 heap.total_used -= hdr->size;
416#endif
417
418 // Regroup with block before
419 //
420 if( hdr->prev != NULL && hdr->prev->alloc == 0 )
421 {
422#if defined(POLARSSL_MEMORY_DEBUG)
423 heap.header_count--;
424#endif
425 hdr->prev->size += sizeof(memory_header) + hdr->size;
426 hdr->prev->next = hdr->next;
427 old = hdr;
428 hdr = hdr->prev;
429
430 if( hdr->next != NULL )
431 hdr->next->prev = hdr;
432
433#if defined(POLARSSL_MEMORY_BACKTRACE)
434 free( old->trace );
435#endif
436 memset( old, 0, sizeof(memory_header) );
437 }
438
439 // Regroup with block after
440 //
441 if( hdr->next != NULL && hdr->next->alloc == 0 )
442 {
443#if defined(POLARSSL_MEMORY_DEBUG)
444 heap.header_count--;
445#endif
446 hdr->size += sizeof(memory_header) + hdr->next->size;
447 old = hdr->next;
448 hdr->next = hdr->next->next;
449
450 if( hdr->prev_free != NULL || hdr->next_free != NULL )
451 {
452 if( hdr->prev_free != NULL )
453 hdr->prev_free->next_free = hdr->next_free;
454 else
455 heap.first_free = hdr->next_free;
456
457 if( hdr->next_free != NULL )
458 hdr->next_free->prev_free = hdr->prev_free;
459 }
460
461 hdr->prev_free = old->prev_free;
462 hdr->next_free = old->next_free;
463
464 if( hdr->prev_free != NULL )
465 hdr->prev_free->next_free = hdr;
466 else
467 heap.first_free = hdr;
468
469 if( hdr->next_free != NULL )
470 hdr->next_free->prev_free = hdr;
471
472 if( hdr->next != NULL )
473 hdr->next->prev = hdr;
474
475#if defined(POLARSSL_MEMORY_BACKTRACE)
476 free( old->trace );
477#endif
478 memset( old, 0, sizeof(memory_header) );
479 }
480
481 // Prepend to free_list if we have not merged
482 // (Does not have to stay in same order as prev / next list)
483 //
484 if( old == NULL )
485 {
486 hdr->next_free = heap.first_free;
487 heap.first_free->prev_free = hdr;
488 heap.first_free = hdr;
489 }
490
491#if defined(POLARSSL_MEMORY_BACKTRACE)
492 hdr->trace = NULL;
493 hdr->trace_count = 0;
494#endif
495
496 if( ( heap.verify & MEMORY_VERIFY_FREE ) && verify_chain() != 0 )
497 exit( 1 );
498}
499
500void memory_buffer_set_verify( int verify )
501{
502 heap.verify = verify;
503}
504
505int memory_buffer_alloc_verify()
506{
507 return verify_chain();
508}
509
510#if defined(POLARSSL_MEMORY_DEBUG)
511void memory_buffer_alloc_status()
512{
513 polarssl_fprintf( stderr,
514 "Current use: %zu blocks / %zu bytes, max: %zu blocks / "
515 "%zu bytes (total %zu bytes), malloc / free: %zu / %zu\n",
516 heap.header_count, heap.total_used,
517 heap.maximum_header_count, heap.maximum_used,
518 heap.maximum_header_count * sizeof( memory_header )
519 + heap.maximum_used,
520 heap.malloc_count, heap.free_count );
521
522 if( heap.first->next == NULL )
523 polarssl_fprintf( stderr, "All memory de-allocated in stack buffer\n" );
524 else
525 {
526 polarssl_fprintf( stderr, "Memory currently allocated:\n" );
527 debug_chain();
528 }
529}
530#endif /* POLARSSL_MEMORY_DEBUG */
531
532#if defined(POLARSSL_THREADING_C)
533static void *buffer_alloc_malloc_mutexed( size_t len )
534{
535 void *buf;
536 polarssl_mutex_lock( &heap.mutex );
537 buf = buffer_alloc_malloc( len );
538 polarssl_mutex_unlock( &heap.mutex );
539 return( buf );
540}
541
542static void buffer_alloc_free_mutexed( void *ptr )
543{
544 polarssl_mutex_lock( &heap.mutex );
545 buffer_alloc_free( ptr );
546 polarssl_mutex_unlock( &heap.mutex );
547}
548#endif /* POLARSSL_THREADING_C */
549
550int memory_buffer_alloc_init( unsigned char *buf, size_t len )
551{
552 memset( &heap, 0, sizeof(buffer_alloc_ctx) );
553 memset( buf, 0, len );
554
555#if defined(POLARSSL_THREADING_C)
556 polarssl_mutex_init( &heap.mutex );
557 platform_set_malloc_free( buffer_alloc_malloc_mutexed,
558 buffer_alloc_free_mutexed );
559#else
560 platform_set_malloc_free( buffer_alloc_malloc, buffer_alloc_free );
561#endif
562
563 if( (size_t) buf % POLARSSL_MEMORY_ALIGN_MULTIPLE )
564 {
565 buf += POLARSSL_MEMORY_ALIGN_MULTIPLE
566 - (size_t) buf % POLARSSL_MEMORY_ALIGN_MULTIPLE;
567 len -= (size_t) buf % POLARSSL_MEMORY_ALIGN_MULTIPLE;
568 }
569
570 heap.buf = buf;
571 heap.len = len;
572
573 heap.first = (memory_header *) buf;
574 heap.first->size = len - sizeof(memory_header);
575 heap.first->magic1 = MAGIC1;
576 heap.first->magic2 = MAGIC2;
577 heap.first_free = heap.first;
578 return( 0 );
579}
580
581void memory_buffer_alloc_free()
582{
583#if defined(POLARSSL_THREADING_C)
584 polarssl_mutex_free( &heap.mutex );
585#endif
586 polarssl_zeroize( &heap, sizeof(buffer_alloc_ctx) );
587}
588
589#endif /* POLARSSL_MEMORY_BUFFER_ALLOC_C */
config.h
Configuration options (set of defines)
memory_buffer_alloc.h
Buffer-based memory allocator.
memory_buffer_set_verify
void memory_buffer_set_verify(int verify)
Determine when the allocator should automatically verify the state of the entire chain of headers / m...
MEMORY_VERIFY_ALLOC
#define MEMORY_VERIFY_ALLOC
Definition memory_buffer_alloc.h:53
POLARSSL_MEMORY_ALIGN_MULTIPLE
#define POLARSSL_MEMORY_ALIGN_MULTIPLE
Align on multiples of this value.
Definition memory_buffer_alloc.h:47
memory_buffer_alloc_free
void memory_buffer_alloc_free(void)
Free the mutex for thread-safety and clear remaining memory.
memory_buffer_alloc_verify
int memory_buffer_alloc_verify(void)
Verifies that all headers in the memory buffer are correct and contain sane values.
MEMORY_VERIFY_FREE
#define MEMORY_VERIFY_FREE
Definition memory_buffer_alloc.h:54
memory_buffer_alloc_init
int memory_buffer_alloc_init(unsigned char *buf, size_t len)
Initialize use of stack-based memory allocator.
platform.h
PolarSSL Platform abstraction layer.
polarssl_fprintf
#define polarssl_fprintf
Definition platform.h:121
threading.h
Threading abstraction layer.
polarssl_mutex_init
int(* polarssl_mutex_init)(threading_mutex_t *mutex)
polarssl_mutex_free
int(* polarssl_mutex_free)(threading_mutex_t *mutex)
polarssl_mutex_unlock
int(* polarssl_mutex_unlock)(threading_mutex_t *mutex)
polarssl_mutex_lock
int(* polarssl_mutex_lock)(threading_mutex_t *mutex)
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