src/util/memdebug.c

   1 /* Memory debugging (leaks, overflows & co) */
   2
   3 /* Wrappers for libc memory managment providing protection against common
   4  * pointers manipulation mistakes - bad realloc()/free() pointers, double
   5  * free() problem, using uninitialized/freed memory, underflow/overflow
   6  * protection, leaks tracking...
   7  *
   8  * Copyright (C) 1999 - 2002  Mikulas Patocka
   9  * Copyright (C) 2001 - 2004  Petr Baudis
  10  * Copyright (C) 2002 - 2003  Laurent Monin
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  25  * This file is covered by the General Public Licence v2. */
  26
  27 /* This file is very useful even for projects other than ELinks and I like to
  28  * refer to it through its cvsweb URL, therefore it is a good thing to include
  29  * the full copyright header here, contrary to the usual ELinks customs. */
  30
  31 #ifdef HAVE_CONFIG_H
  32 #include "config.h"
  33 #endif
  34
  35 #include <signal.h>
  36 #include <stdarg.h>
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40 #ifdef HAVE_UNISTD_H
  41 #include <unistd.h>
  42 #endif
  43
  44 #include "elinks.h"
  45
  46 #include "util/error.h"
  47 #include "util/lists.h"
  48 #include "util/memdebug.h"
  49 #include "util/memory.h"
  50 #include "util/string.h"
  51
  52
  53 #ifdef DEBUG_MEMLEAK
  54
  55 /* Eat less memory, but sacrifice speed?
  56  * Default is defined. */
  57 #define LESS_MEMORY_SPEED
  58
  59 /* Fill memory on alloc() ?
  60  * Default is defined. */
  61 #define FILL_ON_ALLOC
  62 #define FILL_ON_ALLOC_VALUE 'X'
  63
  64 /* Fill memory on realloc() ?
  65  * Default is defined. */
  66 #define FILL_ON_REALLOC
  67 #define FILL_ON_REALLOC_VALUE 'Y'
  68
  69 /* Fill memory before free() ?
  70  * Default is undef. */
  71 #undef FILL_ON_FREE
  72 #define FILL_ON_FREE_VALUE 'Z'
  73
  74 /* Check alloc_header block sanity ?
  75  * Default is defined. */
  76 #define CHECK_AH_SANITY
  77 #define AH_SANITY_MAGIC 0xD3BA110C
  78
  79 /* Check for useless reallocation ?
  80  * If oldsize is equal to newsize, print a message to stderr.
  81  * It may help to find inefficient code.
  82  * Default is undefined.
  83  */
  84 #undef CHECK_USELESS_REALLOC
  85
  86 /* Check for validity of address passed to free() ?
  87  * Note that this is VERY slow, as we iterate through whole memory_list each
  88  * time. We can't check magics etc, as it would break double free() check.
  89  * Default is undef. */
  90 #undef CHECK_INVALID_FREE
  91
  92 /* Check for double free ?
  93  * Default is defined. */
  94 #define CHECK_DOUBLE_FREE
  95 #define AH_FREE_MAGIC 0xD3BF110C
  96
  97 /* Check for overflows and underflows ?
  98  * Default is defined. */
  99 #define CHECK_XFLOWS
 100 #define XFLOW_MAGIC (char) 0xFA
 101
 102 /* Log all (de-)allocations to stderr (huge and slow)
 103  * Default is undefined. */
 104 /* #define LOG_MEMORY_ALLOC */
 105
 106 /* --------- end of debugger configuration section */
 107
 108
 109 struct alloc_header {
 110         LIST_HEAD(struct alloc_header);
 111
 112 #ifdef CHECK_AH_SANITY
 113         int magic;
 114 #endif
 115         int size;
 116         int line;
 117         unsigned char *file;
 118         unsigned char *comment;
 119
 120 #ifdef CHECK_XFLOWS
 121         /* This is a little magic. We want to keep the main pointer aligned,
 122          * that means we want to have the xflow underflow mark in the
 123          * alloc_header space, but at the _end_ of the aligned reserved space.
 124          * This means we in fact live at [SIZE_AH_ALIGNED - 1], not here. (Of
 125          * course this might be equivalent in some cases, but it is very
 126          * unlikely in practice.) */
 127         unsigned char xflow_underflow_placeholder;
 128 #endif
 129 };
 130
 131 /* Size is set to be on boundary of 8 (a multiple of 7) in order to have the
 132  * main ptr aligned properly (faster access). We hope that  */
 133 #ifdef LESS_MEMORY_SPEED
 134 #define SIZE_AH_ALIGNED ((sizeof(struct alloc_header) + 7) & ~7)
 135 #else
 136 /* Especially on 128bit machines, this can be faster, but eats more memory. */
 137 #define SIZE_AH_ALIGNED ((sizeof(struct alloc_header) + 15) & ~15)
 138 #endif
 139
 140 #ifdef CHECK_XFLOWS
 141 #define XFLOW_INC 1
 142 #else
 143 #define XFLOW_INC 0
 144 #endif
 145
 146 /* These macros are used to convert pointers and sizes to or from real ones
 147  * when using alloc_header stuff. */
 148 #define PTR_AH2BASE(ah) (void *) ((char *) (ah) + SIZE_AH_ALIGNED)
 149 #define PTR_BASE2AH(ptr) (struct alloc_header *) \
 150                                 ((char *) (ptr) - SIZE_AH_ALIGNED)
 151
 152 /* The second overflow mark is not embraced in SIZE_AH_ALIGNED. */
 153 #define SIZE_BASE2AH(size) ((size) + SIZE_AH_ALIGNED + XFLOW_INC)
 154 #define SIZE_AH2BASE(size) ((size) - SIZE_AH_ALIGNED - XFLOW_INC)
 155
 156 #ifdef CHECK_XFLOWS
 157 #define PTR_OVERFLOW_MAGIC(ah) ((char *) PTR_AH2BASE(ah) + (ah)->size)
 158 #define PTR_UNDERFLOW_MAGIC(ah) ((char *) PTR_AH2BASE(ah) - 1)
 159 #define SET_OVERFLOW_MAGIC(ah) (*PTR_OVERFLOW_MAGIC(ah) = XFLOW_MAGIC)
 160 #define SET_UNDERFLOW_MAGIC(ah) (*PTR_UNDERFLOW_MAGIC(ah) = XFLOW_MAGIC)
 161 #define SET_XFLOW_MAGIC(ah) SET_OVERFLOW_MAGIC(ah), SET_UNDERFLOW_MAGIC(ah)
 162 #endif
 163
 164 struct mem_stats mem_stats;
 165
 166 INIT_LIST_HEAD(memory_list);
 167
 168 #ifdef LOG_MEMORY_ALLOC
 169 static void
 170 dump_short_info(struct alloc_header *ah, unsigned char *file, int line,
 171                 unsigned char *type)
 172 {
 173         fprintf(stderr, "%p", PTR_AH2BASE(ah)), fflush(stderr);
 174         fprintf(stderr, ":%d", ah->size), fflush(stderr);
 175         if (type && *type) fprintf(stderr, " %s", type), fflush(stderr);
 176         fprintf(stderr, " @ %s:%d ", file, line), fflush(stderr);
 177         if (strcmp(file, ah->file) || line != ah->line)
 178                 fprintf(stderr, "< %s:%d", ah->file, ah->line), fflush(stderr);
 179         if (ah->comment) fprintf(stderr, " [%s]", ah->comment), fflush(stderr);
 180         fprintf(stderr, "\n"), fflush(stderr);
 181 }
 182 #else
 183 #define dump_short_info(a, b, c, d)
 184 #endif
 185
 186 static void
 187 dump_info(struct alloc_header *ah, unsigned char *info,
 188           unsigned char *file, int line, unsigned char *type)
 189 {
 190         fprintf(stderr, "%p", PTR_AH2BASE(ah)); fflush(stderr);
 191         /* In some extreme cases, we may core here, as 'ah' can no longer point
 192          * to valid memory area (esp. when used in debug_mem_free()). */
 193         fprintf(stderr, ":%d", ah->size);
 194
 195         if (type && *type) fprintf(stderr, " \033[1m%s\033[0m", type);
 196
 197         if (info && *info) fprintf(stderr, " %s", info);
 198
 199         fprintf(stderr, " @ ");
 200
 201         /* Following is commented out, as we want to print this out even when
 202          * there're lions in ah, pointing us to evil places in memory, leading
 203          * to segfaults and stuff like that. --pasky */
 204         /* if (file && (strcmp(file, ah->file) || line != ah->line)) */
 205         if (file) fprintf(stderr, "%s:%d, ", file, line), fflush(stderr);
 206
 207         fprintf(stderr, "alloc'd at %s:%d", ah->file, ah->line);
 208
 209         if (ah->comment) fprintf(stderr, " [%s]", ah->comment);
 210
 211         fprintf(stderr, "\n");
 212 }
 213
 214 #ifdef CHECK_AH_SANITY
 215 static inline int
 216 bad_ah_sanity(struct alloc_header *ah, unsigned char *info,
 217               unsigned char *file, int line)
 218 {
 219         if (!ah) return 1;
 220         if (ah->magic != AH_SANITY_MAGIC) {
 221                 dump_info(ah, info, file, line, "bad alloc_header block");
 222                 return 1;
 223         }
 224
 225         return 0;
 226 }
 227 #endif /* CHECK_AH_SANITY */
 228
 229 #ifdef CHECK_XFLOWS
 230 static inline int
 231 bad_xflow_magic(struct alloc_header *ah, unsigned char *info,
 232                 unsigned char *file, int line)
 233 {
 234         if (!ah) return 1;
 235
 236         if (*PTR_OVERFLOW_MAGIC(ah) != XFLOW_MAGIC) {
 237                 dump_info(ah, info, file, line, "overflow detected");
 238                 return 1;
 239         }
 240
 241         if (*PTR_UNDERFLOW_MAGIC(ah) != XFLOW_MAGIC) {
 242                 dump_info(ah, info, file, line, "underflow detected");
 243                 return 1;
 244         }
 245
 246         return 0;
 247 }
 248 #endif /* CHECK_XFLOWS */
 249
 250
 251 void
 252 check_memory_leaks(void)
 253 {
 254         struct alloc_header *ah;
 255
 256         if (!mem_stats.amount) {
 257                 /* No leaks - escape now. */
 258                 if (mem_stats.true_amount) /* debug memory leak ? */
 259                         fprintf(stderr, "\n\033[1mDebug memory leak by %ld bytes\033[0m\n",
 260                                 mem_stats.true_amount);
 261
 262                 return;
 263         }
 264
 265         fprintf(stderr, "\n\033[1mMemory leak by %ld bytes\033[0m\n",
 266                 mem_stats.amount);
 267
 268         fprintf(stderr, "List of blocks:\n");
 269         foreach (ah, memory_list) {
 270 #ifdef CHECK_AH_SANITY
 271                 if (bad_ah_sanity(ah, "Skipped", NULL, 0)) continue;
 272 #endif
 273 #ifdef CHECK_XFLOWS
 274                 if (bad_xflow_magic(ah, NULL, NULL, 0)) continue;
 275 #endif
 276                 dump_info(ah, NULL, NULL, 0, NULL);
 277         }
 278
 279         force_dump();
 280 }
 281
 282 static int alloc_try = 0;
 283
 284 static int
 285 patience(unsigned char *file, int line, unsigned char *of)
 286 {
 287         errfile = file;
 288         errline = line;
 289
 290         ++alloc_try;
 291         if (alloc_try < ALLOC_MAXTRIES) {
 292                 elinks_error("Out of memory (%s returned NULL): retry #%d/%d, "
 293                         "I still exercise my patience and retry tirelessly.",
 294                         of, alloc_try, ALLOC_MAXTRIES);
 295                 sleep(ALLOC_DELAY);
 296                 return alloc_try;
 297         }
 298
 299 #ifdef CRASH_IF_ALLOC_MAXTRIES
 300         elinks_internal("Out of memory (%s returned NULL) after %d tries, "
 301                         "I give up. See ya on the other side.",
 302                         of, alloc_try);
 303 #else
 304         elinks_error("Out of memory (%s returned NULL) after %d tries, "
 305                      "I give up and try to continue. Pray for me, please.",
 306                      of, alloc_try);
 307 #endif
 308         alloc_try = 0;
 309         return 0;
 310 }
 311
 312 void *
 313 debug_mem_alloc(unsigned char *file, int line, size_t size)
 314 {
 315         struct alloc_header *ah;
 316         size_t true_size;
 317
 318         if (!size) return NULL;
 319
 320         true_size = SIZE_BASE2AH(size);
 321         do {
 322                 ah = malloc(true_size);
 323                 if (ah) break;
 324         } while (patience(file, line, "malloc"));
 325         if (!ah) return NULL;
 326
 327 #ifdef FILL_ON_ALLOC
 328         memset(ah, FILL_ON_ALLOC_VALUE, SIZE_BASE2AH(size));
 329 #endif
 330
 331         mem_stats.true_amount += true_size;
 332         mem_stats.amount += size;
 333
 334         ah->size = size;
 335 #ifdef CHECK_AH_SANITY
 336         ah->magic = AH_SANITY_MAGIC;
 337 #endif
 338         ah->file = file;
 339         ah->line = line;
 340         ah->comment = NULL;
 341 #ifdef CHECK_XFLOWS
 342         SET_XFLOW_MAGIC(ah);
 343 #endif
 344
 345         add_to_list(memory_list, ah);
 346
 347         dump_short_info(ah, file, line, "malloc");
 348
 349         return PTR_AH2BASE(ah);
 350 }
 351
 352 void *
 353 debug_mem_calloc(unsigned char *file, int line, size_t eltcount, size_t eltsize)
 354 {
 355         struct alloc_header *ah;
 356         size_t size = eltcount * eltsize;
 357         size_t true_size;
 358
 359         if (!size) return NULL;
 360
 361         /* FIXME: Unfortunately, we can't pass eltsize through to calloc()
 362          * itself, because we add bloat like alloc_header to it, which is
 363          * difficult to be measured in eltsize. Maybe we should round it up to
 364          * next eltsize multiple, but would it be worth the possibly wasted
 365          * space? Someone should make some benchmarks. If you still read this
 366          * comment, it means YOU should help us and do the benchmarks! :)
 367          * Thanks a lot. --pasky */
 368
 369         true_size = SIZE_BASE2AH(size);
 370         do {
 371                 ah = calloc(1, SIZE_BASE2AH(size));
 372                 if (ah) break;
 373         } while (patience(file, line, "calloc"));
 374         if (!ah) return NULL;
 375
 376         /* No, we do NOT want to fill this with FILL_ON_ALLOC_VALUE ;)). */
 377
 378         mem_stats.true_amount += true_size;
 379         mem_stats.amount += size;
 380
 381         ah->size = size;
 382 #ifdef CHECK_AH_SANITY
 383         ah->magic = AH_SANITY_MAGIC;
 384 #endif
 385         ah->file = file;
 386         ah->line = line;
 387         ah->comment = NULL;
 388 #ifdef CHECK_XFLOWS
 389         SET_XFLOW_MAGIC(ah);
 390 #endif
 391
 392         add_to_list(memory_list, ah);
 393
 394         dump_short_info(ah, file, line, "calloc");
 395
 396         return PTR_AH2BASE(ah);
 397 }
 398
 399 void
 400 debug_mem_free(unsigned char *file, int line, void *ptr)
 401 {
 402         struct alloc_header *ah;
 403         int ok = 1;
 404
 405         if (!ptr) {
 406                 errfile = file;
 407                 errline = line;
 408                 elinks_internal("mem_free(NULL)");
 409                 return;
 410         }
 411
 412 #ifdef CHECK_INVALID_FREE
 413         ok = 0;
 414         foreach (ah, memory_list) {
 415                 if (ah == PTR_BASE2AH(ptr)) {
 416                         ok = 1;
 417                         break;
 418                 }
 419         }
 420 #endif
 421
 422         ah = PTR_BASE2AH(ptr);
 423
 424         if (!ok) {
 425                 /* This will get optimized out when not CHECK_INVALID_FREE. */
 426                 dump_info(ah, "free()", file, line, "invalid address");
 427                 return;
 428         }
 429
 430 #ifdef CHECK_DOUBLE_FREE
 431         if (ah->magic == AH_FREE_MAGIC) {
 432                 dump_info(ah, "free()", file, line, "double free");
 433                 /* If we already survived it chances are we could get over it.
 434                  * So let's not be overly tragic immediatelly. Just make sure
 435                  * the developer saw it. */
 436                 sleep(1);
 437         }
 438 #endif
 439
 440 #ifdef CHECK_AH_SANITY
 441         if (bad_ah_sanity(ah, "free()", file, line))
 442                 force_dump();
 443 #endif
 444 #ifdef CHECK_XFLOWS
 445         if (bad_xflow_magic(ah, "free()", file, line))
 446                 force_dump();
 447 #endif
 448
 449         dump_short_info(ah, file, line, "free");
 450
 451         if (ah->comment) {
 452                 mem_stats.true_amount -= strlen(ah->comment) + 1;
 453                 free(ah->comment);
 454         }
 455
 456         del_from_list(ah);
 457
 458         mem_stats.true_amount -= SIZE_BASE2AH(ah->size);
 459         mem_stats.amount -= ah->size;
 460
 461 #ifdef FILL_ON_FREE
 462         memset(ah, FILL_ON_FREE_VALUE, SIZE_BASE2AH(ah->size));
 463 #endif
 464 #ifdef CHECK_DOUBLE_FREE
 465         ah->magic = AH_FREE_MAGIC;
 466 #endif
 467
 468         free(ah);
 469 }
 470
 471 void *
 472 debug_mem_realloc(unsigned char *file, int line, void *ptr, size_t size)
 473 {
 474         struct alloc_header *ah, *ah2;
 475         size_t true_size;
 476
 477         if (!ptr) return debug_mem_alloc(file, line, size);
 478
 479         /* Frees memory if size is zero. */
 480         if (!size) {
 481                 debug_mem_free(file, line, ptr);
 482                 return NULL;
 483         }
 484
 485         ah = PTR_BASE2AH(ptr);
 486
 487 #ifdef CHECK_AH_SANITY
 488         if (bad_ah_sanity(ah, "realloc()", file, line)) force_dump();
 489 #endif
 490 #ifdef CHECK_XFLOWS
 491         if (bad_xflow_magic(ah, "realloc()", file, line)) force_dump();
 492 #endif
 493
 494         /* We compare oldsize to new size, and if equal we just return ptr
 495          * and change nothing, this conforms to usual realloc() behavior. */
 496         if (ah->size == size) {
 497 #ifdef CHECK_USELESS_REALLOC
 498                 fprintf(stderr, "[%s:%d] mem_realloc() oldsize = newsize = %zu\n", file, line, size);
 499 #endif
 500                 return (void *) ptr;
 501         }
 502
 503         true_size = SIZE_BASE2AH(size);
 504         do {
 505                 ah2 = realloc(ah, true_size);
 506                 if (ah2) {
 507                         ah = ah2;
 508                         break;
 509                 }
 510         } while (patience(file, line, "realloc"));
 511         if (!ah2) return NULL;
 512
 513         mem_stats.true_amount += true_size - SIZE_BASE2AH(ah->size);
 514         mem_stats.amount += size - ah->size;
 515
 516 #ifdef FILL_ON_REALLOC
 517         if (size > ah->size)
 518                 memset((char *) PTR_AH2BASE(ah) + ah->size,
 519                        FILL_ON_REALLOC_VALUE, size - ah->size);
 520 #endif
 521
 522         ah->size = size;
 523 #ifdef CHECK_AH_SANITY
 524         ah->magic = AH_SANITY_MAGIC;
 525 #endif
 526         ah->file = file;
 527         ah->line = line;
 528 #ifdef CHECK_XFLOWS
 529         SET_XFLOW_MAGIC(ah);
 530 #endif
 531
 532         ah->prev->next = ah;
 533         ah->next->prev = ah;
 534
 535         dump_short_info(ah, file, line, "realloc");
 536
 537         return PTR_AH2BASE(ah);
 538 }
 539
 540 void
 541 set_mem_comment(void *ptr, unsigned char *str, int len)
 542 {
 543         struct alloc_header *ah;
 544
 545         ah = PTR_BASE2AH(ptr);
 546
 547         if (ah->comment) {
 548                 mem_stats.true_amount -= strlen(ah->comment) + 1;
 549                 free(ah->comment);
 550         }
 551
 552         ah->comment = malloc(len + 1);
 553         if (ah->comment) {
 554                 safe_strncpy(ah->comment, str, len + 1);
 555                 mem_stats.true_amount += len + 1;
 556         }
 557 }
 558
 559 #endif /* DEBUG_MEMLEAK */