malloc/hooks.c

   1 /* Malloc implementation for multiple threads without lock contention.
   2    Copyright (C) 2001-2006, 2007, 2008 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 /* What to do if the standard debugging hooks are in place and a
  22    corrupt pointer is detected: do nothing (0), print an error message
  23    (1), or call abort() (2). */
  24
  25 /* Hooks for debugging versions.  The initial hooks just call the
  26    initialization routine, then do the normal work. */
  27
  28 static Void_t*
  29 #if __STD_C
  30 malloc_hook_ini(size_t sz, const __malloc_ptr_t caller)
  31 #else
  32 malloc_hook_ini(sz, caller)
  33      size_t sz; const __malloc_ptr_t caller;
  34 #endif
  35 {
  36   __malloc_hook = NULL;
  37   ptmalloc_init();
  38   return public_mALLOc(sz);
  39 }
  40
  41 static Void_t*
  42 #if __STD_C
  43 realloc_hook_ini(Void_t* ptr, size_t sz, const __malloc_ptr_t caller)
  44 #else
  45 realloc_hook_ini(ptr, sz, caller)
  46      Void_t* ptr; size_t sz; const __malloc_ptr_t caller;
  47 #endif
  48 {
  49   __malloc_hook = NULL;
  50   __realloc_hook = NULL;
  51   ptmalloc_init();
  52   return public_rEALLOc(ptr, sz);
  53 }
  54
  55 static Void_t*
  56 #if __STD_C
  57 memalign_hook_ini(size_t alignment, size_t sz, const __malloc_ptr_t caller)
  58 #else
  59 memalign_hook_ini(alignment, sz, caller)
  60      size_t alignment; size_t sz; const __malloc_ptr_t caller;
  61 #endif
  62 {
  63   __memalign_hook = NULL;
  64   ptmalloc_init();
  65   return public_mEMALIGn(alignment, sz);
  66 }
  67
  68 /* Whether we are using malloc checking.  */
  69 static int using_malloc_checking;
  70
  71 /* A flag that is set by malloc_set_state, to signal that malloc checking
  72    must not be enabled on the request from the user (via the MALLOC_CHECK_
  73    environment variable).  It is reset by __malloc_check_init to tell
  74    malloc_set_state that the user has requested malloc checking.
  75
  76    The purpose of this flag is to make sure that malloc checking is not
  77    enabled when the heap to be restored was constructed without malloc
  78    checking, and thus does not contain the required magic bytes.
  79    Otherwise the heap would be corrupted by calls to free and realloc.  If
  80    it turns out that the heap was created with malloc checking and the
  81    user has requested it malloc_set_state just calls __malloc_check_init
  82    again to enable it.  On the other hand, reusing such a heap without
  83    further malloc checking is safe.  */
  84 static int disallow_malloc_check;
  85
  86 /* Activate a standard set of debugging hooks. */
  87 void
  88 __malloc_check_init()
  89 {
  90   if (disallow_malloc_check) {
  91     disallow_malloc_check = 0;
  92     return;
  93   }
  94   using_malloc_checking = 1;
  95   __malloc_hook = malloc_check;
  96   __free_hook = free_check;
  97   __realloc_hook = realloc_check;
  98   __memalign_hook = memalign_check;
  99 }
 100
 101 /* A simple, standard set of debugging hooks.  Overhead is `only' one
 102    byte per chunk; still this will catch most cases of double frees or
 103    overruns.  The goal here is to avoid obscure crashes due to invalid
 104    usage, unlike in the MALLOC_DEBUG code. */
 105
 106 #define MAGICBYTE(p) ( ( ((size_t)p >> 3) ^ ((size_t)p >> 11)) & 0xFF )
 107
 108 /* Instrument a chunk with overrun detector byte(s) and convert it
 109    into a user pointer with requested size sz. */
 110
 111 static Void_t*
 112 internal_function
 113 #if __STD_C
 114 mem2mem_check(Void_t *ptr, size_t sz)
 115 #else
 116 mem2mem_check(ptr, sz) Void_t *ptr; size_t sz;
 117 #endif
 118 {
 119   mchunkptr p;
 120   unsigned char* m_ptr = (unsigned char*)BOUNDED_N(ptr, sz);
 121   size_t i;
 122
 123   if (!ptr)
 124     return ptr;
 125   p = mem2chunk(ptr);
 126   for(i = chunksize(p) - (chunk_is_mmapped(p) ? 2*SIZE_SZ+1 : SIZE_SZ+1);
 127       i > sz;
 128       i -= 0xFF) {
 129     if(i-sz < 0x100) {
 130       m_ptr[i] = (unsigned char)(i-sz);
 131       break;
 132     }
 133     m_ptr[i] = 0xFF;
 134   }
 135   m_ptr[sz] = MAGICBYTE(p);
 136   return (Void_t*)m_ptr;
 137 }
 138
 139 /* Convert a pointer to be free()d or realloc()ed to a valid chunk
 140    pointer.  If the provided pointer is not valid, return NULL. */
 141
 142 static mchunkptr
 143 internal_function
 144 #if __STD_C
 145 mem2chunk_check(Void_t* mem, unsigned char **magic_p)
 146 #else
 147 mem2chunk_check(mem, magic_p) Void_t* mem; unsigned char **magic_p;
 148 #endif
 149 {
 150   mchunkptr p;
 151   INTERNAL_SIZE_T sz, c;
 152   unsigned char magic;
 153
 154   if(!aligned_OK(mem)) return NULL;
 155   p = mem2chunk(mem);
 156   if (!chunk_is_mmapped(p)) {
 157     /* Must be a chunk in conventional heap memory. */
 158     int contig = contiguous(&main_arena);
 159     sz = chunksize(p);
 160     if((contig &&
 161         ((char*)p<mp_.sbrk_base ||
 162          ((char*)p + sz)>=(mp_.sbrk_base+main_arena.system_mem) )) ||
 163        sz<MINSIZE || sz&MALLOC_ALIGN_MASK || !inuse(p) ||
 164        ( !prev_inuse(p) && (p->prev_size&MALLOC_ALIGN_MASK ||
 165                             (contig && (char*)prev_chunk(p)<mp_.sbrk_base) ||
 166                             next_chunk(prev_chunk(p))!=p) ))
 167       return NULL;
 168     magic = MAGICBYTE(p);
 169     for(sz += SIZE_SZ-1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
 170       if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
 171     }
 172   } else {
 173     unsigned long offset, page_mask = malloc_getpagesize-1;
 174
 175     /* mmap()ed chunks have MALLOC_ALIGNMENT or higher power-of-two
 176        alignment relative to the beginning of a page.  Check this
 177        first. */
 178     offset = (unsigned long)mem & page_mask;
 179     if((offset!=MALLOC_ALIGNMENT && offset!=0 && offset!=0x10 &&
 180         offset!=0x20 && offset!=0x40 && offset!=0x80 && offset!=0x100 &&
 181         offset!=0x200 && offset!=0x400 && offset!=0x800 && offset!=0x1000 &&
 182         offset<0x2000) ||
 183        !chunk_is_mmapped(p) || (p->size & PREV_INUSE) ||
 184        ( (((unsigned long)p - p->prev_size) & page_mask) != 0 ) ||
 185        ( (sz = chunksize(p)), ((p->prev_size + sz) & page_mask) != 0 ) )
 186       return NULL;
 187     magic = MAGICBYTE(p);
 188     for(sz -= 1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
 189       if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
 190     }
 191   }
 192   ((unsigned char*)p)[sz] ^= 0xFF;
 193   if (magic_p)
 194     *magic_p = (unsigned char *)p + sz;
 195   return p;
 196 }
 197
 198 /* Check for corruption of the top chunk, and try to recover if
 199    necessary. */
 200
 201 static int
 202 internal_function
 203 #if __STD_C
 204 top_check(void)
 205 #else
 206 top_check()
 207 #endif
 208 {
 209   mchunkptr t = top(&main_arena);
 210   char* brk, * new_brk;
 211   INTERNAL_SIZE_T front_misalign, sbrk_size;
 212   unsigned long pagesz = malloc_getpagesize;
 213
 214   if (t == initial_top(&main_arena) ||
 215       (!chunk_is_mmapped(t) &&
 216        chunksize(t)>=MINSIZE &&
 217        prev_inuse(t) &&
 218        (!contiguous(&main_arena) ||
 219         (char*)t + chunksize(t) == mp_.sbrk_base + main_arena.system_mem)))
 220     return 0;
 221
 222   malloc_printerr (check_action, "malloc: top chunk is corrupt", t);
 223
 224   /* Try to set up a new top chunk. */
 225   brk = MORECORE(0);
 226   front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
 227   if (front_misalign > 0)
 228     front_misalign = MALLOC_ALIGNMENT - front_misalign;
 229   sbrk_size = front_misalign + mp_.top_pad + MINSIZE;
 230   sbrk_size += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1));
 231   new_brk = (char*)(MORECORE (sbrk_size));
 232   if (new_brk == (char*)(MORECORE_FAILURE))
 233     {
 234       MALLOC_FAILURE_ACTION;
 235       return -1;
 236     }
 237   /* Call the `morecore' hook if necessary.  */
 238   if (__after_morecore_hook)
 239     (*__after_morecore_hook) ();
 240   main_arena.system_mem = (new_brk - mp_.sbrk_base) + sbrk_size;
 241
 242   top(&main_arena) = (mchunkptr)(brk + front_misalign);
 243   set_head(top(&main_arena), (sbrk_size - front_misalign) | PREV_INUSE);
 244
 245   return 0;
 246 }
 247
 248 static Void_t*
 249 #if __STD_C
 250 malloc_check(size_t sz, const Void_t *caller)
 251 #else
 252 malloc_check(sz, caller) size_t sz; const Void_t *caller;
 253 #endif
 254 {
 255   Void_t *victim;
 256
 257   if (sz+1 == 0) {
 258     MALLOC_FAILURE_ACTION;
 259     return NULL;
 260   }
 261
 262   (void)mutex_lock(&main_arena.mutex);
 263   victim = (top_check() >= 0) ? _int_malloc(&main_arena, sz+1) : NULL;
 264   (void)mutex_unlock(&main_arena.mutex);
 265   return mem2mem_check(victim, sz);
 266 }
 267
 268 static void
 269 #if __STD_C
 270 free_check(Void_t* mem, const Void_t *caller)
 271 #else
 272 free_check(mem, caller) Void_t* mem; const Void_t *caller;
 273 #endif
 274 {
 275   mchunkptr p;
 276
 277   if(!mem) return;
 278   (void)mutex_lock(&main_arena.mutex);
 279   p = mem2chunk_check(mem, NULL);
 280   if(!p) {
 281     (void)mutex_unlock(&main_arena.mutex);
 282
 283     malloc_printerr(check_action, "free(): invalid pointer", mem);
 284     return;
 285   }
 286 #if HAVE_MMAP
 287   if (chunk_is_mmapped(p)) {
 288     (void)mutex_unlock(&main_arena.mutex);
 289     munmap_chunk(p);
 290     return;
 291   }
 292 #endif
 293 #if 0 /* Erase freed memory. */
 294   memset(mem, 0, chunksize(p) - (SIZE_SZ+1));
 295 #endif
 296   _int_free(&main_arena, mem);
 297   (void)mutex_unlock(&main_arena.mutex);
 298 }
 299
 300 static Void_t*
 301 #if __STD_C
 302 realloc_check(Void_t* oldmem, size_t bytes, const Void_t *caller)
 303 #else
 304 realloc_check(oldmem, bytes, caller)
 305      Void_t* oldmem; size_t bytes; const Void_t *caller;
 306 #endif
 307 {
 308   mchunkptr oldp;
 309   INTERNAL_SIZE_T nb, oldsize;
 310   Void_t* newmem = 0;
 311   unsigned char *magic_p;
 312
 313   if (bytes+1 == 0) {
 314     MALLOC_FAILURE_ACTION;
 315     return NULL;
 316   }
 317   if (oldmem == 0) return malloc_check(bytes, NULL);
 318   if (bytes == 0) {
 319     free_check (oldmem, NULL);
 320     return NULL;
 321   }
 322   (void)mutex_lock(&main_arena.mutex);
 323   oldp = mem2chunk_check(oldmem, &magic_p);
 324   (void)mutex_unlock(&main_arena.mutex);
 325   if(!oldp) {
 326     malloc_printerr(check_action, "realloc(): invalid pointer", oldmem);
 327     return malloc_check(bytes, NULL);
 328   }
 329   oldsize = chunksize(oldp);
 330
 331   checked_request2size(bytes+1, nb);
 332   (void)mutex_lock(&main_arena.mutex);
 333
 334 #if HAVE_MMAP
 335   if (chunk_is_mmapped(oldp)) {
 336 #if HAVE_MREMAP
 337     mchunkptr newp = mremap_chunk(oldp, nb);
 338     if(newp)
 339       newmem = chunk2mem(newp);
 340     else
 341 #endif
 342     {
 343       /* Note the extra SIZE_SZ overhead. */
 344       if(oldsize - SIZE_SZ >= nb)
 345         newmem = oldmem; /* do nothing */
 346       else {
 347         /* Must alloc, copy, free. */
 348         if (top_check() >= 0)
 349           newmem = _int_malloc(&main_arena, bytes+1);
 350         if (newmem) {
 351           MALLOC_COPY(BOUNDED_N(newmem, bytes+1), oldmem, oldsize - 2*SIZE_SZ);
 352           munmap_chunk(oldp);
 353         }
 354       }
 355     }
 356   } else {
 357 #endif /* HAVE_MMAP */
 358     if (top_check() >= 0)
 359       newmem = _int_realloc(&main_arena, oldmem, bytes+1);
 360 #if 0 /* Erase freed memory. */
 361     if(newmem)
 362       newp = mem2chunk(newmem);
 363     nb = chunksize(newp);
 364     if(oldp<newp || oldp>=chunk_at_offset(newp, nb)) {
 365       memset((char*)oldmem + 2*sizeof(mbinptr), 0,
 366              oldsize - (2*sizeof(mbinptr)+2*SIZE_SZ+1));
 367     } else if(nb > oldsize+SIZE_SZ) {
 368       memset((char*)BOUNDED_N(chunk2mem(newp), bytes) + oldsize,
 369              0, nb - (oldsize+SIZE_SZ));
 370     }
 371 #endif
 372 #if HAVE_MMAP
 373   }
 374 #endif
 375
 376   /* mem2chunk_check changed the magic byte in the old chunk.
 377      If newmem is NULL, then the old chunk will still be used though,
 378      so we need to invert that change here.  */
 379   if (newmem == NULL) *magic_p ^= 0xFF;
 380
 381   (void)mutex_unlock(&main_arena.mutex);
 382
 383   return mem2mem_check(newmem, bytes);
 384 }
 385
 386 static Void_t*
 387 #if __STD_C
 388 memalign_check(size_t alignment, size_t bytes, const Void_t *caller)
 389 #else
 390 memalign_check(alignment, bytes, caller)
 391      size_t alignment; size_t bytes; const Void_t *caller;
 392 #endif
 393 {
 394   INTERNAL_SIZE_T nb;
 395   Void_t* mem;
 396
 397   if (alignment <= MALLOC_ALIGNMENT) return malloc_check(bytes, NULL);
 398   if (alignment <  MINSIZE) alignment = MINSIZE;
 399
 400   if (bytes+1 == 0) {
 401     MALLOC_FAILURE_ACTION;
 402     return NULL;
 403   }
 404   checked_request2size(bytes+1, nb);
 405   (void)mutex_lock(&main_arena.mutex);
 406   mem = (top_check() >= 0) ? _int_memalign(&main_arena, alignment, bytes+1) :
 407     NULL;
 408   (void)mutex_unlock(&main_arena.mutex);
 409   return mem2mem_check(mem, bytes);
 410 }
 411
 412 #ifndef NO_THREADS
 413
 414 # ifdef _LIBC
 415 #  if USE___THREAD || !defined SHARED
 416     /* These routines are never needed in this configuration.  */
 417 #   define NO_STARTER
 418 #  endif
 419 # endif
 420
 421 # ifdef NO_STARTER
 422 #  undef NO_STARTER
 423 # else
 424
 425 /* The following hooks are used when the global initialization in
 426    ptmalloc_init() hasn't completed yet. */
 427
 428 static Void_t*
 429 #if __STD_C
 430 malloc_starter(size_t sz, const Void_t *caller)
 431 #else
 432 malloc_starter(sz, caller) size_t sz; const Void_t *caller;
 433 #endif
 434 {
 435   Void_t* victim;
 436
 437   victim = _int_malloc(&main_arena, sz);
 438
 439   return victim ? BOUNDED_N(victim, sz) : 0;
 440 }
 441
 442 static Void_t*
 443 #if __STD_C
 444 memalign_starter(size_t align, size_t sz, const Void_t *caller)
 445 #else
 446 memalign_starter(align, sz, caller) size_t align, sz; const Void_t *caller;
 447 #endif
 448 {
 449   Void_t* victim;
 450
 451   victim = _int_memalign(&main_arena, align, sz);
 452
 453   return victim ? BOUNDED_N(victim, sz) : 0;
 454 }
 455
 456 static void
 457 #if __STD_C
 458 free_starter(Void_t* mem, const Void_t *caller)
 459 #else
 460 free_starter(mem, caller) Void_t* mem; const Void_t *caller;
 461 #endif
 462 {
 463   mchunkptr p;
 464
 465   if(!mem) return;
 466   p = mem2chunk(mem);
 467 #if HAVE_MMAP
 468   if (chunk_is_mmapped(p)) {
 469     munmap_chunk(p);
 470     return;
 471   }
 472 #endif
 473   _int_free(&main_arena, mem);
 474 }
 475
 476 # endif /* !defiend NO_STARTER */
 477 #endif /* NO_THREADS */
 478
 479
 480 /* Get/set state: malloc_get_state() records the current state of all
 481    malloc variables (_except_ for the actual heap contents and `hook'
 482    function pointers) in a system dependent, opaque data structure.
 483    This data structure is dynamically allocated and can be free()d
 484    after use.  malloc_set_state() restores the state of all malloc
 485    variables to the previously obtained state.  This is especially
 486    useful when using this malloc as part of a shared library, and when
 487    the heap contents are saved/restored via some other method.  The
 488    primary example for this is GNU Emacs with its `dumping' procedure.
 489    `Hook' function pointers are never saved or restored by these
 490    functions, with two exceptions: If malloc checking was in use when
 491    malloc_get_state() was called, then malloc_set_state() calls
 492    __malloc_check_init() if possible; if malloc checking was not in
 493    use in the recorded state but the user requested malloc checking,
 494    then the hooks are reset to 0.  */
 495
 496 #define MALLOC_STATE_MAGIC   0x444c4541l
 497 #define MALLOC_STATE_VERSION (0*0x100l + 3l) /* major*0x100 + minor */
 498
 499 struct malloc_save_state {
 500   long          magic;
 501   long          version;
 502   mbinptr       av[NBINS * 2 + 2];
 503   char*         sbrk_base;
 504   int           sbrked_mem_bytes;
 505   unsigned long trim_threshold;
 506   unsigned long top_pad;
 507   unsigned int  n_mmaps_max;
 508   unsigned long mmap_threshold;
 509   int           check_action;
 510   unsigned long max_sbrked_mem;
 511   unsigned long max_total_mem;
 512   unsigned int  n_mmaps;
 513   unsigned int  max_n_mmaps;
 514   unsigned long mmapped_mem;
 515   unsigned long max_mmapped_mem;
 516   int           using_malloc_checking;
 517 };
 518
 519 Void_t*
 520 public_gET_STATe(void)
 521 {
 522   struct malloc_save_state* ms;
 523   int i;
 524   mbinptr b;
 525
 526   ms = (struct malloc_save_state*)public_mALLOc(sizeof(*ms));
 527   if (!ms)
 528     return 0;
 529   (void)mutex_lock(&main_arena.mutex);
 530   malloc_consolidate(&main_arena);
 531   ms->magic = MALLOC_STATE_MAGIC;
 532   ms->version = MALLOC_STATE_VERSION;
 533   ms->av[0] = 0;
 534   ms->av[1] = 0; /* used to be binblocks, now no longer used */
 535   ms->av[2] = top(&main_arena);
 536   ms->av[3] = 0; /* used to be undefined */
 537   for(i=1; i<NBINS; i++) {
 538     b = bin_at(&main_arena, i);
 539     if(first(b) == b)
 540       ms->av[2*i+2] = ms->av[2*i+3] = 0; /* empty bin */
 541     else {
 542       ms->av[2*i+2] = first(b);
 543       ms->av[2*i+3] = last(b);
 544     }
 545   }
 546   ms->sbrk_base = mp_.sbrk_base;
 547   ms->sbrked_mem_bytes = main_arena.system_mem;
 548   ms->trim_threshold = mp_.trim_threshold;
 549   ms->top_pad = mp_.top_pad;
 550   ms->n_mmaps_max = mp_.n_mmaps_max;
 551   ms->mmap_threshold = mp_.mmap_threshold;
 552   ms->check_action = check_action;
 553   ms->max_sbrked_mem = main_arena.max_system_mem;
 554 #ifdef NO_THREADS
 555   ms->max_total_mem = mp_.max_total_mem;
 556 #else
 557   ms->max_total_mem = 0;
 558 #endif
 559   ms->n_mmaps = mp_.n_mmaps;
 560   ms->max_n_mmaps = mp_.max_n_mmaps;
 561   ms->mmapped_mem = mp_.mmapped_mem;
 562   ms->max_mmapped_mem = mp_.max_mmapped_mem;
 563   ms->using_malloc_checking = using_malloc_checking;
 564   (void)mutex_unlock(&main_arena.mutex);
 565   return (Void_t*)ms;
 566 }
 567
 568 int
 569 public_sET_STATe(Void_t* msptr)
 570 {
 571   struct malloc_save_state* ms = (struct malloc_save_state*)msptr;
 572   size_t i;
 573   mbinptr b;
 574
 575   disallow_malloc_check = 1;
 576   ptmalloc_init();
 577   if(ms->magic != MALLOC_STATE_MAGIC) return -1;
 578   /* Must fail if the major version is too high. */
 579   if((ms->version & ~0xffl) > (MALLOC_STATE_VERSION & ~0xffl)) return -2;
 580   (void)mutex_lock(&main_arena.mutex);
 581   /* There are no fastchunks.  */
 582   clear_fastchunks(&main_arena);
 583   set_max_fast(DEFAULT_MXFAST);
 584   for (i=0; i<NFASTBINS; ++i)
 585     main_arena.fastbins[i] = 0;
 586   for (i=0; i<BINMAPSIZE; ++i)
 587     main_arena.binmap[i] = 0;
 588   top(&main_arena) = ms->av[2];
 589   main_arena.last_remainder = 0;
 590   for(i=1; i<NBINS; i++) {
 591     b = bin_at(&main_arena, i);
 592     if(ms->av[2*i+2] == 0) {
 593       assert(ms->av[2*i+3] == 0);
 594       first(b) = last(b) = b;
 595     } else {
 596       if(ms->version >= 3 &&
 597          (i<NSMALLBINS || (largebin_index(chunksize(ms->av[2*i+2]))==i &&
 598                            largebin_index(chunksize(ms->av[2*i+3]))==i))) {
 599         first(b) = ms->av[2*i+2];
 600         last(b) = ms->av[2*i+3];
 601         /* Make sure the links to the bins within the heap are correct.  */
 602         first(b)->bk = b;
 603         last(b)->fd = b;
 604         /* Set bit in binblocks.  */
 605         mark_bin(&main_arena, i);
 606       } else {
 607         /* Oops, index computation from chunksize must have changed.
 608            Link the whole list into unsorted_chunks.  */
 609         first(b) = last(b) = b;
 610         b = unsorted_chunks(&main_arena);
 611         ms->av[2*i+2]->bk = b;
 612         ms->av[2*i+3]->fd = b->fd;
 613         b->fd->bk = ms->av[2*i+3];
 614         b->fd = ms->av[2*i+2];
 615       }
 616     }
 617   }
 618   if (ms->version < 3) {
 619     /* Clear fd_nextsize and bk_nextsize fields.  */
 620     b = unsorted_chunks(&main_arena)->fd;
 621     while (b != unsorted_chunks(&main_arena)) {
 622       if (!in_smallbin_range(chunksize(b))) {
 623         b->fd_nextsize = NULL;
 624         b->bk_nextsize = NULL;
 625       }
 626       b = b->fd;
 627     }
 628   }
 629   mp_.sbrk_base = ms->sbrk_base;
 630   main_arena.system_mem = ms->sbrked_mem_bytes;
 631   mp_.trim_threshold = ms->trim_threshold;
 632   mp_.top_pad = ms->top_pad;
 633   mp_.n_mmaps_max = ms->n_mmaps_max;
 634   mp_.mmap_threshold = ms->mmap_threshold;
 635   check_action = ms->check_action;
 636   main_arena.max_system_mem = ms->max_sbrked_mem;
 637 #ifdef NO_THREADS
 638   mp_.max_total_mem = ms->max_total_mem;
 639 #endif
 640   mp_.n_mmaps = ms->n_mmaps;
 641   mp_.max_n_mmaps = ms->max_n_mmaps;
 642   mp_.mmapped_mem = ms->mmapped_mem;
 643   mp_.max_mmapped_mem = ms->max_mmapped_mem;
 644   /* add version-dependent code here */
 645   if (ms->version >= 1) {
 646     /* Check whether it is safe to enable malloc checking, or whether
 647        it is necessary to disable it.  */
 648     if (ms->using_malloc_checking && !using_malloc_checking &&
 649         !disallow_malloc_check)
 650       __malloc_check_init ();
 651     else if (!ms->using_malloc_checking && using_malloc_checking) {
 652       __malloc_hook = 0;
 653       __free_hook = 0;
 654       __realloc_hook = 0;
 655       __memalign_hook = 0;
 656       using_malloc_checking = 0;
 657     }
 658   }
 659   check_malloc_state(&main_arena);
 660
 661   (void)mutex_unlock(&main_arena.mutex);
 662   return 0;
 663 }
 664
 665 /*
 666  * Local variables:
 667  * c-basic-offset: 2
 668  * End:
 669  */