malloc/hooks.c

   1 /* Malloc implementation for multiple threads without lock contention.
   2    Copyright (C) 2001-2006, 2007, 2008, 2009 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   void (*hook) (void) = __after_morecore_hook;
 239   if (hook)
 240     (*hook) ();
 241   main_arena.system_mem = (new_brk - mp_.sbrk_base) + sbrk_size;
 242
 243   top(&main_arena) = (mchunkptr)(brk + front_misalign);
 244   set_head(top(&main_arena), (sbrk_size - front_misalign) | PREV_INUSE);
 245
 246   return 0;
 247 }
 248
 249 static Void_t*
 250 #if __STD_C
 251 malloc_check(size_t sz, const Void_t *caller)
 252 #else
 253 malloc_check(sz, caller) size_t sz; const Void_t *caller;
 254 #endif
 255 {
 256   Void_t *victim;
 257
 258   if (sz+1 == 0) {
 259     MALLOC_FAILURE_ACTION;
 260     return NULL;
 261   }
 262
 263   (void)mutex_lock(&main_arena.mutex);
 264   victim = (top_check() >= 0) ? _int_malloc(&main_arena, sz+1) : NULL;
 265   (void)mutex_unlock(&main_arena.mutex);
 266   return mem2mem_check(victim, sz);
 267 }
 268
 269 static void
 270 #if __STD_C
 271 free_check(Void_t* mem, const Void_t *caller)
 272 #else
 273 free_check(mem, caller) Void_t* mem; const Void_t *caller;
 274 #endif
 275 {
 276   mchunkptr p;
 277
 278   if(!mem) return;
 279   p = mem2chunk_check(mem, NULL);
 280   if(!p) {
 281     malloc_printerr(check_action, "free(): invalid pointer", mem);
 282     return;
 283   }
 284 #if HAVE_MMAP
 285   if (chunk_is_mmapped(p)) {
 286     munmap_chunk(p);
 287     return;
 288   }
 289 #endif
 290 #if 0 /* Erase freed memory. */
 291   memset(mem, 0, chunksize(p) - (SIZE_SZ+1));
 292 #endif
 293 #ifdef ATOMIC_FASTBINS
 294   _int_free(&main_arena, p, 0);
 295 #else
 296   (void)mutex_lock(&main_arena.mutex);
 297   _int_free(&main_arena, p);
 298   (void)mutex_unlock(&main_arena.mutex);
 299 #endif
 300 }
 301
 302 static Void_t*
 303 #if __STD_C
 304 realloc_check(Void_t* oldmem, size_t bytes, const Void_t *caller)
 305 #else
 306 realloc_check(oldmem, bytes, caller)
 307      Void_t* oldmem; size_t bytes; const Void_t *caller;
 308 #endif
 309 {
 310   INTERNAL_SIZE_T nb;
 311   Void_t* newmem = 0;
 312   unsigned char *magic_p;
 313
 314   if (bytes+1 == 0) {
 315     MALLOC_FAILURE_ACTION;
 316     return NULL;
 317   }
 318   if (oldmem == 0) return malloc_check(bytes, NULL);
 319   if (bytes == 0) {
 320     free_check (oldmem, NULL);
 321     return NULL;
 322   }
 323   (void)mutex_lock(&main_arena.mutex);
 324   const mchunkptr oldp = mem2chunk_check(oldmem, &magic_p);
 325   (void)mutex_unlock(&main_arena.mutex);
 326   if(!oldp) {
 327     malloc_printerr(check_action, "realloc(): invalid pointer", oldmem);
 328     return malloc_check(bytes, NULL);
 329   }
 330   const INTERNAL_SIZE_T oldsize = chunksize(oldp);
 331
 332   checked_request2size(bytes+1, nb);
 333   (void)mutex_lock(&main_arena.mutex);
 334
 335 #if HAVE_MMAP
 336   if (chunk_is_mmapped(oldp)) {
 337 #if HAVE_MREMAP
 338     mchunkptr newp = mremap_chunk(oldp, nb);
 339     if(newp)
 340       newmem = chunk2mem(newp);
 341     else
 342 #endif
 343     {
 344       /* Note the extra SIZE_SZ overhead. */
 345       if(oldsize - SIZE_SZ >= nb)
 346         newmem = oldmem; /* do nothing */
 347       else {
 348         /* Must alloc, copy, free. */
 349         if (top_check() >= 0)
 350           newmem = _int_malloc(&main_arena, bytes+1);
 351         if (newmem) {
 352           MALLOC_COPY(BOUNDED_N(newmem, bytes+1), oldmem, oldsize - 2*SIZE_SZ);
 353           munmap_chunk(oldp);
 354         }
 355       }
 356     }
 357   } else {
 358 #endif /* HAVE_MMAP */
 359     if (top_check() >= 0) {
 360       INTERNAL_SIZE_T nb;
 361       checked_request2size(bytes + 1, nb);
 362       newmem = _int_realloc(&main_arena, oldp, oldsize, nb);
 363     }
 364 #if 0 /* Erase freed memory. */
 365     if(newmem)
 366       newp = mem2chunk(newmem);
 367     nb = chunksize(newp);
 368     if(oldp<newp || oldp>=chunk_at_offset(newp, nb)) {
 369       memset((char*)oldmem + 2*sizeof(mbinptr), 0,
 370              oldsize - (2*sizeof(mbinptr)+2*SIZE_SZ+1));
 371     } else if(nb > oldsize+SIZE_SZ) {
 372       memset((char*)BOUNDED_N(chunk2mem(newp), bytes) + oldsize,
 373              0, nb - (oldsize+SIZE_SZ));
 374     }
 375 #endif
 376 #if HAVE_MMAP
 377   }
 378 #endif
 379
 380   /* mem2chunk_check changed the magic byte in the old chunk.
 381      If newmem is NULL, then the old chunk will still be used though,
 382      so we need to invert that change here.  */
 383   if (newmem == NULL) *magic_p ^= 0xFF;
 384
 385   (void)mutex_unlock(&main_arena.mutex);
 386
 387   return mem2mem_check(newmem, bytes);
 388 }
 389
 390 static Void_t*
 391 #if __STD_C
 392 memalign_check(size_t alignment, size_t bytes, const Void_t *caller)
 393 #else
 394 memalign_check(alignment, bytes, caller)
 395      size_t alignment; size_t bytes; const Void_t *caller;
 396 #endif
 397 {
 398   INTERNAL_SIZE_T nb;
 399   Void_t* mem;
 400
 401   if (alignment <= MALLOC_ALIGNMENT) return malloc_check(bytes, NULL);
 402   if (alignment <  MINSIZE) alignment = MINSIZE;
 403
 404   if (bytes+1 == 0) {
 405     MALLOC_FAILURE_ACTION;
 406     return NULL;
 407   }
 408   checked_request2size(bytes+1, nb);
 409   (void)mutex_lock(&main_arena.mutex);
 410   mem = (top_check() >= 0) ? _int_memalign(&main_arena, alignment, bytes+1) :
 411     NULL;
 412   (void)mutex_unlock(&main_arena.mutex);
 413   return mem2mem_check(mem, bytes);
 414 }
 415
 416 #ifndef NO_THREADS
 417
 418 # ifdef _LIBC
 419 #  if USE___THREAD || !defined SHARED
 420     /* These routines are never needed in this configuration.  */
 421 #   define NO_STARTER
 422 #  endif
 423 # endif
 424
 425 # ifdef NO_STARTER
 426 #  undef NO_STARTER
 427 # else
 428
 429 /* The following hooks are used when the global initialization in
 430    ptmalloc_init() hasn't completed yet. */
 431
 432 static Void_t*
 433 #if __STD_C
 434 malloc_starter(size_t sz, const Void_t *caller)
 435 #else
 436 malloc_starter(sz, caller) size_t sz; const Void_t *caller;
 437 #endif
 438 {
 439   Void_t* victim;
 440
 441   victim = _int_malloc(&main_arena, sz);
 442
 443   return victim ? BOUNDED_N(victim, sz) : 0;
 444 }
 445
 446 static Void_t*
 447 #if __STD_C
 448 memalign_starter(size_t align, size_t sz, const Void_t *caller)
 449 #else
 450 memalign_starter(align, sz, caller) size_t align, sz; const Void_t *caller;
 451 #endif
 452 {
 453   Void_t* victim;
 454
 455   victim = _int_memalign(&main_arena, align, sz);
 456
 457   return victim ? BOUNDED_N(victim, sz) : 0;
 458 }
 459
 460 static void
 461 #if __STD_C
 462 free_starter(Void_t* mem, const Void_t *caller)
 463 #else
 464 free_starter(mem, caller) Void_t* mem; const Void_t *caller;
 465 #endif
 466 {
 467   mchunkptr p;
 468
 469   if(!mem) return;
 470   p = mem2chunk(mem);
 471 #if HAVE_MMAP
 472   if (chunk_is_mmapped(p)) {
 473     munmap_chunk(p);
 474     return;
 475   }
 476 #endif
 477 #ifdef ATOMIC_FASTBINS
 478   _int_free(&main_arena, p, 1);
 479 #else
 480   _int_free(&main_arena, p);
 481 #endif
 482 }
 483
 484 # endif /* !defiend NO_STARTER */
 485 #endif /* NO_THREADS */
 486
 487
 488 /* Get/set state: malloc_get_state() records the current state of all
 489    malloc variables (_except_ for the actual heap contents and `hook'
 490    function pointers) in a system dependent, opaque data structure.
 491    This data structure is dynamically allocated and can be free()d
 492    after use.  malloc_set_state() restores the state of all malloc
 493    variables to the previously obtained state.  This is especially
 494    useful when using this malloc as part of a shared library, and when
 495    the heap contents are saved/restored via some other method.  The
 496    primary example for this is GNU Emacs with its `dumping' procedure.
 497    `Hook' function pointers are never saved or restored by these
 498    functions, with two exceptions: If malloc checking was in use when
 499    malloc_get_state() was called, then malloc_set_state() calls
 500    __malloc_check_init() if possible; if malloc checking was not in
 501    use in the recorded state but the user requested malloc checking,
 502    then the hooks are reset to 0.  */
 503
 504 #define MALLOC_STATE_MAGIC   0x444c4541l
 505 #define MALLOC_STATE_VERSION (0*0x100l + 4l) /* major*0x100 + minor */
 506
 507 struct malloc_save_state {
 508   long          magic;
 509   long          version;
 510   mbinptr       av[NBINS * 2 + 2];
 511   char*         sbrk_base;
 512   int           sbrked_mem_bytes;
 513   unsigned long trim_threshold;
 514   unsigned long top_pad;
 515   unsigned int  n_mmaps_max;
 516   unsigned long mmap_threshold;
 517   int           check_action;
 518   unsigned long max_sbrked_mem;
 519   unsigned long max_total_mem;
 520   unsigned int  n_mmaps;
 521   unsigned int  max_n_mmaps;
 522   unsigned long mmapped_mem;
 523   unsigned long max_mmapped_mem;
 524   int           using_malloc_checking;
 525   unsigned long max_fast;
 526   unsigned long arena_test;
 527   unsigned long arena_max;
 528   unsigned long narenas;
 529 };
 530
 531 Void_t*
 532 public_gET_STATe(void)
 533 {
 534   struct malloc_save_state* ms;
 535   int i;
 536   mbinptr b;
 537
 538   ms = (struct malloc_save_state*)public_mALLOc(sizeof(*ms));
 539   if (!ms)
 540     return 0;
 541   (void)mutex_lock(&main_arena.mutex);
 542   malloc_consolidate(&main_arena);
 543   ms->magic = MALLOC_STATE_MAGIC;
 544   ms->version = MALLOC_STATE_VERSION;
 545   ms->av[0] = 0;
 546   ms->av[1] = 0; /* used to be binblocks, now no longer used */
 547   ms->av[2] = top(&main_arena);
 548   ms->av[3] = 0; /* used to be undefined */
 549   for(i=1; i<NBINS; i++) {
 550     b = bin_at(&main_arena, i);
 551     if(first(b) == b)
 552       ms->av[2*i+2] = ms->av[2*i+3] = 0; /* empty bin */
 553     else {
 554       ms->av[2*i+2] = first(b);
 555       ms->av[2*i+3] = last(b);
 556     }
 557   }
 558   ms->sbrk_base = mp_.sbrk_base;
 559   ms->sbrked_mem_bytes = main_arena.system_mem;
 560   ms->trim_threshold = mp_.trim_threshold;
 561   ms->top_pad = mp_.top_pad;
 562   ms->n_mmaps_max = mp_.n_mmaps_max;
 563   ms->mmap_threshold = mp_.mmap_threshold;
 564   ms->check_action = check_action;
 565   ms->max_sbrked_mem = main_arena.max_system_mem;
 566 #ifdef NO_THREADS
 567   ms->max_total_mem = mp_.max_total_mem;
 568 #else
 569   ms->max_total_mem = 0;
 570 #endif
 571   ms->n_mmaps = mp_.n_mmaps;
 572   ms->max_n_mmaps = mp_.max_n_mmaps;
 573   ms->mmapped_mem = mp_.mmapped_mem;
 574   ms->max_mmapped_mem = mp_.max_mmapped_mem;
 575   ms->using_malloc_checking = using_malloc_checking;
 576   ms->max_fast = get_max_fast();
 577 #ifdef PER_THREAD
 578   ms->arena_test = mp_.arena_test;
 579   ms->arena_max = mp_.arena_max;
 580   ms->narenas = narenas;
 581 #endif
 582   (void)mutex_unlock(&main_arena.mutex);
 583   return (Void_t*)ms;
 584 }
 585
 586 int
 587 public_sET_STATe(Void_t* msptr)
 588 {
 589   struct malloc_save_state* ms = (struct malloc_save_state*)msptr;
 590   size_t i;
 591   mbinptr b;
 592
 593   disallow_malloc_check = 1;
 594   ptmalloc_init();
 595   if(ms->magic != MALLOC_STATE_MAGIC) return -1;
 596   /* Must fail if the major version is too high. */
 597   if((ms->version & ~0xffl) > (MALLOC_STATE_VERSION & ~0xffl)) return -2;
 598   (void)mutex_lock(&main_arena.mutex);
 599   /* There are no fastchunks.  */
 600   clear_fastchunks(&main_arena);
 601   if (ms->version >= 4)
 602     set_max_fast(ms->max_fast);
 603   else
 604     set_max_fast(64);   /* 64 used to be the value we always used.  */
 605   for (i=0; i<NFASTBINS; ++i)
 606     fastbin (&main_arena, i) = 0;
 607   for (i=0; i<BINMAPSIZE; ++i)
 608     main_arena.binmap[i] = 0;
 609   top(&main_arena) = ms->av[2];
 610   main_arena.last_remainder = 0;
 611   for(i=1; i<NBINS; i++) {
 612     b = bin_at(&main_arena, i);
 613     if(ms->av[2*i+2] == 0) {
 614       assert(ms->av[2*i+3] == 0);
 615       first(b) = last(b) = b;
 616     } else {
 617       if(ms->version >= 3 &&
 618          (i<NSMALLBINS || (largebin_index(chunksize(ms->av[2*i+2]))==i &&
 619                            largebin_index(chunksize(ms->av[2*i+3]))==i))) {
 620         first(b) = ms->av[2*i+2];
 621         last(b) = ms->av[2*i+3];
 622         /* Make sure the links to the bins within the heap are correct.  */
 623         first(b)->bk = b;
 624         last(b)->fd = b;
 625         /* Set bit in binblocks.  */
 626         mark_bin(&main_arena, i);
 627       } else {
 628         /* Oops, index computation from chunksize must have changed.
 629            Link the whole list into unsorted_chunks.  */
 630         first(b) = last(b) = b;
 631         b = unsorted_chunks(&main_arena);
 632         ms->av[2*i+2]->bk = b;
 633         ms->av[2*i+3]->fd = b->fd;
 634         b->fd->bk = ms->av[2*i+3];
 635         b->fd = ms->av[2*i+2];
 636       }
 637     }
 638   }
 639   if (ms->version < 3) {
 640     /* Clear fd_nextsize and bk_nextsize fields.  */
 641     b = unsorted_chunks(&main_arena)->fd;
 642     while (b != unsorted_chunks(&main_arena)) {
 643       if (!in_smallbin_range(chunksize(b))) {
 644         b->fd_nextsize = NULL;
 645         b->bk_nextsize = NULL;
 646       }
 647       b = b->fd;
 648     }
 649   }
 650   mp_.sbrk_base = ms->sbrk_base;
 651   main_arena.system_mem = ms->sbrked_mem_bytes;
 652   mp_.trim_threshold = ms->trim_threshold;
 653   mp_.top_pad = ms->top_pad;
 654   mp_.n_mmaps_max = ms->n_mmaps_max;
 655   mp_.mmap_threshold = ms->mmap_threshold;
 656   check_action = ms->check_action;
 657   main_arena.max_system_mem = ms->max_sbrked_mem;
 658 #ifdef NO_THREADS
 659   mp_.max_total_mem = ms->max_total_mem;
 660 #endif
 661   mp_.n_mmaps = ms->n_mmaps;
 662   mp_.max_n_mmaps = ms->max_n_mmaps;
 663   mp_.mmapped_mem = ms->mmapped_mem;
 664   mp_.max_mmapped_mem = ms->max_mmapped_mem;
 665   /* add version-dependent code here */
 666   if (ms->version >= 1) {
 667     /* Check whether it is safe to enable malloc checking, or whether
 668        it is necessary to disable it.  */
 669     if (ms->using_malloc_checking && !using_malloc_checking &&
 670         !disallow_malloc_check)
 671       __malloc_check_init ();
 672     else if (!ms->using_malloc_checking && using_malloc_checking) {
 673       __malloc_hook = NULL;
 674       __free_hook = NULL;
 675       __realloc_hook = NULL;
 676       __memalign_hook = NULL;
 677       using_malloc_checking = 0;
 678     }
 679   }
 680   if (ms->version >= 4) {
 681 #ifdef PER_THREAD
 682     mp_.arena_test = ms->arena_test;
 683     mp_.arena_max = ms->arena_max;
 684     narenas = ms->narenas;
 685 #endif
 686   }
 687   check_malloc_state(&main_arena);
 688
 689   (void)mutex_unlock(&main_arena.mutex);
 690   return 0;
 691 }
 692
 693 /*
 694  * Local variables:
 695  * c-basic-offset: 2
 696  * End:
 697  */