memcheck/mc_malloc_wrappers.c

/*--------------------------------------------------------------------*/
/*--- malloc/free wrappers for detecting errors and updating bits. ---*/
/*---                                         mc_malloc_wrappers.c ---*/
/*--------------------------------------------------------------------*/

/*
   This file is part of MemCheck, a heavyweight Valgrind tool for
   detecting memory errors.

   Copyright (C) 2000-2012 Julian Seward 
      jseward@acm.org

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.

   The GNU General Public License is contained in the file COPYING.
*/

#include "pub_tool_basics.h"
#include "pub_tool_execontext.h"
#include "pub_tool_poolalloc.h"
#include "pub_tool_hashtable.h"
#include "pub_tool_libcbase.h"
#include "pub_tool_libcassert.h"
#include "pub_tool_libcprint.h"
#include "pub_tool_mallocfree.h"
#include "pub_tool_options.h"
#include "pub_tool_replacemalloc.h"
#include "pub_tool_threadstate.h"
#include "pub_tool_tooliface.h"     // Needed for mc_include.h
#include "pub_tool_stacktrace.h"    // For VG_(get_and_pp_StackTrace)

#include "mc_include.h"

/*------------------------------------------------------------*/
/*--- Defns                                                ---*/
/*------------------------------------------------------------*/

/* Stats ... */
static SizeT cmalloc_n_mallocs  = 0;
static SizeT cmalloc_n_frees    = 0;
static ULong cmalloc_bs_mallocd = 0;

/* For debug printing to do with mempools: what stack trace
   depth to show. */
#define MEMPOOL_DEBUG_STACKTRACE_DEPTH 16


/*------------------------------------------------------------*/
/*--- Tracking malloc'd and free'd blocks                  ---*/
/*------------------------------------------------------------*/

SizeT MC_(Malloc_Redzone_SzB) = -10000000; // If used before set, should BOMB

/* Record malloc'd blocks. */
VgHashTable MC_(malloc_list) = NULL;

/* Memory pools: a hash table of MC_Mempools.  Search key is
   MC_Mempool::pool. */
VgHashTable MC_(mempool_list) = NULL;

/* Pool allocator for MC_Chunk. */   
PoolAlloc *MC_(chunk_poolalloc) = NULL;
static
MC_Chunk* create_MC_Chunk ( ThreadId tid, Addr p, SizeT szB,
                            MC_AllocKind kind);
static inline
void delete_MC_Chunk (MC_Chunk* mc);

/* Records blocks after freeing. */
/* Blocks freed by the client are queued in one of two lists of
   freed blocks not yet physically freed:
   "big blocks" freed list.
   "small blocks" freed list
   The blocks with a size >= MC_(clo_freelist_big_blocks)
   are linked in the big blocks freed list.
   This allows a client to allocate and free big blocks
   (e.g. bigger than VG_(clo_freelist_vol)) without losing
   immediately all protection against dangling pointers.
   position [0] is for big blocks, [1] is for small blocks. */
static MC_Chunk* freed_list_start[2]  = {NULL, NULL};
static MC_Chunk* freed_list_end[2]    = {NULL, NULL};

/* Put a shadow chunk on the freed blocks queue, possibly freeing up
   some of the oldest blocks in the queue at the same time. */
static void add_to_freed_queue ( MC_Chunk* mc )
{
   const Bool show = False;
   const int l = (mc->szB >= MC_(clo_freelist_big_blocks) ? 0 : 1);

   /* Put it at the end of the freed list, unless the block
      would be directly released any way : in this case, we
      put it at the head of the freed list. */
   if (freed_list_end[l] == NULL) {
      tl_assert(freed_list_start[l] == NULL);
      mc->next = NULL;
      freed_list_end[l]    = freed_list_start[l] = mc;
   } else {
      tl_assert(freed_list_end[l]->next == NULL);
      if (mc->szB >= MC_(clo_freelist_vol)) {
         mc->next = freed_list_start[l];
         freed_list_start[l] = mc;
      } else {
         mc->next = NULL;
         freed_list_end[l]->next = mc;
         freed_list_end[l]       = mc;
      }
   }
   VG_(free_queue_volume) += (Long)mc->szB;
   if (show)
      VG_(printf)("mc_freelist: acquire: volume now %lld\n", 
                  VG_(free_queue_volume));
   VG_(free_queue_length)++;
}

/* Release enough of the oldest blocks to bring the free queue
   volume below vg_clo_freelist_vol. 
   Start with big block list first.
   On entry, VG_(free_queue_volume) must be > MC_(clo_freelist_vol).
   On exit, VG_(free_queue_volume) will be <= MC_(clo_freelist_vol). */
static void release_oldest_block(void)
{
   const Bool show = False;
   int i;
   tl_assert (VG_(free_queue_volume) > MC_(clo_freelist_vol));
   tl_assert (freed_list_start[0] != NULL || freed_list_start[1] != NULL);

   for (i = 0; i < 2; i++) {
      while (VG_(free_queue_volume) > MC_(clo_freelist_vol)
             && freed_list_start[i] != NULL) {
         MC_Chunk* mc1;

         tl_assert(freed_list_end[i] != NULL);
         
         mc1 = freed_list_start[i];
         VG_(free_queue_volume) -= (Long)mc1->szB;
         VG_(free_queue_length)--;
         if (show)
            VG_(printf)("mc_freelist: discard: volume now %lld\n", 
                        VG_(free_queue_volume));
         tl_assert(VG_(free_queue_volume) >= 0);
         
         if (freed_list_start[i] == freed_list_end[i]) {
            freed_list_start[i] = freed_list_end[i] = NULL;
         } else {
            freed_list_start[i] = mc1->next;
         }
         mc1->next = NULL; /* just paranoia */

         /* free MC_Chunk */
         if (MC_AllocCustom != mc1->allockind)
            VG_(cli_free) ( (void*)(mc1->data) );
         delete_MC_Chunk ( mc1 );
      }
   }
}

MC_Chunk* MC_(get_freed_block_bracketting) (Addr a)
{
   int i;
   for (i = 0; i < 2; i++) {
      MC_Chunk*  mc;
      mc = freed_list_start[i];
      while (mc) {
         if (VG_(addr_is_in_block)( a, mc->data, mc->szB,
                                    MC_(Malloc_Redzone_SzB) ))
            return mc;
         mc = mc->next;
      }
   }
   return NULL;
}

/* Allocate a shadow chunk, put it on the appropriate list.
   If needed, release oldest blocks from freed list. */
static
MC_Chunk* create_MC_Chunk ( ThreadId tid, Addr p, SizeT szB,
                            MC_AllocKind kind)
{
   MC_Chunk* mc  = VG_(allocEltPA)(MC_(chunk_poolalloc));
   mc->data      = p;
   mc->szB       = szB;
   mc->allockind = kind;
   switch ( MC_(n_where_pointers)() ) {
      case 2: mc->where[1] = 0; // fallback to 1
      case 1: mc->where[0] = 0; // fallback to 0
      case 0: break;
      default: tl_assert(0);
   }
   MC_(set_allocated_at) (tid, mc);

   /* Each time a new MC_Chunk is created, release oldest blocks
      if the free list volume is exceeded. */
   if (VG_(free_queue_volume) > MC_(clo_freelist_vol))
      release_oldest_block();

   /* Paranoia ... ensure the MC_Chunk is off-limits to the client, so
      the mc->data field isn't visible to the leak checker.  If memory
      management is working correctly, any pointer returned by VG_(malloc)
      should be noaccess as far as the client is concerned. */
   if (!MC_(check_mem_is_noaccess)( (Addr)mc, sizeof(MC_Chunk), NULL )) {
      VG_(tool_panic)("create_MC_Chunk: shadow area is accessible");
   } 
   return mc;
}

static inline
void delete_MC_Chunk (MC_Chunk* mc)
{
   VG_(freeEltPA) (MC_(chunk_poolalloc), mc);
}

// True if mc is in the given block list.
static Bool in_block_list (VgHashTable block_list, MC_Chunk* mc)
{
   MC_Chunk* found_mc = VG_(HT_lookup) ( block_list, (UWord)mc->data );
   if (found_mc) {
      tl_assert (found_mc->data == mc->data);
      /* If a user builds a pool from a malloc-ed superblock
         and uses VALGRIND_MALLOCLIKE_BLOCK to "mark"
         an address at the beginning of this superblock, then
         this address will be twice in the block_list.
         We handle this case by checking size and allockind.
         Note: I suspect that having the same block
         twice in MC_(malloc_list) is a recipe for bugs.
         We might maybe better create a "standard" mempool to
         handle all this more cleanly. */
      if (found_mc->szB != mc->szB
          || found_mc->allockind != mc->allockind)
         return False;
      tl_assert (found_mc == mc);
      return True;
   } else
      return False;
}

// True if mc is a live block (not yet freed).
static Bool live_block (MC_Chunk* mc)
{
   if (mc->allockind == MC_AllocCustom) {
      MC_Mempool* mp;
      VG_(HT_ResetIter)(MC_(mempool_list));
      while ( (mp = VG_(HT_Next)(MC_(mempool_list))) ) {
         if ( in_block_list (mp->chunks, mc) )
            return True;
      }
   }
   /* Note: we fallback here for a not found MC_AllocCustom
      as such a block can be inserted in MC_(malloc_list)
      by VALGRIND_MALLOCLIKE_BLOCK. */
   return in_block_list ( MC_(malloc_list), mc );
}

ExeContext* MC_(allocated_at) (MC_Chunk* mc)
{
   switch (MC_(clo_keep_stacktraces)) {
      case KS_none:            return VG_(null_ExeContext) ();
      case KS_alloc:           return mc->where[0];
      case KS_free:            return VG_(null_ExeContext) ();
      case KS_alloc_then_free: return (live_block(mc) ?
                                       mc->where[0] : VG_(null_ExeContext) ());
      case KS_alloc_and_free:  return mc->where[0];
      default: tl_assert (0);
   }
}

ExeContext* MC_(freed_at) (MC_Chunk* mc)
{
   switch (MC_(clo_keep_stacktraces)) {
      case KS_none:            return VG_(null_ExeContext) ();
      case KS_alloc:           return VG_(null_ExeContext) ();
      case KS_free:            return (mc->where[0] ?
                                       mc->where[0] : VG_(null_ExeContext) ());
      case KS_alloc_then_free: return (live_block(mc) ?
                                       VG_(null_ExeContext) () : mc->where[0]);
      case KS_alloc_and_free:  return (mc->where[1] ?
                                       mc->where[1] : VG_(null_ExeContext) ());
      default: tl_assert (0);
   }
}

void  MC_(set_allocated_at) (ThreadId tid, MC_Chunk* mc)
{
   switch (MC_(clo_keep_stacktraces)) {
      case KS_none:            return;
      case KS_alloc:           break;
      case KS_free:            return;
      case KS_alloc_then_free: break;
      case KS_alloc_and_free:  break;
      default: tl_assert (0);
   }
   mc->where[0] = VG_(record_ExeContext) ( tid, 0/*first_ip_delta*/ );
}

void  MC_(set_freed_at) (ThreadId tid, MC_Chunk* mc)
{
   UInt pos;
   switch (MC_(clo_keep_stacktraces)) {
      case KS_none:            return;
      case KS_alloc:           return;
      case KS_free:            pos = 0; break;
      case KS_alloc_then_free: pos = 0; break;
      case KS_alloc_and_free:  pos = 1; break;
      default: tl_assert (0);
   }
   mc->where[pos] = VG_(record_ExeContext) ( tid, 0/*first_ip_delta*/ );
}

UInt MC_(n_where_pointers) (void)
{
   switch (MC_(clo_keep_stacktraces)) {
      case KS_none:            return 0;
      case KS_alloc:
      case KS_free:
      case KS_alloc_then_free: return 1;
      case KS_alloc_and_free:  return 2;
      default: tl_assert (0);
   }
}

/*------------------------------------------------------------*/
/*--- client_malloc(), etc                                 ---*/
/*------------------------------------------------------------*/

// XXX: should make this a proper error (bug #79311).
static Bool complain_about_silly_args(SizeT sizeB, const HChar* fn)
{
   // Cast to a signed type to catch any unexpectedly negative args.  We're
   // assuming here that the size asked for is not greater than 2^31 bytes
   // (for 32-bit platforms) or 2^63 bytes (for 64-bit platforms).
   if ((SSizeT)sizeB < 0) {
      if (!VG_(clo_xml)) 
         VG_(message)(Vg_UserMsg, "Warning: silly arg (%ld) to %s()\n",
                      (SSizeT)sizeB, fn );
      return True;
   }
   return False;
}

static Bool complain_about_silly_args2(SizeT n, SizeT sizeB)
{
   if ((SSizeT)n < 0 || (SSizeT)sizeB < 0) {
      if (!VG_(clo_xml))
         VG_(message)(Vg_UserMsg,
                      "Warning: silly args (%ld,%ld) to calloc()\n",
                      (SSizeT)n, (SSizeT)sizeB);
      return True;
   }
   return False;
}

/* Allocate memory and note change in memory available */
void* MC_(new_block) ( ThreadId tid,
                       Addr p, SizeT szB, SizeT alignB,
                       Bool is_zeroed, MC_AllocKind kind, VgHashTable table)
{
   MC_Chunk* mc;

   // Allocate and zero if necessary
   if (p) {
      tl_assert(MC_AllocCustom == kind);
   } else {
      tl_assert(MC_AllocCustom != kind);
      p = (Addr)VG_(cli_malloc)( alignB, szB );
      if (!p) {
         return NULL;
      }
      if (is_zeroed) {
         VG_(memset)((void*)p, 0, szB);
      } else 
      if (MC_(clo_malloc_fill) != -1) {
         tl_assert(MC_(clo_malloc_fill) >= 0x00 && MC_(clo_malloc_fill) <= 0xFF);
         VG_(memset)((void*)p, MC_(clo_malloc_fill), szB);
      }
   }

   // Only update stats if allocation succeeded.
   cmalloc_n_mallocs ++;
   cmalloc_bs_mallocd += (ULong)szB;
   mc = create_MC_Chunk (tid, p, szB, kind);
   VG_(HT_add_node)( table, mc );

   if (is_zeroed)
      MC_(make_mem_defined)( p, szB );
   else {
      UInt ecu = VG_(get_ECU_from_ExeContext)(MC_(allocated_at)(mc));
      tl_assert(VG_(is_plausible_ECU)(ecu));
      MC_(make_mem_undefined_w_otag)( p, szB, ecu | MC_OKIND_HEAP );
   }

   return (void*)p;
}

void* MC_(malloc) ( ThreadId tid, SizeT n )
{
   if (complain_about_silly_args(n, "malloc")) {
      return NULL;
   } else {
      return MC_(new_block) ( tid, 0, n, VG_(clo_alignment), 
         /*is_zeroed*/False, MC_AllocMalloc, MC_(malloc_list));
   }
}

void* MC_(__builtin_new) ( ThreadId tid, SizeT n )
{
   if (complain_about_silly_args(n, "__builtin_new")) {
      return NULL;
   } else {
      return MC_(new_block) ( tid, 0, n, VG_(clo_alignment), 
         /*is_zeroed*/False, MC_AllocNew, MC_(malloc_list));
   }
}

void* MC_(__builtin_vec_new) ( ThreadId tid, SizeT n )
{
   if (complain_about_silly_args(n, "__builtin_vec_new")) {
      return NULL;
   } else {
      return MC_(new_block) ( tid, 0, n, VG_(clo_alignment), 
         /*is_zeroed*/False, MC_AllocNewVec, MC_(malloc_list));
   }
}

void* MC_(memalign) ( ThreadId tid, SizeT alignB, SizeT n )
{
   if (complain_about_silly_args(n, "memalign")) {
      return NULL;
   } else {
      return MC_(new_block) ( tid, 0, n, alignB, 
         /*is_zeroed*/False, MC_AllocMalloc, MC_(malloc_list));
   }
}

void* MC_(calloc) ( ThreadId tid, SizeT nmemb, SizeT size1 )
{
   if (complain_about_silly_args2(nmemb, size1)) {
      return NULL;
   } else {
      return MC_(new_block) ( tid, 0, nmemb*size1, VG_(clo_alignment),
         /*is_zeroed*/True, MC_AllocMalloc, MC_(malloc_list));
   }
}

static
void die_and_free_mem ( ThreadId tid, MC_Chunk* mc, SizeT rzB )
{
   /* Note: we do not free fill the custom allocs produced
      by MEMPOOL or by MALLOC/FREELIKE_BLOCK requests. */
   if (MC_(clo_free_fill) != -1 && MC_AllocCustom != mc->allockind ) {
      tl_assert(MC_(clo_free_fill) >= 0x00 && MC_(clo_free_fill) <= 0xFF);
      VG_(memset)((void*)mc->data, MC_(clo_free_fill), mc->szB);
   }

   /* Note: make redzones noaccess again -- just in case user made them
      accessible with a client request... */
   MC_(make_mem_noaccess)( mc->data-rzB, mc->szB + 2*rzB );

   /* Record where freed */
   MC_(set_freed_at) (tid, mc);
   /* Put it out of harm's way for a while */
   add_to_freed_queue ( mc );
   /* If the free list volume is bigger than MC_(clo_freelist_vol),
      we wait till the next block allocation to release blocks.
      This increase the chance to discover dangling pointer usage,
      even for big blocks being freed by the client. */
}


static
void record_freemismatch_error (ThreadId tid, MC_Chunk* mc)
{
   /* MC_(record_freemismatch_error) reports errors for still
      allocated blocks but we are in the middle of freeing it.  To
      report the error correctly, we re-insert the chunk (making it
      again a "clean allocated block", report the error, and then
      re-remove the chunk.  This avoids to do a VG_(HT_lookup)
      followed by a VG_(HT_remove) in all "non-erroneous cases". */
   VG_(HT_add_node)( MC_(malloc_list), mc );
   MC_(record_freemismatch_error) ( tid, mc );
   if ((mc != VG_(HT_remove) ( MC_(malloc_list), (UWord)mc->data )))
      tl_assert(0);
}

void MC_(handle_free) ( ThreadId tid, Addr p, UInt rzB, MC_AllocKind kind )
{
   MC_Chunk* mc;

   cmalloc_n_frees++;

   mc = VG_(HT_remove) ( MC_(malloc_list), (UWord)p );
   if (mc == NULL) {
      MC_(record_free_error) ( tid, p );
   } else {
      /* check if it is a matching free() / delete / delete [] */
      if (kind != mc->allockind) {
         tl_assert(p == mc->data);
         record_freemismatch_error ( tid, mc );
      }
      die_and_free_mem ( tid, mc, rzB );
   }
}

void MC_(free) ( ThreadId tid, void* p )
{
   MC_(handle_free)( 
      tid, (Addr)p, MC_(Malloc_Redzone_SzB), MC_AllocMalloc );
}

void MC_(__builtin_delete) ( ThreadId tid, void* p )
{
   MC_(handle_free)(
      tid, (Addr)p, MC_(Malloc_Redzone_SzB), MC_AllocNew);
}

void MC_(__builtin_vec_delete) ( ThreadId tid, void* p )
{
   MC_(handle_free)(
      tid, (Addr)p, MC_(Malloc_Redzone_SzB), MC_AllocNewVec);
}

void* MC_(realloc) ( ThreadId tid, void* p_old, SizeT new_szB )
{
   MC_Chunk* old_mc;
   MC_Chunk* new_mc;
   Addr      a_new; 
   SizeT     old_szB;

   if (complain_about_silly_args(new_szB, "realloc")) 
      return NULL;

   cmalloc_n_frees ++;
   cmalloc_n_mallocs ++;
   cmalloc_bs_mallocd += (ULong)new_szB;

   /* Remove the old block */
   old_mc = VG_(HT_remove) ( MC_(malloc_list), (UWord)p_old );
   if (old_mc == NULL) {
      MC_(record_free_error) ( tid, (Addr)p_old );
      /* We return to the program regardless. */
      return NULL;
   }

   /* check if its a matching free() / delete / delete [] */
   if (MC_AllocMalloc != old_mc->allockind) {
      /* can not realloc a range that was allocated with new or new [] */
      tl_assert((Addr)p_old == old_mc->data);
      record_freemismatch_error ( tid, old_mc );
      /* but keep going anyway */
   }

   old_szB = old_mc->szB;

   /* Get new memory */
   a_new = (Addr)VG_(cli_malloc)(VG_(clo_alignment), new_szB);

   if (a_new) {
      /* In all cases, even when the new size is smaller or unchanged, we
         reallocate and copy the contents, and make the old block
         inaccessible.  This is so as to guarantee to catch all cases of
         accesses via the old address after reallocation, regardless of
         the change in size.  (Of course the ability to detect accesses
         to the old block also depends on the size of the freed blocks
         queue). */

      // Allocate a new chunk.
      new_mc = create_MC_Chunk( tid, a_new, new_szB, MC_AllocMalloc );

      // Now insert the new mc (with a new 'data' field) into malloc_list.
      VG_(HT_add_node)( MC_(malloc_list), new_mc );

      /* Retained part is copied, red zones set as normal */

      /* Redzone at the front */
      MC_(make_mem_noaccess)( a_new-MC_(Malloc_Redzone_SzB), 
                              MC_(Malloc_Redzone_SzB) );

      /* payload */
      if (old_szB >= new_szB) {
         /* new size is smaller or the same */

         /* Copy address range state and value from old to new */
         MC_(copy_address_range_state) ( (Addr)p_old, a_new, new_szB );
         VG_(memcpy)((void*)a_new, p_old, new_szB);
      } else {
         /* new size is bigger */
         UInt        ecu;

         /* Copy address range state and value from old to new */
         MC_(copy_address_range_state) ( (Addr)p_old, a_new, old_szB );
         VG_(memcpy)((void*)a_new, p_old, old_szB);

         // If the block has grown, we mark the grown area as undefined.
         // We have to do that after VG_(HT_add_node) to ensure the ecu
         // execontext is for a fully allocated block.
         ecu = VG_(get_ECU_from_ExeContext)(MC_(allocated_at)(new_mc));
         tl_assert(VG_(is_plausible_ECU)(ecu));
         MC_(make_mem_undefined_w_otag)( a_new+old_szB,
                                         new_szB-old_szB,
                                         ecu | MC_OKIND_HEAP );

         /* Possibly fill new area with specified junk */
         if (MC_(clo_malloc_fill) != -1) {
            tl_assert(MC_(clo_malloc_fill) >= 0x00
                      && MC_(clo_malloc_fill) <= 0xFF);
            VG_(memset)((void*)(a_new+old_szB), MC_(clo_malloc_fill), 
                                                new_szB-old_szB);
         }
      }

      /* Redzone at the back. */
      MC_(make_mem_noaccess)        ( a_new+new_szB, MC_(Malloc_Redzone_SzB));

      /* Possibly fill freed area with specified junk. */
      if (MC_(clo_free_fill) != -1) {
         tl_assert(MC_(clo_free_fill) >= 0x00 && MC_(clo_free_fill) <= 0xFF);
         VG_(memset)((void*)p_old, MC_(clo_free_fill), old_szB);
      }

      /* Free old memory */
      /* Nb: we have to allocate a new MC_Chunk for the new memory rather
         than recycling the old one, so that any erroneous accesses to the
         old memory are reported. */
      die_and_free_mem ( tid, old_mc, MC_(Malloc_Redzone_SzB) );

   } else {
      /* Could not allocate new client memory.
         Re-insert the old_mc (with the old ptr) in the HT, as old_mc was
         unconditionally removed at the beginning of the function. */
      VG_(HT_add_node)( MC_(malloc_list), old_mc );
   }

   return (void*)a_new;
}

SizeT MC_(malloc_usable_size) ( ThreadId tid, void* p )
{
   MC_Chunk* mc = VG_(HT_lookup) ( MC_(malloc_list), (UWord)p );

   // There may be slop, but pretend there isn't because only the asked-for
   // area will be marked as addressable.
   return ( mc ? mc->szB : 0 );
}

/* This handles the in place resize of a block, as performed by the
   VALGRIND_RESIZEINPLACE_BLOCK client request.  It is unrelated to,
   and not used for, handling of the normal libc realloc()
   function. */
void MC_(handle_resizeInPlace)(ThreadId tid, Addr p,
                               SizeT oldSizeB, SizeT newSizeB, SizeT rzB)
{
   MC_Chunk* mc = VG_(HT_lookup) ( MC_(malloc_list), (UWord)p );
   if (!mc || mc->szB != oldSizeB || newSizeB == 0) {
      /* Reject if: p is not found, or oldSizeB is wrong,
         or new block would be empty. */
      MC_(record_free_error) ( tid, p );
      return;
   }

   if (oldSizeB == newSizeB)
      return;

   mc->szB = newSizeB;
   if (newSizeB < oldSizeB) {
      MC_(make_mem_noaccess)( p + newSizeB, oldSizeB - newSizeB + rzB );
   } else {
      ExeContext* ec  = VG_(record_ExeContext)(tid, 0/*first_ip_delta*/);
      UInt        ecu = VG_(get_ECU_from_ExeContext)(ec);
      MC_(make_mem_undefined_w_otag)( p + oldSizeB, newSizeB - oldSizeB,
                                      ecu | MC_OKIND_HEAP );
      if (rzB > 0)
         MC_(make_mem_noaccess)( p + newSizeB, rzB );
   }
}


/*------------------------------------------------------------*/
/*--- Memory pool stuff.                                   ---*/
/*------------------------------------------------------------*/

/* Set to 1 for intensive sanity checking.  Is very expensive though
   and should not be used in production scenarios.  See #255966. */
#define MP_DETAILED_SANITY_CHECKS 0

static void check_mempool_sane(MC_Mempool* mp); /*forward*/


void MC_(create_mempool)(Addr pool, UInt rzB, Bool is_zeroed)
{
   MC_Mempool* mp;

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, "create_mempool(0x%lx, %d, %d)\n",
                               pool, rzB, is_zeroed);
      VG_(get_and_pp_StackTrace)
         (VG_(get_running_tid)(), MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   mp = VG_(HT_lookup)(MC_(mempool_list), (UWord)pool);
   if (mp != NULL) {
     VG_(tool_panic)("MC_(create_mempool): duplicate pool creation");
   }
   
   mp = VG_(malloc)("mc.cm.1", sizeof(MC_Mempool));
   mp->pool       = pool;
   mp->rzB        = rzB;
   mp->is_zeroed  = is_zeroed;
   mp->chunks     = VG_(HT_construct)( "MC_(create_mempool)" );
   check_mempool_sane(mp);

   /* Paranoia ... ensure this area is off-limits to the client, so
      the mp->data field isn't visible to the leak checker.  If memory
      management is working correctly, anything pointer returned by
      VG_(malloc) should be noaccess as far as the client is
      concerned. */
   if (!MC_(check_mem_is_noaccess)( (Addr)mp, sizeof(MC_Mempool), NULL )) {
      VG_(tool_panic)("MC_(create_mempool): shadow area is accessible");
   } 

   VG_(HT_add_node)( MC_(mempool_list), mp );
}

void MC_(destroy_mempool)(Addr pool)
{
   MC_Chunk*   mc;
   MC_Mempool* mp;

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, "destroy_mempool(0x%lx)\n", pool);
      VG_(get_and_pp_StackTrace)
         (VG_(get_running_tid)(), MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   mp = VG_(HT_remove) ( MC_(mempool_list), (UWord)pool );

   if (mp == NULL) {
      ThreadId tid = VG_(get_running_tid)();
      MC_(record_illegal_mempool_error) ( tid, pool );
      return;
   }
   check_mempool_sane(mp);

   // Clean up the chunks, one by one
   VG_(HT_ResetIter)(mp->chunks);
   while ( (mc = VG_(HT_Next)(mp->chunks)) ) {
      /* Note: make redzones noaccess again -- just in case user made them
         accessible with a client request... */
      MC_(make_mem_noaccess)(mc->data-mp->rzB, mc->szB + 2*mp->rzB );
   }
   // Destroy the chunk table
   VG_(HT_destruct)(mp->chunks, (void (*)(void *))delete_MC_Chunk);

   VG_(free)(mp);
}

static Int 
mp_compar(const void* n1, const void* n2)
{
   const MC_Chunk* mc1 = *(const MC_Chunk *const *)n1;
   const MC_Chunk* mc2 = *(const MC_Chunk *const *)n2;
   if (mc1->data < mc2->data) return -1;
   if (mc1->data > mc2->data) return  1;
   return 0;
}

static void 
check_mempool_sane(MC_Mempool* mp)
{
   UInt n_chunks, i, bad = 0;   
   static UInt tick = 0;

   MC_Chunk **chunks = (MC_Chunk**) VG_(HT_to_array)( mp->chunks, &n_chunks );
   if (!chunks)
      return;

   if (VG_(clo_verbosity) > 1) {
     if (tick++ >= 10000)
       {
	 UInt total_pools = 0, total_chunks = 0;
	 MC_Mempool* mp2;
	 
	 VG_(HT_ResetIter)(MC_(mempool_list));
	 while ( (mp2 = VG_(HT_Next)(MC_(mempool_list))) ) {
	   total_pools++;
	   VG_(HT_ResetIter)(mp2->chunks);
	   while (VG_(HT_Next)(mp2->chunks)) {
	     total_chunks++;
	   }
	 }
	 
         VG_(message)(Vg_UserMsg, 
                      "Total mempools active: %d pools, %d chunks\n", 
		      total_pools, total_chunks);
	 tick = 0;
       }
   }


   VG_(ssort)((void*)chunks, n_chunks, sizeof(VgHashNode*), mp_compar);
         
   /* Sanity check; assert that the blocks are now in order */
   for (i = 0; i < n_chunks-1; i++) {
      if (chunks[i]->data > chunks[i+1]->data) {
         VG_(message)(Vg_UserMsg, 
                      "Mempool chunk %d / %d is out of order "
                      "wrt. its successor\n", 
                      i+1, n_chunks);
         bad = 1;
      }
   }
   
   /* Sanity check -- make sure they don't overlap */
   for (i = 0; i < n_chunks-1; i++) {
      if (chunks[i]->data + chunks[i]->szB > chunks[i+1]->data ) {
         VG_(message)(Vg_UserMsg, 
                      "Mempool chunk %d / %d overlaps with its successor\n", 
                      i+1, n_chunks);
         bad = 1;
      }
   }

   if (bad) {
         VG_(message)(Vg_UserMsg, 
                "Bad mempool (%d chunks), dumping chunks for inspection:\n",
                n_chunks);
         for (i = 0; i < n_chunks; ++i) {
            VG_(message)(Vg_UserMsg, 
                         "Mempool chunk %d / %d: %ld bytes "
                         "[%lx,%lx), allocated:\n",
                         i+1, 
                         n_chunks, 
                         chunks[i]->szB + 0UL,
                         chunks[i]->data, 
                         chunks[i]->data + chunks[i]->szB);

            VG_(pp_ExeContext)(MC_(allocated_at)(chunks[i]));
         }
   }
   VG_(free)(chunks);
}

void MC_(mempool_alloc)(ThreadId tid, Addr pool, Addr addr, SizeT szB)
{
   MC_Mempool* mp;

   if (VG_(clo_verbosity) > 2) {     
      VG_(message)(Vg_UserMsg, "mempool_alloc(0x%lx, 0x%lx, %ld)\n",
                               pool, addr, szB);
      VG_(get_and_pp_StackTrace) (tid, MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   mp = VG_(HT_lookup) ( MC_(mempool_list), (UWord)pool );
   if (mp == NULL) {
      MC_(record_illegal_mempool_error) ( tid, pool );
   } else {
      if (MP_DETAILED_SANITY_CHECKS) check_mempool_sane(mp);
      MC_(new_block)(tid, addr, szB, /*ignored*/0, mp->is_zeroed,
                     MC_AllocCustom, mp->chunks);
      if (mp->rzB > 0) {
         // This is not needed if the user application has properly
         // marked the superblock noaccess when defining the mempool.
         // We however still mark the redzones noaccess to still catch
         // some bugs if user forgot.
         MC_(make_mem_noaccess) ( addr - mp->rzB, mp->rzB);
         MC_(make_mem_noaccess) ( addr + szB, mp->rzB);
      }
      if (MP_DETAILED_SANITY_CHECKS) check_mempool_sane(mp);
   }
}

void MC_(mempool_free)(Addr pool, Addr addr)
{
   MC_Mempool*  mp;
   MC_Chunk*    mc;
   ThreadId     tid = VG_(get_running_tid)();

   mp = VG_(HT_lookup)(MC_(mempool_list), (UWord)pool);
   if (mp == NULL) {
      MC_(record_illegal_mempool_error)(tid, pool);
      return;
   }

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, "mempool_free(0x%lx, 0x%lx)\n", pool, addr);
      VG_(get_and_pp_StackTrace) (tid, MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   if (MP_DETAILED_SANITY_CHECKS) check_mempool_sane(mp);
   mc = VG_(HT_remove)(mp->chunks, (UWord)addr);
   if (mc == NULL) {
      MC_(record_free_error)(tid, (Addr)addr);
      return;
   }

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, 
		   "mempool_free(0x%lx, 0x%lx) freed chunk of %ld bytes\n",
		   pool, addr, mc->szB + 0UL);
   }

   die_and_free_mem ( tid, mc, mp->rzB );
   if (MP_DETAILED_SANITY_CHECKS) check_mempool_sane(mp);
}


void MC_(mempool_trim)(Addr pool, Addr addr, SizeT szB)
{
   MC_Mempool*  mp;
   MC_Chunk*    mc;
   ThreadId     tid = VG_(get_running_tid)();
   UInt         n_shadows, i;
   VgHashNode** chunks;

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, "mempool_trim(0x%lx, 0x%lx, %ld)\n",
                               pool, addr, szB);
      VG_(get_and_pp_StackTrace) (tid, MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   mp = VG_(HT_lookup)(MC_(mempool_list), (UWord)pool);
   if (mp == NULL) {
      MC_(record_illegal_mempool_error)(tid, pool);
      return;
   }

   check_mempool_sane(mp);
   chunks = VG_(HT_to_array) ( mp->chunks, &n_shadows );
   if (n_shadows == 0) {
     tl_assert(chunks == NULL);
     return;
   }

   tl_assert(chunks != NULL);
   for (i = 0; i < n_shadows; ++i) {

      Addr lo, hi, min, max;

      mc = (MC_Chunk*) chunks[i];

      lo = mc->data;
      hi = mc->szB == 0 ? mc->data : mc->data + mc->szB - 1;

#define EXTENT_CONTAINS(x) ((addr <= (x)) && ((x) < addr + szB))

      if (EXTENT_CONTAINS(lo) && EXTENT_CONTAINS(hi)) {

         /* The current chunk is entirely within the trim extent: keep
            it. */

         continue;

      } else if ( (! EXTENT_CONTAINS(lo)) &&
                  (! EXTENT_CONTAINS(hi)) ) {

         /* The current chunk is entirely outside the trim extent:
            delete it. */

         if (VG_(HT_remove)(mp->chunks, (UWord)mc->data) == NULL) {
            MC_(record_free_error)(tid, (Addr)mc->data);
            VG_(free)(chunks);
            if (MP_DETAILED_SANITY_CHECKS) check_mempool_sane(mp);
            return;
         }
         die_and_free_mem ( tid, mc, mp->rzB );  

      } else {

         /* The current chunk intersects the trim extent: remove,
            trim, and reinsert it. */

         tl_assert(EXTENT_CONTAINS(lo) ||
                   EXTENT_CONTAINS(hi));
         if (VG_(HT_remove)(mp->chunks, (UWord)mc->data) == NULL) {
            MC_(record_free_error)(tid, (Addr)mc->data);
            VG_(free)(chunks);
            if (MP_DETAILED_SANITY_CHECKS) check_mempool_sane(mp);
            return;
         }

         if (mc->data < addr) {
           min = mc->data;
           lo = addr;
         } else {
           min = addr;
           lo = mc->data;
         }

         if (mc->data + szB > addr + szB) {
           max = mc->data + szB;
           hi = addr + szB;
         } else {
           max = addr + szB;
           hi = mc->data + szB;
         }

         tl_assert(min <= lo);
         tl_assert(lo < hi);
         tl_assert(hi <= max);

         if (min < lo && !EXTENT_CONTAINS(min)) {
           MC_(make_mem_noaccess)( min, lo - min);
         }

         if (hi < max && !EXTENT_CONTAINS(max)) {
           MC_(make_mem_noaccess)( hi, max - hi );
         }

         mc->data = lo;
         mc->szB = (UInt) (hi - lo);
         VG_(HT_add_node)( mp->chunks, mc );        
      }

#undef EXTENT_CONTAINS
      
   }
   check_mempool_sane(mp);
   VG_(free)(chunks);
}

void MC_(move_mempool)(Addr poolA, Addr poolB)
{
   MC_Mempool* mp;

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, "move_mempool(0x%lx, 0x%lx)\n", poolA, poolB);
      VG_(get_and_pp_StackTrace)
         (VG_(get_running_tid)(), MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   mp = VG_(HT_remove) ( MC_(mempool_list), (UWord)poolA );

   if (mp == NULL) {
      ThreadId tid = VG_(get_running_tid)();
      MC_(record_illegal_mempool_error) ( tid, poolA );
      return;
   }

   mp->pool = poolB;
   VG_(HT_add_node)( MC_(mempool_list), mp );
}

void MC_(mempool_change)(Addr pool, Addr addrA, Addr addrB, SizeT szB)
{
   MC_Mempool*  mp;
   MC_Chunk*    mc;
   ThreadId     tid = VG_(get_running_tid)();

   if (VG_(clo_verbosity) > 2) {
      VG_(message)(Vg_UserMsg, "mempool_change(0x%lx, 0x%lx, 0x%lx, %ld)\n",
                   pool, addrA, addrB, szB);
      VG_(get_and_pp_StackTrace) (tid, MEMPOOL_DEBUG_STACKTRACE_DEPTH);
   }

   mp = VG_(HT_lookup)(MC_(mempool_list), (UWord)pool);
   if (mp == NULL) {
      MC_(record_illegal_mempool_error)(tid, pool);
      return;
   }

   check_mempool_sane(mp);

   mc = VG_(HT_remove)(mp->chunks, (UWord)addrA);
   if (mc == NULL) {
      MC_(record_free_error)(tid, (Addr)addrA);
      return;
   }

   mc->data = addrB;
   mc->szB  = szB;
   VG_(HT_add_node)( mp->chunks, mc );

   check_mempool_sane(mp);
}

Bool MC_(mempool_exists)(Addr pool)
{
   MC_Mempool*  mp;

   mp = VG_(HT_lookup)(MC_(mempool_list), (UWord)pool);
   if (mp == NULL) {
       return False;
   }
   return True;
}


/*------------------------------------------------------------*/
/*--- Statistics printing                                  ---*/
/*------------------------------------------------------------*/

void MC_(print_malloc_stats) ( void )
{
   MC_Chunk* mc;
   SizeT     nblocks = 0;
   ULong     nbytes  = 0;
   
   if (VG_(clo_verbosity) == 0)
      return;
   if (VG_(clo_xml))
      return;

   /* Count memory still in use. */
   VG_(HT_ResetIter)(MC_(malloc_list));
   while ( (mc = VG_(HT_Next)(MC_(malloc_list))) ) {
      nblocks++;
      nbytes += (ULong)mc->szB;
   }

   VG_(umsg)(
      "HEAP SUMMARY:\n"
      "    in use at exit: %'llu bytes in %'lu blocks\n"
      "  total heap usage: %'lu allocs, %'lu frees, %'llu bytes allocated\n"
      "\n",
      nbytes, nblocks,
      cmalloc_n_mallocs,
      cmalloc_n_frees, cmalloc_bs_mallocd
   );
}

SizeT MC_(get_cmalloc_n_frees) ( void )
{
   return cmalloc_n_frees;
}


/*--------------------------------------------------------------------*/
/*--- end                                                          ---*/
/*--------------------------------------------------------------------*/