text: //===-- asan_allocator.cc -------------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file is a part of AddressSanitizer, an address sanity checker.
  //
  // Implementation of ASan's memory allocator, 2-nd version.
  // This variant uses the allocator from sanitizer_common, i.e. the one shared
  // with ThreadSanitizer and MemorySanitizer.
  //
  //===----------------------------------------------------------------------===//
  #include "asan_allocator.h"
  
  #include "asan_mapping.h"
  #include "asan_poisoning.h"
  #include "asan_report.h"
  #include "asan_stack.h"
  #include "asan_thread.h"
  #include "sanitizer_common/sanitizer_allocator_interface.h"
  #include "sanitizer_common/sanitizer_flags.h"
  #include "sanitizer_common/sanitizer_internal_defs.h"
  #include "sanitizer_common/sanitizer_list.h"
  #include "sanitizer_common/sanitizer_stackdepot.h"
  #include "sanitizer_common/sanitizer_quarantine.h"
  #include "lsan/lsan_common.h"
  
  namespace __asan {
  
  // Valid redzone sizes are 16, 32, 64, ... 2048, so we encode them in 3 bits.
  // We use adaptive redzones: for larger allocation larger redzones are used.
  static u32 RZLog2Size(u32 rz_log) {
    CHECK_LT(rz_log, 8);
    return 16 << rz_log;
  }
  
  static u32 RZSize2Log(u32 rz_size) {
    CHECK_GE(rz_size, 16);
    CHECK_LE(rz_size, 2048);
    CHECK(IsPowerOfTwo(rz_size));
    u32 res = Log2(rz_size) - 4;
    CHECK_EQ(rz_size, RZLog2Size(res));
    return res;
  }
  
  static AsanAllocator &get_allocator();
  
  // The memory chunk allocated from the underlying allocator looks like this:
  // L L L L L L H H U U U U U U R R
  //   L -- left redzone words (0 or more bytes)
  //   H -- ChunkHeader (16 bytes), which is also a part of the left redzone.
  //   U -- user memory.
  //   R -- right redzone (0 or more bytes)
  // ChunkBase consists of ChunkHeader and other bytes that overlap with user
  // memory.
  
  // If the left redzone is greater than the ChunkHeader size we store a magic
  // value in the first uptr word of the memory block and store the address of
  // ChunkBase in the next uptr.
  // M B L L L L L L L L L  H H U U U U U U
  //   |                    ^
  //   ---------------------|
  //   M -- magic value kAllocBegMagic
  //   B -- address of ChunkHeader pointing to the first 'H'
  static const uptr kAllocBegMagic = 0xCC6E96B9;
  
  struct ChunkHeader {
    // 1-st 8 bytes.
    u32 chunk_state       : 8;  // Must be first.
    u32 alloc_tid         : 24;
  
    u32 free_tid          : 24;
    u32 from_memalign     : 1;
    u32 alloc_type        : 2;
    u32 rz_log            : 3;
    u32 lsan_tag          : 2;
    // 2-nd 8 bytes
    // This field is used for small sizes. For large sizes it is equal to
    // SizeClassMap::kMaxSize and the actual size is stored in the
    // SecondaryAllocator's metadata.
    u32 user_requested_size;
    u32 alloc_context_id;
  };
  
  struct ChunkBase : ChunkHeader {
    // Header2, intersects with user memory.
    u32 free_context_id;
  };
  
  static const uptr kChunkHeaderSize = sizeof(ChunkHeader);
  static const uptr kChunkHeader2Size = sizeof(ChunkBase) - kChunkHeaderSize;
  COMPILER_CHECK(kChunkHeaderSize == 16);
  COMPILER_CHECK(kChunkHeader2Size <= 16);
  
  // Every chunk of memory allocated by this allocator can be in one of 3 states:
  // CHUNK_AVAILABLE: the chunk is in the free list and ready to be allocated.
  // CHUNK_ALLOCATED: the chunk is allocated and not yet freed.
  // CHUNK_QUARANTINE: the chunk was freed and put into quarantine zone.
  enum {
    CHUNK_AVAILABLE  = 0,  // 0 is the default value even if we didn't set it.
    CHUNK_ALLOCATED  = 2,
    CHUNK_QUARANTINE = 3
  };
  
  struct AsanChunk: ChunkBase {
    uptr Beg() { return reinterpret_cast<uptr>(this) + kChunkHeaderSize; }
    uptr UsedSize(bool locked_version = false) {
      if (user_requested_size != SizeClassMap::kMaxSize)
        return user_requested_size;
      return *reinterpret_cast<uptr *>(
                 get_allocator().GetMetaData(AllocBeg(locked_version)));
    }
    void *AllocBeg(bool locked_version = false) {
      if (from_memalign) {
        if (locked_version)
          return get_allocator().GetBlockBeginFastLocked(
              reinterpret_cast<void *>(this));
        return get_allocator().GetBlockBegin(reinterpret_cast<void *>(this));
      }
      return reinterpret_cast<void*>(Beg() - RZLog2Size(rz_log));
    }
    bool AddrIsInside(uptr addr, bool locked_version = false) {
      return (addr >= Beg()) && (addr < Beg() + UsedSize(locked_version));
    }
  };
  
  struct QuarantineCallback {
    explicit QuarantineCallback(AllocatorCache *cache)
        : cache_(cache) {
    }
  
    void Recycle(AsanChunk *m) {
      CHECK_EQ(m->chunk_state, CHUNK_QUARANTINE);
      atomic_store((atomic_uint8_t*)m, CHUNK_AVAILABLE, memory_order_relaxed);
      CHECK_NE(m->alloc_tid, kInvalidTid);
      CHECK_NE(m->free_tid, kInvalidTid);
      PoisonShadow(m->Beg(),
                   RoundUpTo(m->UsedSize(), SHADOW_GRANULARITY),
                   kAsanHeapLeftRedzoneMagic);
      void *p = reinterpret_cast<void *>(m->AllocBeg());
      if (p != m) {
        uptr *alloc_magic = reinterpret_cast<uptr *>(p);
        CHECK_EQ(alloc_magic[0], kAllocBegMagic);
        // Clear the magic value, as allocator internals may overwrite the
        // contents of deallocated chunk, confusing GetAsanChunk lookup.
        alloc_magic[0] = 0;
        CHECK_EQ(alloc_magic[1], reinterpret_cast<uptr>(m));
      }
  
      // Statistics.
      AsanStats &thread_stats = GetCurrentThreadStats();
      thread_stats.real_frees++;
      thread_stats.really_freed += m->UsedSize();
  
      get_allocator().Deallocate(cache_, p);
    }
  
    void *Allocate(uptr size) {
      return get_allocator().Allocate(cache_, size, 1, false);
    }
  
    void Deallocate(void *p) {
      get_allocator().Deallocate(cache_, p);
    }
  
    AllocatorCache *cache_;
  };
  
  typedef Quarantine<QuarantineCallback, AsanChunk> AsanQuarantine;
  typedef AsanQuarantine::Cache QuarantineCache;
  
  void AsanMapUnmapCallback::OnMap(uptr p, uptr size) const {
    PoisonShadow(p, size, kAsanHeapLeftRedzoneMagic);
    // Statistics.
    AsanStats &thread_stats = GetCurrentThreadStats();
    thread_stats.mmaps++;
    thread_stats.mmaped += size;
  }
  void AsanMapUnmapCallback::OnUnmap(uptr p, uptr size) const {
    PoisonShadow(p, size, 0);
    // We are about to unmap a chunk of user memory.
    // Mark the corresponding shadow memory as not needed.
    FlushUnneededASanShadowMemory(p, size);
    // Statistics.
    AsanStats &thread_stats = GetCurrentThreadStats();
    thread_stats.munmaps++;
    thread_stats.munmaped += size;
  }
  
  // We can not use THREADLOCAL because it is not supported on some of the
  // platforms we care about (OSX 10.6, Android).
  // static THREADLOCAL AllocatorCache cache;
  AllocatorCache *GetAllocatorCache(AsanThreadLocalMallocStorage *ms) {
    CHECK(ms);
    return &ms->allocator_cache;
  }
  
  QuarantineCache *GetQuarantineCache(AsanThreadLocalMallocStorage *ms) {
    CHECK(ms);
    CHECK_LE(sizeof(QuarantineCache), sizeof(ms->quarantine_cache));
    return reinterpret_cast<QuarantineCache *>(ms->quarantine_cache);
  }
  
  void AllocatorOptions::SetFrom(const Flags *f, const CommonFlags *cf) {
    quarantine_size_mb = f->quarantine_size_mb;
    min_redzone = f->redzone;
    max_redzone = f->max_redzone;
    may_return_null = cf->allocator_may_return_null;
    alloc_dealloc_mismatch = f->alloc_dealloc_mismatch;
  }
  
  void AllocatorOptions::CopyTo(Flags *f, CommonFlags *cf) {
    f->quarantine_size_mb = quarantine_size_mb;
    f->redzone = min_redzone;
    f->max_redzone = max_redzone;
    cf->allocator_may_return_null = may_return_null;
    f->alloc_dealloc_mismatch = alloc_dealloc_mismatch;
  }
  
  struct Allocator {
    static const uptr kMaxAllowedMallocSize =
        FIRST_32_SECOND_64(3UL << 30, 1UL << 40);
    static const uptr kMaxThreadLocalQuarantine =
        FIRST_32_SECOND_64(1 << 18, 1 << 20);
  
    AsanAllocator allocator;
    AsanQuarantine quarantine;
    StaticSpinMutex fallback_mutex;
    AllocatorCache fallback_allocator_cache;
    QuarantineCache fallback_quarantine_cache;
  
    // ------------------- Options --------------------------
    atomic_uint16_t min_redzone;
    atomic_uint16_t max_redzone;
    atomic_uint8_t alloc_dealloc_mismatch;
  
    // ------------------- Initialization ------------------------
    explicit Allocator(LinkerInitialized)
        : quarantine(LINKER_INITIALIZED),
          fallback_quarantine_cache(LINKER_INITIALIZED) {}
  
    void CheckOptions(const AllocatorOptions &options) const {
      CHECK_GE(options.min_redzone, 16);
      CHECK_GE(options.max_redzone, options.min_redzone);
      CHECK_LE(options.max_redzone, 2048);
      CHECK(IsPowerOfTwo(options.min_redzone));
      CHECK(IsPowerOfTwo(options.max_redzone));
    }
  
    void SharedInitCode(const AllocatorOptions &options) {
      CheckOptions(options);
      quarantine.Init((uptr)options.quarantine_size_mb << 20,
                      kMaxThreadLocalQuarantine);
      atomic_store(&alloc_dealloc_mismatch, options.alloc_dealloc_mismatch,
                   memory_order_release);
      atomic_store(&min_redzone, options.min_redzone, memory_order_release);
      atomic_store(&max_redzone, options.max_redzone, memory_order_release);
    }
  
    void Initialize(const AllocatorOptions &options) {
      allocator.Init(options.may_return_null);
      SharedInitCode(options);
    }
  
    void ReInitialize(const AllocatorOptions &options) {
      allocator.SetMayReturnNull(options.may_return_null);
      SharedInitCode(options);
    }
  
    void GetOptions(AllocatorOptions *options) const {
      options->quarantine_size_mb = quarantine.GetSize() >> 20;
      options->min_redzone = atomic_load(&min_redzone, memory_order_acquire);
      options->max_redzone = atomic_load(&max_redzone, memory_order_acquire);
      options->may_return_null = allocator.MayReturnNull();
      options->alloc_dealloc_mismatch =
          atomic_load(&alloc_dealloc_mismatch, memory_order_acquire);
    }
  
    // -------------------- Helper methods. -------------------------
    uptr ComputeRZLog(uptr user_requested_size) {
      u32 rz_log =
        user_requested_size <= 64        - 16   ? 0 :
        user_requested_size <= 128       - 32   ? 1 :
        user_requested_size <= 512       - 64   ? 2 :
        user_requested_size <= 4096      - 128  ? 3 :
        user_requested_size <= (1 << 14) - 256  ? 4 :
        user_requested_size <= (1 << 15) - 512  ? 5 :
        user_requested_size <= (1 << 16) - 1024 ? 6 : 7;
      u32 min_rz = atomic_load(&min_redzone, memory_order_acquire);
      u32 max_rz = atomic_load(&max_redzone, memory_order_acquire);
      return Min(Max(rz_log, RZSize2Log(min_rz)), RZSize2Log(max_rz));
    }
  
    // We have an address between two chunks, and we want to report just one.
    AsanChunk *ChooseChunk(uptr addr, AsanChunk *left_chunk,
                           AsanChunk *right_chunk) {
      // Prefer an allocated chunk over freed chunk and freed chunk
      // over available chunk.
      if (left_chunk->chunk_state != right_chunk->chunk_state) {
        if (left_chunk->chunk_state == CHUNK_ALLOCATED)
          return left_chunk;
        if (right_chunk->chunk_state == CHUNK_ALLOCATED)
          return right_chunk;
        if (left_chunk->chunk_state == CHUNK_QUARANTINE)
          return left_chunk;
        if (right_chunk->chunk_state == CHUNK_QUARANTINE)
          return right_chunk;
      }
      // Same chunk_state: choose based on offset.
      sptr l_offset = 0, r_offset = 0;
      CHECK(AsanChunkView(left_chunk).AddrIsAtRight(addr, 1, &l_offset));
      CHECK(AsanChunkView(right_chunk).AddrIsAtLeft(addr, 1, &r_offset));
      if (l_offset < r_offset)
        return left_chunk;
      return right_chunk;
    }
  
    // -------------------- Allocation/Deallocation routines ---------------
    void *Allocate(uptr size, uptr alignment, BufferedStackTrace *stack,
                   AllocType alloc_type, bool can_fill) {
      if (UNLIKELY(!asan_inited))
        AsanInitFromRtl();
      Flags &fl = *flags();
      CHECK(stack);
      const uptr min_alignment = SHADOW_GRANULARITY;
      if (alignment < min_alignment)
        alignment = min_alignment;
      if (size == 0) {
        // We'd be happy to avoid allocating memory for zero-size requests, but
        // some programs/tests depend on this behavior and assume that malloc
        // would not return NULL even for zero-size allocations. Moreover, it
        // looks like operator new should never return NULL, and results of
        // consecutive "new" calls must be different even if the allocated size
        // is zero.
        size = 1;
      }
      CHECK(IsPowerOfTwo(alignment));
      uptr rz_log = ComputeRZLog(size);
      uptr rz_size = RZLog2Size(rz_log);
      uptr rounded_size = RoundUpTo(Max(size, kChunkHeader2Size), alignment);
      uptr needed_size = rounded_size + rz_size;
      if (alignment > min_alignment)
        needed_size += alignment;
      bool using_primary_allocator = true;
      // If we are allocating from the secondary allocator, there will be no
      // automatic right redzone, so add the right redzone manually.
      if (!PrimaryAllocator::CanAllocate(needed_size, alignment)) {
        needed_size += rz_size;
        using_primary_allocator = false;
      }
      CHECK(IsAligned(needed_size, min_alignment));
      if (size > kMaxAllowedMallocSize || needed_size > kMaxAllowedMallocSize) {
        Report("WARNING: AddressSanitizer failed to allocate 0x%zx bytes\n",
               (void*)size);
        return allocator.ReturnNullOrDie();
      }
  
      AsanThread *t = GetCurrentThread();
      void *allocated;
      bool check_rss_limit = true;
      if (t) {
        AllocatorCache *cache = GetAllocatorCache(&t->malloc_storage());
        allocated =
            allocator.Allocate(cache, needed_size, 8, false, check_rss_limit);
      } else {
        SpinMutexLock l(&fallback_mutex);
        AllocatorCache *cache = &fallback_allocator_cache;
        allocated =
            allocator.Allocate(cache, needed_size, 8, false, check_rss_limit);
      }
  
      if (!allocated)
        return allocator.ReturnNullOrDie();
  
      if (*(u8 *)MEM_TO_SHADOW((uptr)allocated) == 0 && CanPoisonMemory()) {
        // Heap poisoning is enabled, but the allocator provides an unpoisoned
        // chunk. This is possible if CanPoisonMemory() was false for some
        // time, for example, due to flags()->start_disabled.
        // Anyway, poison the block before using it for anything else.
        uptr allocated_size = allocator.GetActuallyAllocatedSize(allocated);
        PoisonShadow((uptr)allocated, allocated_size, kAsanHeapLeftRedzoneMagic);
      }
  
      uptr alloc_beg = reinterpret_cast<uptr>(allocated);
      uptr alloc_end = alloc_beg + needed_size;
      uptr beg_plus_redzone = alloc_beg + rz_size;
      uptr user_beg = beg_plus_redzone;
      if (!IsAligned(user_beg, alignment))
        user_beg = RoundUpTo(user_beg, alignment);
      uptr user_end = user_beg + size;
      CHECK_LE(user_end, alloc_end);
      uptr chunk_beg = user_beg - kChunkHeaderSize;
      AsanChunk *m = reinterpret_cast<AsanChunk *>(chunk_beg);
      m->alloc_type = alloc_type;
      m->rz_log = rz_log;
      u32 alloc_tid = t ? t->tid() : 0;
      m->alloc_tid = alloc_tid;
      CHECK_EQ(alloc_tid, m->alloc_tid);  // Does alloc_tid fit into the bitfield?
      m->free_tid = kInvalidTid;
      m->from_memalign = user_beg != beg_plus_redzone;
      if (alloc_beg != chunk_beg) {
        CHECK_LE(alloc_beg+ 2 * sizeof(uptr), chunk_beg);
        reinterpret_cast<uptr *>(alloc_beg)[0] = kAllocBegMagic;
        reinterpret_cast<uptr *>(alloc_beg)[1] = chunk_beg;
      }
      if (using_primary_allocator) {
        CHECK(size);
        m->user_requested_size = size;
        CHECK(allocator.FromPrimary(allocated));
      } else {
        CHECK(!allocator.FromPrimary(allocated));
        m->user_requested_size = SizeClassMap::kMaxSize;
        uptr *meta = reinterpret_cast<uptr *>(allocator.GetMetaData(allocated));
        meta[0] = size;
        meta[1] = chunk_beg;
      }
  
      m->alloc_context_id = StackDepotPut(*stack);
  
      uptr size_rounded_down_to_granularity =
          RoundDownTo(size, SHADOW_GRANULARITY);
      // Unpoison the bulk of the memory region.
      if (size_rounded_down_to_granularity)
        PoisonShadow(user_beg, size_rounded_down_to_granularity, 0);
      // Deal with the end of the region if size is not aligned to granularity.
      if (size != size_rounded_down_to_granularity && CanPoisonMemory()) {
        u8 *shadow =
            (u8 *)MemToShadow(user_beg + size_rounded_down_to_granularity);
        *shadow = fl.poison_partial ? (size & (SHADOW_GRANULARITY - 1)) : 0;
      }
  
      AsanStats &thread_stats = GetCurrentThreadStats();
      thread_stats.mallocs++;
      thread_stats.malloced += size;
      thread_stats.malloced_redzones += needed_size - size;
      if (needed_size > SizeClassMap::kMaxSize)
        thread_stats.malloc_large++;
      else
        thread_stats.malloced_by_size[SizeClassMap::ClassID(needed_size)]++;
  
      void *res = reinterpret_cast<void *>(user_beg);
      if (can_fill && fl.max_malloc_fill_size) {
        uptr fill_size = Min(size, (uptr)fl.max_malloc_fill_size);
        REAL(memset)(res, fl.malloc_fill_byte, fill_size);
      }
  #if CAN_SANITIZE_LEAKS
      m->lsan_tag = __lsan::DisabledInThisThread() ? __lsan::kIgnored
                                                   : __lsan::kDirectlyLeaked;
  #endif
      // Must be the last mutation of metadata in this function.
      atomic_store((atomic_uint8_t *)m, CHUNK_ALLOCATED, memory_order_release);
      ASAN_MALLOC_HOOK(res, size);
      return res;
    }
  
    void AtomicallySetQuarantineFlag(AsanChunk *m, void *ptr,
                                     BufferedStackTrace *stack) {
      u8 old_chunk_state = CHUNK_ALLOCATED;
      // Flip the chunk_state atomically to avoid race on double-free.
      if (!atomic_compare_exchange_strong((atomic_uint8_t*)m, &old_chunk_state,
                                          CHUNK_QUARANTINE, memory_order_acquire))
        ReportInvalidFree(ptr, old_chunk_state, stack);
      CHECK_EQ(CHUNK_ALLOCATED, old_chunk_state);
    }
  
    // Expects the chunk to already be marked as quarantined by using
    // AtomicallySetQuarantineFlag.
    void QuarantineChunk(AsanChunk *m, void *ptr, BufferedStackTrace *stack,
                         AllocType alloc_type) {
      CHECK_EQ(m->chunk_state, CHUNK_QUARANTINE);
  
      if (m->alloc_type != alloc_type) {
        if (atomic_load(&alloc_dealloc_mismatch, memory_order_acquire)) {
          ReportAllocTypeMismatch((uptr)ptr, stack, (AllocType)m->alloc_type,
                                  (AllocType)alloc_type);
        }
      }
  
      CHECK_GE(m->alloc_tid, 0);
      if (SANITIZER_WORDSIZE == 64)  // On 32-bits this resides in user area.
        CHECK_EQ(m->free_tid, kInvalidTid);
      AsanThread *t = GetCurrentThread();
      m->free_tid = t ? t->tid() : 0;
      m->free_context_id = StackDepotPut(*stack);
      // Poison the region.
      PoisonShadow(m->Beg(),
                   RoundUpTo(m->UsedSize(), SHADOW_GRANULARITY),
                   kAsanHeapFreeMagic);
  
      AsanStats &thread_stats = GetCurrentThreadStats();
      thread_stats.frees++;
      thread_stats.freed += m->UsedSize();
  
      // Push into quarantine.
      if (t) {
        AsanThreadLocalMallocStorage *ms = &t->malloc_storage();
        AllocatorCache *ac = GetAllocatorCache(ms);
        quarantine.Put(GetQuarantineCache(ms), QuarantineCallback(ac), m,
                             m->UsedSize());
      } else {
        SpinMutexLock l(&fallback_mutex);
        AllocatorCache *ac = &fallback_allocator_cache;
        quarantine.Put(&fallback_quarantine_cache, QuarantineCallback(ac), m,
                             m->UsedSize());
      }
    }
  
    void Deallocate(void *ptr, uptr delete_size, BufferedStackTrace *stack,
                    AllocType alloc_type) {
      uptr p = reinterpret_cast<uptr>(ptr);
      if (p == 0) return;
  
      uptr chunk_beg = p - kChunkHeaderSize;
      AsanChunk *m = reinterpret_cast<AsanChunk *>(chunk_beg);
      if (delete_size && flags()->new_delete_type_mismatch &&
          delete_size != m->UsedSize()) {
        ReportNewDeleteSizeMismatch(p, delete_size, stack);
      }
      ASAN_FREE_HOOK(ptr);
      // Must mark the chunk as quarantined before any changes to its metadata.
      AtomicallySetQuarantineFlag(m, ptr, stack);
      QuarantineChunk(m, ptr, stack, alloc_type);
    }
  
    void *Reallocate(void *old_ptr, uptr new_size, BufferedStackTrace *stack) {
      CHECK(old_ptr && new_size);
      uptr p = reinterpret_cast<uptr>(old_ptr);
      uptr chunk_beg = p - kChunkHeaderSize;
      AsanChunk *m = reinterpret_cast<AsanChunk *>(chunk_beg);
  
      AsanStats &thread_stats = GetCurrentThreadStats();
      thread_stats.reallocs++;
      thread_stats.realloced += new_size;
  
      void *new_ptr = Allocate(new_size, 8, stack, FROM_MALLOC, true);
      if (new_ptr) {
        u8 chunk_state = m->chunk_state;
        if (chunk_state != CHUNK_ALLOCATED)
          ReportInvalidFree(old_ptr, chunk_state, stack);
        CHECK_NE(REAL(memcpy), (void*)0);
        uptr memcpy_size = Min(new_size, m->UsedSize());
        // If realloc() races with free(), we may start copying freed memory.
        // However, we will report racy double-free later anyway.
        REAL(memcpy)(new_ptr, old_ptr, memcpy_size);
        Deallocate(old_ptr, 0, stack, FROM_MALLOC);
      }
      return new_ptr;
    }
  
    void *Calloc(uptr nmemb, uptr size, BufferedStackTrace *stack) {
      if (CallocShouldReturnNullDueToOverflow(size, nmemb))
        return allocator.ReturnNullOrDie();
      void *ptr = Allocate(nmemb * size, 8, stack, FROM_MALLOC, false);
      // If the memory comes from the secondary allocator no need to clear it
      // as it comes directly from mmap.
      if (ptr && allocator.FromPrimary(ptr))
        REAL(memset)(ptr, 0, nmemb * size);
      return ptr;
    }
  
    void ReportInvalidFree(void *ptr, u8 chunk_state, BufferedStackTrace *stack) {
      if (chunk_state == CHUNK_QUARANTINE)
        ReportDoubleFree((uptr)ptr, stack);
      else
        ReportFreeNotMalloced((uptr)ptr, stack);
    }
  
    void CommitBack(AsanThreadLocalMallocStorage *ms) {
      AllocatorCache *ac = GetAllocatorCache(ms);
      quarantine.Drain(GetQuarantineCache(ms), QuarantineCallback(ac));
      allocator.SwallowCache(ac);
    }
  
    // -------------------------- Chunk lookup ----------------------
  
    // Assumes alloc_beg == allocator.GetBlockBegin(alloc_beg).
    AsanChunk *GetAsanChunk(void *alloc_beg) {
      if (!alloc_beg) return 0;
      if (!allocator.FromPrimary(alloc_beg)) {
        uptr *meta = reinterpret_cast<uptr *>(allocator.GetMetaData(alloc_beg));
        AsanChunk *m = reinterpret_cast<AsanChunk *>(meta[1]);
        return m;
      }
      uptr *alloc_magic = reinterpret_cast<uptr *>(alloc_beg);
      if (alloc_magic[0] == kAllocBegMagic)
        return reinterpret_cast<AsanChunk *>(alloc_magic[1]);
      return reinterpret_cast<AsanChunk *>(alloc_beg);
    }
  
    AsanChunk *GetAsanChunkByAddr(uptr p) {
      void *alloc_beg = allocator.GetBlockBegin(reinterpret_cast<void *>(p));
      return GetAsanChunk(alloc_beg);
    }
  
    // Allocator must be locked when this function is called.
    AsanChunk *GetAsanChunkByAddrFastLocked(uptr p) {
      void *alloc_beg =
          allocator.GetBlockBeginFastLocked(reinterpret_cast<void *>(p));
      return GetAsanChunk(alloc_beg);
    }
  
    uptr AllocationSize(uptr p) {
      AsanChunk *m = GetAsanChunkByAddr(p);
      if (!m) return 0;
      if (m->chunk_state != CHUNK_ALLOCATED) return 0;
      if (m->Beg() != p) return 0;
      return m->UsedSize();
    }
  
    AsanChunkView FindHeapChunkByAddress(uptr addr) {
      AsanChunk *m1 = GetAsanChunkByAddr(addr);
      if (!m1) return AsanChunkView(m1);
      sptr offset = 0;
      if (AsanChunkView(m1).AddrIsAtLeft(addr, 1, &offset)) {
        // The address is in the chunk's left redzone, so maybe it is actually
        // a right buffer overflow from the other chunk to the left.
        // Search a bit to the left to see if there is another chunk.
        AsanChunk *m2 = 0;
        for (uptr l = 1; l < GetPageSizeCached(); l++) {
          m2 = GetAsanChunkByAddr(addr - l);
          if (m2 == m1) continue;  // Still the same chunk.
          break;
        }
        if (m2 && AsanChunkView(m2).AddrIsAtRight(addr, 1, &offset))
          m1 = ChooseChunk(addr, m2, m1);
      }
      return AsanChunkView(m1);
    }
  
    void PrintStats() {
      allocator.PrintStats();
    }
  
    void ForceLock() {
      allocator.ForceLock();
      fallback_mutex.Lock();
    }
  
    void ForceUnlock() {
      fallback_mutex.Unlock();
      allocator.ForceUnlock();
    }
  };
  
  static Allocator instance(LINKER_INITIALIZED);
  
  static AsanAllocator &get_allocator() {
    return instance.allocator;
  }
  
  bool AsanChunkView::IsValid() {
    return chunk_ != 0 && chunk_->chunk_state != CHUNK_AVAILABLE;
  }
  uptr AsanChunkView::Beg() { return chunk_->Beg(); }
  uptr AsanChunkView::End() { return Beg() + UsedSize(); }
  uptr AsanChunkView::UsedSize() { return chunk_->UsedSize(); }
  uptr AsanChunkView::AllocTid() { return chunk_->alloc_tid; }
  uptr AsanChunkView::FreeTid() { return chunk_->free_tid; }
  
  static StackTrace GetStackTraceFromId(u32 id) {
    CHECK(id);
    StackTrace res = StackDepotGet(id);
    CHECK(res.trace);
    return res;
  }
  
  StackTrace AsanChunkView::GetAllocStack() {
    return GetStackTraceFromId(chunk_->alloc_context_id);
  }
  
  StackTrace AsanChunkView::GetFreeStack() {
    return GetStackTraceFromId(chunk_->free_context_id);
  }
  
  void InitializeAllocator(const AllocatorOptions &options) {
    instance.Initialize(options);
  }
  
  void ReInitializeAllocator(const AllocatorOptions &options) {
    instance.ReInitialize(options);
  }
  
  void GetAllocatorOptions(AllocatorOptions *options) {
    instance.GetOptions(options);
  }
  
  AsanChunkView FindHeapChunkByAddress(uptr addr) {
    return instance.FindHeapChunkByAddress(addr);
  }
  
  void AsanThreadLocalMallocStorage::CommitBack() {
    instance.CommitBack(this);
  }
  
  void PrintInternalAllocatorStats() {
    instance.PrintStats();
  }
  
  void *asan_memalign(uptr alignment, uptr size, BufferedStackTrace *stack,
                      AllocType alloc_type) {
    return instance.Allocate(size, alignment, stack, alloc_type, true);
  }
  
  void asan_free(void *ptr, BufferedStackTrace *stack, AllocType alloc_type) {
    instance.Deallocate(ptr, 0, stack, alloc_type);
  }
  
  void asan_sized_free(void *ptr, uptr size, BufferedStackTrace *stack,
                       AllocType alloc_type) {
    instance.Deallocate(ptr, size, stack, alloc_type);
  }
  
  void *asan_malloc(uptr size, BufferedStackTrace *stack) {
    return instance.Allocate(size, 8, stack, FROM_MALLOC, true);
  }
  
  void *asan_calloc(uptr nmemb, uptr size, BufferedStackTrace *stack) {
    return instance.Calloc(nmemb, size, stack);
  }
  
  void *asan_realloc(void *p, uptr size, BufferedStackTrace *stack) {
    if (p == 0)
      return instance.Allocate(size, 8, stack, FROM_MALLOC, true);
    if (size == 0) {
      instance.Deallocate(p, 0, stack, FROM_MALLOC);
      return 0;
    }
    return instance.Reallocate(p, size, stack);
  }
  
  void *asan_valloc(uptr size, BufferedStackTrace *stack) {
    return instance.Allocate(size, GetPageSizeCached(), stack, FROM_MALLOC, true);
  }
  
  void *asan_pvalloc(uptr size, BufferedStackTrace *stack) {
    uptr PageSize = GetPageSizeCached();
    size = RoundUpTo(size, PageSize);
    if (size == 0) {
      // pvalloc(0) should allocate one page.
      size = PageSize;
    }
    return instance.Allocate(size, PageSize, stack, FROM_MALLOC, true);
  }
  
  int asan_posix_memalign(void **memptr, uptr alignment, uptr size,
                          BufferedStackTrace *stack) {
    void *ptr = instance.Allocate(size, alignment, stack, FROM_MALLOC, true);
    CHECK(IsAligned((uptr)ptr, alignment));
    *memptr = ptr;
    return 0;
  }
  
  uptr asan_malloc_usable_size(void *ptr, uptr pc, uptr bp) {
    if (ptr == 0) return 0;
    uptr usable_size = instance.AllocationSize(reinterpret_cast<uptr>(ptr));
    if (flags()->check_malloc_usable_size && (usable_size == 0)) {
      GET_STACK_TRACE_FATAL(pc, bp);
      ReportMallocUsableSizeNotOwned((uptr)ptr, &stack);
    }
    return usable_size;
  }
  
  uptr asan_mz_size(const void *ptr) {
    return instance.AllocationSize(reinterpret_cast<uptr>(ptr));
  }
  
  void asan_mz_force_lock() {
    instance.ForceLock();
  }
  
  void asan_mz_force_unlock() {
    instance.ForceUnlock();
  }
  
  void AsanSoftRssLimitExceededCallback(bool exceeded) {
    instance.allocator.SetRssLimitIsExceeded(exceeded);
  }
  
  }  // namespace __asan
  
  // --- Implementation of LSan-specific functions --- {{{1
  namespace __lsan {
  void LockAllocator() {
    __asan::get_allocator().ForceLock();
  }
  
  void UnlockAllocator() {
    __asan::get_allocator().ForceUnlock();
  }
  
  void GetAllocatorGlobalRange(uptr *begin, uptr *end) {
    *begin = (uptr)&__asan::get_allocator();
    *end = *begin + sizeof(__asan::get_allocator());
  }
  
  uptr PointsIntoChunk(void* p) {
    uptr addr = reinterpret_cast<uptr>(p);
    __asan::AsanChunk *m = __asan::instance.GetAsanChunkByAddrFastLocked(addr);
    if (!m) return 0;
    uptr chunk = m->Beg();
    if (m->chunk_state != __asan::CHUNK_ALLOCATED)
      return 0;
    if (m->AddrIsInside(addr, /*locked_version=*/true))
      return chunk;
    if (IsSpecialCaseOfOperatorNew0(chunk, m->UsedSize(/*locked_version*/ true),
                                    addr))
      return chunk;
    return 0;
  }
  
  uptr GetUserBegin(uptr chunk) {
    __asan::AsanChunk *m = __asan::instance.GetAsanChunkByAddrFastLocked(chunk);
    CHECK(m);
    return m->Beg();
  }
  
  LsanMetadata::LsanMetadata(uptr chunk) {
    metadata_ = reinterpret_cast<void *>(chunk - __asan::kChunkHeaderSize);
  }
  
  bool LsanMetadata::allocated() const {
    __asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
    return m->chunk_state == __asan::CHUNK_ALLOCATED;
  }
  
  ChunkTag LsanMetadata::tag() const {
    __asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
    return static_cast<ChunkTag>(m->lsan_tag);
  }
  
  void LsanMetadata::set_tag(ChunkTag value) {
    __asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
    m->lsan_tag = value;
  }
  
  uptr LsanMetadata::requested_size() const {
    __asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
    return m->UsedSize(/*locked_version=*/true);
  }
  
  u32 LsanMetadata::stack_trace_id() const {
    __asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
    return m->alloc_context_id;
  }
  
  void ForEachChunk(ForEachChunkCallback callback, void *arg) {
    __asan::get_allocator().ForEachChunk(callback, arg);
  }
  
  IgnoreObjectResult IgnoreObjectLocked(const void *p) {
    uptr addr = reinterpret_cast<uptr>(p);
    __asan::AsanChunk *m = __asan::instance.GetAsanChunkByAddr(addr);
    if (!m) return kIgnoreObjectInvalid;
    if ((m->chunk_state == __asan::CHUNK_ALLOCATED) && m->AddrIsInside(addr)) {
      if (m->lsan_tag == kIgnored)
        return kIgnoreObjectAlreadyIgnored;
      m->lsan_tag = __lsan::kIgnored;
      return kIgnoreObjectSuccess;
    } else {
      return kIgnoreObjectInvalid;
    }
  }
  }  // namespace __lsan
  
  // ---------------------- Interface ---------------- {{{1
  using namespace __asan;  // NOLINT
  
  // ASan allocator doesn't reserve extra bytes, so normally we would
  // just return "size". We don't want to expose our redzone sizes, etc here.
  uptr __sanitizer_get_estimated_allocated_size(uptr size) {
    return size;
  }
  
  int __sanitizer_get_ownership(const void *p) {
    uptr ptr = reinterpret_cast<uptr>(p);
    return instance.AllocationSize(ptr) > 0;
  }
  
  uptr __sanitizer_get_allocated_size(const void *p) {
    if (p == 0) return 0;
    uptr ptr = reinterpret_cast<uptr>(p);
    uptr allocated_size = instance.AllocationSize(ptr);
    // Die if p is not malloced or if it is already freed.
    if (allocated_size == 0) {
      GET_STACK_TRACE_FATAL_HERE;
      ReportSanitizerGetAllocatedSizeNotOwned(ptr, &stack);
    }
    return allocated_size;
  }
  
  #if !SANITIZER_SUPPORTS_WEAK_HOOKS
  // Provide default (no-op) implementation of malloc hooks.
  extern "C" {
  SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
  void __sanitizer_malloc_hook(void *ptr, uptr size) {
    (void)ptr;
    (void)size;
  }
  SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
  void __sanitizer_free_hook(void *ptr) {
    (void)ptr;
  }
  }  // extern "C"
  #endif
  