The Tor Browser: memory/mozalloc/VolatileBufferOSX.cpp@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 #include "VolatileBuffer.h"

     6 #include "mozilla/Assertions.h"

     7 #include "mozilla/DebugOnly.h"

     8 #include "mozilla/mozalloc.h"

    10 #include <mach/mach.h>

    11 #include <sys/mman.h>

    12 #include <unistd.h>

    14 #define MIN_VOLATILE_ALLOC_SIZE 8192

    16 namespace mozilla {

    18 VolatileBuffer::VolatileBuffer()

    19   : mBuf(nullptr)

    20   , mSize(0)

    21   , mLockCount(0)

    22   , mHeap(false)

    23 {

    24 }

    26 bool

    27 VolatileBuffer::Init(size_t aSize, size_t aAlignment)

    28 {

    29   MOZ_ASSERT(!mSize && !mBuf, "Init called twice");

    30   MOZ_ASSERT(!(aAlignment % sizeof(void *)),

    31              "Alignment must be multiple of pointer size");

    33   mSize = aSize;

    35   kern_return_t ret = 0;

    36   if (aSize < MIN_VOLATILE_ALLOC_SIZE) {

    37     goto heap_alloc;

    38   }

    40   ret = vm_allocate(mach_task_self(),

    41                     (vm_address_t*)&mBuf,

    42                     mSize,

    43                     VM_FLAGS_PURGABLE | VM_FLAGS_ANYWHERE);

    44   if (ret == KERN_SUCCESS) {

    45     return true;

    46   }

    48 heap_alloc:

    49   (void)moz_posix_memalign(&mBuf, aAlignment, aSize);

    50   mHeap = true;

    51   return !!mBuf;

    52 }

    54 VolatileBuffer::~VolatileBuffer()

    55 {

    56   if (OnHeap()) {

    57     free(mBuf);

    58   } else {

    59     vm_deallocate(mach_task_self(), (vm_address_t)mBuf, mSize);

    60   }

    61 }

    63 bool

    64 VolatileBuffer::Lock(void** aBuf)

    65 {

    66   MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");

    68   *aBuf = mBuf;

    69   if (++mLockCount > 1 || OnHeap()) {

    70     return true;

    71   }

    73   int state = VM_PURGABLE_NONVOLATILE;

    74   kern_return_t ret =

    75     vm_purgable_control(mach_task_self(),

    76                         (vm_address_t)mBuf,

    77                         VM_PURGABLE_SET_STATE,

    78                         &state);

    79   return ret == KERN_SUCCESS && !(state & VM_PURGABLE_EMPTY);

    80 }

    82 void

    83 VolatileBuffer::Unlock()

    84 {

    85   MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");

    86   if (--mLockCount || OnHeap()) {

    87     return;

    88   }

    90   int state = VM_PURGABLE_VOLATILE | VM_VOLATILE_GROUP_DEFAULT;

    91   DebugOnly<kern_return_t> ret =

    92     vm_purgable_control(mach_task_self(),

    93                         (vm_address_t)mBuf,

    94                         VM_PURGABLE_SET_STATE,

    95                         &state);

    96   MOZ_ASSERT(ret == KERN_SUCCESS, "Failed to set buffer as purgable");

    97 }

    99 bool

   100 VolatileBuffer::OnHeap() const

   101 {

   102   return mHeap;

   103 }

   105 size_t

   106 VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const

   107 {

   108   return OnHeap() ? aMallocSizeOf(mBuf) : 0;

   109 }

   111 size_t

   112 VolatileBuffer::NonHeapSizeOfExcludingThis() const

   113 {

   114   if (OnHeap()) {

   115     return 0;

   116   }

   118   unsigned long pagemask = getpagesize() - 1;

   119   return (mSize + pagemask) & ~pagemask;

   120 }

   122 } // namespace mozilla

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