The Tor Browser: memory/mozalloc/VolatileBufferAshmem.cpp@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     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/NullPtr.h"

     8 #include "mozilla/mozalloc.h"

    10 #include <fcntl.h>

    11 #include <linux/ashmem.h>

    12 #include <sys/mman.h>

    13 #include <sys/stat.h>

    14 #include <sys/types.h>

    15 #include <unistd.h>

    17 #ifdef MOZ_MEMORY

    18 #ifdef MOZ_WIDGET_ANDROID

    19 extern "C" int __wrap_posix_memalign(void** memptr, size_t alignment, size_t size);

    20 #else

    21 extern "C" int posix_memalign(void** memptr, size_t alignment, size_t size);

    22 #endif

    23 #endif

    25 #define MIN_VOLATILE_ALLOC_SIZE 8192

    27 namespace mozilla {

    29 VolatileBuffer::VolatileBuffer()

    30   : mBuf(nullptr)

    31   , mSize(0)

    32   , mLockCount(0)

    33   , mFd(-1)

    34 {

    35 }

    37 bool

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

    39 {

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

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

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

    44   mSize = aSize;

    45   if (aSize < MIN_VOLATILE_ALLOC_SIZE) {

    46     goto heap_alloc;

    47   }

    49   mFd = open("/" ASHMEM_NAME_DEF, O_RDWR);

    50   if (mFd < 0) {

    51     goto heap_alloc;

    52   }

    54   if (ioctl(mFd, ASHMEM_SET_SIZE, mSize) < 0) {

    55     close(mFd);

    56     mFd = -1;

    57     goto heap_alloc;

    58   }

    60   mBuf = mmap(nullptr, mSize, PROT_READ | PROT_WRITE, MAP_SHARED, mFd, 0);

    61   if (mBuf != MAP_FAILED) {

    62     return true;

    63   }

    65 heap_alloc:

    66 #ifdef MOZ_MEMORY

    67 #ifdef MOZ_WIDGET_ANDROID

    68   __wrap_posix_memalign(&mBuf, aAlignment, aSize);

    69 #else

    70   posix_memalign(&mBuf, aAlignment, aSize);

    71 #endif

    72 #else

    73   mBuf = memalign(aAlignment, aSize);

    74 #endif

    75   return !!mBuf;

    76 }

    78 VolatileBuffer::~VolatileBuffer()

    79 {

    80   if (OnHeap()) {

    81     free(mBuf);

    82   } else {

    83     munmap(mBuf, mSize);

    84     close(mFd);

    85   }

    86 }

    88 bool

    89 VolatileBuffer::Lock(void** aBuf)

    90 {

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

    93   *aBuf = mBuf;

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

    95     return true;

    96   }

    98   // Zero offset and zero length means we want to pin/unpin the entire thing.

    99   struct ashmem_pin pin = { 0, 0 };

   100   return ioctl(mFd, ASHMEM_PIN, &pin) == ASHMEM_NOT_PURGED;

   101 }

   103 void

   104 VolatileBuffer::Unlock()

   105 {

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

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

   108     return;

   109   }

   111   struct ashmem_pin pin = { 0, 0 };

   112   ioctl(mFd, ASHMEM_UNPIN, &pin);

   113 }

   115 bool

   116 VolatileBuffer::OnHeap() const

   117 {

   118   return mFd < 0;

   119 }

   121 size_t

   122 VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const

   123 {

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

   125 }

   127 size_t

   128 VolatileBuffer::NonHeapSizeOfExcludingThis() const

   129 {

   130   if (OnHeap()) {

   131     return 0;

   132   }

   134   return (mSize + (PAGE_SIZE - 1)) & PAGE_MASK;

   135 }

   137 } // namespace mozilla

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