js/src/vm/ArrayBufferObjectMaybeShared.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/Assertions.h"  // MOZ_ASSERT
   8
   9 #include <stdint.h>  // uint8_t, uint32_t
  10
  11 #include "jstypes.h"  // JS_PUBLIC_API
  12
  13 #include "js/ArrayBufferMaybeShared.h"
  14 #include "vm/ArrayBufferObject.h"  // js::ArrayBufferObject
  15 #include "vm/JSObject.h"           // JSObject
  16 #include "vm/SharedArrayObject.h"  // js::SharedArrayBufferObject
  17 #include "vm/SharedMem.h"          // SharedMem
  18
  19 using namespace js;
  20
  21 JS_PUBLIC_API bool JS::IsArrayBufferObjectMaybeShared(JSObject* obj) {
  22   return obj->canUnwrapAs<ArrayBufferObjectMaybeShared>();
  23 }
  24
  25 JS_PUBLIC_API JSObject* JS::UnwrapArrayBufferMaybeShared(JSObject* obj) {
  26   return obj->maybeUnwrapIf<ArrayBufferObjectMaybeShared>();
  27 }
  28
  29 JS_PUBLIC_API void JS::GetArrayBufferMaybeSharedLengthAndData(
  30     JSObject* obj, size_t* length, bool* isSharedMemory, uint8_t** data) {
  31   MOZ_ASSERT(obj->is<ArrayBufferObjectMaybeShared>());
  32
  33   if (obj->is<SharedArrayBufferObject>()) {
  34     auto* buffer = &obj->as<SharedArrayBufferObject>();
  35     *length = buffer->byteLength();
  36     *data = buffer->dataPointerShared().unwrap();
  37     *isSharedMemory = true;
  38   } else {
  39     auto* buffer = &obj->as<ArrayBufferObject>();
  40     *length = buffer->byteLength();
  41     *data = buffer->dataPointer();
  42     *isSharedMemory = false;
  43   }
  44 }
  45
  46 JS_PUBLIC_API uint8_t* JS::GetArrayBufferMaybeSharedData(
  47     JSObject* obj, bool* isSharedMemory, const JS::AutoRequireNoGC&) {
  48   MOZ_ASSERT(obj->maybeUnwrapIf<ArrayBufferObjectMaybeShared>());
  49
  50   if (ArrayBufferObject* aobj = obj->maybeUnwrapIf<ArrayBufferObject>()) {
  51     *isSharedMemory = false;
  52     return aobj->dataPointer();
  53   } else if (SharedArrayBufferObject* saobj =
  54                  obj->maybeUnwrapIf<SharedArrayBufferObject>()) {
  55     *isSharedMemory = true;
  56     return saobj->dataPointerShared().unwrap();
  57   }
  58
  59   return nullptr;
  60 }
  61
  62 JS_PUBLIC_API bool JS::IsLargeArrayBufferMaybeShared(JSObject* obj) {
  63 #ifdef JS_64BIT
  64   obj = UnwrapArrayBufferMaybeShared(obj);
  65   MOZ_ASSERT(obj);
  66   size_t len = obj->is<ArrayBufferObject>()
  67                    ? obj->as<ArrayBufferObject>().byteLength()
  68                    : obj->as<SharedArrayBufferObject>().byteLength();
  69   return len > ArrayBufferObject::ByteLengthLimitForSmallBuffer;
  70 #else
  71   // Large ArrayBuffers are not supported on 32-bit.
  72   static_assert(ArrayBufferObject::ByteLengthLimit ==
  73                 ArrayBufferObject::ByteLengthLimitForSmallBuffer);
  74   return false;
  75 #endif
  76 }
  77
  78 JS_PUBLIC_API bool JS::IsResizableArrayBufferMaybeShared(JSObject* obj) {
  79   obj = UnwrapArrayBufferMaybeShared(obj);
  80   MOZ_ASSERT(obj);
  81
  82   if (obj->is<ArrayBufferObject>()) {
  83     return obj->as<ArrayBufferObject>().isResizable();
  84   }
  85   return obj->as<SharedArrayBufferObject>().isGrowable();
  86 }