Draft of a PPAPI interface for ArrayBuffer.

See the TypedArray spec for reference:
http://www.khronos.org/registry/typedarray/specs/latest/

Things in the spec that I'm omiting:
- slice (Having a view of the ArrayBuffer that has a different offset/length)

TODO in future CLs:
-Implementation for in-process/trusted + tests (almost ready)
-NaCl proxy
-OOP proxy
Later still:
- Support for ArrayBufferView and TypedArray based on that.

BUG=103435
TEST=N/A

Review URL: http://codereview.chromium.org/8502030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113355 0039d316-1c4b-4281-b951-d872f2087c98

ppapi/api/dev/ppb_var_array_buffer_dev.idl

+/* Copyright (c) 2011 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * This file defines the <code>PPB_VarArrayBuffer_Dev</code> struct.
+ */
+
+label Chrome {
+  M17 = 0.1
+};
+
+/**
+ * PPB_VarArrayBuffer_Dev API. This provides a way to interact with JavaScript
+ * ArrayBuffers, which represent a contiguous sequence of bytes. To manage the
+ * reference count for a VarArrayBuffer, please see PPB_Var. Note that
+ * these Vars are not part of the embedding page's DOM, and can only be shared
+ * with JavaScript via pp::Instance's PostMessage and HandleMessage functions.
+ */
+[macro="PPB_VAR_ARRAY_BUFFER_DEV_INTERFACE"]
+interface PPB_VarArrayBuffer_Dev {
+  /**
+   * Create a zero-initialized VarArrayBuffer.
+   *
+   * @param[in] size_in_bytes The size of the array buffer that will be created.
+   *
+   * @return A PP_Var which represents an VarArrayBuffer of the requested size
+   *         with a reference count of 1.
+   */
+  PP_Var Create([in] uint32_t size_in_bytes);
+  /**
+   * Returns the length of the VarArrayBuffer in bytes.
+   *
+   * @return The length of the VarArrayBuffer in bytes.
+   */
+  uint32_t ByteLength([in] PP_Var array);
+  /**
+   * Returns a pointer to the beginning of the buffer for the given array.
+   *
+   * @param[in] array The array whose buffer should be returned.
+   *
+   * @return A pointer to the buffer for this array.
+   */
+  mem_t Map([in] PP_Var array);
+};
+

ppapi/api/pp_var.idl

@@ -61,7 +61,16 @@ enum PP_VarType {
    * module will continue to work with future versions of the API.
    */
   PP_VARTYPE_ARRAY = 7,
-  PP_VARTYPE_DICTIONARY = 8
+  PP_VARTYPE_DICTIONARY = 8,
+
+  /**
+   * ArrayBuffer represents a JavaScript ArrayBuffer. This is the type which
+   * represents Typed Arrays in JavaScript. Unlike JavaScript 'Array', it is
+   * only meant to contain basic numeric types, and is always stored
+   * contiguously. See PPB_VarArrayBuffer_Dev for functions special to
+   * ArrayBuffer vars.
+   */
+  PP_VARTYPE_ARRAY_BUFFER = 9
 };
 
 

ppapi/c/dev/ppb_var_array_buffer_dev.h

+/* Copyright (c) 2011 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* From dev/ppb_var_array_buffer_dev.idl modified Fri Dec  2 16:17:08 2011. */
+
+#ifndef PPAPI_C_DEV_PPB_VAR_ARRAY_BUFFER_DEV_H_
+#define PPAPI_C_DEV_PPB_VAR_ARRAY_BUFFER_DEV_H_
+
+#include "ppapi/c/pp_bool.h"
+#include "ppapi/c/pp_macros.h"
+#include "ppapi/c/pp_stdint.h"
+#include "ppapi/c/pp_var.h"
+
+#define PPB_VAR_ARRAY_BUFFER_DEV_INTERFACE_0_1 "PPB_VarArrayBuffer(Dev);0.1"
+#define PPB_VAR_ARRAY_BUFFER_DEV_INTERFACE \
+    PPB_VAR_ARRAY_BUFFER_DEV_INTERFACE_0_1
+
+/**
+ * @file
+ * This file defines the <code>PPB_VarArrayBuffer_Dev</code> struct.
+ */
+
+
+/**
+ * @addtogroup Interfaces
+ * @{
+ */
+/**
+ * PPB_VarArrayBuffer_Dev API. This provides a way to interact with JavaScript
+ * ArrayBuffers, which represent a contiguous sequence of bytes. To manage the
+ * reference count for a VarArrayBuffer, please see PPB_Var. Note that
+ * these Vars are not part of the embedding page's DOM, and can only be shared
+ * with JavaScript via pp::Instance's PostMessage and HandleMessage functions.
+ */
+struct PPB_VarArrayBuffer_Dev {
+  /**
+   * Create a zero-initialized VarArrayBuffer.
+   *
+   * @param[in] size_in_bytes The size of the array buffer that will be created.
+   *
+   * @return A PP_Var which represents an VarArrayBuffer of the requested size
+   *         with a reference count of 1.
+   */
+  struct PP_Var (*Create)(uint32_t size_in_bytes);
+  /**
+   * Returns the length of the VarArrayBuffer in bytes.
+   *
+   * @return The length of the VarArrayBuffer in bytes.
+   */
+  uint32_t (*ByteLength)(struct PP_Var array);
+  /**
+   * Returns a pointer to the beginning of the buffer for the given array.
+   *
+   * @param[in] array The array whose buffer should be returned.
+   *
+   * @return A pointer to the buffer for this array.
+   */
+  void* (*Map)(struct PP_Var array);
+};
+/**
+ * @}
+ */
+
+#endif  /* PPAPI_C_DEV_PPB_VAR_ARRAY_BUFFER_DEV_H_ */
+

ppapi/c/pp_var.h

@@ -3,7 +3,7 @@
  * found in the LICENSE file.
  */
 
-/* From pp_var.idl modified Fri Nov 11 19:57:17 2011. */
+/* From pp_var.idl modified Fri Dec  2 16:45:08 2011. */
 
 #ifndef PPAPI_C_PP_VAR_H_
 #define PPAPI_C_PP_VAR_H_
@@ -68,7 +68,15 @@ typedef enum {
    * module will continue to work with future versions of the API.
    */
   PP_VARTYPE_ARRAY = 7,
-  PP_VARTYPE_DICTIONARY = 8
+  PP_VARTYPE_DICTIONARY = 8,
+  /**
+   * ArrayBuffer represents a JavaScript ArrayBuffer. This is the type which
+   * represents Typed Arrays in JavaScript. Unlike JavaScript 'Array', it is
+   * only meant to contain basic numeric types, and is always stored
+   * contiguously. See PPB_VarArrayBuffer_Dev for functions special to
+   * ArrayBuffer vars.
+   */
+  PP_VARTYPE_ARRAY_BUFFER = 9
 } PP_VarType;
 PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_VarType, 4);
 /**

ppapi/cpp/dev/var_array_buffer_dev.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ppapi/cpp/dev/var_array_buffer_dev.h"
+
+#include "ppapi/c/dev/ppb_var_array_buffer_dev.h"
+#include "ppapi/cpp/logging.h"
+#include "ppapi/cpp/module_impl.h"
+
+namespace pp {
+
+namespace {
+
+template <> const char* interface_name<PPB_VarArrayBuffer_Dev>() {
+  return PPB_VAR_ARRAY_BUFFER_DEV_INTERFACE;
+}
+
+}  // namespace
+
+VarArrayBuffer_Dev::VarArrayBuffer_Dev(const Var& var)
+    : Var(var), buffer_(NULL) {
+  if (var.is_array_buffer()) {
+    buffer_ = Map();
+  } else {
+    PP_NOTREACHED();
+    var_ = PP_MakeNull();
+  }
+}
+
+VarArrayBuffer_Dev::VarArrayBuffer_Dev(uint32_t size_in_bytes)
+    : buffer_(NULL) {
+  if (has_interface<PPB_VarArrayBuffer_Dev>()) {
+    var_ = get_interface<PPB_VarArrayBuffer_Dev>()->Create(size_in_bytes);
+    buffer_ = Map();
+  } else {
+    PP_NOTREACHED();
+    var_ = PP_MakeNull();
+  }
+}
+
+uint32_t VarArrayBuffer_Dev::ByteLength() const {
+  if (has_interface<PPB_VarArrayBuffer_Dev>()) {
+    return get_interface<PPB_VarArrayBuffer_Dev>()->ByteLength(var_);
+  }
+  PP_NOTREACHED();
+  return 0;
+}
+
+const void* VarArrayBuffer_Dev::Map() const {
+  return const_cast<VarArrayBuffer_Dev*>(this)->Map();
+}
+
+void* VarArrayBuffer_Dev::Map() {
+  // TODO(dmichael): This is not thread-safe.
+  if (buffer_)
+    return buffer_;
+  if (has_interface<PPB_VarArrayBuffer_Dev>()) {
+    buffer_ = get_interface<PPB_VarArrayBuffer_Dev>()->Map(var_);
+    return buffer_;
+  }
+  PP_NOTREACHED();
+  return 0;
+}
+
+}  // namespace pp

ppapi/cpp/dev/var_array_buffer_dev.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_CPP_DEV_VAR_ARRAY_BUFFER_DEV_H_
+#define PPAPI_CPP_DEV_VAR_ARRAY_BUFFER_DEV_H_
+
+#include "ppapi/cpp/var.h"
+
+/// @file
+/// This file defines the API for interacting with an ArrayBuffer.
+
+namespace pp {
+
+/// VarArrayBuffer_Dev provides a way to interact with JavaScript ArrayBuffers,
+/// which represent a contiguous sequence of bytes. Note that
+/// VarArrayBuffer_Devs are not part of the embedding page's DOM, and can only
+/// be shared with JavaScript via pp::Instance's PostMessage and HandleMessage
+/// functions.
+class VarArrayBuffer_Dev : public Var {
+ public:
+  /// Contruct a VarArrayBuffer_Dev given a var for which is_array_buffer() is
+  /// true. This will refer to the same buffer as var, but allows you to access
+  /// methods specific to VarArrayBuffer_Dev.
+  ///
+  /// @param[in] var An array buffer Var.
+  explicit VarArrayBuffer_Dev(const Var& var);
+
+  VarArrayBuffer_Dev(const VarArrayBuffer_Dev& buffer) : Var(buffer) {}
+
+  /// Construct a new VarArrayBuffer_Dev which is size_in_bytes bytes long and
+  /// initialized to zero.
+  ///
+  /// @param[in] size_in_bytes The size of the constructed array in bytes.
+  VarArrayBuffer_Dev(uint32_t size_in_bytes);
+
+  /// Return the length of the VarArrayBuffer_Dev in bytes.
+  ///
+  /// @return The length of the VarArrayBuffer_Dev in bytes.
+  uint32_t ByteLength() const;
+
+  /// Return a pointer to the buffer associated with this VarArrayBuffer_Dev.
+  ///
+  /// @return A pointer to the buffer associated with this VarArrayBuffer_Dev.
+  void* Map();
+  const void* Map() const;
+
+  virtual ~VarArrayBuffer_Dev() {}
+
+ private:
+  // We cache the buffer so that repeated calls to Map() are quick.
+  void* buffer_;
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_DEV_VAR_ARRAY_BUFFER_DEV_H_

ppapi/cpp/var.h

@@ -158,6 +158,9 @@ class Var {
            var_.type == PP_VARTYPE_DOUBLE;
   }
 
+  /// This function determines if this <code>Var</code> is an ArrayBuffer.
+  bool is_array_buffer() const { return var_.type == PP_VARTYPE_ARRAY_BUFFER; }
+
   /// AsBool() converts this <code>Var</code> to a bool. Assumes the
   /// internal representation is_bool(). If it's not, it will assert in debug
   /// mode, and return false.

ppapi/native_client/src/shared/ppapi_proxy/object_serialize.cc

@@ -131,6 +131,7 @@ uint32_t PpVarSize(const PP_Var& var) {
     case PP_VARTYPE_OBJECT:
     case PP_VARTYPE_ARRAY:
     case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
       NACL_NOTREACHED();
       break;
   }
@@ -215,6 +216,7 @@ bool SerializePpVar(const PP_Var* vars,
       case PP_VARTYPE_OBJECT:
       case PP_VARTYPE_ARRAY:
       case PP_VARTYPE_DICTIONARY:
+      case PP_VARTYPE_ARRAY_BUFFER:
         NACL_NOTREACHED();
       default:
         return false;
@@ -306,6 +308,7 @@ uint32_t DeserializePpVarSize(char* p,
     case PP_VARTYPE_OBJECT:
     case PP_VARTYPE_ARRAY:
     case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
       NACL_NOTREACHED();
       break;
   }
@@ -377,6 +380,7 @@ bool DeserializePpVar(NaClSrpcChannel* channel,
       case PP_VARTYPE_OBJECT:
       case PP_VARTYPE_ARRAY:
       case PP_VARTYPE_DICTIONARY:
+      case PP_VARTYPE_ARRAY_BUFFER:
         NACL_NOTREACHED();
       default:
         return false;

ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_var.cc

@@ -129,6 +129,7 @@ std::string PluginVar::DebugString(const PP_Var& var) {
       }
     case PP_VARTYPE_ARRAY:
     case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
       NACL_NOTREACHED();
       break;
   }
@@ -191,6 +192,7 @@ void PluginVar::Print(const PP_Var& var) {
       break;
     case PP_VARTYPE_ARRAY:
     case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
       NACL_NOTREACHED();
       break;
   }

ppapi/ppapi_sources.gypi

@@ -65,6 +65,7 @@
       'c/dev/ppb_scrollbar_dev.h',
       'c/dev/ppb_testing_dev.h',
       'c/dev/ppb_url_util_dev.h',
+      'c/dev/ppb_var_array_buffer_dev.h',
       'c/dev/ppb_video_decoder_dev.h',
       'c/dev/ppb_websocket_dev.h',
       'c/dev/ppb_widget_dev.h',
@@ -200,6 +201,8 @@
       'cpp/dev/text_input_dev.h',
       'cpp/dev/url_util_dev.cc',
       'cpp/dev/url_util_dev.h',
+      'cpp/dev/var_array_buffer_dev.cc',
+      'cpp/dev/var_array_buffer_dev.h',
       'cpp/dev/video_capture_client_dev.cc',
       'cpp/dev/video_capture_client_dev.h',
       'cpp/dev/video_capture_dev.cc',
@@ -380,4 +383,4 @@
       },
     }],
   ],
-}
\ No newline at end of file
+}

ppapi/proxy/serialized_var.cc

@@ -157,6 +157,7 @@ void SerializedVar::Inner::WriteToMessage(IPC::Message* m) const {
       break;
     case PP_VARTYPE_ARRAY:
     case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
       // TODO(brettw) when these are supported, implement this.
       NOTIMPLEMENTED();
       break;

webkit/plugins/ppapi/message_channel.cc

@@ -85,13 +85,13 @@ bool PPVarToV8Value(PP_Var var, v8::Handle<v8::Value>* result) {
       break;
     }
     case PP_VARTYPE_OBJECT:
-      // Objects are not currently supported.
+    case PP_VARTYPE_ARRAY:
+    case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
+      // These are not currently supported.
       NOTIMPLEMENTED();
       result->Clear();
       return false;
-    default:
-      result->Clear();
-      return false;
   }
   return true;
 }

webkit/plugins/ppapi/npapi_glue.cc

@@ -75,6 +75,7 @@ bool PPVarToNPVariant(PP_Var var, NPVariant* result) {
     }
     case PP_VARTYPE_ARRAY:
     case PP_VARTYPE_DICTIONARY:
+    case PP_VARTYPE_ARRAY_BUFFER:
       VOID_TO_NPVARIANT(*result);
       break;
   }