PPAPI: Implement PPB_FileMapping on POSIX

ppapi/proxy/file_mapping_resource.cc

+// Copyright (c) 2014 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/proxy/file_mapping_resource.h"
+
+#include "base/bind.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/task_runner_util.h"
+#include "ppapi/c/pp_errors.h"
+#include "ppapi/shared_impl/tracked_callback.h"
+#include "ppapi/shared_impl/var.h"
+#include "ppapi/thunk/enter.h"
+#include "ppapi/thunk/ppb_file_io_api.h"
+
+namespace ppapi {
+namespace proxy {
+
+FileMappingResource::FileMappingResource(Connection connection,
+                                         PP_Instance instance)
+    : PluginResource(connection, instance) {
+}
+
+FileMappingResource::~FileMappingResource() {
+}
+
+thunk::PPB_FileMapping_API* FileMappingResource::AsPPB_FileMapping_API() {
+  return this;
+}
+
+int32_t FileMappingResource::Map(PP_Instance /* instance */,
+                                 PP_Resource file_io,
+                                 int64_t length,
+                                 uint32_t map_protection,
+                                 uint32_t map_flags,
+                                 int64_t offset,
+                                 void** address,
+                                 scoped_refptr<TrackedCallback> callback) {
+  thunk::EnterResourceNoLock<thunk::PPB_FileIO_API> enter(file_io, true);
+  if (enter.failed())
+    return PP_ERROR_BADARGUMENT;
+  FileIOResource* file_io_resource =
+      static_cast<FileIOResource*>(enter.object());
+  scoped_refptr<FileIOResource::FileHandleHolder> file_handle =
+      file_io_resource->file_handle();
+  if (!FileIOResource::FileHandleHolder::IsValid(file_handle))
+    return PP_ERROR_FAILED;
+  if (length < 0 || offset < 0 ||
+      !base::IsValueInRangeForNumericType<off_t>(offset)) {
+    return PP_ERROR_BADARGUMENT;
+  }
+  if (!base::IsValueInRangeForNumericType<size_t>(length)) {
+    return PP_ERROR_NOMEMORY;
+  }
+
+  // Ensure no bits that we don't recognize are set.

[bbudge, 2014/01/25 01:04:55]

This is hard for me to read. How about
// Ensure bits we don't recognize are zero.

[dmichael (off chromium), 2014/01/27 18:29:53]

Done.

+  if (map_protection &
+      ~(PP_FILEMAPPROTECTION_READ | PP_FILEMAPPROTECTION_WRITE)) {
+    return PP_ERROR_BADARGUMENT;
+  }
+  if (map_flags &
+      ~(PP_FILEMAPFLAG_SHARED | PP_FILEMAPFLAG_PRIVATE |
+        PP_FILEMAPFLAG_FIXED)) {
+    return PP_ERROR_BADARGUMENT;
+  }
+  // Ensure at least one of SHARED and PRIVATE is set.
+  if (!(map_flags & (PP_FILEMAPFLAG_SHARED | PP_FILEMAPFLAG_PRIVATE)))
+    return PP_ERROR_BADARGUMENT;
+  // Ensure at most one of SHARED and PRIVATE is set.
+  if ((map_flags & PP_FILEMAPFLAG_SHARED) &&
+      (map_flags & PP_FILEMAPFLAG_PRIVATE)) {
+    return PP_ERROR_BADARGUMENT;
+  }
+  if (!address)
+    return PP_ERROR_BADARGUMENT;
+
+  base::Callback<MapResult()> map_op(

[bbudge, 2014/01/25 01:04:55]

The _op suffix seems to be a carryover from FileIOResource. Maybe _cb or _task
would be better.
Same comment below in Unmap.

[dmichael (off chromium), 2014/01/27 18:29:53]

Done.

+      base::Bind(&FileMappingResource::DoMap, file_handle, *address, length,
+                 map_protection, map_flags, offset));
+  if (callback->is_blocking()) {
+    // The plugin could release its reference to this instance when we release
+    // the proxy lock below.
+    scoped_refptr<FileMappingResource> protect(this);
+    MapResult map_result;
+    {
+      // Release the proxy lock while making a potentially slow file call.
+      ProxyAutoUnlock unlock;
+      map_result = map_op.Run();
+    }
+    OnMapCompleted(address, length, callback, map_result);
+    return map_result.result;
+  } else {
+    base::PostTaskAndReplyWithResult(
+      PpapiGlobals::Get()->GetFileTaskRunner(),
+      FROM_HERE,
+      map_op,
+      RunWhileLocked(Bind(&FileMappingResource::OnMapCompleted,
+                          this,
+                          base::Unretained(address),
+                          length,
+                          callback)));
+    return PP_OK_COMPLETIONPENDING;
+  }
+}
+
+int32_t FileMappingResource::Unmap(PP_Instance /* instance */,
+                                   const void* address,
+                                   int64_t length,
+                                   scoped_refptr<TrackedCallback> callback) {
+  if (!address)
+    return PP_ERROR_BADARGUMENT;
+  if (!base::IsValueInRangeForNumericType<size_t>(length))
+    return PP_ERROR_BADARGUMENT;
+
+  base::Callback<int32_t()> unmap_op(
+      base::Bind(&FileMappingResource::DoUnmap, address, length));
+  if (callback->is_blocking()) {
+    // Release the proxy lock while making a potentially slow file call.
+    ProxyAutoUnlock unlock;
+    return unmap_op.Run();
+  } else {
+    base::PostTaskAndReplyWithResult(
+      PpapiGlobals::Get()->GetFileTaskRunner(),
+      FROM_HERE,
+      unmap_op,
+      RunWhileLocked(Bind(&TrackedCallback::Run, callback)));
+    return PP_OK_COMPLETIONPENDING;
+  }
+}
+
+int64_t FileMappingResource::GetMapPageSize(PP_Instance /* instance */) {
+  return DoGetMapPageSize();
+}
+
+void FileMappingResource::OnMapCompleted(
+    void** mapped_address_out_param,
+    int64_t length,
+    scoped_refptr<TrackedCallback> callback,
+    const MapResult& map_result) {
+  // TODO(dmichael): If the callback is aborted, should we unmap?

[bbudge, 2014/01/25 01:04:55]

remove comment now.

[dmichael (off chromium), 2014/01/27 18:29:53]

Done.

+  if (callback->aborted()) {
+    if (map_result.result == PP_OK) {
+      // If the Map operation was successful, we need to Unmap to avoid leaks.
+      // The plugin won't get the address, so doesn't have a chance to do the
+      // Unmap.
+      PpapiGlobals::Get()->GetFileTaskRunner()->PostTask(
+          FROM_HERE,
+          base::Bind(base::IgnoreResult(&FileMappingResource::DoUnmap),
+                     map_result.address,
+                     length));
+    }
+    return;
+  }
+  if (map_result.result == PP_OK)
+    *mapped_address_out_param = map_result.address;
+  if (!callback->is_blocking())
+    callback->Run(map_result.result);
+}
+
+}  // namespace proxy
+}  // namespace ppapi