Add an interface for nacl to create delete-on-close temp files,

ppapi/native_client/src/trusted/plugin/temporary_file.h

+// Copyright (c) 2012 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 NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_TEMPORARY_FILE_H_
+#define NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_TEMPORARY_FILE_H_
+
+#include "native_client/src/include/nacl_macros.h"
+#include "native_client/src/include/nacl_string.h"
+#include "native_client/src/trusted/desc/nacl_desc_wrapper.h"
+
+#include "ppapi/cpp/completion_callback.h"
+
+namespace plugin {
+
+class Plugin;
+
+// Translation creates two temporary files.  The first temporary file holds
+// the object file created by llc.  The second holds the nexe produced by
+// the linker.  Both of these temporary files are used to both write and
+// read according to the following matrix:
+//
+// PnaclCoordinator::obj_file_:
+//     written by: llc     (passed in explicitly through SRPC)
+//     read by:    ld      (returned via lookup service from SRPC)
+// PnaclCoordinator::nexe_file_:
+//     written by: ld      (passed in explicitly through SRPC)
+//     read by:    sel_ldr (passed in explicitly to command channel)
+//
+
+// TempFile represents a file used as a temporary between stages in
+// translation.  It is automatically deleted when all handles are closed
+// (or earlier -- immediately unlinked on POSIX systems).  The file is only
+// opened, once, but because both reading and writing are necessary (and in
+// different processes), the user should reset / seek back to the beginning
+// of the file between sessions.
+class TempFile {
+ public:
+  // Create a TempFile.
+  explicit TempFile(Plugin* plugin);
+  ~TempFile();
+
+  // Opens a writeable file IO object and descriptor referring to the file.
+  void Open(const pp::CompletionCallback& cb);
+  // Resets file position of the handle, for reuse.
+  bool Reset();
+
+  // Accessors.
+  // The nacl::DescWrapper* for the writeable version of the file.
+  nacl::DescWrapper* get_wrapper() { return wrapper_.get(); }
+  nacl::DescWrapper* release_wrapper() {
+    return wrapper_.release();
+  }
+
+  // For quota management.
+  const nacl::string identifier() const {
+    return nacl::string(reinterpret_cast<const char*>(identifier_));
+  }
+
+ private:
+  NACL_DISALLOW_COPY_AND_ASSIGN(TempFile);
+
+  Plugin* plugin_;
+  nacl::scoped_ptr<nacl::DescWrapper> wrapper_;
+
+  // An identifier string used for quota request processing.  The quota
+  // interface needs a string that is unique per sel_ldr instance only, so
+  // the identifiers can be reused between runs of the translator, start-ups of
+  // the browser, etc.
+  uint8_t identifier_[16];
+  // A counter to dole out unique identifiers.
+  static uint32_t next_identifier;
+};
+
+}  // namespace plugin
+
+#endif  // NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_TEMPORARY_FILE_H_