components/nacl/renderer/plugin/temporary_file.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_NACL_RENDERER_PLUGIN_TEMPORARY_FILE_H_
   6 #define COMPONENTS_NACL_RENDERER_PLUGIN_TEMPORARY_FILE_H_
   7
   8 #include "native_client/src/include/nacl_macros.h"
   9 #include "native_client/src/trusted/desc/nacl_desc_wrapper.h"
  10
  11 #include "ppapi/c/private/pp_file_handle.h"
  12
  13 namespace plugin {
  14
  15 class Plugin;
  16
  17 // Translation creates two temporary files.  The first temporary file holds
  18 // the object file created by llc.  The second holds the nexe produced by
  19 // the linker.  Both of these temporary files are used to both write and
  20 // read according to the following matrix:
  21 //
  22 // PnaclCoordinator::obj_file_:
  23 //     written by: llc     (passed in explicitly through SRPC)
  24 //     read by:    ld      (returned via lookup service from SRPC)
  25 // PnaclCoordinator::nexe_file_:
  26 //     written by: ld      (passed in explicitly through SRPC)
  27 //     read by:    sel_ldr (passed in explicitly to command channel)
  28 //
  29
  30 // TempFile represents a file used as a temporary between stages in
  31 // translation.  It is automatically deleted when all handles are closed
  32 // (or earlier -- immediately unlinked on POSIX systems).  The file is only
  33 // opened, once, but because both reading and writing are necessary (and in
  34 // different processes), the user should reset / seek back to the beginning
  35 // of the file between sessions.
  36 class TempFile {
  37  public:
  38   // Create a TempFile.
  39   TempFile(Plugin* plugin, PP_FileHandle handle);
  40   ~TempFile();
  41
  42   // Opens a temporary file object and descriptor wrapper referring to the file.
  43   // If |writeable| is true, the descriptor will be opened for writing, and
  44   // write_wrapper will return a valid pointer, otherwise it will return NULL.
  45   int32_t Open(bool writeable);
  46   // Resets file position of the handle, for reuse.
  47   bool Reset();
  48
  49   // Accessors.
  50   // The nacl::DescWrapper* for the writeable version of the file.
  51   nacl::DescWrapper* write_wrapper() { return write_wrapper_.get(); }
  52   nacl::DescWrapper* read_wrapper() { return read_wrapper_.get(); }
  53
  54   // Returns the handle to the file repesented and resets the internal handle
  55   // and all wrappers.
  56   PP_FileHandle TakeFileHandle();
  57
  58  private:
  59   NACL_DISALLOW_COPY_AND_ASSIGN(TempFile);
  60
  61   Plugin* plugin_;
  62   nacl::scoped_ptr<nacl::DescWrapper> read_wrapper_;
  63   nacl::scoped_ptr<nacl::DescWrapper> write_wrapper_;
  64   PP_FileHandle internal_handle_;
  65 };
  66
  67 }  // namespace plugin
  68
  69 #endif  // COMPONENTS_NACL_RENDERER_PLUGIN_TEMPORARY_FILE_H_