ppapi/native_client/src/trusted/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 NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_TEMPORARY_FILE_H_
   6 #define NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_TEMPORARY_FILE_H_
   7
   8 #include "native_client/src/include/nacl_macros.h"
   9 #include "native_client/src/include/nacl_string.h"
  10 #include "native_client/src/trusted/desc/nacl_desc_wrapper.h"
  11
  12 #include "ppapi/c/private/pp_file_handle.h"
  13 #include "ppapi/cpp/completion_callback.h"
  14
  15 namespace plugin {
  16
  17 class Plugin;
  18
  19 // Translation creates two temporary files.  The first temporary file holds
  20 // the object file created by llc.  The second holds the nexe produced by
  21 // the linker.  Both of these temporary files are used to both write and
  22 // read according to the following matrix:
  23 //
  24 // PnaclCoordinator::obj_file_:
  25 //     written by: llc     (passed in explicitly through SRPC)
  26 //     read by:    ld      (returned via lookup service from SRPC)
  27 // PnaclCoordinator::nexe_file_:
  28 //     written by: ld      (passed in explicitly through SRPC)
  29 //     read by:    sel_ldr (passed in explicitly to command channel)
  30 //
  31
  32 // TempFile represents a file used as a temporary between stages in
  33 // translation.  It is automatically deleted when all handles are closed
  34 // (or earlier -- immediately unlinked on POSIX systems).  The file is only
  35 // opened, once, but because both reading and writing are necessary (and in
  36 // different processes), the user should reset / seek back to the beginning
  37 // of the file between sessions.
  38 class TempFile {
  39  public:
  40   // Create a TempFile.
  41   explicit TempFile(Plugin* plugin);
  42   ~TempFile();
  43
  44   // Set an existing Fd instead of getting one from the nacl interface on open.
  45   // Must be called before Open.
  46   bool SetExistingFd(PP_FileHandle handle);
  47   // Opens a temporary file object and descriptor wrapper referring to the file.
  48   // If |writeable| is true, the descriptor will be opened for writing, and
  49   // write_wrapper will return a valid pointer, otherwise it will return NULL.
  50   void Open(const pp::CompletionCallback& cb, bool writeable);
  51   // Resets file position of the handle, for reuse.
  52   bool Reset();
  53
  54   // Accessors.
  55   // The nacl::DescWrapper* for the writeable version of the file.
  56   nacl::DescWrapper* write_wrapper() { return write_wrapper_.get(); }
  57   nacl::DescWrapper* read_wrapper() { return read_wrapper_.get(); }
  58   nacl::DescWrapper* release_read_wrapper() {
  59     return read_wrapper_.release();
  60   }
  61
  62   // For quota management.
  63   const nacl::string identifier() const {
  64     return nacl::string(reinterpret_cast<const char*>(identifier_));
  65   }
  66
  67  private:
  68   NACL_DISALLOW_COPY_AND_ASSIGN(TempFile);
  69
  70   Plugin* plugin_;
  71   nacl::scoped_ptr<nacl::DescWrapper> read_wrapper_;
  72   nacl::scoped_ptr<nacl::DescWrapper> write_wrapper_;
  73   PP_FileHandle existing_handle_;
  74
  75   // An identifier string used for quota request processing.  The quota
  76   // interface needs a string that is unique per sel_ldr instance only, so
  77   // the identifiers can be reused between runs of the translator, start-ups of
  78   // the browser, etc.
  79   uint8_t identifier_[16];
  80   // A counter to dole out unique identifiers.
  81   static uint32_t next_identifier;
  82 };
  83
  84 }  // namespace plugin
  85
  86 #endif  // NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_TEMPORARY_FILE_H_