native_client_sdk/src/libraries/nacl_io/kernel_object.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 LIBRARIES_NACL_IO_KERNEL_OBJECT_H_
   6 #define LIBRARIES_NACL_IO_KERNEL_OBJECT_H_
   7
   8 #include <pthread.h>
   9
  10 #include <map>
  11 #include <string>
  12 #include <vector>
  13
  14 #include "nacl_io/error.h"
  15 #include "nacl_io/filesystem.h"
  16 #include "nacl_io/kernel_handle.h"
  17 #include "nacl_io/node.h"
  18 #include "nacl_io/path.h"
  19
  20 #include "sdk_util/macros.h"
  21 #include "sdk_util/simple_lock.h"
  22
  23 namespace nacl_io {
  24
  25 // KernelObject provides basic functionality for threadsafe access to kernel
  26 // objects such as the CWD, mount points, file descriptors and file handles.
  27 // All Kernel locks are private to ensure the lock order.
  28 //
  29 // All calls are assumed to be a relative path.
  30 class KernelObject {
  31  public:
  32   struct Descriptor_t {
  33     Descriptor_t() : flags(0) {}
  34     explicit Descriptor_t(const ScopedKernelHandle& h,
  35                           const std::string& open_path)
  36         : handle(h), flags(0), path(open_path) {}
  37
  38     ScopedKernelHandle handle;
  39     int flags;
  40     std::string path;
  41   };
  42   typedef std::vector<Descriptor_t> HandleMap_t;
  43   typedef std::map<std::string, ScopedFilesystem> FsMap_t;
  44
  45   KernelObject();
  46   virtual ~KernelObject();
  47
  48   // Attach the given Filesystem object at the specified path.
  49   Error AttachFsAtPath(const ScopedFilesystem& fs, const std::string& path);
  50
  51   // Unmap the Filesystem object from the specified path and release it.
  52   Error DetachFsAtPath(const std::string& path, ScopedFilesystem* out_fs);
  53
  54   // Find the filesystem for the given path, and acquires it and return a
  55   // path relative to the filesystem.
  56   // Assumes |out_fs| and |rel_path| are non-NULL.
  57   Error AcquireFsAndRelPath(const std::string& path,
  58                             ScopedFilesystem* out_fs,
  59                             Path* rel_path);
  60
  61   // Find the filesystem and node for the given path, acquiring/creating it as
  62   // specified by the |oflags|.
  63   // Assumes |out_fs| and |out_node| are non-NULL.
  64   Error AcquireFsAndNode(const std::string& path,
  65                          int oflags,
  66                          ScopedFilesystem* out_fs,
  67                          ScopedNode* out_node);
  68
  69   // Get FD-specific flags (currently only FD_CLOEXEC is supported).
  70   Error GetFDFlags(int fd, int* out_flags);
  71   // Set FD-specific flags (currently only FD_CLOEXEC is supported).
  72   Error SetFDFlags(int fd, int flags);
  73
  74   // Convert from FD to KernelHandle, and acquire the handle.
  75   // Assumes |out_handle| is non-NULL.
  76   Error AcquireHandle(int fd, ScopedKernelHandle* out_handle);
  77   Error AcquireHandleAndPath(int fd,
  78                              ScopedKernelHandle* out_handle,
  79                              std::string* out_path);
  80
  81   // Allocate a new fd and assign the handle to it, while
  82   // ref counting the handle and associated filesystem.
  83   // Assumes |handle| is non-NULL;
  84   int AllocateFD(const ScopedKernelHandle& handle,
  85                  const std::string& path = std::string());
  86
  87   // Assumes |handle| is non-NULL;
  88   void FreeAndReassignFD(int fd,
  89                          const ScopedKernelHandle& handle,
  90                          const std::string& path);
  91   void FreeFD(int fd);
  92
  93   // Returns or sets CWD
  94   std::string GetCWD();
  95   Error SetCWD(const std::string& path);
  96
  97   // Returns parts of the absolute path for the given relative path
  98   Path GetAbsParts(const std::string& path);
  99
 100  private:
 101   std::string cwd_;
 102   std::vector<int> free_fds_;
 103   HandleMap_t handle_map_;
 104   FsMap_t filesystems_;
 105
 106   // Lock to protect free_fds_ and handle_map_.
 107   sdk_util::SimpleLock handle_lock_;
 108
 109   // Lock to protect filesystems_.
 110   sdk_util::SimpleLock fs_lock_;
 111
 112   // Lock to protect cwd_.
 113   sdk_util::SimpleLock cwd_lock_;
 114
 115   DISALLOW_COPY_AND_ASSIGN(KernelObject);
 116 };
 117
 118 }  // namespace nacl_io
 119
 120 #endif  // LIBRARIES_NACL_IO_KERNEL_OBJECT_H_