[NaCl SDK] nacl_io: big refactor to return error value (errno).

native_client_sdk/src/libraries/nacl_io/mount_node.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 LIBRARIES_NACL_IO_MOUNT_NODE_H_
 #define LIBRARIES_NACL_IO_MOUNT_NODE_H_
 
 #include <string>
 
+#include "nacl_io/error.h"
 #include "nacl_io/osstat.h"
 #include "sdk_util/ref_object.h"
 
 struct dirent;
 struct stat;
 class Mount;
 
+// NOTE: The KernelProxy is the only class that should be setting errno. All
+// other classes should return Error (as defined by nacl_io/error.h).
 class MountNode : public RefObject {
  protected:
   explicit MountNode(Mount* mount);
   virtual ~MountNode();
 
  protected:
   // Initialize with node specific flags, in this case stat permissions.
-  virtual bool Init(int flags);
+  virtual Error Init(int flags);
   virtual void Destroy();
 
  public:
   // Normal OS operations on a node (file), can be called by the kernel
   // directly so it must lock and unlock appropriately.  These functions
   // must not be called by the mount.
-  virtual int FSync();
-  virtual int FTruncate(off_t length);
-  virtual int GetDents(size_t offs, struct dirent* pdir, size_t count);
-  virtual int GetStat(struct stat* stat);
-  virtual int Ioctl(int request, char* arg);
-  virtual int Read(size_t offs, void* buf, size_t count);
-  virtual int Write(size_t offs, const void* buf, size_t count);
-  virtual void* MMap(void* addr, size_t length, int prot, int flags,
-                     size_t offset);
+  virtual Error FSync();
+  // It is expected that the derived MountNode will fill with 0 when growing
+  // the file.
+  virtual Error FTruncate(off_t length);
+  // Assume that |out_bytes| is non-NULL.
+  virtual Error GetDents(size_t offs,
+                         struct dirent* pdir,
+                         size_t count,
+                         int* out_bytes);
+  // Assume that |stat| is non-NULL.
+  virtual Error GetStat(struct stat* stat);
+  // Assume that |arg| is non-NULL.
+  virtual Error Ioctl(int request, char* arg);
+  // Assume that |buf| and |out_bytes| are non-NULL.
+  virtual Error Read(size_t offs, void* buf, size_t count, int* out_bytes);
+  // Assume that |buf| and |out_bytes| are non-NULL.
+  virtual Error Write(size_t offs,
+                      const void* buf,
+                      size_t count,
+                      int* out_bytes);
+  // Assume that |addr| and |out_addr| are non-NULL.
+  virtual Error MMap(void* addr,
+                     size_t length,
+                     int prot,
+                     int flags,
+                     size_t offset,
+                     void** out_addr);
 
   virtual int GetLinks();
   virtual int GetMode();
   virtual int GetType();
-  virtual size_t GetSize();
+  // Assume that |out_size| is non-NULL.
+  virtual Error GetSize(size_t *out_size);
   virtual bool IsaDir();
   virtual bool IsaFile();
   virtual bool IsaTTY();
 
  protected:
   // Directory operations on the node are done by the Mount. The mount's lock
   // must be held while these calls are made.
 
   // Adds or removes a directory entry updating the link numbers and refcount
-  virtual int AddChild(const std::string& name, MountNode *node);
-  virtual int RemoveChild(const std::string& name);
+  // Assumes that |node| is non-NULL.
+  virtual Error AddChild(const std::string& name, MountNode* node);
+  virtual Error RemoveChild(const std::string& name);
 
   // Find a child and return it without updating the refcount
-  virtual MountNode* FindChild(const std::string& name);
+  // Assumes that |out_node| is non-NULL.
+  virtual Error FindChild(const std::string& name, MountNode** out_node);
   virtual int ChildCount();
 
   // Update the link count
   virtual void Link();
   virtual void Unlink();
 
-protected:
+ protected:
   struct stat stat_;
   Mount* mount_;
 
   friend class Mount;
   friend class MountDev;
   friend class MountHtml5Fs;
   friend class MountHttp;
   friend class MountMem;
   friend class MountNodeDir;
 };
 
 #endif  // LIBRARIES_NACL_IO_MOUNT_NODE_H_