[NaCl SDK] nacl_io: Added support for access() syscall.

native_client_sdk/src/libraries/nacl_io/mount.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_H_
 #define LIBRARIES_NACL_IO_MOUNT_H_
 
 #include <map>
 #include <string>
 
@@ skipping 34 matching lines @@
 
   PepperInterface* ppapi() { return ppapi_; }
 
   // Assumes that |node| is non-NULL.
   void AcquireNode(MountNode* node);
   // Assumes that |node| is non-NULL.
   void ReleaseNode(MountNode* node);
 
   // All paths in functions below are expected to containing a leading "/".
 
+  // Test whether a file at a given path can be accessed.
+  // Returns 0 on success, or an appropriate errno value on failure.

[binji, 2013/06/19 16:46:28]

What is the behavior of access if given a directory?

[Matt Giuca, 2013/06/20 01:43:14]

Should be the same as for normal access. R_OK means you can GetDents on it, W_OK
means you can create files and subdirs in it, X_OK means you can cd to it. Do I
need to say this in comments here or do we assume the reader knows the semantics
of POSIX syscalls?

[binji, 2013/06/20 16:07:21]

Hm. I might like to have something similar to your explanation of why X_OK is
handled the way it is here. The semantics of X_OK w.r.t. directories would be
useful information in that discussion.

+  virtual Error Access(const Path& path, int a_mode) = 0;
+
   // Open a node at |path| with the specified open flags. The resulting
   // MountNode is created with a ref count of 1.
   // Assumes that |out_node| is non-NULL.
   virtual Error Open(const Path& path, int o_flags, MountNode** out_node) = 0;
 
   // OpenResource is only used to read files from the NaCl NMF file. No mount
   // except MountPassthrough should implement it.
   // Assumes that |out_node| is non-NULL.
   virtual Error OpenResource(const Path& path, MountNode** out_node);
 
@@ skipping 41 matching lines @@
     delete mnt;
     *out_mount = NULL;
     return error;
   }
 
   *out_mount = mnt;
   return 0;
 }
 
 #endif  // LIBRARIES_NACL_IO_MOUNT_H_