FS: directory operations will now work on empty directory nodes in the pseudo-filesystem

1 files changed, 71 insertions, 20 deletions

diff --git a/nuttx/fs/fs_opendir.c b/nuttx/fs/fs_opendir.c
index c1f44a9d1..46421c37e 100644
--- a/nuttx/fs/fs_opendir.c
+++ b/nuttx/fs/fs_opendir.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * fs/fs_opendir.c
  *
- *   Copyright (C) 2007-2009, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2013-2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -89,8 +89,8 @@ static inline int open_mountpoint(FAR struct inode *inode,
        return ENOSYS;
     }
 
-  /* Take reference to the mountpoint inode (fd_root).  Note that we do
-   * not use inode_addref() because we already hold the tree semaphore.
+  /* Take reference to the mountpoint inode.  Note that we do not use
+   * inode_addref() because we already hold the tree semaphore.
    */
 
   inode->i_crefs++;
@@ -132,7 +132,7 @@ static inline int open_mountpoint(FAR struct inode *inode,
  *   dir -- the dirent structure to be initialized
  *
  * Return:
- *   On success, OK is returned; Otherwise, a positive errno is returned.
+ *   None
  *
  ****************************************************************************/
 
@@ -144,7 +144,8 @@ static void open_pseudodir(FAR struct inode *inode, FAR struct fs_dirent_s *dir)
    * semaphore and that would result in deadlock.
    */
 
-  inode->i_crefs += 2;
+  inode->i_crefs       += 2;
+  dir->fd_root          = inode; /* Save the inode where we start */
   dir->u.pseudo.fd_next = inode; /* This is the next node to use for readdir() */
 
   /* Flag the inode as belonging to the pseudo-filesystem */
@@ -155,6 +156,43 @@ static void open_pseudodir(FAR struct inode *inode, FAR struct fs_dirent_s *dir)
 }
 
 /****************************************************************************
+ * Name: open_emptydir
+ *
+ * Description:
+ *   Handle the case where the inode to be opened is an empty, directory node
+ *   within the top-level pseudo-file system.  That is, it has no operations
+ *   and, therefore, it must be a directory node.  But is has no children
+ *   to be enumerated either.
+ *
+ * Inputs:
+ *   dir -- the dirent structure to be initialized
+ *
+ * Return:
+ *   None
+ *
+ ****************************************************************************/
+
+static inline void open_emptydir(FAR struct fs_dirent_s *dir)
+{
+  /* We have a valid, but empty pseudo-filesystem node.  fd_next is NULL
+   * meaning that we are already at the end of the list of its children.
+   * fd_root is NULL so that if the directory is rewound, it will still be
+   * at the end of the list.
+   */
+
+#if 0 /* Already nullified by kuzalloc */
+  dir->fd_root          = NULL; /* Save the inode where we start */
+  dir->u.pseudo.fd_next = NULL; /* We are at the end of the list */
+#endif
+
+  /* Flag the inode as belonging to the pseudo-filesystem */
+
+#ifndef CONFIG_DISABLE_MOUNTPOINT
+  DIRENT_SETPSEUDONODE(dir->fd_flags);
+#endif
+}
+
+/****************************************************************************
  * Public Functions
  ****************************************************************************/
 
@@ -189,7 +227,7 @@ FAR DIR *opendir(FAR const char *path)
   FAR struct inode *inode = NULL;
   FAR struct fs_dirent_s *dir;
   FAR const char *relpath;
-  bool bisroot = false;
+  bool isroot = false;
   int ret;
 
   /* If we are given 'nothing' then we will interpret this as
@@ -200,7 +238,7 @@ FAR DIR *opendir(FAR const char *path)
   if (!path || *path == 0 || strcmp(path, "/") == 0)
     {
       inode   = root_inode;
-      bisroot = true;
+      isroot = true;
       relpath = NULL;
     }
   else
@@ -246,14 +284,13 @@ FAR DIR *opendir(FAR const char *path)
    * inode or a file system mountpoint.
    */
 
-  dir->fd_root     = inode;  /* Save the inode where we start */
   dir->fd_position = 0;      /* This is the position in the read stream */
 
   /* First, handle the special case of the root inode.  This must be
    * special-cased here because the root inode might ALSO be a mountpoint.
    */
 
-  if (bisroot)
+  if (isroot)
     {
       /* Whatever payload the root inode carries, the root inode is always
        * a directory inode in the pseudo-file system
@@ -263,13 +300,17 @@ FAR DIR *opendir(FAR const char *path)
     }
 
   /* Is this a node in the pseudo filesystem? Or a mountpoint?  If the node
-   * is the root (bisroot == TRUE), then this is a special case.
+   * is the root (isroot == TRUE), then this is a special case.
    */
 
 #ifndef CONFIG_DISABLE_MOUNTPOINT
    else if (INODE_IS_MOUNTPT(inode))
      {
-       /* Yes, the node is a file system mointpoint. */
+       /* Yes, the node is a file system mountpoint */
+
+      dir->fd_root = inode;  /* Save the inode where we start */
+
+      /* Open the directory at the relative path */
 
       ret = open_mountpoint(inode, relpath, dir);
       if (ret != OK)
@@ -280,21 +321,31 @@ FAR DIR *opendir(FAR const char *path)
 #endif
   else
     {
-      /* The node is part of the root pseudo file system.  Does the inode have a child?
-       * If so that the child would be the 'root' of a list of nodes under
-       * the directory.
+      /* The node is part of the root pseudo file system.  Does the inode
+       * have a child? If so that the child would be the 'root' of a list
+       * of nodes under the directory.
        */
 
-      inode = inode->i_child;
-      if (!inode)
+      FAR struct inode *child = inode->i_child;
+      if (child)
+        {
+          /* It looks we have a valid pseudo-filesystem directory node. */
+
+          open_pseudodir(child, dir);
+        }
+      else if (!inode->u.i_ops)
+        {
+          /* This is a dangling node with no children and no operations. Set
+           * up to enumerate an empty directory.
+           */
+
+          open_emptydir(dir);
+        }
+      else
         {
           ret = ENOTDIR;
           goto errout_with_direntry;
         }
-
-      /* It looks we have a valid pseudo-filesystem directory node. */
-
-      open_pseudodir(inode, dir);
     }
 
   inode_semgive();