Example #1
0
        /// <summary>
        /// Performs an iterative lookup of the given path starting from the root and obeying to the specified flags.
        /// </summary>
        /// <param name="path">The path to lookup. This can be a relative or absolute path. Path.DirectorySeparatorChar or Path.AltDirectorySeparatorChar are valid delimiters.</param>
        /// <param name="root">The root directory to start lookup from.</param>
        /// <param name="flags">The lookup flags, which control the lookup process.</param>
        /// <returns>The directory entry of the resolved path.</returns>
        /// <exception cref="System.Security.SecurityException">The caller does not have access to the path or a component. For example the caller does not have the right to traverse the path.</exception>
        /// <exception cref="System.IO.PathTooLongException">The path is too long to traverse. This can be the result of circular symbolic links in the path.</exception>
        /// <exception cref="System.IO.FileNotFoundException">The path or a component was not found. This exception can be prevented by specifying PathResolutionFlags.DoNotThrowNotFoundException.</exception>
        /// <exception cref="System.IO.DirectoryNotFoundException">A path component was not found. This exception can be prevented by specifying PathResolutionFlags.DoNotThrowNotFoundException.</exception>
        /// <remarks>
        /// This call may result in other exceptions not specified in the above list. Other exceptions can be thrown by IVfsNode implementations, which are visited during the traversal
        /// process. For example a network file system node may throw an exception, if the server is unreachable.
        /// </remarks>
        private DirectoryEntry Resolve(ref string path, PathResolutionFlags flags)
        {
            // DirectoryNode entry found by stepping through the path
            DirectoryEntry entry = null;

            // Split the given path to its components
            PathSplitter dirs = new PathSplitter(path);

            // Determine the number of path components
            int max = dirs.Length;

            // Current path component
            string item;
            // Loop index
            int index = 0;

            // Perform an access check on the root directory
            AccessCheck.Perform(currentDirectory, AccessMode.Traverse, AccessCheckFlags.None);

            // Do not resolve the last name, if we want the parent directory.
            if (PathResolutionFlags.RetrieveParent == (flags & PathResolutionFlags.RetrieveParent))
            {
                path = dirs[dirs.Length - 1];
                max--;
            }

            // Check if this is an absolute path?
            if (dirs[0].Length == 0)
            {
                // Yes, replace the current directory
                currentDirectory = rootDirectory;
                index++;
            }

            // Iterate over the remaining path components
            while ((currentDirectory != null) && (index < max))
            {
                item  = dirs[index];
                entry = null;
                if (currentDirectory.Node.NodeType == VfsNodeType.SymbolicLink)
                {
                    SymbolicLinkNode link = (SymbolicLinkNode)currentDirectory.Node;
                    if (0 != depth--)
                    {
                        // The symlink stores a relative path, use it for a current relative lookup.
                        string target = link.Target;

                        // Build a new flags set for symlink lookups, as we do not want all of them.
                        PathResolutionFlags symflags = (flags & PathResolutionFlags.SymLinkLookupSafe);
                        entry = Resolve(ref target, symflags);
                    }
                    else
                    {
                        if (PathResolutionFlags.DoNotThrowNotFoundException != (PathResolutionFlags.DoNotThrowNotFoundException & flags))
                        {
                            // FIXME: Provide a MUI resource string for the exception
#if VFS_EXCEPTIONS
                            throw new PathTooLongException();
#endif // #if !VFS_EXCEPTIONS
                        }
                    }
                }
                else
                {
                    // Pass the lookup to the DirectoryEntry (and ultimately to the inode itself.)
                    entry = currentDirectory.Lookup(item);

                    // If lookup in the directory entry failed, ask the real INode to perform the lookup.
                    if (entry == null)
                    {
                        IVfsNode node = currentDirectory.Node.Lookup(item);
                        if (node != null)
                        {
                            entry = DirectoryEntry.Allocate(currentDirectory, item, node);
                        }
                    }
                }

                // Increment the path component index
                index++;

                // Check if we have a new path component?
                if ((entry == null) && (PathResolutionFlags.DoNotThrowNotFoundException != (PathResolutionFlags.DoNotThrowNotFoundException & flags)))
                {
                    // FIXME: Move exception messages to MUI resources
#if VFS_EXCEPTIONS
                    if (index == max)
                    {
                        throw new FileNotFoundException(@"Failed to resolve the path.", path);
                    }
                    else
                    {
                        throw new DirectoryNotFoundException(@"Failed to resolve the path.");
                    }
#endif // #if VFS_EXCEPTIONS
                }

                // Set the current resolution directory
                currentDirectory = entry;

                // Check if the caller has traverse access to the directory
                AccessCheck.Perform(currentDirectory, AccessMode.Traverse, AccessCheckFlags.None);
            }

            return(currentDirectory);
        }