/// <summary>
/// Checks if the caller has access to the inode
/// </summary>
/// <param name="path">The resource to check permissions for.</param>
/// <param name="mode"></param>
/// <returns>True if the requested access mode combination is available to the immediate caller. If any one requested access mode is not available, the result is false.</returns>
public static bool Access(string path, AccessMode mode)
{
DirectoryEntry entry = PathResolver.Resolve(rootNode, ref path, PathResolutionFlags.DoNotThrowNotFoundException);
if (null != entry)
{
return(AccessCheck.Perform(entry, mode, AccessCheckFlags.NoThrow));
}
return(false);
}
/// <summary>
/// Deletes the named node from the filesystem.
/// </summary>
/// <param name="path">The path, which identifies a node.</param>
public static void Delete(string path)
{
DirectoryEntry entry = PathResolver.Resolve(rootNode, ref path, PathResolutionFlags.DoNotThrowNotFoundException);
if (null != entry)
{
AccessCheck.Perform(entry, AccessMode.Delete, AccessCheckFlags.None);
//entry.Node.Delete();
entry.Parent.Node.Delete(entry.Node, entry);
entry.Release();
}
}
/// <summary>
/// Creates a new node in the (virtual) filesystem.
/// </summary>
/// <param name="path">The path to create.</param>
/// <param name="type">The type of the node to create.</param>
/// <param name="settings">Settings used to initialize the node.</param>
/// <param name="access">Requests the specified access modes on the created object.</param>
/// <param name="share">Requests the specified sharing settings on the object.</param>
/// <returns>The created filesystem object.</returns>
/// <remarks>
/// This function creates new nodes in the virtual filesystem. In contrast to *nix this call
/// creates all node types, e.g. files, directories, devices and more. Specific types may
/// require additional settings, which are specified in a settings object passed as the third
/// parameter.
/// </remarks>
public static object Create(string path, VfsNodeType type, object settings, System.IO.FileAccess access, System.IO.FileShare share)
{
// Retrieve the parent directory
DirectoryEntry parent = PathResolver.Resolve(rootNode, ref path, PathResolutionFlags.RetrieveParent);
// Check if the caller has write access in the directory
AccessCheck.Perform(parent, AccessMode.Write, AccessCheckFlags.None);
// Yes, we do have write access. Create the new vfs node
IVfsNode node = parent.Node.Create(path, type, settings);
// FIXME: Assert(null != node);
DirectoryEntry entry = DirectoryEntry.Allocate(parent, path, node);
// FIXME: Fix the permissions for this call. *nix does this using its bitmasks, Win32 through its huge CreateFile API.
return(node.Open(access, share));
}
/// <summary>
///
/// </summary>
/// <param name="path"></param>
/// <param name="access"></param>
/// <param name="share"></param>
/// <returns></returns>
public static object Open(string path, System.IO.FileAccess access, System.IO.FileShare share)
{
DirectoryEntry entry = PathResolver.Resolve(rootNode, ref path);
/* HINT:
*
* 1. Do we really need to pass the FileShare flags down to the inode?
* 2. Shouldn't we have some sort of lock deamon governing shared access?
*
* Ansers:
* 1. Yes.
* 2. Yes and no. A lock deamon would only work for local filesystems. For imported
* ones we need to notify the server of the sharing lock anyway, so that the IVfsNode
* (acting as a client to the server) is the best place to do it without giving the
* lock deamon knowledge of all file sharing protocols (afp, smb, ftp, name it.)
* 3. The inode may reject the file sharing requests. We do want to represent devices
* and sync objects in the VFS, which means *they* need to decide if the flags are
* applicable.
*
*/
// FIXME: Perform access checks on the DirectoryEntry/IVfsNode.
AccessMode modeFlags = AccessMode.Exists;
switch (access)
{
case System.IO.FileAccess.Read:
modeFlags = AccessMode.Read;
break;
case System.IO.FileAccess.Write:
modeFlags = AccessMode.Write;
break;
case System.IO.FileAccess.ReadWrite:
modeFlags = AccessMode.Read | AccessMode.Write;
break;
}
AccessCheck.Perform(entry, modeFlags, AccessCheckFlags.None);
return(entry.Node.Open(access, share));
}
/// <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="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);
}
