⚠️ VeridianOS Kernel Documentation - This is low-level kernel code. All functions are unsafe unless explicitly marked otherwise. no_std

VfsNode

veridian_kernel::fs

Trait VfsNode 

Source 
pub trait VfsNode: Send + Sync {

Show 16 methods    // Required methods
    fn node_type(&self) -> NodeType;
    fn read(
        &self,
        offset: usize,
        buffer: &mut [u8],
    ) -> Result<usize, KernelError>;
    fn write(&self, offset: usize, data: &[u8]) -> Result<usize, KernelError>;
    fn metadata(&self) -> Result<Metadata, KernelError>;
    fn readdir(&self) -> Result<Vec<DirEntry>, KernelError>;
    fn lookup(&self, name: &str) -> Result<Arc<dyn VfsNode>, KernelError>;
    fn create(
        &self,
        name: &str,
        permissions: Permissions,
    ) -> Result<Arc<dyn VfsNode>, KernelError>;
    fn mkdir(
        &self,
        name: &str,
        permissions: Permissions,
    ) -> Result<Arc<dyn VfsNode>, KernelError>;
    fn unlink(&self, name: &str) -> Result<(), KernelError>;
    fn truncate(&self, size: usize) -> Result<(), KernelError>;

    // Provided methods
    fn link(
        &self,
        _name: &str,
        _target: Arc<dyn VfsNode>,
    ) -> Result<(), KernelError> { ... }
    fn symlink(
        &self,
        _name: &str,
        _target: &str,
    ) -> Result<Arc<dyn VfsNode>, KernelError> { ... }
    fn readlink(&self) -> Result<String, KernelError> { ... }
    fn chmod(&self, _permissions: Permissions) -> Result<(), KernelError> { ... }
    fn poll_readiness(&self) -> u16 { ... }
    fn as_any(&self) -> Option<&dyn Any> { ... }

}
Expand description

VFS node operations trait

Required Methods§

Source

fn node_type(&self) -> NodeType

Node type query (also serves as vtable slot padding for AArch64)

Source

fn read(&self, offset: usize, buffer: &mut [u8]) -> Result<usize, KernelError>

Read data from the node

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fn write(&self, offset: usize, data: &[u8]) -> Result<usize, KernelError>

Write data to the node

Source

fn metadata(&self) -> Result<Metadata, KernelError>

Get metadata for the node

Source

fn readdir(&self) -> Result<Vec<DirEntry>, KernelError>

List directory entries (if this is a directory)

Source

fn lookup(&self, name: &str) -> Result<Arc<dyn VfsNode>, KernelError>

Look up a child node by name (if this is a directory)

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fn create( &self, name: &str, permissions: Permissions, ) -> Result<Arc<dyn VfsNode>, KernelError>

Create a new file in this directory

Source

fn mkdir( &self, name: &str, permissions: Permissions, ) -> Result<Arc<dyn VfsNode>, KernelError>

Create a new directory in this directory

Remove a file or empty directory

Source

fn truncate(&self, size: usize) -> Result<(), KernelError>

Truncate the file to the specified size

Provided Methods§

Create a hard link to this node

Create a symbolic link in this directory.

Creates a new symlink entry named name in this directory node that points to target. The target path is stored as the symlink’s data content and is not validated (it may be relative or absolute, and the target need not exist).

§Default Implementation

Returns NotImplemented for filesystems that do not support symbolic links (e.g., DevFS, ProcFS). Filesystems that support symlinks (e.g., RamFS, BlockFS) override this method.

§Arguments
  • name: The name of the symlink entry to create in this directory.
  • target: The target path that the symlink points to.
§Returns

An Arc<dyn VfsNode> representing the newly created symlink node.

Read the target of a symbolic link.

If this node is a symbolic link, returns the target path as a String. The target is the raw path stored when the symlink was created and is not resolved or canonicalized.

§Default Implementation

Returns NotImplemented for filesystem nodes that are not symbolic links or for filesystems that do not support symlinks. Callers should check node_type() == NodeType::Symlink before calling, or handle the error.

§Returns
  • Ok(String): The symlink target path.
  • Err(NotImplemented): This node is not a symlink or the filesystem does not support readlink.
  • Err(FsError(NotASymlink)): The node exists but is not a symlink (used by BlockFS for type-checked readlink).
Source

fn chmod(&self, _permissions: Permissions) -> Result<(), KernelError>

Change permissions on this node

Source

fn poll_readiness(&self) -> u16

Poll readiness for I/O multiplexing (poll/epoll).

Returns a bitmask of ready events using POLL* constants:

  • bit 0 (POLLIN=1): readable without blocking
  • bit 2 (POLLOUT=4): writable without blocking
  • bit 3 (POLLERR=8): error condition
  • bit 4 (POLLHUP=16): hangup (peer closed)

Default: regular files are always readable and writable. Pipe nodes override this to check actual buffer state.

Source

fn as_any(&self) -> Option<&dyn Any>

Downcast to &dyn core::any::Any for type-specific operations.

Used by syscall handlers that need to extract implementation-specific state from a VfsNode (e.g., timerfd_settime needs the internal timer ID from a TimerFdNode). Default returns None; only nodes that need downcasting override this.

Implementors§