Struct VfsHostState 

pub struct VfsHostState {
    pub wasi_ctx: WasiCtx,
    pub table: ResourceTable,
    pub shared_vfs: Arc<Fs>,
}

Host state that uses fs-core directly for filesystem operations. Multiple instances can share the same VFS via Arc<Fs>.

Since fs-core uses DashMap internally with fine-grained locking, no external lock is required. All Fs methods take &self.

Fields

wasi_ctx: WasiCtx

WASI context for host operations (stdio, env, etc.)

table: ResourceTable

Resource table for managing WASM resources

shared_vfs: Arc<Fs>

Shared VFS: multiple VfsHostState instances can reference the same VFS No external lock needed - fs-core uses DashMap for internal thread safety

Implementations

impl VfsHostState

pub fn new() -> Result<Self>

Create a new VfsHostState with a fresh fs-core filesystem

pub fn clone_shared(&self) -> Self

Create a new VfsHostState that shares the same VFS core This enables multiple applications to access the same VFS concurrently

pub fn clone_shared_with_args(&self, args: &[&str]) -> Self

Create a new VfsHostState that shares the same VFS core with custom CLI arguments This enables passing arguments to WASM applications via WASI

pub fn clone_shared_with_env(&self, env_vars: &[(&str, &str)]) -> Self

Create a new VfsHostState that shares the same VFS core with custom environment variables This enables passing configuration to WASM handlers

pub fn from_shared_vfs_with_env( shared_vfs: Arc<Fs>, env_vars: &[(&str, &str)], ) -> Self

Create a new VfsHostState from an existing shared VFS with custom environment variables This is useful when sharing VFS across threads (e.g., in HTTP server handlers)

pub fn get_shared_vfs(&self) -> Arc<Fs>

Get the shared VFS for external use (e.g., sharing across threads)

Trait Implementations

impl Default for VfsHostState

fn default() -> Self

Returns the “default value” for a type.

impl Host for VfsHostState

fn get_directories( &mut self, ) -> Result<Vec<(Resource<Descriptor>, String)>, Error>

Return the set of preopened directories, and their paths.

impl Host for VfsHostState

fn filesystem_error_code( &mut self, err: Resource<Error>, ) -> Result<Option<ErrorCode>, Error>

Attempts to extract a filesystem-related error-code from the stream error provided.

fn convert_error_code( &mut self, err: TrappableError<ErrorCode>, ) -> Result<ErrorCode, Error>

impl HostDescriptor for VfsHostState

fn read( &mut self, self_: Resource<Descriptor>, len: u64, offset: u64, ) -> Result<(Vec<u8>, bool), TrappableError<ErrorCode>>

Read from a descriptor, without using and updating the descriptor’s offset.

fn write( &mut self, self_: Resource<Descriptor>, buffer: Vec<u8>, offset: u64, ) -> Result<u64, TrappableError<ErrorCode>>

Write to a descriptor, without using and updating the descriptor’s offset.

fn drop(&mut self, rep: Resource<Descriptor>) -> Result<(), Error>

fn read_via_stream( &mut self, self_: Resource<Descriptor>, offset: u64, ) -> Result<Resource<DynInputStream>, TrappableError<ErrorCode>>

Return a stream for reading from a file, if available.

fn write_via_stream( &mut self, self_: Resource<Descriptor>, offset: u64, ) -> Result<Resource<DynOutputStream>, TrappableError<ErrorCode>>

Return a stream for writing to a file, if available.

fn append_via_stream( &mut self, self_: Resource<Descriptor>, ) -> Result<Resource<DynOutputStream>, TrappableError<ErrorCode>>

Return a stream for appending to a file, if available.

fn advise( &mut self, _self_: Resource<Descriptor>, _offset: u64, _len: u64, _advice: Advice, ) -> Result<(), TrappableError<ErrorCode>>

Provide file advisory information on a descriptor.

fn sync_data( &mut self, _self_: Resource<Descriptor>, ) -> Result<(), TrappableError<ErrorCode>>

Synchronize the data of a file to disk.

fn get_flags( &mut self, _self_: Resource<Descriptor>, ) -> Result<DescriptorFlags, TrappableError<ErrorCode>>

Get flags associated with a descriptor.

fn get_type( &mut self, self_: Resource<Descriptor>, ) -> Result<DescriptorType, TrappableError<ErrorCode>>

Get the dynamic type of a descriptor.

fn set_size( &mut self, self_: Resource<Descriptor>, size: u64, ) -> Result<(), TrappableError<ErrorCode>>

Adjust the size of an open file. If this increases the file’s size, the extra bytes are filled with zeros.

fn set_times( &mut self, _self_: Resource<Descriptor>, _data_access_timestamp: NewTimestamp, _data_modification_timestamp: NewTimestamp, ) -> Result<(), TrappableError<ErrorCode>>

Adjust the timestamps of an open file or directory.

fn set_times_at( &mut self, _self_: Resource<Descriptor>, _path_flags: PathFlags, _path: String, _data_access_timestamp: NewTimestamp, _data_modification_timestamp: NewTimestamp, ) -> Result<(), TrappableError<ErrorCode>>

Adjust the timestamps of a file or directory.

fn read_directory( &mut self, self_: Resource<Descriptor>, ) -> Result<Resource<DirectoryEntryStream>, TrappableError<ErrorCode>>

Read directory entries from a directory.

fn sync( &mut self, _self_: Resource<Descriptor>, ) -> Result<(), TrappableError<ErrorCode>>

Synchronize the data and metadata of a file to disk.

fn create_directory_at( &mut self, self_: Resource<Descriptor>, path: String, ) -> Result<(), TrappableError<ErrorCode>>

Create a directory.

fn stat( &mut self, self_: Resource<Descriptor>, ) -> Result<DescriptorStat, TrappableError<ErrorCode>>

Return the attributes of an open file or directory.

fn stat_at( &mut self, self_: Resource<Descriptor>, _path_flags: PathFlags, path: String, ) -> Result<DescriptorStat, TrappableError<ErrorCode>>

Return the attributes of a file or directory.

fn link_at( &mut self, _self_: Resource<Descriptor>, _old_path_flags: PathFlags, _old_path: String, _new_descriptor: Resource<Descriptor>, _new_path: String, ) -> Result<(), TrappableError<ErrorCode>>

Create a hard link.

fn open_at( &mut self, self_: Resource<Descriptor>, _path_flags: PathFlags, path: String, open_flags: OpenFlags, flags: DescriptorFlags, ) -> Result<Resource<Descriptor>, TrappableError<ErrorCode>>

Open a file or directory.

fn readlink_at( &mut self, _self_: Resource<Descriptor>, _path: String, ) -> Result<String, TrappableError<ErrorCode>>

Read the contents of a symbolic link.

fn remove_directory_at( &mut self, self_: Resource<Descriptor>, path: String, ) -> Result<(), TrappableError<ErrorCode>>

Remove a directory.

fn rename_at( &mut self, self_: Resource<Descriptor>, old_path: String, _new_descriptor: Resource<Descriptor>, new_path: String, ) -> Result<(), TrappableError<ErrorCode>>

Rename a filesystem object.

fn symlink_at( &mut self, _self_: Resource<Descriptor>, _old_path: String, _new_path: String, ) -> Result<(), TrappableError<ErrorCode>>

Create a symbolic link (also known as a “symlink”).

fn unlink_file_at( &mut self, self_: Resource<Descriptor>, path: String, ) -> Result<(), TrappableError<ErrorCode>>

Unlink a filesystem object that is not a directory.

fn is_same_object( &mut self, self_: Resource<Descriptor>, other: Resource<Descriptor>, ) -> Result<bool, Error>

Test whether two descriptors refer to the same filesystem object.

fn metadata_hash( &mut self, self_: Resource<Descriptor>, ) -> Result<MetadataHashValue, TrappableError<ErrorCode>>

Return a hash of the metadata associated with a filesystem object referred to by a descriptor.

fn metadata_hash_at( &mut self, self_: Resource<Descriptor>, _path_flags: PathFlags, path: String, ) -> Result<MetadataHashValue, TrappableError<ErrorCode>>

Return a hash of the metadata associated with a filesystem object referred to by a directory descriptor and a relative path.

impl HostDirectoryEntryStream for VfsHostState

fn read_directory_entry( &mut self, self_: Resource<DirectoryEntryStream>, ) -> Result<Option<DirectoryEntry>, TrappableError<ErrorCode>>

Read a single directory entry from a directory-entry-stream.

fn drop(&mut self, rep: Resource<DirectoryEntryStream>) -> Result<(), Error>

impl WasiView for VfsHostState

fn ctx(&mut self) -> WasiCtxView<'_>

Yields mutable access to the WasiCtx configuration used for this context.