Struct devices::virtio::fs::passthrough::PassthroughFs

pub struct PassthroughFs {

    process_lock: Mutex<()>,
    tag: String,
    inodes: Mutex<MultikeyBTreeMap<Inode, InodeAltKey, Arc<InodeData>>>,
    next_inode: AtomicU64,
    handles: Mutex<BTreeMap<u64, Arc<HandleData>>>,
    next_handle: AtomicU64,
    proc: File,
    writeback: AtomicBool,
    zero_message_open: AtomicBool,
    zero_message_opendir: AtomicBool,
    dbus_connection: Option<Mutex<Connection>>,
    dbus_fd: Option<RawFd>,
    expiring_casefold_lookup_caches: Option<Mutex<ExpiringCasefoldLookupCaches>>,
    permission_paths: RwLock<Vec<PermissionData>>,
    xattr_paths: RwLock<Vec<XattrData>>,
    cfg: Config,
    root_dir: String,
}

A file system that simply “passes through” all requests it receives to the underlying file system. To keep the implementation simple it servers the contents of its root directory. Users that wish to serve only a specific directory should set up the environment so that that directory ends up as the root of the file system process. One way to accomplish this is via a combination of mount namespaces and the pivot_root system call.

Fields

process_lock: Mutex<()>

tag: String

inodes: Mutex<MultikeyBTreeMap<Inode, InodeAltKey, Arc<InodeData>>>

next_inode: AtomicU64

handles: Mutex<BTreeMap<u64, Arc<HandleData>>>

next_handle: AtomicU64

proc: File

writeback: AtomicBool

zero_message_open: AtomicBool

zero_message_opendir: AtomicBool

dbus_connection: Option<Mutex<Connection>>

dbus_fd: Option<RawFd>

expiring_casefold_lookup_caches: Option<Mutex<ExpiringCasefoldLookupCaches>>

permission_paths: RwLock<Vec<PermissionData>>

xattr_paths: RwLock<Vec<XattrData>>

cfg: Config

root_dir: String

Implementations

impl PassthroughFs

pub fn new(tag: &str, cfg: Config) -> Result<PassthroughFs>

fn set_permission_path(&mut self)

pub fn set_root_dir(&mut self, shared_dir: String) -> Result<()>

pub fn cfg(&self) -> &Config

pub fn keep_rds(&self) -> Vec<RawDescriptor>

fn rewrite_xattr_name<'xattr>(&self, name: &'xattr CStr) -> Cow<'xattr, CStr>

fn find_inode(&self, inode: Inode) -> Result<Arc<InodeData>>

fn find_handle(&self, handle: u64, inode: Inode) -> Result<Arc<HandleData>>

fn open_fd(&self, fd: RawDescriptor, flags: i32) -> Result<File>

fn update_open_flags(&self, flags: i32) -> i32

Modifies the provided open flags based on the writeback caching configuration. Return the updated open flags.

fn open_inode(&self, inode: &InodeData, flags: i32) -> Result<File>

fn increase_inode_refcount(&self, inode_data: &InodeData) -> Inode

fn add_entry( &self, f: File, st: stat64, open_flags: c_int, path: String ) -> Entry

fn lock_casefold_lookup_caches( &self ) -> Option<MutexGuard<'_, ExpiringCasefoldLookupCaches>>

Acquires lock of expiring_casefold_lookup_caches if ascii_casefold is enabled.

fn get_case_unfolded_name( &self, parent: &InodeData, name: &[u8] ) -> Result<Option<CString>>

fn ascii_casefold_lookup( &self, parent: &InodeData, name: &[u8] ) -> Result<Entry>

fn do_lookup(&self, parent: &InodeData, name: &CStr) -> Result<Entry>

fn get_cache_open_options(&self, flags: u32) -> OpenOptions

fn do_lookup_with_casefold_fallback( &self, parent: &InodeData, name: &CStr ) -> Result<Entry>

fn do_open( &self, inode: Inode, flags: u32 ) -> Result<(Option<u64>, OpenOptions)>

fn do_open_at( &self, parent_data: Arc<InodeData>, name: &CStr, inode: Inode, flags: u32 ) -> Result<(Option<u64>, OpenOptions)>

fn do_release(&self, inode: Inode, handle: u64) -> Result<()>

fn do_getattr(&self, inode: &InodeData) -> Result<(stat64, Duration)>

fn do_unlink(&self, parent: &InodeData, name: &CStr, flags: c_int) -> Result<()>

fn do_fsync<F: AsRawDescriptor>(&self, file: &F, datasync: bool) -> Result<()>

fn with_proc_chdir<F, T>(&self, f: F) -> T

where F: FnOnce() -> T,

fn do_getxattr( &self, inode: &InodeData, name: &CStr, value: &mut [u8] ) -> Result<usize>

fn get_encryption_policy_ex<R: Read>( &self, inode: Inode, handle: u64, r: R ) -> Result<IoctlReply>

fn get_fsxattr(&self, inode: Inode, handle: u64) -> Result<IoctlReply>

fn set_fsxattr<R: Read>( &self, ctx: Context, inode: Inode, handle: u64, r: R ) -> Result<IoctlReply>

fn get_flags(&self, inode: Inode, handle: u64) -> Result<IoctlReply>

fn set_flags<R: Read>( &self, ctx: Context, inode: Inode, handle: u64, r: R ) -> Result<IoctlReply>

fn enable_verity<R: Read>( &self, inode: Inode, handle: u64, r: R ) -> Result<IoctlReply>

fn measure_verity<R: Read>( &self, inode: Inode, handle: u64, r: R, out_size: u32 ) -> Result<IoctlReply>

impl PassthroughFs

fn find_and_set_ugid_permission( &self, st: &mut stat64, path: &str, is_root_path: bool ) -> bool

fn set_permission_from_data(&self, st: &mut stat64, perm_data: &PermissionData)

fn set_ugid_permission(&self, st: &mut stat64, path: &str)

Set permission according to path

fn change_ugid_creds( &self, ctx: &Context, parent_data: &InodeData, name: &CStr ) -> (u32, u32)

Set host uid/gid to configured value according to path

fn find_ugid_creds_for_path( &self, path: &str, is_root_path: bool ) -> Option<(u32, u32)>

impl PassthroughFs

fn string_from_u8_slice(&self, buf: &[u8]) -> Result<String>

Convert u8 slice to string

fn set_permission(&self, st: &mut stat64, path: &str)

Set permission according to path

fn change_creds( &self, ctx: &Context, parent_data: &InodeData, name: &CStr ) -> (u32, u32)

Set host uid/gid to configured value according to path

fn read_permission_data<R: Read>(&self, r: R) -> Result<PermissionData>

fn set_permission_by_path<R: Read>(&self, r: R) -> IoctlReply

Sets uid/gid/umask for all files and directories under a specific path.

This ioctl does not correspond to any upstream FUSE feature. It is used for arcvm It associates the specified path with the provide uid, gid, and umask values within the filesystem metadata.

During subsequent lookup operations, the stored uid/gid/umask values are retrieved and applied to all files and directories found under the registered path. Before sending file stat information to the client, the uid and gid are substituted by guest_uid and guest_gid if the file falls under the registered path. The file mode is masked by the umask.

When the guest creates a file within the specified path, the file gid/uid stat in host will be overwritten to host_uid and host_gid values.

This functionality enables dynamic configuration of ownership and permissions for a specific directory hierarchy within the filesystem.

Notes

• This method affects all existing and future files under the registered path.
• The original file ownership and permissions are overridden by the provided values.
• The registered path should not be renamed
• Refer go/remove-mount-passthrough-fuse for more design details

fn get_xattr_by_path(&self, path: &str, name: &str) -> Option<String>

fn skip_host_set_xattr(&self, path: &str, name: &str) -> bool

fn read_xattr_data<R: Read>(&self, r: R) -> Result<XattrData>

fn set_xattr_by_path<R: Read>(&self, r: R) -> IoctlReply

Sets xattr value for all files and directories under a specific path.

This ioctl does not correspond to any upstream FUSE feature. It is used for arcvm. It associates the specified path and xattr name with a value.

When the getxattr is called for the specified path and name, the predefined value is returned.

Notes

• This method affects all existing and future files under the registered path.
• The SECURITY_CONTEXT feature will be disabled if this ioctl is enabled.
• The registered path should not be renamed
• Refer go/remove-mount-passthrough-fuse for more design details

fn do_getxattr_with_filter( &self, data: Arc<InodeData>, name: Cow<'_, CStr>, buf: &mut [u8] ) -> Result<usize>

Trait Implementations

impl Debug for PassthroughFs

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FileSystem for PassthroughFs

type Inode = u64

Represents a location in the filesystem tree and can be used to perform operations that act on the metadata of a file/directory (e.g., getattr and setattr). Can also be used as the starting point for looking up paths in the filesystem tree. An Inode may support operating directly on the content of the path that to which it points. FileSystem implementations that support this should set the FsOptions::ZERO_MESSAGE_OPEN option in the return value of the init function. On linux based systems, an Inode is equivalent to opening a file or directory with the libc::O_PATH flag.

type Handle = u64

Represents a file or directory that is open for reading/writing.

type DirIter = ReadDir<Box<[u8]>>

An iterator over the entries of a directory. See the documentation for readdir for more details.

fn init(&self, capable: FsOptions) -> Result<FsOptions>

Initialize the file system.

fn destroy(&self)

Clean up the file system.

fn statfs(&self, _ctx: Context, inode: Inode) -> Result<statvfs64>

Get information about the file system.

fn lookup(&self, _ctx: Context, parent: Inode, name: &CStr) -> Result<Entry>

Look up a directory entry by name and get its attributes.

fn forget(&self, _ctx: Context, inode: Inode, count: u64)

Forget about an inode.

fn batch_forget(&self, _ctx: Context, requests: Vec<(Inode, u64)>)

Forget about multiple inodes.

fn opendir( &self, _ctx: Context, inode: Inode, flags: u32 ) -> Result<(Option<u64>, OpenOptions)>

Open a directory for reading.

fn releasedir( &self, _ctx: Context, inode: Inode, _flags: u32, handle: u64 ) -> Result<()>

Release an open directory.

fn mkdir( &self, ctx: Context, parent: Inode, name: &CStr, mode: u32, umask: u32, security_ctx: Option<&CStr> ) -> Result<Entry>

Create a directory.

fn rmdir(&self, _ctx: Context, parent: Inode, name: &CStr) -> Result<()>

Remove a directory.

fn readdir( &self, _ctx: Context, inode: Inode, handle: u64, size: u32, offset: u64 ) -> Result<Self::DirIter>

Read a directory.

fn open( &self, _ctx: Context, inode: Inode, flags: u32 ) -> Result<(Option<u64>, OpenOptions)>

Open a file.

fn release( &self, _ctx: Context, inode: Inode, _flags: u32, handle: u64, _flush: bool, _flock_release: bool, _lock_owner: Option<u64> ) -> Result<()>

Release an open file.

fn chromeos_tmpfile( &self, ctx: Context, parent: Self::Inode, mode: u32, umask: u32, security_ctx: Option<&CStr> ) -> Result<Entry>

Create an unnamed temporary file.

fn create( &self, ctx: Context, parent: Inode, name: &CStr, mode: u32, flags: u32, umask: u32, security_ctx: Option<&CStr> ) -> Result<(Entry, Option<u64>, OpenOptions)>

Create and open a file.

fn unlink(&self, _ctx: Context, parent: Inode, name: &CStr) -> Result<()>

Remove a file.

fn read<W: Write + ZeroCopyWriter>( &self, _ctx: Context, inode: Inode, handle: u64, w: W, size: u32, offset: u64, _lock_owner: Option<u64>, _flags: u32 ) -> Result<usize>

Read data from a file.

fn write<R: Read + ZeroCopyReader>( &self, _ctx: Context, inode: Inode, handle: u64, r: R, size: u32, offset: u64, _lock_owner: Option<u64>, _delayed_write: bool, flags: u32 ) -> Result<usize>

Write data to a file.

fn getattr( &self, _ctx: Context, inode: Inode, _handle: Option<u64> ) -> Result<(stat64, Duration)>

Get attributes for a file / directory.

fn setattr( &self, _ctx: Context, inode: Inode, attr: stat64, handle: Option<u64>, valid: SetattrValid ) -> Result<(stat64, Duration)>

Set attributes for a file / directory.

fn rename( &self, _ctx: Context, olddir: Inode, oldname: &CStr, newdir: Inode, newname: &CStr, flags: u32 ) -> Result<()>

Rename a file / directory.

fn mknod( &self, ctx: Context, parent: Inode, name: &CStr, mode: u32, rdev: u32, umask: u32, security_ctx: Option<&CStr> ) -> Result<Entry>

Create a file node.

fn link( &self, _ctx: Context, inode: Inode, newparent: Inode, newname: &CStr ) -> Result<Entry>

Create a hard link.

fn symlink( &self, ctx: Context, linkname: &CStr, parent: Inode, name: &CStr, security_ctx: Option<&CStr> ) -> Result<Entry>

Create a symbolic link.

fn readlink(&self, _ctx: Context, inode: Inode) -> Result<Vec<u8>>

Read a symbolic link.

fn flush( &self, _ctx: Context, inode: Inode, handle: u64, _lock_owner: u64 ) -> Result<()>

Flush the contents of a file.

fn fsync( &self, _ctx: Context, inode: Inode, datasync: bool, handle: u64 ) -> Result<()>

Synchronize file contents.

fn fsyncdir( &self, _ctx: Context, inode: Inode, datasync: bool, handle: u64 ) -> Result<()>

Synchronize the contents of a directory.

fn access(&self, ctx: Context, inode: Inode, mask: u32) -> Result<()>

Check file access permissions.

fn setxattr( &self, _ctx: Context, inode: Inode, name: &CStr, value: &[u8], flags: u32 ) -> Result<()>

Set an extended attribute.

fn getxattr( &self, _ctx: Context, inode: Inode, name: &CStr, size: u32 ) -> Result<GetxattrReply>

Get an extended attribute.

fn listxattr( &self, _ctx: Context, inode: Inode, size: u32 ) -> Result<ListxattrReply>

List extended attribute names.

fn removexattr(&self, _ctx: Context, inode: Inode, name: &CStr) -> Result<()>

Remove an extended attribute.

fn fallocate( &self, _ctx: Context, inode: Inode, handle: u64, mode: u32, offset: u64, length: u64 ) -> Result<()>

Allocate requested space for file data.

fn ioctl<R: Read>( &self, ctx: Context, inode: Inode, handle: u64, _flags: IoctlFlags, cmd: u32, _arg: u64, in_size: u32, out_size: u32, r: R ) -> Result<IoctlReply>

Perform an ioctl on a file or directory.

fn copy_file_range( &self, ctx: Context, inode_src: Inode, handle_src: u64, offset_src: u64, inode_dst: Inode, handle_dst: u64, offset_dst: u64, length: u64, flags: u64 ) -> Result<usize>

Copy a range of data from one file to another

fn set_up_mapping<M: Mapper>( &self, _ctx: Context, inode: Self::Inode, _handle: Self::Handle, file_offset: u64, mem_offset: u64, size: usize, prot: u32, mapper: M ) -> Result<()>

Set up memory mappings.

fn remove_mapping<M: Mapper>( &self, msgs: &[RemoveMappingOne], mapper: M ) -> Result<()>

Remove memory mappings.

fn atomic_open( &self, ctx: Context, parent: Self::Inode, name: &CStr, mode: u32, flags: u32, umask: u32, security_ctx: Option<&CStr> ) -> Result<(Entry, Option<Self::Handle>, OpenOptions)>

Lookup and open/create the file

fn max_buffer_size(&self) -> u32

Maximum size of the buffer that the filesystem can generate data to, including the header. This corresponds to max_write in the initialization.

fn getlk(&self) -> Result<(), Error>

TODO: support this

fn setlk(&self) -> Result<(), Error>

TODO: support this

fn setlkw(&self) -> Result<(), Error>

TODO: support this

fn bmap(&self) -> Result<(), Error>

TODO: support this

fn poll(&self) -> Result<(), Error>

TODO: support this

fn notify_reply(&self) -> Result<(), Error>

TODO: support this

fn lseek(&self) -> Result<(), Error>

TODO: support this