[−][src]Trait fuse::FuseHandlers

pub trait FuseHandlers {
    fn fuse_init(
        &mut self, 
        request: &FuseInitRequest
    ) -> Result<FuseInitResponse> { ... }

    fn access(
        &self, 
        ctx: ServerContext, 
        request: &AccessRequest, 
        respond: impl for<'a> RespondOnce<AccessResponse<'a>>
    ) { ... }

    fn bmap(
        &self, 
        ctx: ServerContext, 
        request: &BmapRequest, 
        respond: impl for<'a> RespondOnce<BmapResponse<'a>>
    ) { ... }

    fn create(
        &self, 
        ctx: ServerContext, 
        request: &CreateRequest, 
        respond: impl for<'a> RespondOnce<CreateResponse<'a>>
    ) { ... }

    fn fallocate(
        &self, 
        ctx: ServerContext, 
        request: &FallocateRequest, 
        respond: impl for<'a> RespondOnce<FallocateResponse<'a>>
    ) { ... }

    fn flush(
        &self, 
        ctx: ServerContext, 
        request: &FlushRequest, 
        respond: impl for<'a> RespondOnce<FlushResponse<'a>>
    ) { ... }

    fn forget(&self, ctx: ServerContext, request: &ForgetRequest) { ... }

    fn fsync(
        &self, 
        ctx: ServerContext, 
        request: &FsyncRequest, 
        respond: impl for<'a> RespondOnce<FsyncResponse<'a>>
    ) { ... }

    fn fsyncdir(
        &self, 
        ctx: ServerContext, 
        request: &FsyncdirRequest, 
        respond: impl for<'a> RespondOnce<FsyncdirResponse<'a>>
    ) { ... }

    fn getattr(
        &self, 
        ctx: ServerContext, 
        request: &GetattrRequest, 
        respond: impl for<'a> RespondOnce<GetattrResponse<'a>>
    ) { ... }

    fn getlk(
        &self, 
        ctx: ServerContext, 
        request: &GetlkRequest, 
        respond: impl for<'a> RespondOnce<GetlkResponse<'a>>
    ) { ... }

    fn getxattr(
        &self, 
        ctx: ServerContext, 
        request: &GetxattrRequest, 
        respond: impl for<'a> RespondOnce<GetxattrResponse<'a>>
    ) { ... }

    fn ioctl(
        &self, 
        ctx: ServerContext, 
        request: &IoctlRequest, 
        respond: impl for<'a> RespondOnce<IoctlResponse<'a>>
    ) { ... }

    fn link(
        &self, 
        ctx: ServerContext, 
        request: &LinkRequest, 
        respond: impl for<'a> RespondOnce<LinkResponse<'a>>
    ) { ... }

    fn listxattr(
        &self, 
        ctx: ServerContext, 
        request: &ListxattrRequest, 
        respond: impl for<'a> RespondOnce<ListxattrResponse<'a>>
    ) { ... }

    fn lookup(
        &self, 
        ctx: ServerContext, 
        request: &LookupRequest, 
        respond: impl for<'a> RespondOnce<LookupResponse<'a>>
    ) { ... }

    fn lseek(
        &self, 
        ctx: ServerContext, 
        request: &LseekRequest, 
        respond: impl for<'a> RespondOnce<LseekResponse<'a>>
    ) { ... }

    fn mkdir(
        &self, 
        ctx: ServerContext, 
        request: &MkdirRequest, 
        respond: impl for<'a> RespondOnce<MkdirResponse<'a>>
    ) { ... }

    fn mknod(
        &self, 
        ctx: ServerContext, 
        request: &MknodRequest, 
        respond: impl for<'a> RespondOnce<MknodResponse<'a>>
    ) { ... }

    fn open(
        &self, 
        ctx: ServerContext, 
        request: &OpenRequest, 
        respond: impl for<'a> RespondOnce<OpenResponse<'a>>
    ) { ... }

    fn opendir(
        &self, 
        ctx: ServerContext, 
        request: &OpendirRequest, 
        respond: impl for<'a> RespondOnce<OpendirResponse<'a>>
    ) { ... }

    fn read(
        &self, 
        ctx: ServerContext, 
        request: &ReadRequest, 
        respond: impl for<'a> RespondOnce<ReadResponse<'a>>
    ) { ... }

    fn readdir(
        &self, 
        ctx: ServerContext, 
        request: &ReaddirRequest, 
        respond: impl for<'a> RespondOnce<ReaddirResponse<'a>>
    ) { ... }

    fn readlink(
        &self, 
        ctx: ServerContext, 
        request: &ReadlinkRequest, 
        respond: impl for<'a> RespondOnce<ReadlinkResponse<'a>>
    ) { ... }

    fn release(
        &self, 
        ctx: ServerContext, 
        request: &ReleaseRequest, 
        respond: impl for<'a> RespondOnce<ReleaseResponse<'a>>
    ) { ... }

    fn releasedir(
        &self, 
        ctx: ServerContext, 
        request: &ReleasedirRequest, 
        respond: impl for<'a> RespondOnce<ReleasedirResponse<'a>>
    ) { ... }

    fn removexattr(
        &self, 
        ctx: ServerContext, 
        request: &RemovexattrRequest, 
        respond: impl for<'a> RespondOnce<RemovexattrResponse<'a>>
    ) { ... }

    fn rename(
        &self, 
        ctx: ServerContext, 
        request: &RenameRequest, 
        respond: impl for<'a> RespondOnce<RenameResponse<'a>>
    ) { ... }

    fn rmdir(
        &self, 
        ctx: ServerContext, 
        request: &RmdirRequest, 
        respond: impl for<'a> RespondOnce<RmdirResponse<'a>>
    ) { ... }

    fn setattr(
        &self, 
        ctx: ServerContext, 
        request: &SetattrRequest, 
        respond: impl for<'a> RespondOnce<SetattrResponse<'a>>
    ) { ... }

    fn setlk(
        &self, 
        ctx: ServerContext, 
        request: &SetlkRequest, 
        respond: impl for<'a> RespondOnce<SetlkResponse<'a>>
    ) { ... }

    fn setxattr(
        &self, 
        ctx: ServerContext, 
        request: &SetxattrRequest, 
        respond: impl for<'a> RespondOnce<SetxattrResponse<'a>>
    ) { ... }

    fn statfs(
        &self, 
        ctx: ServerContext, 
        request: &StatfsRequest, 
        respond: impl for<'a> RespondOnce<StatfsResponse<'a>>
    ) { ... }

    fn symlink(
        &self, 
        ctx: ServerContext, 
        request: &SymlinkRequest, 
        respond: impl for<'a> RespondOnce<SymlinkResponse<'a>>
    ) { ... }

    fn unlink(
        &self, 
        ctx: ServerContext, 
        request: &UnlinkRequest, 
        respond: impl for<'a> RespondOnce<UnlinkResponse<'a>>
    ) { ... }

    fn write(
        &self, 
        ctx: ServerContext, 
        request: &WriteRequest, 
        respond: impl for<'a> RespondOnce<WriteResponse<'a>>
    ) { ... }
}

User-provided handlers for FUSE operations.

Most FUSE handlers (with the exception of FuseHandlers::fuse_init) are asynchronous. These handlers receive a ServerContext containing information about the request itself, along with a ServerResponseWriter that must be used to send the response.

The default implementation for all async handlers is to respond with error code ENOSYS.

Provided methods

fn fuse_init(&mut self, request: &FuseInitRequest) -> Result<FuseInitResponse>

Initialize the FUSE connection parameters.

Most servers do not need to override this method.

The default implementation returns a response created by the helper function FuseInitResponse::for_request, which is also a good starting point for custom implementations.

fn access(
    &self,
    ctx: ServerContext,
    request: &AccessRequest,
    respond: impl for<'a> RespondOnce<AccessResponse<'a>>
)

Check file access permissions

This will be called for the access(2) and chdir(2) system calls. If the default_permissions mount option is given, this method is not called.

This method is not called under Linux kernel versions 2.4.x

If this request is answered with an error code of ENOSYS, this is treated as a permanent success, i.e. this and all future access() requests will succeed without being send to the filesystem process.

fn bmap(
    &self,
    ctx: ServerContext,
    request: &BmapRequest,
    respond: impl for<'a> RespondOnce<BmapResponse<'a>>
)

Map block index within file to block index within device

Note: This makes sense only for block device backed filesystems mounted with the blkdev option

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure, i.e. all future bmap() requests will fail with the same error code without being send to the filesystem process.

fn create(
    &self,
    ctx: ServerContext,
    request: &CreateRequest,
    respond: impl for<'a> RespondOnce<CreateResponse<'a>>
)

Create and open a file

If the file does not exist, first create it with the specified mode, and then open it.

See the description of FuseHandlers::open for more information.

If this method is not implemented or under Linux kernel versions earlier than 2.6.15, the FuseHandlers::mknod and FuseHandlers::open handlers will be called instead.

If this request is answered with an error code of ENOSYS, the handler is treated as not implemented (i.e., for this and future requests the FuseHandlers::mknod and FuseHandlers::open handlers will be called instead).

fn fallocate(
    &self,
    ctx: ServerContext,
    request: &FallocateRequest,
    respond: impl for<'a> RespondOnce<FallocateResponse<'a>>
)

fn flush(
    &self,
    ctx: ServerContext,
    request: &FlushRequest,
    respond: impl for<'a> RespondOnce<FlushResponse<'a>>
)

Flush method

This is called on each close() of the opened file.

Since file descriptors can be duplicated (dup, dup2, fork), for one open call there may be many flush calls.

Filesystems shouldn't assume that flush will always be called after some writes, or that if will be called at all.

fi->fh will contain the value set by the open method, or will be undefined if the open method didn't set any value.

NOTE: the name of the method is misleading, since (unlike fsync) the filesystem is not forced to flush pending writes. One reason to flush data is if the filesystem wants to return write errors during close. However, such use is non-portable because POSIX does not require close to wait for delayed I/O to complete.

If the filesystem supports file locking operations (setlk, getlk) it should remove all locks belonging to 'fi->owner'.

If this request is answered with an error code of ENOSYS, this is treated as success and future calls to flush() will succeed automatically without being send to the filesystem process.

fn forget(&self, ctx: ServerContext, request: &ForgetRequest)

Forget about an inode

This function is called when the kernel removes an inode from its internal caches.

The inode's lookup count increases by one for every call to fuse_reply_entry and fuse_reply_create. The nlookup parameter indicates by how much the lookup count should be decreased.

Inodes with a non-zero lookup count may receive request from the kernel even after calls to unlink, rmdir or (when overwriting an existing file) rename. Filesystems must handle such requests properly and it is recommended to defer removal of the inode until the lookup count reaches zero. Calls to unlink, rmdir or rename will be followed closely by forget unless the file or directory is open, in which case the kernel issues forget only after the release or releasedir calls.

Note that if a file system will be exported over NFS the inodes lifetime must extend even beyond forget. See the generation field in struct fuse_entry_param above.

On unmount the lookup count for all inodes implicitly drops to zero. It is not guaranteed that the file system will receive corresponding forget messages for the affected inodes.

fn fsync(
    &self,
    ctx: ServerContext,
    request: &FsyncRequest,
    respond: impl for<'a> RespondOnce<FsyncResponse<'a>>
)

Synchronize file contents

If the datasync parameter is non-zero, then only the user data should be flushed, not the meta data.

If this request is answered with an error code of ENOSYS, this is treated as success and future calls to fsync() will succeed automatically without being send to the filesystem process.

fn fsyncdir(
    &self,
    ctx: ServerContext,
    request: &FsyncdirRequest,
    respond: impl for<'a> RespondOnce<FsyncdirResponse<'a>>
)

Synchronize directory contents

If the datasync parameter is non-zero, then only the directory contents should be flushed, not the meta data.

fi->fh will contain the value set by the opendir method, or will be undefined if the opendir method didn't set any value.

If this request is answered with an error code of ENOSYS, this is treated as success and future calls to fsyncdir() will succeed automatically without being send to the filesystem process.

fn getattr(
    &self,
    ctx: ServerContext,
    request: &GetattrRequest,
    respond: impl for<'a> RespondOnce<GetattrResponse<'a>>
)

Get file attributes.

If writeback caching is enabled, the kernel may have a better idea of a file's length than the FUSE file system (eg if there has been a write that extended the file size, but that has not yet been passed to the filesystem.

In this case, the NodeAttr::size value provided by the file system will be ignored.

fn getlk(
    &self,
    ctx: ServerContext,
    request: &GetlkRequest,
    respond: impl for<'a> RespondOnce<GetlkResponse<'a>>
)

Test for a POSIX file lock

fn getxattr(
    &self,
    ctx: ServerContext,
    request: &GetxattrRequest,
    respond: impl for<'a> RespondOnce<GetxattrResponse<'a>>
)

Get an extended attribute

If size is zero, the size of the value should be sent with fuse_reply_xattr.

If the size is non-zero, and the value fits in the buffer, the value should be sent with fuse_reply_buf.

If the size is too small for the value, the ERANGE error should be sent.

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure with error code EOPNOTSUPP, i.e. all future getxattr() requests will fail with EOPNOTSUPP without being send to the filesystem process.

fn ioctl(
    &self,
    ctx: ServerContext,
    request: &IoctlRequest,
    respond: impl for<'a> RespondOnce<IoctlResponse<'a>>
)

Ioctl

Note: For unrestricted ioctls (not allowed for FUSE servers), data in and out areas can be discovered by giving iovs and setting FUSE_IOCTL_RETRY in flags. For restricted ioctls, kernel prepares in/out data area according to the information encoded in cmd.

Valid replies: fuse_reply_ioctl_retry fuse_reply_ioctl fuse_reply_ioctl_iov fuse_reply_err

@param req request handle @param ino the inode number @param cmd ioctl command @param arg ioctl argument @param fi file information @param flags for FUSE_IOCTL_* flags @param in_buf data fetched from the caller @param in_bufsz number of fetched bytes @param out_bufsz maximum size of output data

Note : the unsigned long request submitted by the application is truncated to 32 bits.

Create a hard link

fn listxattr(
    &self,
    ctx: ServerContext,
    request: &ListxattrRequest,
    respond: impl for<'a> RespondOnce<ListxattrResponse<'a>>
)

List extended attribute names

If size is zero, the total size of the attribute list should be sent with fuse_reply_xattr.

If the size is non-zero, and the null character separated attribute list fits in the buffer, the list should be sent with fuse_reply_buf.

If the size is too small for the list, the ERANGE error should be sent.

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure with error code EOPNOTSUPP, i.e. all future listxattr() requests will fail with EOPNOTSUPP without being send to the filesystem process.

fn lookup(
    &self,
    ctx: ServerContext,
    request: &LookupRequest,
    respond: impl for<'a> RespondOnce<LookupResponse<'a>>
)

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

fn lseek(
    &self,
    ctx: ServerContext,
    request: &LseekRequest,
    respond: impl for<'a> RespondOnce<LseekResponse<'a>>
)

Find next data or hole after the specified offset

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure, i.e. all future lseek() requests will fail with the same error code without being send to the filesystem process.

fn mkdir(
    &self,
    ctx: ServerContext,
    request: &MkdirRequest,
    respond: impl for<'a> RespondOnce<MkdirResponse<'a>>
)

Create a directory

fn mknod(
    &self,
    ctx: ServerContext,
    request: &MknodRequest,
    respond: impl for<'a> RespondOnce<MknodResponse<'a>>
)

Create file node

Create a regular file, character device, block device, fifo or socket node.

fn open(
    &self,
    ctx: ServerContext,
    request: &OpenRequest,
    respond: impl for<'a> RespondOnce<OpenResponse<'a>>
)

Open a file

Open flags are available in fi->flags. The following rules apply.

  • Creation (O_CREAT, O_EXCL, O_NOCTTY) flags will be filtered out / handled by the kernel.

  • Access modes (O_RDONLY, O_WRONLY, O_RDWR) should be used by the filesystem to check if the operation is permitted. If the -o default_permissions mount option is given, this check is already done by the kernel before calling open() and may thus be omitted by the filesystem.

  • When writeback caching is enabled, the kernel may send read requests even for files opened with O_WRONLY. The filesystem should be prepared to handle this.

  • When writeback caching is disabled, the filesystem is expected to properly handle the O_APPEND flag and ensure that each write is appending to the end of the file.

  • When writeback caching is enabled, the kernel will handle O_APPEND. However, unless all changes to the file come through the kernel this will not work reliably. The filesystem should thus either ignore the O_APPEND flag (and let the kernel handle it), or return an error (indicating that reliably O_APPEND is not available).

Filesystem may store an arbitrary file handle (pointer, index, etc) in fi->fh, and use this in other all other file operations (read, write, flush, release, fsync).

Filesystem may also implement stateless file I/O and not store anything in fi->fh.

There are also some flags (direct_io, keep_cache) which the filesystem may set in fi, to change the way the file is opened. See fuse_file_info structure in <fuse_common.h> for more details.

If this request is answered with an error code of ENOSYS and FUSE_CAP_NO_OPEN_SUPPORT is set in fuse_conn_info.capable, this is treated as success and future calls to open and release will also succeed without being sent to the filesystem process.

fn opendir(
    &self,
    ctx: ServerContext,
    request: &OpendirRequest,
    respond: impl for<'a> RespondOnce<OpendirResponse<'a>>
)

Open a directory

Filesystem may store an arbitrary file handle (pointer, index, etc) in fi->fh, and use this in other all other directory stream operations (readdir, releasedir, fsyncdir).

If this request is answered with an error code of ENOSYS and FUSE_CAP_NO_OPENDIR_SUPPORT is set in fuse_conn_info.capable, this is treated as success and future calls to opendir and releasedir will also succeed without being sent to the filesystem process. In addition, the kernel will cache readdir results as if opendir returned FOPEN_KEEP_CACHE | FOPEN_CACHE_DIR.

fn read(
    &self,
    ctx: ServerContext,
    request: &ReadRequest,
    respond: impl for<'a> RespondOnce<ReadResponse<'a>>
)

Read data

Read should send exactly the number of bytes requested except on EOF or error, otherwise the rest of the data will be substituted with zeroes. An exception to this is when the file has been opened in 'direct_io' mode, in which case the return value of the read system call will reflect the return value of this operation.

fi->fh will contain the value set by the open method, or will be undefined if the open method didn't set any value.

fn readdir(
    &self,
    ctx: ServerContext,
    request: &ReaddirRequest,
    respond: impl for<'a> RespondOnce<ReaddirResponse<'a>>
)

Read directory

Send a buffer filled using fuse_add_direntry(), with size not exceeding the requested size. Send an empty buffer on end of stream.

fi->fh will contain the value set by the opendir method, or will be undefined if the opendir method didn't set any value.

Returning a directory entry from readdir() does not affect its lookup count.

If off_t is non-zero, then it will correspond to one of the off_t values that was previously returned by readdir() for the same directory handle. In this case, readdir() should skip over entries coming before the position defined by the off_t value. If entries are added or removed while the directory handle is open, they filesystem may still include the entries that have been removed, and may not report the entries that have been created. However, addition or removal of entries must never cause readdir() to skip over unrelated entries or to report them more than once. This means that off_t can not be a simple index that enumerates the entries that have been returned but must contain sufficient information to uniquely determine the next directory entry to return even when the set of entries is changing.

The function does not have to report the '.' and '..' entries, but is allowed to do so. Note that, if readdir does not return '.' or '..', they will not be implicitly returned, and this behavior is observable by the caller.

Read symbolic link

fn release(
    &self,
    ctx: ServerContext,
    request: &ReleaseRequest,
    respond: impl for<'a> RespondOnce<ReleaseResponse<'a>>
)

Release an open file

Release is called when there are no more references to an open file: all file descriptors are closed and all memory mappings are unmapped.

For every open call there will be exactly one release call (unless the filesystem is force-unmounted).

The filesystem may reply with an error, but error values are not returned to close() or munmap() which triggered the release.

fi->fh will contain the value set by the open method, or will be undefined if the open method didn't set any value. fi->flags will contain the same flags as for open.

fn releasedir(
    &self,
    ctx: ServerContext,
    request: &ReleasedirRequest,
    respond: impl for<'a> RespondOnce<ReleasedirResponse<'a>>
)

Release an open directory

For every opendir call there will be exactly one releasedir call (unless the filesystem is force-unmounted).

fi->fh will contain the value set by the opendir method, or will be undefined if the opendir method didn't set any value.

fn removexattr(
    &self,
    ctx: ServerContext,
    request: &RemovexattrRequest,
    respond: impl for<'a> RespondOnce<RemovexattrResponse<'a>>
)

Remove an extended attribute

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure with error code EOPNOTSUPP, i.e. all future removexattr() requests will fail with EOPNOTSUPP without being send to the filesystem process.

fn rename(
    &self,
    ctx: ServerContext,
    request: &RenameRequest,
    respond: impl for<'a> RespondOnce<RenameResponse<'a>>
)

Rename a file

If the target exists it should be atomically replaced. If the target's inode's lookup count is non-zero, the file system is expected to postpone any removal of the inode until the lookup count reaches zero (see description of the forget function).

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure with error code EINVAL, i.e. all future bmap requests will fail with EINVAL without being send to the filesystem process.

flags may be RENAME_EXCHANGE or RENAME_NOREPLACE. If RENAME_NOREPLACE is specified, the filesystem must not overwrite newname if it exists and return an error instead. If RENAME_EXCHANGE is specified, the filesystem must atomically exchange the two files, i.e. both must exist and neither may be deleted.

fn rmdir(
    &self,
    ctx: ServerContext,
    request: &RmdirRequest,
    respond: impl for<'a> RespondOnce<RmdirResponse<'a>>
)

Remove a directory

If the directory's inode's lookup count is non-zero, the file system is expected to postpone any removal of the inode until the lookup count reaches zero (see description of the forget function).

fn setattr(
    &self,
    ctx: ServerContext,
    request: &SetattrRequest,
    respond: impl for<'a> RespondOnce<SetattrResponse<'a>>
)

Set file attributes

In the 'attr' argument only members indicated by the 'to_set' bitmask contain valid values. Other members contain undefined values.

Unless FUSE_CAP_HANDLE_KILLPRIV is disabled, this method is expected to reset the setuid and setgid bits if the file size or owner is being changed.

If the setattr was invoked from the ftruncate() system call under Linux kernel versions 2.6.15 or later, the fi->fh will contain the value set by the open method or will be undefined if the open method didn't set any value. Otherwise (not ftruncate call, or kernel version earlier than 2.6.15) the fi parameter will be NULL.

fn setlk(
    &self,
    ctx: ServerContext,
    request: &SetlkRequest,
    respond: impl for<'a> RespondOnce<SetlkResponse<'a>>
)

Acquire, modify or release a POSIX file lock

For POSIX threads (NPTL) there's a 1-1 relation between pid and owner, but otherwise this is not always the case. For checking lock ownership, 'fi->owner' must be used. The l_pid field in 'struct flock' should only be used to fill in this field in getlk().

Note: if the locking methods are not implemented, the kernel will still allow file locking to work locally. Hence these are only interesting for network filesystems and similar.

fn setxattr(
    &self,
    ctx: ServerContext,
    request: &SetxattrRequest,
    respond: impl for<'a> RespondOnce<SetxattrResponse<'a>>
)

Set an extended attribute

If this request is answered with an error code of ENOSYS, this is treated as a permanent failure with error code EOPNOTSUPP, i.e. all future setxattr() requests will fail with EOPNOTSUPP without being send to the filesystem process.

fn statfs(
    &self,
    ctx: ServerContext,
    request: &StatfsRequest,
    respond: impl for<'a> RespondOnce<StatfsResponse<'a>>
)

Get file system statistics

Create a symbolic link

Remove a file

If the file's inode's lookup count is non-zero, the file system is expected to postpone any removal of the inode until the lookup count reaches zero (see description of the forget function).

fn write(
    &self,
    ctx: ServerContext,
    request: &WriteRequest,
    respond: impl for<'a> RespondOnce<WriteResponse<'a>>
)

Write data

Write should return exactly the number of bytes requested except on error. An exception to this is when the file has been opened in 'direct_io' mode, in which case the return value of the write system call will reflect the return value of this operation.

Unless FUSE_CAP_HANDLE_KILLPRIV is disabled, this method is expected to reset the setuid and setgid bits.

fi->fh will contain the value set by the open method, or will be undefined if the open method didn't set any value.

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Implementors

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