include/fuse_lowlevel.h File Reference

#include "fuse_common.h"
#include <utime.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/uio.h>
#include "fuse_lowlevel_compat.h"

Data Structures
struct	fuse_entry_param
struct	fuse_ctx
struct	fuse_lowlevel_ops
struct	fuse_session_ops
struct	fuse_chan_ops
Defines
#define	FUSE_ROOT_ID   1
Typedefs
typedef unsigned long	fuse_ino_t
typedef struct fuse_req *	fuse_req_t
typedef void(*	fuse_interrupt_func_t )(fuse_req_t req, void *data)
Functions
int	fuse_reply_err (fuse_req_t req, int err)
void	fuse_reply_none (fuse_req_t req)
int	fuse_reply_entry (fuse_req_t req, const struct fuse_entry_param *e)
int	fuse_reply_create (fuse_req_t req, const struct fuse_entry_param *e, const struct fuse_file_info *fi)
int	fuse_reply_attr (fuse_req_t req, const struct stat *attr, double attr_timeout)
int	fuse_reply_readlink (fuse_req_t req, const char *link)
int	fuse_reply_open (fuse_req_t req, const struct fuse_file_info *fi)
int	fuse_reply_write (fuse_req_t req, size_t count)
int	fuse_reply_buf (fuse_req_t req, const char *buf, size_t size)
int	fuse_reply_iov (fuse_req_t req, const struct iovec *iov, int count)
int	fuse_reply_statfs (fuse_req_t req, const struct statvfs *stbuf)
int	fuse_reply_xattr (fuse_req_t req, size_t count)
int	fuse_reply_lock (fuse_req_t req, struct flock *lock)
int	fuse_reply_bmap (fuse_req_t req, uint64_t idx)
size_t	fuse_add_direntry (fuse_req_t req, char *buf, size_t bufsize, const char *name, const struct stat *stbuf, off_t off)
int	fuse_reply_ioctl_retry (fuse_req_t req, const struct iovec *in_iov, size_t in_count, const struct iovec *out_iov, size_t out_count)
int	fuse_reply_ioctl (fuse_req_t req, int result, const void *buf, size_t size)
int	fuse_reply_poll (fuse_req_t req, unsigned revents)
int	fuse_lowlevel_notify_poll (struct fuse_pollhandle *ph)
void *	fuse_req_userdata (fuse_req_t req)
struct fuse_ctx *	fuse_req_ctx (fuse_req_t req)
void	fuse_req_interrupt_func (fuse_req_t req, fuse_interrupt_func_t func, void *data)
int	fuse_req_interrupted (fuse_req_t req)
struct fuse_session *	fuse_lowlevel_new (struct fuse_args *args, const struct fuse_lowlevel_ops *op, size_t op_size, void *userdata)
struct fuse_session *	fuse_session_new (struct fuse_session_ops *op, void *data)
void	fuse_session_add_chan (struct fuse_session *se, struct fuse_chan *ch)
void	fuse_session_remove_chan (struct fuse_chan *ch)
struct fuse_chan *	fuse_session_next_chan (struct fuse_session *se, struct fuse_chan *ch)
void	fuse_session_process (struct fuse_session *se, const char *buf, size_t len, struct fuse_chan *ch)
void	fuse_session_destroy (struct fuse_session *se)
void	fuse_session_exit (struct fuse_session *se)
void	fuse_session_reset (struct fuse_session *se)
int	fuse_session_exited (struct fuse_session *se)
int	fuse_session_loop (struct fuse_session *se)
int	fuse_session_loop_mt (struct fuse_session *se)
struct fuse_chan *	fuse_chan_new (struct fuse_chan_ops *op, int fd, size_t bufsize, void *data)
int	fuse_chan_fd (struct fuse_chan *ch)
size_t	fuse_chan_bufsize (struct fuse_chan *ch)
void *	fuse_chan_data (struct fuse_chan *ch)
struct fuse_session *	fuse_chan_session (struct fuse_chan *ch)
int	fuse_chan_recv (struct fuse_chan **ch, char *buf, size_t size)
int	fuse_chan_send (struct fuse_chan *ch, const struct iovec iov[], size_t count)
void	fuse_chan_destroy (struct fuse_chan *ch)

---

Detailed Description

Low level API

IMPORTANT: you should define FUSE_USE_VERSION before including this header. To use the newest API define it to 26 (recommended for any new application), to use the old API define it to 24 (default) or 25

---

Define Documentation

#define FUSE_ROOT_ID   1

The node ID of the root inode

---

Typedef Documentation

typedef unsigned long fuse_ino_t

Inode number type

typedef void(* fuse_interrupt_func_t)(fuse_req_t req, void *data)

Callback function for an interrupt

Parameters:

	req	interrupted request
	data	user data

typedef struct fuse_req* fuse_req_t

Request pointer type

---

Function Documentation

size_t fuse_add_direntry	(	fuse_req_t	req,
		char *	buf,
		size_t	bufsize,
		const char *	name,
		const struct stat *	stbuf,
		off_t	off
	)

Add a directory entry to the buffer

Buffer needs to be large enough to hold the entry. Of it's not, then the entry is not filled in but the size of the entry is still returned. The caller can check this by comparing the bufsize parameter with the returned entry size. If the entry size is larger than the buffer size, the operation failed.

From the 'stbuf' argument the st_ino field and bits 12-15 of the st_mode field are used. The other fields are ignored.

Note: offsets do not necessarily represent physical offsets, and could be any marker, that enables the implementation to find a specific point in the directory stream.

Parameters:

	req	request handle
	buf	the point where the new entry will be added to the buffer
	bufsize	remaining size of the buffer
	name	the name of the entry
	stbuf	the file attributes
	off	the offset of the next entry

Returns:

the space needed for the entry

size_t fuse_chan_bufsize

(

struct fuse_chan *

ch

)

Query the minimal receive buffer size

Parameters:

ch

the channel

Returns:

the buffer size passed to fuse_chan_new()

void* fuse_chan_data

(

struct fuse_chan *

ch

)

Query the user data

Parameters:

ch

the channel

Returns:

the user data passed to fuse_chan_new()

void fuse_chan_destroy

(

struct fuse_chan *

ch

)

Destroy a channel

Parameters:

ch

the channel

int fuse_chan_fd

(

struct fuse_chan *

ch

)

Query the file descriptor of the channel

Parameters:

ch

the channel

Returns:

the file descriptor passed to fuse_chan_new()

struct fuse_chan* fuse_chan_new	(	struct fuse_chan_ops *	op,
		int	fd,
		size_t	bufsize,
		void *	data
	)			[read]

Create a new channel

Parameters:

	op	channel operations
	fd	file descriptor of the channel
	bufsize	the minimal receive buffer size
	data	user data

Returns:

the new channel object, or NULL on failure

int fuse_chan_recv	(	struct fuse_chan **	ch,
		char *	buf,
		size_t	size
	)

Receive a raw request

A return value of -ENODEV means, that the filesystem was unmounted

Parameters:

	ch	pointer to the channel
	buf	the buffer to store the request in
	size	the size of the buffer

Returns:

the actual size of the raw request, or -errno on error

int fuse_chan_send	(	struct fuse_chan *	ch,
		const struct iovec	iov[],
		size_t	count
	)

Send a raw reply

A return value of -ENOENT means, that the request was interrupted, and the reply was discarded

Parameters:

	ch	the channel
	iov	vector of blocks
	count	the number of blocks in vector

Returns:

zero on success, -errno on failure

struct fuse_session* fuse_chan_session

(

struct fuse_chan *

ch

)

[read]

Query the session to which this channel is assigned

Parameters:

ch

the channel

Returns:

the session, or NULL if the channel is not assigned

struct fuse_session* fuse_lowlevel_new	(	struct fuse_args *	args,
		const struct fuse_lowlevel_ops *	op,
		size_t	op_size,
		void *	userdata
	)			[read]

Create a low level session

Parameters:

	args	argument vector
	op	the low level filesystem operations
	op_size	sizeof(struct fuse_lowlevel_ops)
	userdata	user data

Returns:

the created session object, or NULL on failure

int fuse_lowlevel_notify_poll

(

struct fuse_pollhandle *

ph

)

Notify IO readiness event

For more information, please read comment for poll operation.

Parameters:

ph

poll handle to notify IO readiness event for

int fuse_reply_attr	(	fuse_req_t	req,
		const struct stat *	attr,
		double	attr_timeout
	)

Reply with attributes

Possible requests: getattr, setattr

Parameters:

	req	request handle
	attr	the attributes
	attr_timeout	validity timeout (in seconds) for the attributes

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_bmap	(	fuse_req_t	req,
		uint64_t	idx
	)

Reply with block index

Possible requests: bmap

Parameters:

	req	request handle
	idx	block index within device

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_buf	(	fuse_req_t	req,
		const char *	buf,
		size_t	size
	)

Reply with data

Possible requests: read, readdir, getxattr, listxattr

Parameters:

	req	request handle
	buf	buffer containing data
	size	the size of data in bytes

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_create	(	fuse_req_t	req,
		const struct fuse_entry_param *	e,
		const struct fuse_file_info *	fi
	)

Reply with a directory entry and open parameters

currently the following members of 'fi' are used: fh, direct_io, keep_cache

Possible requests: create

Parameters:

	req	request handle
	e	the entry parameters
	fi	file information

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_entry	(	fuse_req_t	req,
		const struct fuse_entry_param *	e
	)

Reply with a directory entry

Possible requests: lookup, mknod, mkdir, symlink, link

Parameters:

	req	request handle
	e	the entry parameters

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_err	(	fuse_req_t	req,
		int	err
	)

Reply with an error code or success

Possible requests: all except forget

unlink, rmdir, rename, flush, release, fsync, fsyncdir, setxattr, removexattr and setlk may send a zero code

Parameters:

	req	request handle
	err	the positive error value, or zero for success

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_ioctl	(	fuse_req_t	req,
		int	result,
		const void *	buf,
		size_t	size
	)

Reply to finish ioctl

Possible requests: ioctl

Parameters:

	req	request handle
	result	result to be passed to the caller
	buf	buffer containing output data
	size	length of output data

int fuse_reply_ioctl_retry	(	fuse_req_t	req,
		const struct iovec *	in_iov,
		size_t	in_count,
		const struct iovec *	out_iov,
		size_t	out_count
	)

Reply to ask for data fetch and output buffer preparation. ioctl will be retried with the specified input data fetched and output buffer prepared.

Possible requests: ioctl

Parameters:

	req	request handle
	in_iov	iovec specifying data to fetch from the caller
	in_count	number of entries in in_iov
	out_iov	iovec specifying addresses to write output to
	out_count	number of entries in out_iov

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_iov	(	fuse_req_t	req,
		const struct iovec *	iov,
		int	count
	)

Reply with data vector

Possible requests: read, readdir, getxattr, listxattr

Parameters:

	req	request handle
	iov	the vector containing the data
	count	the size of vector

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_lock	(	fuse_req_t	req,
		struct flock *	lock
	)

Reply with file lock information

Possible requests: getlk

Parameters:

	req	request handle
	lock	the lock information

Returns:

zero for success, -errno for failure to send reply

void fuse_reply_none

(

fuse_req_t

req

)

Don't send reply

Possible requests: forget

Parameters:

req

request handle

int fuse_reply_open	(	fuse_req_t	req,
		const struct fuse_file_info *	fi
	)

Reply with open parameters

currently the following members of 'fi' are used: fh, direct_io, keep_cache

Possible requests: open, opendir

Parameters:

	req	request handle
	fi	file information

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_poll	(	fuse_req_t	req,
		unsigned	revents
	)

Reply with poll result event mask

Parameters:

	req	request handle
	revents	poll result event mask

int fuse_reply_readlink	(	fuse_req_t	req,
		const char *	link
	)

Reply with the contents of a symbolic link

Possible requests: readlink

Parameters:

	req	request handle
	link	symbolic link contents

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_statfs	(	fuse_req_t	req,
		const struct statvfs *	stbuf
	)

Reply with filesystem statistics

Possible requests: statfs

Parameters:

	req	request handle
	stbuf	filesystem statistics

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_write	(	fuse_req_t	req,
		size_t	count
	)

Reply with number of bytes written

Possible requests: write

Parameters:

	req	request handle
	count	the number of bytes written

Returns:

zero for success, -errno for failure to send reply

int fuse_reply_xattr	(	fuse_req_t	req,
		size_t	count
	)

Reply with needed buffer size

Possible requests: getxattr, listxattr

Parameters:

	req	request handle
	count	the buffer size needed in bytes

Returns:

zero for success, -errno for failure to send reply

struct fuse_ctx* fuse_req_ctx

(

fuse_req_t

req

)

[read]

Get the context from the request

The pointer returned by this function will only be valid for the request's lifetime

Parameters:

req

request handle

Returns:

the context structure

void fuse_req_interrupt_func	(	fuse_req_t	req,
		fuse_interrupt_func_t	func,
		void *	data
	)

Register/unregister callback for an interrupt

If an interrupt has already happened, then the callback function is called from within this function, hence it's not possible for interrupts to be lost.

Parameters:

	req	request handle
	func	the callback function or NULL for unregister
	data	user data passed to the callback function

int fuse_req_interrupted

(

fuse_req_t

req

)

Check if a request has already been interrupted

Parameters:

req

request handle

Returns:

1 if the request has been interrupted, 0 otherwise

void* fuse_req_userdata

(

fuse_req_t

req

)

Get the userdata from the request

Parameters:

req

request handle

Returns:

the user data passed to fuse_lowlevel_new()

void fuse_session_add_chan	(	struct fuse_session *	se,
		struct fuse_chan *	ch
	)

Assign a channel to a session

Note: currently only a single channel may be assigned. This may change in the future

If a session is destroyed, the assigned channel is also destroyed

Parameters:

	se	the session
	ch	the channel

void fuse_session_destroy

(

struct fuse_session *

se

)

Destroy a session

Parameters:

se

the session

void fuse_session_exit

(

struct fuse_session *

se

)

Exit a session

Parameters:

se

the session

int fuse_session_exited

(

struct fuse_session *

se

)

Query the exited status of a session

Parameters:

se

the session

Returns:

1 if exited, 0 if not exited

int fuse_session_loop

(

struct fuse_session *

se

)

Enter a single threaded event loop

Parameters:

se

the session

Returns:

0 on success, -1 on error

int fuse_session_loop_mt

(

struct fuse_session *

se

)

Enter a multi-threaded event loop

Parameters:

se

the session

Returns:

0 on success, -1 on error

struct fuse_session* fuse_session_new	(	struct fuse_session_ops *	op,
		void *	data
	)			[read]

Create a new session

Parameters:

	op	session operations
	data	user data

Returns:

new session object, or NULL on failure

struct fuse_chan* fuse_session_next_chan	(	struct fuse_session *	se,
		struct fuse_chan *	ch
	)			[read]

Iterate over the channels assigned to a session

The iterating function needs to start with a NULL channel, and after that needs to pass the previously returned channel to the function.

Parameters:

	se	the session
	ch	the previous channel, or NULL

Returns:

the next channel, or NULL if no more channels exist

void fuse_session_process	(	struct fuse_session *	se,
		const char *	buf,
		size_t	len,
		struct fuse_chan *	ch
	)

Process a raw request

Parameters:

	se	the session
	buf	buffer containing the raw request
	len	request length
	ch	channel on which the request was received

void fuse_session_remove_chan

(

struct fuse_chan *

ch

)

Remove a channel from a session

If the channel is not assigned to a session, then this is a no-op

Parameters:

ch

the channel to remove

void fuse_session_reset

(

struct fuse_session *

se

)

Reset the exited status of a session

Parameters:

se

the session