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mergerfs/libfuse/include/fuse_lowlevel.h

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/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU LGPLv2.
See the file COPYING.LIB.
*/
#ifndef _FUSE_LOWLEVEL_H_
#define _FUSE_LOWLEVEL_H_
/** @file
*
* 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
*/
#ifndef FUSE_USE_VERSION
#define FUSE_USE_VERSION 24
#endif
#include "fuse_common.h"
#include <fcntl.h>
#include <stdint.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <utime.h>
#ifdef __cplusplus
extern "C" {
#endif
/* ----------------------------------------------------------- *
* Miscellaneous definitions *
* ----------------------------------------------------------- */
/** The node ID of the root inode */
#define FUSE_ROOT_ID 1
/** Inode number type */
typedef uint64_t fuse_ino_t;
/** Request pointer type */
typedef struct fuse_req *fuse_req_t;
/**
* Session
*
* This provides hooks for processing requests, and exiting
*/
struct fuse_session;
/**
* Channel
*
* A communication channel, providing hooks for sending and receiving
* messages
*/
struct fuse_chan;
/** Directory entry parameters supplied to fuse_reply_entry() */
struct fuse_entry_param
{
/** Unique inode number
*
* In lookup, zero means negative entry (from version 2.5)
* Returning ENOENT also means negative entry, but by setting zero
* ino the kernel may cache negative entries for entry_timeout
* seconds.
*/
fuse_ino_t ino;
/** Generation number for this entry.
*
* If the file system will be exported over NFS, the
* ino/generation pairs need to be unique over the file
* system's lifetime (rather than just the mount time). So if
* the file system reuses an inode after it has been deleted,
* it must assign a new, previously unused generation number
* to the inode at the same time.
*
* The generation must be non-zero, otherwise FUSE will treat
* it as an error.
*
*/
uint64_t generation;
/** Inode attributes.
*
* Even if attr_timeout == 0, attr must be correct. For example,
* for open(), FUSE uses attr.st_size from lookup() to determine
* how many bytes to request. If this value is not correct,
* incorrect data will be returned.
*/
struct stat attr;
fuse_timeouts_t timeout;
};
/** Additional context associated with requests */
struct fuse_ctx
{
/** User ID of the calling process */
uid_t uid;
/** Group ID of the calling process */
gid_t gid;
/** Thread ID of the calling process */
pid_t pid;
/** Umask of the calling process (introduced in version 2.8) */
mode_t umask;
};
struct fuse_forget_data
{
fuse_ino_t ino;
uint64_t nlookup;
};
/* ----------------------------------------------------------- *
* Request methods and replies *
* ----------------------------------------------------------- */
/**
* Low level filesystem operations
*
* Most of the methods (with the exception of init and destroy)
* receive a request handle (fuse_req_t) as their first argument.
* This handle must be passed to one of the specified reply functions.
*
* This may be done inside the method invocation, or after the call
* has returned. The request handle is valid until one of the reply
* functions is called.
*
* Other pointer arguments (name, fuse_file_info, etc) are not valid
* after the call has returned, so if they are needed later, their
* contents have to be copied.
*
* The filesystem sometimes needs to handle a return value of -ENOENT
* from the reply function, which means, that the request was
* interrupted, and the reply discarded. For example if
* fuse_reply_open() return -ENOENT means, that the release method for
* this file will not be called.
*/
struct fuse_lowlevel_ops
{
/**
* Initialize filesystem
*
* Called before any other filesystem method
*
* There's no reply to this function
*
* @param userdata the user data passed to fuse_lowlevel_new()
*/
void (*init) (void *userdata, struct fuse_conn_info *conn);
/**
* Clean up filesystem
*
* Called on filesystem exit
*
* There's no reply to this function
*
* @param userdata the user data passed to fuse_lowlevel_new()
*/
void (*destroy) (void *userdata);
/**
* Look up a directory entry by name and get its attributes.
*
* Valid replies:
* fuse_reply_entry
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the parent directory
* @param name the name to look up
*/
void (*lookup) (fuse_req_t req, fuse_ino_t parent, const char *name);
/**
* 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, remdir 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.
*
* Valid replies:
* fuse_reply_none
*
* @param req request handle
* @param ino the inode number
* @param nlookup the number of lookups to forget
*/
void (*forget) (fuse_req_t req, fuse_ino_t ino, uint64_t nlookup);
/**
* Get file attributes
*
* Valid replies:
* fuse_reply_attr
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi for future use, currently always NULL
*/
void (*getattr) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi);
/**
* Set file attributes
*
* In the 'attr' argument only members indicated by the 'to_set'
* bitmask contain valid values. Other members contain undefined
* values.
*
* 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.
*
* Valid replies:
* fuse_reply_attr
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param attr the attributes
* @param to_set bit mask of attributes which should be set
* @param fi file information, or NULL
*
* Changed in version 2.5:
* file information filled in for ftruncate
*/
void (*setattr) (fuse_req_t req, fuse_ino_t ino, struct stat *attr,
int to_set, struct fuse_file_info *fi);
/**
* Read symbolic link
*
* Valid replies:
* fuse_reply_readlink
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
*/
void (*readlink) (fuse_req_t req, fuse_ino_t ino);
/**
* Create file node
*
* Create a regular file, character device, block device, fifo or
* socket node.
*
* Valid replies:
* fuse_reply_entry
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the parent directory
* @param name to create
* @param mode file type and mode with which to create the new file
* @param rdev the device number (only valid if created file is a device)
*/
void (*mknod) (fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, dev_t rdev);
/**
* Create a directory
*
* Valid replies:
* fuse_reply_entry
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the parent directory
* @param name to create
* @param mode with which to create the new file
*/
void (*mkdir) (fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode);
/**
* 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).
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the parent directory
* @param name to remove
*/
void (*unlink) (fuse_req_t req, fuse_ino_t parent, const char *name);
/**
* 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).
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the parent directory
* @param name to remove
*/
void (*rmdir) (fuse_req_t req, fuse_ino_t parent, const char *name);
/**
* Create a symbolic link
*
* Valid replies:
* fuse_reply_entry
* fuse_reply_err
*
* @param req request handle
* @param link the contents of the symbolic link
* @param parent inode number of the parent directory
* @param name to create
*/
void (*symlink) (fuse_req_t req, const char *link, fuse_ino_t parent,
const char *name);
/** 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).
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the old parent directory
* @param name old name
* @param newparent inode number of the new parent directory
* @param newname new name
*/
void (*rename) (fuse_req_t req, fuse_ino_t parent, const char *name,
fuse_ino_t newparent, const char *newname);
/**
* Create a hard link
*
* Valid replies:
* fuse_reply_entry
* fuse_reply_err
*
* @param req request handle
* @param ino the old inode number
* @param newparent inode number of the new parent directory
* @param newname new name to create
*/
void (*link) (fuse_req_t req, fuse_ino_t ino, fuse_ino_t newparent,
const char *newname);
/**
* Open a file
*
* Open flags (with the exception of O_CREAT, O_EXCL, O_NOCTTY and
* O_TRUNC) are available in fi->flags.
*
* 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.
*
* Valid replies:
* fuse_reply_open
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
void (*open) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi);
/**
* 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.
*
* Valid replies:
* fuse_reply_buf
* fuse_reply_iov
* fuse_reply_data
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param size number of bytes to read
* @param off offset to read from
* @param fi file information
*/
void (*read) (fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
struct fuse_file_info *fi);
/**
* 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.
*
* fi->fh will contain the value set by the open method, or will
* be undefined if the open method didn't set any value.
*
* Valid replies:
* fuse_reply_write
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param buf data to write
* @param size number of bytes to write
* @param off offset to write to
* @param fi file information
*/
void (*write) (fuse_req_t req, fuse_ino_t ino, const char *buf,
size_t size, off_t off, struct fuse_file_info *fi);
/**
* 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.
*
* If the filesystem supports file locking operations (setlk,
* getlk) it should remove all locks belonging to 'fi->owner'.
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
void (*flush) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi);
/**
* 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.
*
* 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.
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
void (*release) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi);
/**
* Synchronize file contents
*
* If the datasync parameter is non-zero, then only the user data
* should be flushed, not the meta data.
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param datasync flag indicating if only data should be flushed
* @param fi file information
*/
void (*fsync) (fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi);
/**
* 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).
*
* Filesystem may also implement stateless directory I/O and not
* store anything in fi->fh, though that makes it impossible to
* implement standard conforming directory stream operations in
* case the contents of the directory can change between opendir
* and releasedir.
*
* Valid replies:
* fuse_reply_open
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
void (*opendir) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi);
/**
* 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.
*
* Valid replies:
* fuse_reply_buf
* fuse_reply_data
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param size maximum number of bytes to send
* @param off offset to continue reading the directory stream
* @param fi file information
*/
void (*readdir) (fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
struct fuse_file_info *llffi);
void (*readdir_plus)(fuse_req_t req, fuse_ino_t ino,
size_t size, off_t off,
struct fuse_file_info *ffi);
/**
* Release an open directory
*
* For every opendir call there will be exactly one releasedir
* call.
*
* fi->fh will contain the value set by the opendir method, or
* will be undefined if the opendir method didn't set any value.
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
void (*releasedir) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi);
/**
* 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.
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param datasync flag indicating if only data should be flushed
* @param fi file information
*/
void (*fsyncdir) (fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi);
/**
* Get file system statistics
*
* Valid replies:
* fuse_reply_statfs
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number, zero means "undefined"
*/
void (*statfs) (fuse_req_t req, fuse_ino_t ino);
/**
* Set an extended attribute
*
* Valid replies:
* fuse_reply_err
*/
void (*setxattr) (fuse_req_t req, fuse_ino_t ino, const char *name,
const char *value, size_t size, int flags);
/**
* 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.
*
* Valid replies:
* fuse_reply_buf
* fuse_reply_data
* fuse_reply_xattr
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param name of the extended attribute
* @param size maximum size of the value to send
*/
void (*getxattr) (fuse_req_t req, fuse_ino_t ino, const char *name,
size_t size);
/**
* 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.
*
* Valid replies:
* fuse_reply_buf
* fuse_reply_data
* fuse_reply_xattr
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param size maximum size of the list to send
*/
void (*listxattr) (fuse_req_t req, fuse_ino_t ino, size_t size);
/**
* Remove an extended attribute
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param name of the extended attribute
*/
void (*removexattr) (fuse_req_t req, fuse_ino_t ino, const char *name);
/**
* Check file access permissions
*
* This will be called for the access() system call. 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
*
* Introduced in version 2.5
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param mask requested access mode
*/
void (*access) (fuse_req_t req, fuse_ino_t ino, int mask);
/**
* Create and open a file
*
* If the file does not exist, first create it with the specified
* mode, and then open it.
*
* Open flags (with the exception of O_NOCTTY) are available in
* fi->flags.
*
* 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).
*
* 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 method is not implemented or under Linux kernel
* versions earlier than 2.6.15, the mknod() and open() methods
* will be called instead.
*
* Introduced in version 2.5
*
* Valid replies:
* fuse_reply_create
* fuse_reply_err
*
* @param req request handle
* @param parent inode number of the parent directory
* @param name to create
* @param mode file type and mode with which to create the new file
* @param fi file information
*/
void (*create) (fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi);
/**
* Test for a POSIX file lock
*
* Introduced in version 2.6
*
* Valid replies:
* fuse_reply_lock
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
* @param lock the region/type to test
*/
void (*getlk) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi, struct flock *lock);
/**
* 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.
*
* Introduced in version 2.6
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
* @param lock the region/type to set
* @param sleep locking operation may sleep
*/
void (*setlk) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi,
struct flock *lock, int sleep);
/**
* 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
*
* Introduced in version 2.6
*
* Valid replies:
* fuse_reply_bmap
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param blocksize unit of block index
* @param idx block index within file
*/
void (*bmap) (fuse_req_t req, fuse_ino_t ino, size_t blocksize,
uint64_t idx);
/**
* 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.
*
* Introduced in version 2.8
*
* 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
*/
void (*ioctl) (fuse_req_t req, fuse_ino_t ino, unsigned long cmd, void *arg,
struct fuse_file_info *fi, unsigned flags,
const void *in_buf, uint32_t in_bufsz, uint32_t out_bufsz);
/**
* Poll for IO readiness
*
* Introduced in version 2.8
*
* Note: If ph is non-NULL, the client should notify
* when IO readiness events occur by calling
* fuse_lowelevel_notify_poll() with the specified ph.
*
* Regardless of the number of times poll with a non-NULL ph
* is received, single notification is enough to clear all.
* Notifying more times incurs overhead but doesn't harm
* correctness.
*
* The callee is responsible for destroying ph with
* fuse_pollhandle_destroy() when no longer in use.
*
* Valid replies:
* fuse_reply_poll
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
* @param ph poll handle to be used for notification
*/
void (*poll) (fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi,
struct fuse_pollhandle *ph);
/**
* Write data made available in a buffer
*
* This is a more generic version of the ->write() method. If
* FUSE_CAP_SPLICE_READ is set in fuse_conn_info.want and the
* kernel supports splicing from the fuse device, then the
* data will be made available in pipe for supporting zero
* copy data transfer.
*
* buf->count is guaranteed to be one (and thus buf->idx is
* always zero). The write_buf handler must ensure that
* bufv->off is correctly updated (reflecting the number of
* bytes read from bufv->buf[0]).
*
* Introduced in version 2.9
*
* Valid replies:
* fuse_reply_write
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param bufv buffer containing the data
* @param off offset to write to
* @param fi file information
*/
void (*write_buf) (fuse_req_t req, fuse_ino_t ino,
struct fuse_bufvec *bufv, off_t off,
struct fuse_file_info *fi);
/**
* Callback function for the retrieve request
*
* Introduced in version 2.9
*
* Valid replies:
* fuse_reply_none
*
* @param req request handle
* @param cookie user data supplied to fuse_lowlevel_notify_retrieve()
* @param ino the inode number supplied to fuse_lowlevel_notify_retrieve()
* @param offset the offset supplied to fuse_lowlevel_notify_retrieve()
* @param bufv the buffer containing the returned data
*/
void (*retrieve_reply) (fuse_req_t req, void *cookie, fuse_ino_t ino,
off_t offset, struct fuse_bufvec *bufv);
/**
* Forget about multiple inodes
*
* See description of the forget function for more
* information.
*
* Introduced in version 2.9
*
* Valid replies:
* fuse_reply_none
*
* @param req request handle
*/
void (*forget_multi) (fuse_req_t req, size_t count,
struct fuse_forget_data *forgets);
/**
* Acquire, modify or release a BSD file lock
*
* 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.
*
* Introduced in version 2.9
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
* @param op the locking operation, see flock(2)
*/
void (*flock) (fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi, int op);
/**
* Allocate requested space. If this function returns success then
* subsequent writes to the specified range shall not fail due to the lack
* of free space on the file system storage media.
*
* Introduced in version 2.9
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param offset starting point for allocated region
* @param length size of allocated region
* @param mode determines the operation to be performed on the given range,
* see fallocate(2)
*/
void (*fallocate) (fuse_req_t req, fuse_ino_t ino, int mode,
off_t offset, off_t length, struct fuse_file_info *fi);
/**
* Copy a range of data from one file to another
*
* Performs an optimized copy between two file descriptors without
* the
* additional cost of transferring data through the FUSE kernel
* module
* to user space (glibc) and then back into the FUSE filesystem
* again.
*
* In case this method is not implemented, glibc falls back to
* reading
* data from the source and writing to the destination. Effectively
* doing an inefficient copy of the data.
*
* 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 copy_file_range() requests will fail with EOPNOTSUPP
* without
* being send to the filesystem process.
*
* Valid replies:
* fuse_reply_write
* fuse_reply_err
*
* @param req request handle
* @param ino_in the inode number of the source file
* @param off_in starting point from were the data should be read
* @param fi_in file information of the source file
* @param ino_out the inode number of the destination file
* @param off_out starting point where the data should be written
* @param fi_out file information of the destination file
* @param len maximum size of the data to copy
* @param flags passed along with the copy_file_range() syscall
*/
void (*copy_file_range)(fuse_req_t req,
fuse_ino_t ino_in,
off_t off_in,
struct fuse_file_info *fi_in,
fuse_ino_t ino_out,
off_t off_out,
struct fuse_file_info *fi_out,
size_t len,
int flags);
};
/**
* 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
*
* @param req request handle
* @param err the positive error value, or zero for success
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_err(fuse_req_t req, int err);
/**
* Don't send reply
*
* Possible requests:
* forget
*
* @param req request handle
*/
void fuse_reply_none(fuse_req_t req);
/**
* Reply with a directory entry
*
* Possible requests:
* lookup, mknod, mkdir, symlink, link
*
* Side effects:
* increments the lookup count on success
*
* @param req request handle
* @param e the entry parameters
* @return 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 and open parameters
*
* currently the following members of 'fi' are used:
* fh, direct_io, keep_cache
*
* Possible requests:
* create
*
* Side effects:
* increments the lookup count on success
*
* @param req request handle
* @param e the entry parameters
* @param fi file information
* @return 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 attributes
*
* Possible requests:
* getattr, setattr
*
* @param req request handle
* @param attr the attributes
* @param attr_timeout validity timeout (in seconds) for the attributes
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_attr(fuse_req_t req,
const struct stat *attr,
const uint64_t timeout);
/**
* Reply with the contents of a symbolic link
*
* Possible requests:
* readlink
*
* @param req request handle
* @param link symbolic link contents
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_readlink(fuse_req_t req, const char *link);
/**
* Reply with open parameters
*
* currently the following members of 'fi' are used:
* fh, direct_io, keep_cache
*
* Possible requests:
* open, opendir
*
* @param req request handle
* @param fi file information
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_open(fuse_req_t req, const struct fuse_file_info *fi);
/**
* Reply with number of bytes written
*
* Possible requests:
* write
*
* @param req request handle
* @param count the number of bytes written
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_write(fuse_req_t req, size_t count);
/**
* Reply with data
*
* Possible requests:
* read, readdir, getxattr, listxattr
*
* @param req request handle
* @param buf buffer containing data
* @param size the size of data in bytes
* @return 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 copied/moved from buffer(s)
*
* Possible requests:
* read, readdir, getxattr, listxattr
*
* @param req request handle
* @param bufv buffer vector
* @param flags flags controlling the copy
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_data(fuse_req_t req, struct fuse_bufvec *bufv,
enum fuse_buf_copy_flags flags);
/**
* Reply with data vector
*
* Possible requests:
* read, readdir, getxattr, listxattr
*
* @param req request handle
* @param iov the vector containing the data
* @param count the size of vector
* @return 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 filesystem statistics
*
* Possible requests:
* statfs
*
* @param req request handle
* @param stbuf filesystem statistics
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_statfs(fuse_req_t req, const struct statvfs *stbuf);
/**
* Reply with needed buffer size
*
* Possible requests:
* getxattr, listxattr
*
* @param req request handle
* @param count the buffer size needed in bytes
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_xattr(fuse_req_t req, size_t count);
/**
* Reply with file lock information
*
* Possible requests:
* getlk
*
* @param req request handle
* @param lock the lock information
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_lock(fuse_req_t req, const struct flock *lock);
/**
* Reply with block index
*
* Possible requests:
* bmap
*
* @param req request handle
* @param idx block index within device
* @return zero for success, -errno for failure to send reply
*/
int fuse_reply_bmap(fuse_req_t req, uint64_t idx);
/**
* 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
*
* @param req request handle
* @param in_iov iovec specifying data to fetch from the caller
* @param in_count number of entries in in_iov
* @param out_iov iovec specifying addresses to write output to
* @param out_count number of entries in out_iov
* @return zero for success, -errno for failure to send reply
*/
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 finish ioctl
*
* Possible requests:
* ioctl
*
* @param req request handle
* @param result result to be passed to the caller
* @param buf buffer containing output data
* @param size length of output data
*/
int fuse_reply_ioctl(fuse_req_t req, int result, const void *buf, uint32_t size);
/**
* Reply to finish ioctl with iov buffer
*
* Possible requests:
* ioctl
*
* @param req request handle
* @param result result to be passed to the caller
* @param iov the vector containing the data
* @param count the size of vector
*/
int fuse_reply_ioctl_iov(fuse_req_t req, int result, const struct iovec *iov,
int count);
/**
* Reply with poll result event mask
*
* @param req request handle
* @param revents poll result event mask
*/
int fuse_reply_poll(fuse_req_t req, unsigned revents);
/* ----------------------------------------------------------- *
* Notification *
* ----------------------------------------------------------- */
/**
* Notify IO readiness event
*
* For more information, please read comment for poll operation.
*
* @param ph poll handle to notify IO readiness event for
*/
int fuse_lowlevel_notify_poll(struct fuse_pollhandle *ph);
/**
* Notify to invalidate cache for an inode
*
* @param ch the channel through which to send the invalidation
* @param ino the inode number
* @param off the offset in the inode where to start invalidating
* or negative to invalidate attributes only
* @param len the amount of cache to invalidate or 0 for all
* @return zero for success, -errno for failure
*/
int fuse_lowlevel_notify_inval_inode(struct fuse_chan *ch, fuse_ino_t ino,
off_t off, off_t len);
/**
* Notify to invalidate parent attributes and the dentry matching
* parent/name
*
* To avoid a deadlock don't call this function from a filesystem operation and
* don't call it with a lock held that can also be held by a filesystem
* operation.
*
* @param ch the channel through which to send the invalidation
* @param parent inode number
* @param name file name
* @param namelen strlen() of file name
* @return zero for success, -errno for failure
*/
int fuse_lowlevel_notify_inval_entry(struct fuse_chan *ch, fuse_ino_t parent,
const char *name, size_t namelen);
/**
* Notify to invalidate parent attributes and delete the dentry matching
* parent/name if the dentry's inode number matches child (otherwise it
* will invalidate the matching dentry).
*
* To avoid a deadlock don't call this function from a filesystem operation and
* don't call it with a lock held that can also be held by a filesystem
* operation.
*
* @param ch the channel through which to send the notification
* @param parent inode number
* @param child inode number
* @param name file name
* @param namelen strlen() of file name
* @return zero for success, -errno for failure
*/
int fuse_lowlevel_notify_delete(struct fuse_chan *ch,
fuse_ino_t parent, fuse_ino_t child,
const char *name, size_t namelen);
/**
* Store data to the kernel buffers
*
* Synchronously store data in the kernel buffers belonging to the
* given inode. The stored data is marked up-to-date (no read will be
* performed against it, unless it's invalidated or evicted from the
* cache).
*
* If the stored data overflows the current file size, then the size
* is extended, similarly to a write(2) on the filesystem.
*
* If this function returns an error, then the store wasn't fully
* completed, but it may have been partially completed.
*
* @param ch the channel through which to send the invalidation
* @param ino the inode number
* @param offset the starting offset into the file to store to
* @param bufv buffer vector
* @param flags flags controlling the copy
* @return zero for success, -errno for failure
*/
int fuse_lowlevel_notify_store(struct fuse_chan *ch, fuse_ino_t ino,
off_t offset, struct fuse_bufvec *bufv,
enum fuse_buf_copy_flags flags);
/**
* Retrieve data from the kernel buffers
*
* Retrieve data in the kernel buffers belonging to the given inode.
* If successful then the retrieve_reply() method will be called with
* the returned data.
*
* Only present pages are returned in the retrieve reply. Retrieving
* stops when it finds a non-present page and only data prior to that is
* returned.
*
* If this function returns an error, then the retrieve will not be
* completed and no reply will be sent.
*
* This function doesn't change the dirty state of pages in the kernel
* buffer. For dirty pages the write() method will be called
* regardless of having been retrieved previously.
*
* @param ch the channel through which to send the invalidation
* @param ino the inode number
* @param size the number of bytes to retrieve
* @param offset the starting offset into the file to retrieve from
* @param cookie user data to supply to the reply callback
* @return zero for success, -errno for failure
*/
int fuse_lowlevel_notify_retrieve(struct fuse_chan *ch, fuse_ino_t ino,
size_t size, off_t offset, void *cookie);
/* ----------------------------------------------------------- *
* Utility functions *
* ----------------------------------------------------------- */
/**
* Get the userdata from the request
*
* @param req request handle
* @return the user data passed to fuse_lowlevel_new()
*/
void *fuse_req_userdata(fuse_req_t req);
/**
* Get the context from the request
*
* The pointer returned by this function will only be valid for the
* request's lifetime
*
* @param req request handle
* @return the context structure
*/
const struct fuse_ctx *fuse_req_ctx(fuse_req_t req);
/**
* Get the current supplementary group IDs for the specified request
*
* Similar to the getgroups(2) system call, except the return value is
* always the total number of group IDs, even if it is larger than the
* specified size.
*
* The current fuse kernel module in linux (as of 2.6.30) doesn't pass
* the group list to userspace, hence this function needs to parse
* "/proc/$TID/task/$TID/status" to get the group IDs.
*
* This feature may not be supported on all operating systems. In
* such a case this function will return -ENOSYS.
*
* @param req request handle
* @param size size of given array
* @param list array of group IDs to be filled in
* @return the total number of supplementary group IDs or -errno on failure
*/
int fuse_req_getgroups(fuse_req_t req, int size, gid_t list[]);
/**
* Callback function for an interrupt
*
* @param req interrupted request
* @param data user data
*/
typedef void (*fuse_interrupt_func_t)(fuse_req_t req, 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.
*
* @param req request handle
* @param func the callback function or NULL for unregister
* @param data user data passed to the callback function
*/
void fuse_req_interrupt_func(fuse_req_t req, fuse_interrupt_func_t func,
void *data);
/**
* Check if a request has already been interrupted
*
* @param req request handle
* @return 1 if the request has been interrupted, 0 otherwise
*/
int fuse_req_interrupted(fuse_req_t req);
/* ----------------------------------------------------------- *
* Filesystem setup *
* ----------------------------------------------------------- */
/* Deprecated, don't use */
int fuse_lowlevel_is_lib_option(const char *opt);
/**
* Create a low level session
*
* @param args argument vector
* @param op the low level filesystem operations
* @param op_size sizeof(struct fuse_lowlevel_ops)
* @param userdata user data
* @return the created session object, or NULL on failure
*/
struct fuse_session *fuse_lowlevel_new(struct fuse_args *args,
const struct fuse_lowlevel_ops *op,
size_t op_size, void *userdata);
/* ----------------------------------------------------------- *
* Session interface *
* ----------------------------------------------------------- */
/**
* Session operations
*
* This is used in session creation
*/
struct fuse_session_ops
{
/**
* Hook to process a request (mandatory)
*
* @param data user data passed to fuse_session_new()
* @param buf buffer containing the raw request
* @param len request length
* @param ch channel on which the request was received
*/
void (*process) (void *data, const char *buf, size_t len,
struct fuse_chan *ch);
/**
* Hook for session exit and reset (optional)
*
* @param data user data passed to fuse_session_new()
* @param val exited status (1 - exited, 0 - not exited)
*/
void (*exit) (void *data, int val);
/**
* Hook for querying the current exited status (optional)
*
* @param data user data passed to fuse_session_new()
* @return 1 if exited, 0 if not exited
*/
int (*exited) (void *data);
/**
* Hook for cleaning up the channel on destroy (optional)
*
* @param data user data passed to fuse_session_new()
*/
void (*destroy) (void *data);
};
/**
* Create a new session
*
* @param op session operations
* @param data user data
* @return new session object, or NULL on failure
*/
struct fuse_session *fuse_session_new(struct fuse_session_ops *op, void *data);
/**
* 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
*
* @param se the session
* @param ch the channel
*/
void fuse_session_add_chan(struct fuse_session *se, 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
*
* @param ch the channel to remove
*/
void fuse_session_remove_chan(struct fuse_chan *ch);
/**
* 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.
*
* @param se the session
* @param ch the previous channel, or NULL
* @return the next channel, or NULL if no more channels exist
*/
struct fuse_chan *fuse_session_next_chan(struct fuse_session *se,
struct fuse_chan *ch);
/**
* Process a raw request
*
* @param se the session
* @param buf buffer containing the raw request
* @param len request length
* @param ch channel on which the request was received
*/
void fuse_session_process(struct fuse_session *se, const char *buf, size_t len,
struct fuse_chan *ch);
/**
* Process a raw request supplied in a generic buffer
*
* This is a more generic version of fuse_session_process(). The
* fuse_buf may contain a memory buffer or a pipe file descriptor.
*
* @param se the session
* @param buf the fuse_buf containing the request
* @param ch channel on which the request was received
*/
void fuse_session_process_buf(struct fuse_session *se,
const struct fuse_buf *buf, struct fuse_chan *ch);
/**
* Receive a raw request supplied in a generic buffer
*
* This is a more generic version of fuse_chan_recv(). The fuse_buf
* supplied to this function contains a suitably allocated memory
* buffer. This may be overwritten with a file descriptor buffer.
*
* @param se the session
* @param buf the fuse_buf to store the request in
* @param chp pointer to the channel
* @return the actual size of the raw request, or -errno on error
*/
int fuse_session_receive_buf(struct fuse_session *se, struct fuse_buf *buf,
struct fuse_chan **chp);
/**
* Destroy a session
*
* @param se the session
*/
void fuse_session_destroy(struct fuse_session *se);
/**
* Exit a session
*
* @param se the session
*/
void fuse_session_exit(struct fuse_session *se);
/**
* Reset the exited status of a session
*
* @param se the session
*/
void fuse_session_reset(struct fuse_session *se);
/**
* Query the exited status of a session
*
* @param se the session
* @return 1 if exited, 0 if not exited
*/
int fuse_session_exited(struct fuse_session *se);
/**
* Get the user data provided to the session
*
* @param se the session
* @return the user data
*/
void *fuse_session_data(struct fuse_session *se);
/**
* Enter a single threaded event loop
*
* @param se the session
* @return 0 on success, -1 on error
*/
int fuse_session_loop(struct fuse_session *se);
/**
* Enter a multi-threaded event loop
*
* @param se the session
* @return 0 on success, -1 on error
*/
int fuse_session_loop_mt(struct fuse_session *se, const int threads);
/* ----------------------------------------------------------- *
* Channel interface *
* ----------------------------------------------------------- */
/**
* Channel operations
*
* This is used in channel creation
*/
struct fuse_chan_ops
{
/**
* Hook for receiving a raw request
*
* @param ch pointer to the channel
* @param buf the buffer to store the request in
* @param size the size of the buffer
* @return the actual size of the raw request, or -1 on error
*/
int (*receive)(struct fuse_chan **chp, char *buf, size_t size);
/**
* Hook for sending a raw reply
*
* A return value of -ENOENT means, that the request was
* interrupted, and the reply was discarded
*
* @param ch the channel
* @param iov vector of blocks
* @param count the number of blocks in vector
* @return zero on success, -errno on failure
*/
int (*send)(struct fuse_chan *ch, const struct iovec iov[],
size_t count);
/**
* Destroy the channel
*
* @param ch the channel
*/
void (*destroy)(struct fuse_chan *ch);
};
/**
* Create a new channel
*
* @param op channel operations
* @param fd file descriptor of the channel
* @param bufsize the minimal receive buffer size
* @param data user data
* @return the new channel object, or NULL on failure
*/
struct fuse_chan *fuse_chan_new(struct fuse_chan_ops *op, int fd,
size_t bufsize, void *data);
/**
* Query the file descriptor of the channel
*
* @param ch the channel
* @return the file descriptor passed to fuse_chan_new()
*/
int fuse_chan_fd(struct fuse_chan *ch);
/**
* Query the minimal receive buffer size
*
* @param ch the channel
* @return the buffer size passed to fuse_chan_new()
*/
size_t fuse_chan_bufsize(struct fuse_chan *ch);
/**
* Query the user data
*
* @param ch the channel
* @return the user data passed to fuse_chan_new()
*/
void *fuse_chan_data(struct fuse_chan *ch);
/**
* Query the session to which this channel is assigned
*
* @param ch the channel
* @return the session, or NULL if the channel is not assigned
*/
struct fuse_session *fuse_chan_session(struct fuse_chan *ch);
/**
* Receive a raw request
*
* A return value of -ENODEV means, that the filesystem was unmounted
*
* @param ch pointer to the channel
* @param buf the buffer to store the request in
* @param size the size of the buffer
* @return the actual size of the raw request, or -errno on error
*/
int fuse_chan_recv(struct fuse_chan **ch, char *buf, size_t size);
/**
* Send a raw reply
*
* A return value of -ENOENT means, that the request was
* interrupted, and the reply was discarded
*
* @param ch the channel
* @param iov vector of blocks
* @param count the number of blocks in vector
* @return zero on success, -errno on failure
*/
int fuse_chan_send(struct fuse_chan *ch, const struct iovec iov[],
size_t count);
/**
* Destroy a channel
*
* @param ch the channel
*/
void fuse_chan_destroy(struct fuse_chan *ch);
#ifdef __cplusplus
}
#endif
#endif /* _FUSE_LOWLEVEL_H_ */