/* 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 <utime.h> #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/statvfs.h> #include <sys/uio.h> #ifdef __cplusplus extern "C" { #endif /* ----------------------------------------------------------- * * Miscellaneous definitions * * ----------------------------------------------------------- */ /** The node ID of the root inode */ #define FUSE_ROOT_ID 1 /** Inode number type */ typedef unsigned long 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. * */ unsigned long 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; /** Validity timeout (in seconds) for the attributes */ double attr_timeout; /** Validity timeout (in seconds) for the name */ double entry_timeout; }; /** * Additional context associated with requests. * * Note that the reported client uid, gid and pid may be zero in some * situations. For example, if the FUSE file system is running in a * PID or user namespace but then accessed from outside the namespace, * there is no valid uid/pid/gid that could be reported. */ 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 { uint64_t ino; uint64_t nlookup; }; /* 'to_set' flags in setattr */ #define FUSE_SET_ATTR_MODE (1 << 0) #define FUSE_SET_ATTR_UID (1 << 1) #define FUSE_SET_ATTR_GID (1 << 2) #define FUSE_SET_ATTR_SIZE (1 << 3) #define FUSE_SET_ATTR_ATIME (1 << 4) #define FUSE_SET_ATTR_MTIME (1 << 5) #define FUSE_SET_ATTR_ATIME_NOW (1 << 7) #define FUSE_SET_ATTR_MTIME_NOW (1 << 8) /* ----------------------------------------------------------- * * 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, unsigned long 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 *fi); /** * 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, int cmd, void *arg, struct fuse_file_info *fi, unsigned flags, const void *in_buf, size_t in_bufsz, size_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); }; /** * 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, double attr_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); /* ----------------------------------------------------------- * * Filling a buffer in readdir * * ----------------------------------------------------------- */ /** * Add a directory entry to the buffer * * Buffer needs to be large enough to hold the entry. If 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. * * @param req request handle * @param buf the point where the new entry will be added to the buffer * @param bufsize remaining size of the buffer * @param name the name of the entry * @param stbuf the file attributes * @param off the offset of the next entry * @return the space needed for the entry */ size_t fuse_add_direntry(fuse_req_t req, char *buf, size_t bufsize, const char *name, const struct stat *stbuf, off_t off); /** * 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, size_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); /* ----------------------------------------------------------- * * 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); /* ----------------------------------------------------------- * * Compatibility stuff * * ----------------------------------------------------------- */ #if FUSE_USE_VERSION < 26 # include "fuse_lowlevel_compat.h" # define fuse_chan_ops fuse_chan_ops_compat24 # define fuse_chan_new fuse_chan_new_compat24 # if FUSE_USE_VERSION == 25 # define fuse_lowlevel_ops fuse_lowlevel_ops_compat25 # define fuse_lowlevel_new fuse_lowlevel_new_compat25 # elif FUSE_USE_VERSION == 24 # define fuse_lowlevel_ops fuse_lowlevel_ops_compat # define fuse_lowlevel_new fuse_lowlevel_new_compat # define fuse_file_info fuse_file_info_compat # define fuse_reply_statfs fuse_reply_statfs_compat # define fuse_reply_open fuse_reply_open_compat # else # error Compatibility with low-level API version < 24 not supported # endif #endif #ifdef __cplusplus } #endif #endif /* _FUSE_LOWLEVEL_H_ */
