1 files changed, 1577 insertions, 0 deletions

diff --git a/fuse/include/fuse_lowlevel.h b/fuse/include/fuse_lowlevel.h
new file mode 100644
index 000000000..f1cfeb954
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+++ b/fuse/include/fuse_lowlevel.h
@@ -0,0 +1,1577 @@
+/*
+  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.
+	 *
+	 * The ino/generation pair should be unique for the filesystem's
+	 * lifetime. It 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 */
+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;
+};
+
+/* '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
+	 *
+	 * The nlookup parameter indicates the number of lookups
+	 * previously performed on this inode.
+	 *
+	 * If the filesystem implements inode lifetimes, it is recommended
+	 * that inodes acquire a single reference on each lookup, and lose
+	 * nlookup references on each forget.
+	 *
+	 * The filesystem may ignore forget calls, if the inodes don't
+	 * need to have a limited lifetime.
+	 *
+	 * On unmount it is not guaranteed, that all referenced inodes
+	 * will receive a forget message.
+	 *
+	 * 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
+	 *
+	 * 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
+	 *
+	 * 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
+	 *
+	 * 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_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, off64_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, off64_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_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, off64_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_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_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 test
+	 * @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);
+};
+
+/**
+ * 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
+ *
+ * @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
+ *
+ * @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 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, 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,
+			 off64_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,
+                                     off64_t off, off64_t len);
+
+/**
+ * Notify to invalidate parent attributes and the dentry matching
+ * parent/name
+ *
+ * @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);
+
+/* ----------------------------------------------------------- *
+ * 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);
+
+/**
+ * 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_ */