include/linux/inotify.h

/*
 * Inode based directory notification for Linux
 *
 * Copyright (C) 2005 John McCutchan
 */

#ifndef _LINUX_INOTIFY_H
#define _LINUX_INOTIFY_H

#include <linux/types.h>

/*
 * struct inotify_event - structure read from the inotify device for each event
 *
 * When you are watching a directory, you will receive the filename for events
 * such as IN_CREATE, IN_DELETE, IN_OPEN, IN_CLOSE, ..., relative to the wd.
 */
struct inotify_event {
	__s32		wd;		/* watch descriptor */
	__u32		mask;		/* watch mask */
	__u32		cookie;		/* cookie to synchronize two events */
	__u32		len;		/* length (including nulls) of name */
	char		name[0];	/* stub for possible name */
};

/* the following are legal, implemented events that user-space can watch for */
#define IN_ACCESS		0x00000001	/* File was accessed */
#define IN_MODIFY		0x00000002	/* File was modified */
#define IN_ATTRIB		0x00000004	/* Metadata changed */
#define IN_CLOSE_WRITE		0x00000008	/* Writtable file was closed */
#define IN_CLOSE_NOWRITE	0x00000010	/* Unwrittable file closed */
#define IN_OPEN			0x00000020	/* File was opened */
#define IN_MOVED_FROM		0x00000040	/* File was moved from X */
#define IN_MOVED_TO		0x00000080	/* File was moved to Y */
#define IN_CREATE		0x00000100	/* Subfile was created */
#define IN_DELETE		0x00000200	/* Subfile was deleted */
#define IN_DELETE_SELF		0x00000400	/* Self was deleted */
#define IN_MOVE_SELF		0x00000800	/* Self was moved */

/* the following are legal events.  they are sent as needed to any watch */
#define IN_UNMOUNT		0x00002000	/* Backing fs was unmounted */
#define IN_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
#define IN_IGNORED		0x00008000	/* File was ignored */

/* helper events */
#define IN_CLOSE		(IN_CLOSE_WRITE | IN_CLOSE_NOWRITE) /* close */
#define IN_MOVE			(IN_MOVED_FROM | IN_MOVED_TO) /* moves */

/* special flags */
#define IN_ONLYDIR		0x01000000	/* only watch the path if it is a directory */
#define IN_DONT_FOLLOW		0x02000000	/* don't follow a sym link */
#define IN_MASK_ADD		0x20000000	/* add to the mask of an already existing watch */
#define IN_ISDIR		0x40000000	/* event occurred against dir */
#define IN_ONESHOT		0x80000000	/* only send event once */

/*
 * All of the events - we build the list by hand so that we can add flags in
 * the future and not break backward compatibility.  Apps will get only the
 * events that they originally wanted.  Be sure to add new events here!
 */
#define IN_ALL_EVENTS	(IN_ACCESS | IN_MODIFY | IN_ATTRIB | IN_CLOSE_WRITE | \
			 IN_CLOSE_NOWRITE | IN_OPEN | IN_MOVED_FROM | \
			 IN_MOVED_TO | IN_DELETE | IN_CREATE | IN_DELETE_SELF | \
			 IN_MOVE_SELF)

#ifdef __KERNEL__

#include <linux/dcache.h>
#include <linux/fs.h>

/*
 * struct inotify_watch - represents a watch request on a specific inode
 *
 * h_list is protected by ih->mutex of the associated inotify_handle.
 * i_list, mask are protected by inode->inotify_mutex of the associated inode.
 * ih, inode, and wd are never written to once the watch is created.
 *
 * Callers must use the established inotify interfaces to access inotify_watch
 * contents.  The content of this structure is private to the inotify
 * implementation.
 */
struct inotify_watch {
	struct list_head	h_list;	/* entry in inotify_handle's list */
	struct list_head	i_list;	/* entry in inode's list */
	atomic_t		count;	/* reference count */
	struct inotify_handle	*ih;	/* associated inotify handle */
	struct inode		*inode;	/* associated inode */
	__s32			wd;	/* watch descriptor */
	__u32			mask;	/* event mask for this watch */
};

struct inotify_operations {
	void (*handle_event)(struct inotify_watch *, u32, u32, u32,
			     const char *, struct inode *);
	void (*destroy_watch)(struct inotify_watch *);
};

#ifdef CONFIG_INOTIFY

/* Kernel API for producing events */

extern void inotify_d_instantiate(struct dentry *, struct inode *);
extern void inotify_d_move(struct dentry *);
extern void inotify_inode_queue_event(struct inode *, __u32, __u32,
				      const char *, struct inode *);
extern void inotify_dentry_parent_queue_event(struct dentry *, __u32, __u32,
					      const char *);
extern void inotify_unmount_inodes(struct list_head *);
extern void inotify_inode_is_dead(struct inode *);
extern u32 inotify_get_cookie(void);

/* Kernel Consumer API */

extern struct inotify_handle *inotify_init(const struct inotify_operations *);
extern void inotify_init_watch(struct inotify_watch *);
extern void inotify_destroy(struct inotify_handle *);
extern __s32 inotify_find_watch(struct inotify_handle *, struct inode *,
				struct inotify_watch **);
extern __s32 inotify_find_update_watch(struct inotify_handle *, struct inode *,
				       u32);
extern __s32 inotify_add_watch(struct inotify_handle *, struct inotify_watch *,
			       struct inode *, __u32);
extern int inotify_rm_watch(struct inotify_handle *, struct inotify_watch *);
extern int inotify_rm_wd(struct inotify_handle *, __u32);
extern void inotify_remove_watch_locked(struct inotify_handle *,
					struct inotify_watch *);
extern void get_inotify_watch(struct inotify_watch *);
extern void put_inotify_watch(struct inotify_watch *);

#else

static inline void inotify_d_instantiate(struct dentry *dentry,
					struct inode *inode)
{
}

static inline void inotify_d_move(struct dentry *dentry)
{
}

static inline void inotify_inode_queue_event(struct inode *inode,
					     __u32 mask, __u32 cookie,
					     const char *filename,
					     struct inode *n_inode)
{
}

static inline void inotify_dentry_parent_queue_event(struct dentry *dentry,
						     __u32 mask, __u32 cookie,
						     const char *filename)
{
}

static inline void inotify_unmount_inodes(struct list_head *list)
{
}

static inline void inotify_inode_is_dead(struct inode *inode)
{
}

static inline u32 inotify_get_cookie(void)
{
	return 0;
}

static inline struct inotify_handle *inotify_init(const struct inotify_operations *ops)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline void inotify_init_watch(struct inotify_watch *watch)
{
}

static inline void inotify_destroy(struct inotify_handle *ih)
{
}

static inline __s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode,
				       struct inotify_watch **watchp)
{
	return -EOPNOTSUPP;
}

static inline __s32 inotify_find_update_watch(struct inotify_handle *ih,
					      struct inode *inode, u32 mask)
{
	return -EOPNOTSUPP;
}

static inline __s32 inotify_add_watch(struct inotify_handle *ih,
				      struct inotify_watch *watch,
				      struct inode *inode, __u32 mask)
{
	return -EOPNOTSUPP;
}

static inline int inotify_rm_watch(struct inotify_handle *ih,
				   struct inotify_watch *watch)
{
	return -EOPNOTSUPP;
}

static inline int inotify_rm_wd(struct inotify_handle *ih, __u32 wd)
{
	return -EOPNOTSUPP;
}

static inline void inotify_remove_watch_locked(struct inotify_handle *ih,
					       struct inotify_watch *watch)
{
}

static inline void get_inotify_watch(struct inotify_watch *watch)
{
}

static inline void put_inotify_watch(struct inotify_watch *watch)
{
}

#endif	/* CONFIG_INOTIFY */

#endif	/* __KERNEL __ */

#endif	/* _LINUX_INOTIFY_H */