namei.h 3.31 KB
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#ifndef _LINUX_NAMEI_H
#define _LINUX_NAMEI_H

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#include <linux/kernel.h>
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#include <linux/path.h>
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#include <linux/fcntl.h>
#include <linux/errno.h>
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enum { MAX_NESTED_LINKS = 8 };
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#define MAXSYMLINKS 40

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/*
 * Type of the last component on LOOKUP_PARENT
 */
enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};

/*
 * The bitmask for a lookup event:
 *  - follow links at the end
 *  - require a directory
 *  - ending slashes ok even for nonexistent files
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 *  - internal "there are more path components" flag
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 *  - dentry cache is untrusted; force a real lookup
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 *  - suppress terminal automount
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 */
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#define LOOKUP_FOLLOW		0x0001
#define LOOKUP_DIRECTORY	0x0002
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#define LOOKUP_AUTOMOUNT	0x0004
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#define LOOKUP_PARENT		0x0010
#define LOOKUP_REVAL		0x0020
#define LOOKUP_RCU		0x0040
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#define LOOKUP_NO_REVAL		0x0080
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/*
 * Intent data
 */
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#define LOOKUP_OPEN		0x0100
#define LOOKUP_CREATE		0x0200
#define LOOKUP_EXCL		0x0400
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#define LOOKUP_RENAME_TARGET	0x0800
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#define LOOKUP_JUMPED		0x1000
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#define LOOKUP_ROOT		0x2000
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#define LOOKUP_EMPTY		0x4000
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extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
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static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
		 struct path *path)
{
	return user_path_at_empty(dfd, name, flags, path, NULL);
}

static inline int user_path(const char __user *name, struct path *path)
{
	return user_path_at_empty(AT_FDCWD, name, LOOKUP_FOLLOW, path, NULL);
}

static inline int user_lpath(const char __user *name, struct path *path)
{
	return user_path_at_empty(AT_FDCWD, name, 0, path, NULL);
}

static inline int user_path_dir(const char __user *name, struct path *path)
{
	return user_path_at_empty(AT_FDCWD, name,
				  LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path, NULL);
}
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extern int kern_path(const char *, unsigned, struct path *);

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extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
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extern void done_path_create(struct path *, struct dentry *);
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extern struct dentry *kern_path_locked(const char *, struct path *);
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extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
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extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
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extern int follow_down_one(struct path *);
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extern int follow_down(struct path *);
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extern int follow_up(struct path *);
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extern struct dentry *lock_rename(struct dentry *, struct dentry *);
extern void unlock_rename(struct dentry *, struct dentry *);

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extern void nd_jump_link(struct path *path);
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static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
{
	((char *) name)[min(len, maxlen)] = '\0';
}

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/**
 * retry_estale - determine whether the caller should retry an operation
 * @error: the error that would currently be returned
 * @flags: flags being used for next lookup attempt
 *
 * Check to see if the error code was -ESTALE, and then determine whether
 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 *
 * Returns true if the caller should try the operation again.
 */
static inline bool
retry_estale(const long error, const unsigned int flags)
{
	return error == -ESTALE && !(flags & LOOKUP_REVAL);
}

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#endif /* _LINUX_NAMEI_H */