LXR linux/include/linux/namei.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_NAMEI_H
   3#define _LINUX_NAMEI_H
   4
   5#include <linux/kernel.h>
   6#include <linux/path.h>
   7#include <linux/fcntl.h>
   8#include <linux/errno.h>
   9
  10enum { MAX_NESTED_LINKS = 8 };
  11
  12#define MAXSYMLINKS 40
  13
  14/*
  15 * Type of the last component on LOOKUP_PARENT
  16 */
  17enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
  18
  19/* pathwalk mode */
  20#define LOOKUP_FOLLOW           0x0001  /* follow links at the end */
  21#define LOOKUP_DIRECTORY        0x0002  /* require a directory */
  22#define LOOKUP_AUTOMOUNT        0x0004  /* force terminal automount */
  23#define LOOKUP_EMPTY            0x4000  /* accept empty path [user_... only] */
  24#define LOOKUP_DOWN             0x8000  /* follow mounts in the starting point */
  25
  26#define LOOKUP_REVAL            0x0020  /* tell ->d_revalidate() to trust no cache */
  27#define LOOKUP_RCU              0x0040  /* RCU pathwalk mode; semi-internal */
  28
  29/* These tell filesystem methods that we are dealing with the final component... */
  30#define LOOKUP_OPEN             0x0100  /* ... in open */
  31#define LOOKUP_CREATE           0x0200  /* ... in object creation */
  32#define LOOKUP_EXCL             0x0400  /* ... in exclusive creation */
  33#define LOOKUP_RENAME_TARGET    0x0800  /* ... in destination of rename() */
  34
  35/* internal use only */
  36#define LOOKUP_PARENT           0x0010
  37#define LOOKUP_NO_REVAL         0x0080
  38#define LOOKUP_JUMPED           0x1000
  39#define LOOKUP_ROOT             0x2000
  40#define LOOKUP_ROOT_GRABBED     0x0008
  41
  42extern int path_pts(struct path *path);
  43
  44extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  45
  46static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
  47                 struct path *path)
  48{
  49        return user_path_at_empty(dfd, name, flags, path, NULL);
  50}
  51
  52extern int kern_path(const char *, unsigned, struct path *);
  53
  54extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  55extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  56extern void done_path_create(struct path *, struct dentry *);
  57extern struct dentry *kern_path_locked(const char *, struct path *);
  58extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  59
  60extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
  61extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  62extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  63extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
  64
  65extern int follow_down_one(struct path *);
  66extern int follow_down(struct path *);
  67extern int follow_up(struct path *);
  68
  69extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  70extern void unlock_rename(struct dentry *, struct dentry *);
  71
  72extern void nd_jump_link(struct path *path);
  73
  74static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  75{
  76        ((char *) name)[min(len, maxlen)] = '\0';
  77}
  78
  79/**
  80 * retry_estale - determine whether the caller should retry an operation
  81 * @error: the error that would currently be returned
  82 * @flags: flags being used for next lookup attempt
  83 *
  84 * Check to see if the error code was -ESTALE, and then determine whether
  85 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
  86 *
  87 * Returns true if the caller should try the operation again.
  88 */
  89static inline bool
  90retry_estale(const long error, const unsigned int flags)
  91{
  92        return error == -ESTALE && !(flags & LOOKUP_REVAL);
  93}
  94
  95#endif /* _LINUX_NAMEI_H */
  96