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/fs.h>
   6#include <linux/kernel.h>
   7#include <linux/path.h>
   8#include <linux/fcntl.h>
   9#include <linux/errno.h>
  10
  11enum { MAX_NESTED_LINKS = 8 };
  12
  13#define MAXSYMLINKS 40
  14
  15/*
  16 * Type of the last component on LOOKUP_PARENT
  17 */
  18enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
  19
  20/* pathwalk mode */
  21#define LOOKUP_FOLLOW           0x0001  /* follow links at the end */
  22#define LOOKUP_DIRECTORY        0x0002  /* require a directory */
  23#define LOOKUP_AUTOMOUNT        0x0004  /* force terminal automount */
  24#define LOOKUP_EMPTY            0x4000  /* accept empty path [user_... only] */
  25#define LOOKUP_DOWN             0x8000  /* follow mounts in the starting point */
  26#define LOOKUP_MOUNTPOINT       0x0080  /* follow mounts in the end */
  27
  28#define LOOKUP_REVAL            0x0020  /* tell ->d_revalidate() to trust no cache */
  29#define LOOKUP_RCU              0x0040  /* RCU pathwalk mode; semi-internal */
  30
  31/* These tell filesystem methods that we are dealing with the final component... */
  32#define LOOKUP_OPEN             0x0100  /* ... in open */
  33#define LOOKUP_CREATE           0x0200  /* ... in object creation */
  34#define LOOKUP_EXCL             0x0400  /* ... in exclusive creation */
  35#define LOOKUP_RENAME_TARGET    0x0800  /* ... in destination of rename() */
  36
  37/* internal use only */
  38#define LOOKUP_PARENT           0x0010
  39
  40/* Scoping flags for lookup. */
  41#define LOOKUP_NO_SYMLINKS      0x010000 /* No symlink crossing. */
  42#define LOOKUP_NO_MAGICLINKS    0x020000 /* No nd_jump_link() crossing. */
  43#define LOOKUP_NO_XDEV          0x040000 /* No mountpoint crossing. */
  44#define LOOKUP_BENEATH          0x080000 /* No escaping from starting point. */
  45#define LOOKUP_IN_ROOT          0x100000 /* Treat dirfd as fs root. */
  46#define LOOKUP_CACHED           0x200000 /* Only do cached lookup */
  47/* LOOKUP_* flags which do scope-related checks based on the dirfd. */
  48#define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
  49
  50extern int path_pts(struct path *path);
  51
  52extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  53
  54static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
  55                 struct path *path)
  56{
  57        return user_path_at_empty(dfd, name, flags, path, NULL);
  58}
  59
  60extern int kern_path(const char *, unsigned, struct path *);
  61
  62extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  63extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  64extern void done_path_create(struct path *, struct dentry *);
  65extern struct dentry *kern_path_locked(const char *, struct path *);
  66
  67extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
  68extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  69extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  70extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
  71struct dentry *lookup_one(struct user_namespace *, const char *, struct dentry *, int);
  72struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns,
  73                                   const char *name, struct dentry *base,
  74                                   int len);
  75struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
  76                                            const char *name,
  77                                            struct dentry *base, int len);
  78
  79extern int follow_down_one(struct path *);
  80extern int follow_down(struct path *);
  81extern int follow_up(struct path *);
  82
  83extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  84extern void unlock_rename(struct dentry *, struct dentry *);
  85
  86extern int __must_check nd_jump_link(struct path *path);
  87
  88static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  89{
  90        ((char *) name)[min(len, maxlen)] = '\0';
  91}
  92
  93/**
  94 * retry_estale - determine whether the caller should retry an operation
  95 * @error: the error that would currently be returned
  96 * @flags: flags being used for next lookup attempt
  97 *
  98 * Check to see if the error code was -ESTALE, and then determine whether
  99 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 100 *
 101 * Returns true if the caller should try the operation again.
 102 */
 103static inline bool
 104retry_estale(const long error, const unsigned int flags)
 105{
 106        return error == -ESTALE && !(flags & LOOKUP_REVAL);
 107}
 108
 109#endif /* _LINUX_NAMEI_H */
 110