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/*
  20 * The bitmask for a lookup event:
  21 *  - follow links at the end
  22 *  - require a directory
  23 *  - ending slashes ok even for nonexistent files
  24 *  - internal "there are more path components" flag
  25 *  - dentry cache is untrusted; force a real lookup
  26 *  - suppress terminal automount
  27 */
  28#define LOOKUP_FOLLOW           0x0001
  29#define LOOKUP_DIRECTORY        0x0002
  30#define LOOKUP_AUTOMOUNT        0x0004
  31
  32#define LOOKUP_PARENT           0x0010
  33#define LOOKUP_REVAL            0x0020
  34#define LOOKUP_RCU              0x0040
  35#define LOOKUP_NO_REVAL         0x0080
  36
  37/*
  38 * Intent data
  39 */
  40#define LOOKUP_OPEN             0x0100
  41#define LOOKUP_CREATE           0x0200
  42#define LOOKUP_EXCL             0x0400
  43#define LOOKUP_RENAME_TARGET    0x0800
  44
  45#define LOOKUP_JUMPED           0x1000
  46#define LOOKUP_ROOT             0x2000
  47#define LOOKUP_EMPTY            0x4000
  48#define LOOKUP_DOWN             0x8000
  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
  60static inline int user_path(const char __user *name, struct path *path)
  61{
  62        return user_path_at_empty(AT_FDCWD, name, LOOKUP_FOLLOW, path, NULL);
  63}
  64
  65static inline int user_lpath(const char __user *name, struct path *path)
  66{
  67        return user_path_at_empty(AT_FDCWD, name, 0, path, NULL);
  68}
  69
  70static inline int user_path_dir(const char __user *name, struct path *path)
  71{
  72        return user_path_at_empty(AT_FDCWD, name,
  73                                  LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path, NULL);
  74}
  75
  76extern int kern_path(const char *, unsigned, struct path *);
  77
  78extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  79extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  80extern void done_path_create(struct path *, struct dentry *);
  81extern struct dentry *kern_path_locked(const char *, struct path *);
  82extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  83
  84extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  85extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  86
  87extern int follow_down_one(struct path *);
  88extern int follow_down(struct path *);
  89extern int follow_up(struct path *);
  90
  91extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  92extern void unlock_rename(struct dentry *, struct dentry *);
  93
  94extern void nd_jump_link(struct path *path);
  95
  96static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  97{
  98        ((char *) name)[min(len, maxlen)] = '\0';
  99}
 100
 101/**
 102 * retry_estale - determine whether the caller should retry an operation
 103 * @error: the error that would currently be returned
 104 * @flags: flags being used for next lookup attempt
 105 *
 106 * Check to see if the error code was -ESTALE, and then determine whether
 107 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 108 *
 109 * Returns true if the caller should try the operation again.
 110 */
 111static inline bool
 112retry_estale(const long error, const unsigned int flags)
 113{
 114        return error == -ESTALE && !(flags & LOOKUP_REVAL);
 115}
 116
 117#endif /* _LINUX_NAMEI_H */
 118