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 *  - skip revalidation
  28 *  - don't fetch xattrs on audit_inode
  29 */
  30#define LOOKUP_FOLLOW           0x0001
  31#define LOOKUP_DIRECTORY        0x0002
  32#define LOOKUP_AUTOMOUNT        0x0004
  33
  34#define LOOKUP_PARENT           0x0010
  35#define LOOKUP_REVAL            0x0020
  36#define LOOKUP_RCU              0x0040
  37#define LOOKUP_NO_REVAL         0x0080
  38#define LOOKUP_NO_EVAL          0x0100
  39
  40/*
  41 * Intent data
  42 */
  43#define LOOKUP_OPEN             0x0100
  44#define LOOKUP_CREATE           0x0200
  45#define LOOKUP_EXCL             0x0400
  46#define LOOKUP_RENAME_TARGET    0x0800
  47
  48#define LOOKUP_JUMPED           0x1000
  49#define LOOKUP_ROOT             0x2000
  50#define LOOKUP_EMPTY            0x4000
  51#define LOOKUP_DOWN             0x8000
  52
  53extern int path_pts(struct path *path);
  54
  55extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  56
  57static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
  58                 struct path *path)
  59{
  60        return user_path_at_empty(dfd, name, flags, path, NULL);
  61}
  62
  63static inline int user_path(const char __user *name, struct path *path)
  64{
  65        return user_path_at_empty(AT_FDCWD, name, LOOKUP_FOLLOW, path, NULL);
  66}
  67
  68static inline int user_lpath(const char __user *name, struct path *path)
  69{
  70        return user_path_at_empty(AT_FDCWD, name, 0, path, NULL);
  71}
  72
  73static inline int user_path_dir(const char __user *name, struct path *path)
  74{
  75        return user_path_at_empty(AT_FDCWD, name,
  76                                  LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path, NULL);
  77}
  78
  79extern int kern_path(const char *, unsigned, struct path *);
  80
  81extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  82extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  83extern void done_path_create(struct path *, struct dentry *);
  84extern struct dentry *kern_path_locked(const char *, struct path *);
  85extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  86
  87extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
  88extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  89extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  90
  91extern int follow_down_one(struct path *);
  92extern int follow_down(struct path *);
  93extern int follow_up(struct path *);
  94
  95extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  96extern void unlock_rename(struct dentry *, struct dentry *);
  97
  98extern void nd_jump_link(struct path *path);
  99
 100static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
 101{
 102        ((char *) name)[min(len, maxlen)] = '\0';
 103}
 104
 105/**
 106 * retry_estale - determine whether the caller should retry an operation
 107 * @error: the error that would currently be returned
 108 * @flags: flags being used for next lookup attempt
 109 *
 110 * Check to see if the error code was -ESTALE, and then determine whether
 111 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 112 *
 113 * Returns true if the caller should try the operation again.
 114 */
 115static inline bool
 116retry_estale(const long error, const unsigned int flags)
 117{
 118        return error == -ESTALE && !(flags & LOOKUP_REVAL);
 119}
 120
 121#endif /* _LINUX_NAMEI_H */
 122