root/include/linux/namei.h

INCLUDED FROM

DEFINITIONS

1. user_path_at
2. nd_terminate_link
3. retry_estale

   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 
  10 enum { MAX_NESTED_LINKS = 8 };
  11 
  12 #define MAXSYMLINKS 40
  13 
  14 /*
  15  * Type of the last component on LOOKUP_PARENT
  16  */
  17 enum {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 
  42 extern int path_pts(struct path *path);
  43 
  44 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  45 
  46 static 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 
  52 extern int kern_path(const char *, unsigned, struct path *);
  53 
  54 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  55 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  56 extern void done_path_create(struct path *, struct dentry *);
  57 extern struct dentry *kern_path_locked(const char *, struct path *);
  58 extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  59 
  60 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
  61 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  62 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  63 
  64 extern int follow_down_one(struct path *);
  65 extern int follow_down(struct path *);
  66 extern int follow_up(struct path *);
  67 
  68 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  69 extern void unlock_rename(struct dentry *, struct dentry *);
  70 
  71 extern void nd_jump_link(struct path *path);
  72 
  73 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  74 {
  75         ((char *) name)[min(len, maxlen)] = '\0';
  76 }
  77 
  78 /**
  79  * retry_estale - determine whether the caller should retry an operation
  80  * @error: the error that would currently be returned
  81  * @flags: flags being used for next lookup attempt
  82  *
  83  * Check to see if the error code was -ESTALE, and then determine whether
  84  * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
  85  *
  86  * Returns true if the caller should try the operation again.
  87  */
  88 static inline bool
  89 retry_estale(const long error, const unsigned int flags)
  90 {
  91         return error == -ESTALE && !(flags & LOOKUP_REVAL);
  92 }
  93 
  94 #endif /* _LINUX_NAMEI_H */