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
  11 enum { MAX_NESTED_LINKS = 8 };
  12
  13 #define MAXSYMLINKS 40
  14
  15 /*
  16  * Type of the last component on LOOKUP_PARENT
  17  */
  18 enum {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
  50 extern int path_pts(struct path *path);
  51
  52 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  53
  54 static 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
  60 extern int kern_path(const char *, unsigned, struct path *);
  61
  62 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  63 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  64 extern void done_path_create(struct path *, struct dentry *);
  65 extern struct dentry *kern_path_locked(const char *, struct path *);
  66
  67 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
  68 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  69 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  70 extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
  71
  72 extern int follow_down_one(struct path *);
  73 extern int follow_down(struct path *);
  74 extern int follow_up(struct path *);
  75
  76 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  77 extern void unlock_rename(struct dentry *, struct dentry *);
  78
  79 extern int __must_check nd_jump_link(struct path *path);
  80
  81 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  82 {
  83         ((char *) name)[min(len, maxlen)] = '\0';
  84 }
  85
  86 /**
  87  * retry_estale - determine whether the caller should retry an operation
  88  * @error: the error that would currently be returned
  89  * @flags: flags being used for next lookup attempt
  90  *
  91  * Check to see if the error code was -ESTALE, and then determine whether
  92  * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
  93  *
  94  * Returns true if the caller should try the operation again.
  95  */
  96 static inline bool
  97 retry_estale(const long error, const unsigned int flags)
  98 {
  99         return error == -ESTALE && !(flags & LOOKUP_REVAL);
 100 }
 101
 102 #endif /* _LINUX_NAMEI_H */