include/linux/namei.h

   1 #ifndef _LINUX_NAMEI_H
   2 #define _LINUX_NAMEI_H
   3
   4 #include <linux/kernel.h>
   5 #include <linux/path.h>
   6 #include <linux/fcntl.h>
   7 #include <linux/errno.h>
   8
   9 enum { MAX_NESTED_LINKS = 8 };
  10
  11 #define MAXSYMLINKS 40
  12
  13 /*
  14  * Type of the last component on LOOKUP_PARENT
  15  */
  16 enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
  17
  18 /*
  19  * The bitmask for a lookup event:
  20  *  - follow links at the end
  21  *  - require a directory
  22  *  - ending slashes ok even for nonexistent files
  23  *  - internal "there are more path components" flag
  24  *  - dentry cache is untrusted; force a real lookup
  25  *  - suppress terminal automount
  26  */
  27 #define LOOKUP_FOLLOW           0x0001
  28 #define LOOKUP_DIRECTORY        0x0002
  29 #define LOOKUP_AUTOMOUNT        0x0004
  30
  31 #define LOOKUP_PARENT           0x0010
  32 #define LOOKUP_REVAL            0x0020
  33 #define LOOKUP_RCU              0x0040
  34 #define LOOKUP_NO_REVAL         0x0080
  35
  36 /*
  37  * Intent data
  38  */
  39 #define LOOKUP_OPEN             0x0100
  40 #define LOOKUP_CREATE           0x0200
  41 #define LOOKUP_EXCL             0x0400
  42 #define LOOKUP_RENAME_TARGET    0x0800
  43
  44 #define LOOKUP_JUMPED           0x1000
  45 #define LOOKUP_ROOT             0x2000
  46 #define LOOKUP_EMPTY            0x4000
  47
  48 extern int path_pts(struct path *path);
  49
  50 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  51
  52 static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
  53                  struct path *path)
  54 {
  55         return user_path_at_empty(dfd, name, flags, path, NULL);
  56 }
  57
  58 static inline int user_path(const char __user *name, struct path *path)
  59 {
  60         return user_path_at_empty(AT_FDCWD, name, LOOKUP_FOLLOW, path, NULL);
  61 }
  62
  63 static inline int user_lpath(const char __user *name, struct path *path)
  64 {
  65         return user_path_at_empty(AT_FDCWD, name, 0, path, NULL);
  66 }
  67
  68 static inline int user_path_dir(const char __user *name, struct path *path)
  69 {
  70         return user_path_at_empty(AT_FDCWD, name,
  71                                   LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path, NULL);
  72 }
  73
  74 extern int kern_path(const char *, unsigned, struct path *);
  75
  76 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  77 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  78 extern void done_path_create(struct path *, struct dentry *);
  79 extern struct dentry *kern_path_locked(const char *, struct path *);
  80 extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  81
  82 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  83 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  84
  85 extern int follow_down_one(struct path *);
  86 extern int follow_down(struct path *);
  87 extern int follow_up(struct path *);
  88
  89 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  90 extern void unlock_rename(struct dentry *, struct dentry *);
  91
  92 extern void nd_jump_link(struct path *path);
  93
  94 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  95 {
  96         ((char *) name)[min(len, maxlen)] = '\0';
  97 }
  98
  99 /**
 100  * retry_estale - determine whether the caller should retry an operation
 101  * @error: the error that would currently be returned
 102  * @flags: flags being used for next lookup attempt
 103  *
 104  * Check to see if the error code was -ESTALE, and then determine whether
 105  * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 106  *
 107  * Returns true if the caller should try the operation again.
 108  */
 109 static inline bool
 110 retry_estale(const long error, const unsigned int flags)
 111 {
 112         return error == -ESTALE && !(flags & LOOKUP_REVAL);
 113 }
 114
 115 #endif /* _LINUX_NAMEI_H */