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
  35 /*
  36  * Intent data
  37  */
  38 #define LOOKUP_OPEN             0x0100
  39 #define LOOKUP_CREATE           0x0200
  40 #define LOOKUP_EXCL             0x0400
  41 #define LOOKUP_RENAME_TARGET    0x0800
  42
  43 #define LOOKUP_JUMPED           0x1000
  44 #define LOOKUP_ROOT             0x2000
  45 #define LOOKUP_EMPTY            0x4000
  46
  47 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  48
  49 static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
  50                  struct path *path)
  51 {
  52         return user_path_at_empty(dfd, name, flags, path, NULL);
  53 }
  54
  55 static inline int user_path(const char __user *name, struct path *path)
  56 {
  57         return user_path_at_empty(AT_FDCWD, name, LOOKUP_FOLLOW, path, NULL);
  58 }
  59
  60 static inline int user_lpath(const char __user *name, struct path *path)
  61 {
  62         return user_path_at_empty(AT_FDCWD, name, 0, path, NULL);
  63 }
  64
  65 static inline int user_path_dir(const char __user *name, struct path *path)
  66 {
  67         return user_path_at_empty(AT_FDCWD, name,
  68                                   LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path, NULL);
  69 }
  70
  71 extern int kern_path(const char *, unsigned, struct path *);
  72
  73 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  74 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  75 extern void done_path_create(struct path *, struct dentry *);
  76 extern struct dentry *kern_path_locked(const char *, struct path *);
  77 extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  78
  79 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  80
  81 extern int follow_down_one(struct path *);
  82 extern int follow_down(struct path *);
  83 extern int follow_up(struct path *);
  84
  85 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  86 extern void unlock_rename(struct dentry *, struct dentry *);
  87
  88 extern void nd_jump_link(struct path *path);
  89
  90 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  91 {
  92         ((char *) name)[min(len, maxlen)] = '\0';
  93 }
  94
  95 /**
  96  * retry_estale - determine whether the caller should retry an operation
  97  * @error: the error that would currently be returned
  98  * @flags: flags being used for next lookup attempt
  99  *
 100  * Check to see if the error code was -ESTALE, and then determine whether
 101  * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 102  *
 103  * Returns true if the caller should try the operation again.
 104  */
 105 static inline bool
 106 retry_estale(const long error, const unsigned int flags)
 107 {
 108         return error == -ESTALE && !(flags & LOOKUP_REVAL);
 109 }
 110
 111 #endif /* _LINUX_NAMEI_H */