include/linux/namei.h

   1 #ifndef _LINUX_NAMEI_H
   2 #define _LINUX_NAMEI_H
   3
   4 #include <linux/dcache.h>
   5 #include <linux/linkage.h>
   6 #include <linux/path.h>
   7
   8 struct vfsmount;
   9
  10 enum { MAX_NESTED_LINKS = 8 };
  11
  12 struct nameidata {
  13         struct path     path;
  14         struct qstr     last;
  15         struct path     root;
  16         struct inode    *inode; /* path.dentry.d_inode */
  17         unsigned int    flags;
  18         unsigned        seq;
  19         int             last_type;
  20         unsigned        depth;
  21         char *saved_names[MAX_NESTED_LINKS + 1];
  22 };
  23
  24 /*
  25  * Type of the last component on LOOKUP_PARENT
  26  */
  27 enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
  28
  29 /*
  30  * The bitmask for a lookup event:
  31  *  - follow links at the end
  32  *  - require a directory
  33  *  - ending slashes ok even for nonexistent files
  34  *  - internal "there are more path components" flag
  35  *  - dentry cache is untrusted; force a real lookup
  36  *  - suppress terminal automount
  37  */
  38 #define LOOKUP_FOLLOW           0x0001
  39 #define LOOKUP_DIRECTORY        0x0002
  40 #define LOOKUP_AUTOMOUNT        0x0004
  41
  42 #define LOOKUP_PARENT           0x0010
  43 #define LOOKUP_REVAL            0x0020
  44 #define LOOKUP_RCU              0x0040
  45
  46 /*
  47  * Intent data
  48  */
  49 #define LOOKUP_OPEN             0x0100
  50 #define LOOKUP_CREATE           0x0200
  51 #define LOOKUP_EXCL             0x0400
  52 #define LOOKUP_RENAME_TARGET    0x0800
  53
  54 #define LOOKUP_JUMPED           0x1000
  55 #define LOOKUP_ROOT             0x2000
  56 #define LOOKUP_EMPTY            0x4000
  57
  58 extern int user_path_at(int, const char __user *, unsigned, struct path *);
  59 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  60
  61 #define user_path(name, path) user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW, path)
  62 #define user_lpath(name, path) user_path_at(AT_FDCWD, name, 0, path)
  63 #define user_path_dir(name, path) \
  64         user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path)
  65
  66 extern int kern_path(const char *, unsigned, struct path *);
  67
  68 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  69 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  70 extern void done_path_create(struct path *, struct dentry *);
  71 extern struct dentry *kern_path_locked(const char *, struct path *);
  72 extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
  73                            const char *, unsigned int, struct path *);
  74
  75 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  76
  77 extern int follow_down_one(struct path *);
  78 extern int follow_down(struct path *);
  79 extern int follow_up(struct path *);
  80
  81 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  82 extern void unlock_rename(struct dentry *, struct dentry *);
  83
  84 extern void nd_jump_link(struct nameidata *nd, struct path *path);
  85
  86 static inline void nd_set_link(struct nameidata *nd, char *path)
  87 {
  88         nd->saved_names[nd->depth] = path;
  89 }
  90
  91 static inline char *nd_get_link(struct nameidata *nd)
  92 {
  93         return nd->saved_names[nd->depth];
  94 }
  95
  96 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
  97 {
  98         ((char *) name)[min(len, maxlen)] = '\0';
  99 }
 100
 101 /**
 102  * retry_estale - determine whether the caller should retry an operation
 103  * @error: the error that would currently be returned
 104  * @flags: flags being used for next lookup attempt
 105  *
 106  * Check to see if the error code was -ESTALE, and then determine whether
 107  * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 108  *
 109  * Returns true if the caller should try the operation again.
 110  */
 111 static inline bool
 112 retry_estale(const long error, const unsigned int flags)
 113 {
 114         return error == -ESTALE && !(flags & LOOKUP_REVAL);
 115 }
 116
 117 #endif /* _LINUX_NAMEI_H */