xref: /original-bsd/sys/sys/namei.h (revision f43778ea)
1 /*
2  * Copyright (c) 1985, 1989, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * %sccs.include.redist.c%
6  *
7  *	@(#)namei.h	8.5 (Berkeley) 01/09/95
8  */
9 
10 #ifndef _SYS_NAMEI_H_
11 #define	_SYS_NAMEI_H_
12 
13 #include <sys/queue.h>
14 
15 /*
16  * Encapsulation of namei parameters.
17  */
18 struct nameidata {
19 	/*
20 	 * Arguments to namei/lookup.
21 	 */
22 	caddr_t	ni_dirp;		/* pathname pointer */
23 	enum	uio_seg ni_segflg;	/* location of pathname */
24      /* u_long	ni_nameiop;		   namei operation */
25      /* u_long	ni_flags;		   flags to namei */
26      /* struct	proc *ni_proc;		   process requesting lookup */
27 	/*
28 	 * Arguments to lookup.
29 	 */
30      /* struct	ucred *ni_cred;		   credentials */
31 	struct	vnode *ni_startdir;	/* starting directory */
32 	struct	vnode *ni_rootdir;	/* logical root directory */
33 	/*
34 	 * Results: returned from/manipulated by lookup
35 	 */
36 	struct	vnode *ni_vp;		/* vnode of result */
37 	struct	vnode *ni_dvp;		/* vnode of intermediate directory */
38 	/*
39 	 * Shared between namei and lookup/commit routines.
40 	 */
41 	long	ni_pathlen;		/* remaining chars in path */
42 	char	*ni_next;		/* next location in pathname */
43 	u_long	ni_loopcnt;		/* count of symlinks encountered */
44 	/*
45 	 * Lookup parameters: this structure describes the subset of
46 	 * information from the nameidata structure that is passed
47 	 * through the VOP interface.
48 	 */
49 	struct componentname {
50 		/*
51 		 * Arguments to lookup.
52 		 */
53 		u_long	cn_nameiop;	/* namei operation */
54 		u_long	cn_flags;	/* flags to namei */
55 		struct	proc *cn_proc;	/* process requesting lookup */
56 		struct	ucred *cn_cred;	/* credentials */
57 		/*
58 		 * Shared between lookup and commit routines.
59 		 */
60 		char	*cn_pnbuf;	/* pathname buffer */
61 		char	*cn_nameptr;	/* pointer to looked up name */
62 		long	cn_namelen;	/* length of looked up component */
63 		u_long	cn_hash;	/* hash value of looked up name */
64 		long	cn_consume;	/* chars to consume in lookup() */
65 	} ni_cnd;
66 };
67 
68 #ifdef KERNEL
69 /*
70  * namei operations
71  */
72 #define	LOOKUP		0	/* perform name lookup only */
73 #define	CREATE		1	/* setup for file creation */
74 #define	DELETE		2	/* setup for file deletion */
75 #define	RENAME		3	/* setup for file renaming */
76 #define	OPMASK		3	/* mask for operation */
77 /*
78  * namei operational modifier flags, stored in ni_cnd.flags
79  */
80 #define	LOCKLEAF	0x0004	/* lock inode on return */
81 #define	LOCKPARENT	0x0008	/* want parent vnode returned locked */
82 #define	WANTPARENT	0x0010	/* want parent vnode returned unlocked */
83 #define	NOCACHE		0x0020	/* name must not be left in cache */
84 #define	FOLLOW		0x0040	/* follow symbolic links */
85 #define	NOFOLLOW	0x0000	/* do not follow symbolic links (pseudo) */
86 #define	MODMASK		0x00fc	/* mask of operational modifiers */
87 /*
88  * Namei parameter descriptors.
89  *
90  * SAVENAME may be set by either the callers of namei or by VOP_LOOKUP.
91  * If the caller of namei sets the flag (for example execve wants to
92  * know the name of the program that is being executed), then it must
93  * free the buffer. If VOP_LOOKUP sets the flag, then the buffer must
94  * be freed by either the commit routine or the VOP_ABORT routine.
95  * SAVESTART is set only by the callers of namei. It implies SAVENAME
96  * plus the addition of saving the parent directory that contains the
97  * name in ni_startdir. It allows repeated calls to lookup for the
98  * name being sought. The caller is responsible for releasing the
99  * buffer and for vrele'ing ni_startdir.
100  */
101 #define	NOCROSSMOUNT	0x00100	/* do not cross mount points */
102 #define	RDONLY		0x00200	/* lookup with read-only semantics */
103 #define	HASBUF		0x00400	/* has allocated pathname buffer */
104 #define	SAVENAME	0x00800	/* save pathanme buffer */
105 #define	SAVESTART	0x01000	/* save starting directory */
106 #define ISDOTDOT	0x02000	/* current component name is .. */
107 #define MAKEENTRY	0x04000	/* entry is to be added to name cache */
108 #define ISLASTCN	0x08000	/* this is last component of pathname */
109 #define ISSYMLINK	0x10000	/* symlink needs interpretation */
110 #define	ISWHITEOUT	0x20000	/* found whiteout */
111 #define	DOWHITEOUT	0x40000	/* do whiteouts */
112 #define PARAMASK	0xfff00	/* mask of parameter descriptors */
113 /*
114  * Initialization of an nameidata structure.
115  */
116 #define NDINIT(ndp, op, flags, segflg, namep, p) { \
117 	(ndp)->ni_cnd.cn_nameiop = op; \
118 	(ndp)->ni_cnd.cn_flags = flags; \
119 	(ndp)->ni_segflg = segflg; \
120 	(ndp)->ni_dirp = namep; \
121 	(ndp)->ni_cnd.cn_proc = p; \
122 }
123 #endif
124 
125 /*
126  * This structure describes the elements in the cache of recent
127  * names looked up by namei. NCHNAMLEN is sized to make structure
128  * size a power of two to optimize malloc's. Minimum reasonable
129  * size is 15.
130  */
131 
132 #define	NCHNAMLEN	31	/* maximum name segment length we bother with */
133 
134 struct	namecache {
135 	LIST_ENTRY(namecache) nc_hash;	/* hash chain */
136 	TAILQ_ENTRY(namecache) nc_lru;	/* LRU chain */
137 	struct	vnode *nc_dvp;		/* vnode of parent of name */
138 	u_long	nc_dvpid;		/* capability number of nc_dvp */
139 	struct	vnode *nc_vp;		/* vnode the name refers to */
140 	u_long	nc_vpid;		/* capability number of nc_vp */
141 	char	nc_nlen;		/* length of name */
142 	char	nc_name[NCHNAMLEN];	/* segment name */
143 };
144 
145 #ifdef KERNEL
146 u_long	nextvnodeid;
147 int	namei __P((struct nameidata *ndp));
148 int	lookup __P((struct nameidata *ndp));
149 int	relookup __P((struct vnode *dvp, struct vnode **vpp,
150 	    struct componentname *cnp));
151 #endif
152 
153 /*
154  * Stats on usefulness of namei caches.
155  */
156 struct	nchstats {
157 	long	ncs_goodhits;		/* hits that we can really use */
158 	long	ncs_neghits;		/* negative hits that we can use */
159 	long	ncs_badhits;		/* hits we must drop */
160 	long	ncs_falsehits;		/* hits with id mismatch */
161 	long	ncs_miss;		/* misses */
162 	long	ncs_long;		/* long names that ignore cache */
163 	long	ncs_pass2;		/* names found with passes == 2 */
164 	long	ncs_2passes;		/* number of times we attempt it */
165 };
166 #endif /* !_SYS_NAMEI_H_ */
167