bsd/sys/namei.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  23 /*
  24  * Copyright (c) 1985, 1989, 1991, 1993
  25  *      The Regents of the University of California.  All rights reserved.
  26  *
  27  * Redistribution and use in source and binary forms, with or without
  28  * modification, are permitted provided that the following conditions
  29  * are met:
  30  * 1. Redistributions of source code must retain the above copyright
  31  *    notice, this list of conditions and the following disclaimer.
  32  * 2. Redistributions in binary form must reproduce the above copyright
  33  *    notice, this list of conditions and the following disclaimer in the
  34  *    documentation and/or other materials provided with the distribution.
  35  * 3. All advertising materials mentioning features or use of this software
  36  *    must display the following acknowledgement:
  37  *      This product includes software developed by the University of
  38  *      California, Berkeley and its contributors.
  39  * 4. Neither the name of the University nor the names of its contributors
  40  *    may be used to endorse or promote products derived from this software
  41  *    without specific prior written permission.
  42  *
  43  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  44  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  45  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  46  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  47  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  48  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  49  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  50  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  51  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  52  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  53  * SUCH DAMAGE.
  54  *
  55  *      @(#)namei.h     8.4 (Berkeley) 8/20/94
  56  */
  57
  58 #ifndef _SYS_NAMEI_H_
  59 #define _SYS_NAMEI_H_
  60
  61 #include <sys/queue.h>
  62 #include <sys/uio.h>
  63
  64 /*
  65  * Lookup parameters: this structure describes the subset of
  66  * information from the nameidata structure that is passed
  67  * through the VOP interface.
  68  */
  69 struct componentname {
  70         /*
  71          * Arguments to lookup.
  72          */
  73         u_long  cn_nameiop;     /* namei operation */
  74         u_long  cn_flags;       /* flags to namei */
  75         struct  proc *cn_proc;  /* process requesting lookup */
  76         struct  ucred *cn_cred; /* credentials */
  77         /*
  78          * Shared between lookup and commit routines.
  79          */
  80         char    *cn_pnbuf;      /* pathname buffer */
  81         long    cn_pnlen;       /* length of allocated buffer */
  82         char    *cn_nameptr;    /* pointer to looked up name */
  83         long    cn_namelen;     /* length of looked up component */
  84         u_long  cn_hash;        /* hash value of looked up name */
  85         long    cn_consume;     /* chars to consume in lookup() */
  86 };
  87
  88 /*
  89  * Encapsulation of namei parameters.
  90  */
  91 struct nameidata {
  92         /*
  93          * Arguments to namei/lookup.
  94          */
  95         caddr_t ni_dirp;                /* pathname pointer */
  96         enum    uio_seg ni_segflg;      /* location of pathname */
  97      /* u_long  ni_nameiop;                namei operation */
  98      /* u_long  ni_flags;                  flags to namei */
  99      /* struct  proc *ni_proc;             process requesting lookup */
 100         /*
 101          * Arguments to lookup.
 102          */
 103      /* struct  ucred *ni_cred;            credentials */
 104         struct  vnode *ni_startdir;     /* starting directory */
 105         struct  vnode *ni_rootdir;      /* logical root directory */
 106         /*
 107          * Results: returned from/manipulated by lookup
 108          */
 109         struct  vnode *ni_vp;           /* vnode of result */
 110         struct  vnode *ni_dvp;          /* vnode of intermediate directory */
 111         /*
 112          * Shared between namei and lookup/commit routines.
 113          */
 114         u_int   ni_pathlen;             /* remaining chars in path */
 115         char    *ni_next;               /* next location in pathname */
 116         u_long  ni_loopcnt;             /* count of symlinks encountered */
 117         struct componentname ni_cnd;
 118 };
 119
 120 #ifdef KERNEL
 121 /*
 122  * namei operations
 123  */
 124 #define LOOKUP          0       /* perform name lookup only */
 125 #define CREATE          1       /* setup for file creation */
 126 #define DELETE          2       /* setup for file deletion */
 127 #define RENAME          3       /* setup for file renaming */
 128 #define OPMASK          3       /* mask for operation */
 129 /*
 130  * namei operational modifier flags, stored in ni_cnd.flags
 131  */
 132 #define LOCKLEAF        0x0004  /* lock inode on return */
 133 #define LOCKPARENT      0x0008  /* want parent vnode returned locked */
 134 #define WANTPARENT      0x0010  /* want parent vnode returned unlocked */
 135 #define NOCACHE         0x0020  /* name must not be left in cache */
 136 #define FOLLOW          0x0040  /* follow symbolic links */
 137 #define NOFOLLOW        0x0000  /* do not follow symbolic links (pseudo) */
 138 #define MODMASK         0x00fc  /* mask of operational modifiers */
 139 /*
 140  * Namei parameter descriptors.
 141  *
 142  * SAVENAME may be set by either the callers of namei or by VOP_LOOKUP.
 143  * If the caller of namei sets the flag (for example execve wants to
 144  * know the name of the program that is being executed), then it must
 145  * free the buffer. If VOP_LOOKUP sets the flag, then the buffer must
 146  * be freed by either the commit routine or the VOP_ABORT routine.
 147  * SAVESTART is set only by the callers of namei. It implies SAVENAME
 148  * plus the addition of saving the parent directory that contains the
 149  * name in ni_startdir. It allows repeated calls to lookup for the
 150  * name being sought. The caller is responsible for releasing the
 151  * buffer and for vrele'ing ni_startdir.
 152  */
 153 #define NOCROSSMOUNT    0x000100 /* do not cross mount points */
 154 #define RDONLY          0x000200 /* lookup with read-only semantics */
 155 #define HASBUF          0x000400 /* has allocated pathname buffer */
 156 #define SAVENAME        0x000800 /* save pathanme buffer */
 157 #define SAVESTART       0x001000 /* save starting directory */
 158 #define ISDOTDOT        0x002000 /* current component name is .. */
 159 #define MAKEENTRY       0x004000 /* entry is to be added to name cache */
 160 #define ISLASTCN        0x008000 /* this is last component of pathname */
 161 #define ISSYMLINK       0x010000 /* symlink needs interpretation */
 162 #define ISWHITEOUT      0x020000 /* found whiteout */
 163 #define DOWHITEOUT      0x040000 /* do whiteouts */
 164 #define NODELETEBUSY    0x800000 /* do not delete busy files (HFS semantic) */
 165 #define PARAMASK        0x0fff00 /* mask of parameter descriptors */
 166 /*
 167  * Initialization of an nameidata structure.
 168  */
 169 #define NDINIT(ndp, op, flags, segflg, namep, p) { \
 170         (ndp)->ni_cnd.cn_nameiop = op; \
 171         (ndp)->ni_cnd.cn_flags = flags; \
 172         (ndp)->ni_segflg = segflg; \
 173         (ndp)->ni_dirp = namep; \
 174         (ndp)->ni_cnd.cn_proc = p; \
 175 }
 176 #endif /* KERNEL */
 177
 178 /*
 179  * This structure describes the elements in the cache of recent
 180  * names looked up by namei. NCHNAMLEN is sized to make structure
 181  * size a power of two to optimize malloc's. Minimum reasonable
 182  * size is 15.
 183  */
 184
 185 #define NCHNAMLEN       31      /* maximum name segment length we bother with */
 186
 187 struct  namecache {
 188         LIST_ENTRY(namecache) nc_hash;  /* hash chain */
 189         TAILQ_ENTRY(namecache) nc_lru;  /* LRU chain */
 190         struct  vnode *nc_dvp;          /* vnode of parent of name */
 191         u_long  nc_dvpid;               /* capability number of nc_dvp */
 192         struct  vnode *nc_vp;           /* vnode the name refers to */
 193         u_long  nc_vpid;                /* capability number of nc_vp */
 194         char    nc_nlen;                /* length of name */
 195         char    nc_name[NCHNAMLEN];     /* segment name */
 196 };
 197
 198 #ifdef KERNEL
 199 extern u_long   nextvnodeid;
 200 int     namei __P((struct nameidata *ndp));
 201 int     lookup __P((struct nameidata *ndp));
 202 int     relookup __P((struct vnode *dvp, struct vnode **vpp,
 203                 struct componentname *cnp));
 204
 205 /* namecache function prototypes */
 206 int     cache_lookup __P((struct vnode *dvp, struct vnode **vpp,
 207                 struct componentname *cnp));
 208 void    cache_enter __P((struct vnode *dvp, struct vnode *vpp,
 209                 struct componentname *cnp));
 210 void    cache_purge __P((struct vnode *vp));
 211 void    cache_purgevfs __P((struct mount *mp));
 212 #endif /* KERNEL */
 213
 214 /*
 215  * Stats on usefulness of namei caches.
 216  */
 217 struct  nchstats {
 218         long    ncs_goodhits;           /* hits that we can really use */
 219         long    ncs_neghits;            /* negative hits that we can use */
 220         long    ncs_badhits;            /* hits we must drop */
 221         long    ncs_falsehits;          /* hits with id mismatch */
 222         long    ncs_miss;               /* misses */
 223         long    ncs_long;               /* long names that ignore cache */
 224         long    ncs_pass2;              /* names found with passes == 2 */
 225         long    ncs_2passes;            /* number of times we attempt it */
 226 };
 227 #endif /* !_SYS_NAMEI_H_ */