The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/sys/namei.h

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    1 /*      $NetBSD: namei.h,v 1.34.2.1 2004/07/10 14:23:00 tron Exp $      */
    2 
    3 /*
    4  * Copyright (c) 1985, 1989, 1991, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the University nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  *
   31  *      @(#)namei.h     8.5 (Berkeley) 8/20/94
   32  */
   33 
   34 #ifndef _SYS_NAMEI_H_
   35 #define _SYS_NAMEI_H_
   36 
   37 #include <sys/queue.h>
   38 
   39 /*
   40  * Encapsulation of namei parameters.
   41  */
   42 struct nameidata {
   43         /*
   44          * Arguments to namei/lookup.
   45          */
   46         const char *ni_dirp;            /* pathname pointer */
   47         enum    uio_seg ni_segflg;      /* location of pathname */
   48      /* u_long  ni_nameiop;                namei operation */
   49      /* u_long  ni_flags;                  flags to namei */
   50      /* struct  proc *ni_proc;             process requesting lookup */
   51         /*
   52          * Arguments to lookup.
   53          */
   54      /* struct  ucred *ni_cred;            credentials */
   55         struct  vnode *ni_startdir;     /* starting directory */
   56         struct  vnode *ni_rootdir;      /* logical root directory */
   57         /*
   58          * Results: returned from/manipulated by lookup
   59          */
   60         struct  vnode *ni_vp;           /* vnode of result */
   61         struct  vnode *ni_dvp;          /* vnode of intermediate directory */
   62         /*
   63          * Shared between namei and lookup/commit routines.
   64          */
   65         size_t  ni_pathlen;             /* remaining chars in path */
   66         const char *ni_next;            /* next location in pathname */
   67         u_long  ni_loopcnt;             /* count of symlinks encountered */
   68         /*
   69          * Lookup parameters: this structure describes the subset of
   70          * information from the nameidata structure that is passed
   71          * through the VOP interface.
   72          */
   73         struct componentname {
   74                 /*
   75                  * Arguments to lookup.
   76                  */
   77                 u_long  cn_nameiop;     /* namei operation */
   78                 u_long  cn_flags;       /* flags to namei */
   79                 struct  proc *cn_proc;  /* process requesting lookup */
   80                 struct  ucred *cn_cred; /* credentials */
   81                 /*
   82                  * Shared between lookup and commit routines.
   83                  */
   84                 char    *cn_pnbuf;      /* pathname buffer */
   85                 const char *cn_nameptr; /* pointer to looked up name */
   86                 long    cn_namelen;     /* length of looked up component */
   87                 u_long  cn_hash;        /* hash value of looked up name */
   88                 long    cn_consume;     /* chars to consume in lookup() */
   89         } ni_cnd;
   90 };
   91 
   92 #ifdef _KERNEL
   93 /*
   94  * namei operations
   95  */
   96 #define LOOKUP          0       /* perform name lookup only */
   97 #define CREATE          1       /* setup for file creation */
   98 #define DELETE          2       /* setup for file deletion */
   99 #define RENAME          3       /* setup for file renaming */
  100 #define OPMASK          3       /* mask for operation */
  101 /*
  102  * namei operational modifier flags, stored in ni_cnd.cn_flags
  103  */
  104 #define LOCKLEAF        0x0004  /* lock inode on return */
  105 #define LOCKPARENT      0x0008  /* want parent vnode returned locked */
  106 #define WANTPARENT      0x0010  /* want parent vnode returned unlocked */
  107 #define NOCACHE         0x0020  /* name must not be left in cache */
  108 #define FOLLOW          0x0040  /* follow symbolic links */
  109 #define NOFOLLOW        0x0000  /* do not follow symbolic links (pseudo) */
  110 #define MODMASK         0x00fc  /* mask of operational modifiers */
  111 /*
  112  * Namei parameter descriptors.
  113  *
  114  * SAVENAME may be set by either the callers of namei or by VOP_LOOKUP.
  115  * If the caller of namei sets the flag (for example execve wants to
  116  * know the name of the program that is being executed), then it must
  117  * free the buffer. If VOP_LOOKUP sets the flag, then the buffer must
  118  * be freed by either the commit routine or the VOP_ABORT routine.
  119  * SAVESTART is set only by the callers of namei. It implies SAVENAME
  120  * plus the addition of saving the parent directory that contains the
  121  * name in ni_startdir. It allows repeated calls to lookup for the
  122  * name being sought. The caller is responsible for releasing the
  123  * buffer and for vrele'ing ni_startdir.
  124  */
  125 #define NOCROSSMOUNT    0x0000100       /* do not cross mount points */
  126 #define RDONLY          0x0000200       /* lookup with read-only semantics */
  127 #define HASBUF          0x0000400       /* has allocated pathname buffer */
  128 #define SAVENAME        0x0000800       /* save pathname buffer */
  129 #define SAVESTART       0x0001000       /* save starting directory */
  130 #define ISDOTDOT        0x0002000       /* current component name is .. */
  131 #define MAKEENTRY       0x0004000       /* entry is to be added to name cache */
  132 #define ISLASTCN        0x0008000       /* this is last component of pathname */
  133 #define ISSYMLINK       0x0010000       /* symlink needs interpretation */
  134 #define ISWHITEOUT      0x0020000       /* found whiteout */
  135 #define DOWHITEOUT      0x0040000       /* do whiteouts */
  136 #define REQUIREDIR      0x0080000       /* must be a directory */
  137 #define PDIRUNLOCK      0x0100000       /* vfs_lookup() unlocked parent dir */
  138 #define CREATEDIR       0x0200000       /* creating entry is a directory */
  139 #define PARAMASK        0x03fff00       /* mask of parameter descriptors */
  140 /*
  141  * Initialization of an nameidata structure.
  142  */
  143 #define NDINIT(ndp, op, flags, segflg, namep, p) { \
  144         (ndp)->ni_cnd.cn_nameiop = op; \
  145         (ndp)->ni_cnd.cn_flags = flags; \
  146         (ndp)->ni_segflg = segflg; \
  147         (ndp)->ni_dirp = namep; \
  148         (ndp)->ni_cnd.cn_proc = p; \
  149         (ndp)->ni_cnd.cn_cred = p->p_ucred; \
  150 }
  151 #endif
  152 
  153 /*
  154  * This structure describes the elements in the cache of recent
  155  * names looked up by namei. NCHNAMLEN is sized to make structure
  156  * size a power of two to optimize malloc's. Minimum reasonable
  157  * size is 15.
  158  */
  159 
  160 #define NCHNAMLEN       31      /* maximum name segment length we bother with */
  161 
  162 struct  namecache {
  163         LIST_ENTRY(namecache) nc_hash;  /* hash chain */
  164         TAILQ_ENTRY(namecache) nc_lru;  /* LRU chain */
  165         LIST_ENTRY(namecache) nc_vhash; /* directory hash chain */
  166         LIST_ENTRY(namecache) nc_dvlist;
  167         struct  vnode *nc_dvp;          /* vnode of parent of name */
  168         LIST_ENTRY(namecache) nc_vlist;
  169         struct  vnode *nc_vp;           /* vnode the name refers to */
  170         int     nc_flags;               /* copy of componentname's ISWHITEOUT */
  171         char    nc_nlen;                /* length of name */
  172         char    nc_name[NCHNAMLEN];     /* segment name */
  173 };
  174 
  175 #ifdef _KERNEL
  176 #include <sys/mallocvar.h>
  177 #include <sys/pool.h>
  178 
  179 extern struct pool pnbuf_pool;          /* pathname buffer pool */
  180 extern struct pool_cache pnbuf_cache;   /* pathname buffer cache */
  181 
  182 MALLOC_DECLARE(M_NAMEI);
  183 
  184 #define PNBUF_GET()     pool_cache_get(&pnbuf_cache, PR_WAITOK)
  185 #define PNBUF_PUT(pnb)  pool_cache_put(&pnbuf_cache, (pnb))
  186 
  187 int     namei __P((struct nameidata *));
  188 uint32_t namei_hash __P((const char *, const char **));
  189 int     lookup __P((struct nameidata *));
  190 int     relookup __P((struct vnode *, struct vnode **, struct componentname *));
  191 void cache_purge __P((struct vnode *));
  192 void cache_purge1 __P((struct vnode *, const struct componentname *, int));
  193 #define PURGE_PARENTS   1
  194 #define PURGE_CHILDREN  2
  195 #define cache_purge(vp) cache_purge1((vp), NULL, PURGE_PARENTS|PURGE_CHILDREN)
  196 int cache_lookup __P((struct vnode *, struct vnode **, struct componentname *));
  197 int cache_revlookup __P((struct vnode *, struct vnode **, char **, char *));
  198 void cache_enter __P((struct vnode *, struct vnode *, struct componentname *));
  199 void nchinit __P((void));
  200 void nchreinit __P((void));
  201 struct mount;
  202 void cache_purgevfs __P((struct mount *));
  203 void namecache_print(struct vnode *, void (*)(const char *, ...));
  204 #endif
  205 
  206 /*
  207  * Stats on usefulness of namei caches.
  208  */
  209 struct  nchstats {
  210         long    ncs_goodhits;           /* hits that we can really use */
  211         long    ncs_neghits;            /* negative hits that we can use */
  212         long    ncs_badhits;            /* hits we must drop */
  213         long    ncs_falsehits;          /* hits with id mismatch */
  214         long    ncs_miss;               /* misses */
  215         long    ncs_long;               /* long names that ignore cache */
  216         long    ncs_pass2;              /* names found with passes == 2 */
  217         long    ncs_2passes;            /* number of times we attempt it */
  218         long    ncs_revhits;            /* reverse-cache hits */
  219         long    ncs_revmiss;            /* reverse-cache misses */
  220 };
  221 
  222 #ifdef _KERNEL
  223 extern struct nchstats nchstats;
  224 #endif
  225 #endif /* !_SYS_NAMEI_H_ */

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