FreeBSD/Linux Kernel Cross Reference
sys/sys/namei.h

     /*
      * Copyright (c) 1985, 1989, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)namei.h     8.5 (Berkeley) 1/9/95
     * $FreeBSD: src/sys/sys/namei.h,v 1.11.2.1 1999/09/05 08:22:42 peter Exp $
     */
    
    #ifndef _SYS_NAMEI_H_
    #define _SYS_NAMEI_H_
    
    #include <sys/queue.h>
    
    /*
     * Encapsulation of namei parameters.
     */
    struct nameidata {
            /*
             * Arguments to namei/lookup.
             */
            const   char *ni_dirp;          /* pathname pointer */
            enum    uio_seg ni_segflg;      /* location of pathname */
         /* u_long  ni_nameiop;                namei operation */
         /* u_long  ni_flags;                  flags to namei */
         /* struct  proc *ni_proc;             process requesting lookup */
            /*
             * Arguments to lookup.
             */
         /* struct  ucred *ni_cred;            credentials */
            struct  vnode *ni_startdir;     /* starting directory */
            struct  vnode *ni_rootdir;      /* logical root directory */
            /*
             * Results: returned from/manipulated by lookup
             */
            struct  vnode *ni_vp;           /* vnode of result */
            struct  vnode *ni_dvp;          /* vnode of intermediate directory */
            /*
             * Shared between namei and lookup/commit routines.
             */
            long    ni_pathlen;             /* remaining chars in path */
            char    *ni_next;               /* next location in pathname */
            u_long  ni_loopcnt;             /* count of symlinks encountered */
            /*
             * Lookup parameters: this structure describes the subset of
             * information from the nameidata structure that is passed
             * through the VOP interface.
             */
            struct componentname {
                    /*
                     * Arguments to lookup.
                     */
                    u_long  cn_nameiop;     /* namei operation */
                    u_long  cn_flags;       /* flags to namei */
                    struct  proc *cn_proc;  /* process requesting lookup */
                    struct  ucred *cn_cred; /* credentials */
                    /*
                     * Shared between lookup and commit routines.
                     */
                    char    *cn_pnbuf;      /* pathname buffer */
                    char    *cn_nameptr;    /* pointer to looked up name */
                    long    cn_namelen;     /* length of looked up component */
                    u_long  cn_hash;        /* hash value of looked up name */
                    long    cn_consume;     /* chars to consume in lookup() */
            } ni_cnd;
    };
    
    #ifdef KERNEL
    /*
     * namei operations
     */
    #define LOOKUP          0       /* perform name lookup only */
   #define CREATE          1       /* setup for file creation */
   #define DELETE          2       /* setup for file deletion */
   #define RENAME          3       /* setup for file renaming */
   #define OPMASK          3       /* mask for operation */
   /*
    * namei operational modifier flags, stored in ni_cnd.flags
    */
   #define LOCKLEAF        0x0004  /* lock inode on return */
   #define LOCKPARENT      0x0008  /* want parent vnode returned locked */
   #define WANTPARENT      0x0010  /* want parent vnode returned unlocked */
   #define NOCACHE         0x0020  /* name must not be left in cache */
   #define FOLLOW          0x0040  /* follow symbolic links */
   #define NOFOLLOW        0x0000  /* do not follow symbolic links (pseudo) */
   #define MODMASK         0x00fc  /* mask of operational modifiers */
   /*
    * Namei parameter descriptors.
    *
    * SAVENAME may be set by either the callers of namei or by VOP_LOOKUP.
    * If the caller of namei sets the flag (for example execve wants to
    * know the name of the program that is being executed), then it must
    * free the buffer. If VOP_LOOKUP sets the flag, then the buffer must
    * be freed by either the commit routine or the VOP_ABORT routine.
    * SAVESTART is set only by the callers of namei. It implies SAVENAME
    * plus the addition of saving the parent directory that contains the
    * name in ni_startdir. It allows repeated calls to lookup for the
    * name being sought. The caller is responsible for releasing the
    * buffer and for vrele'ing ni_startdir.
    */
   #define NOCROSSMOUNT    0x000100 /* do not cross mount points */
   #define RDONLY          0x000200 /* lookup with read-only semantics */
   #define HASBUF          0x000400 /* has allocated pathname buffer */
   #define SAVENAME        0x000800 /* save pathname buffer */
   #define SAVESTART       0x001000 /* save starting directory */
   #define ISDOTDOT        0x002000 /* current component name is .. */
   #define MAKEENTRY       0x004000 /* entry is to be added to name cache */
   #define ISLASTCN        0x008000 /* this is last component of pathname */
   #define ISSYMLINK       0x010000 /* symlink needs interpretation */
   #define ISWHITEOUT      0x020000 /* found whiteout */
   #define DOWHITEOUT      0x040000 /* do whiteouts */
   #define WILLBEDIR       0x080000 /* new files will be dirs; allow trailing / */
   #define ISUNICODE       0x100000 /* current component name is unicode*/
   #define PARAMASK        0x1fff00 /* mask of parameter descriptors */
   /*
    * Initialization of an nameidata structure.
    */
   #define NDINIT(ndp, op, flags, segflg, namep, p) { \
           (ndp)->ni_cnd.cn_nameiop = op; \
           (ndp)->ni_cnd.cn_flags = flags; \
           (ndp)->ni_segflg = segflg; \
           (ndp)->ni_dirp = namep; \
           (ndp)->ni_cnd.cn_proc = p; \
   }
   #endif
   
   /*
    * This structure describes the elements in the cache of recent
    * names looked up by namei. NCHNAMLEN is sized to make structure
    * size a power of two to optimize malloc's. Minimum reasonable
    * size is 15.
    */
   
   #ifdef NCH_STATISTICS
   #define NCHNAMLEN       23      /* maximum name segment length we bother with */
   #else
   #define NCHNAMLEN       31      /* maximum name segment length we bother with */
   #endif
   
   struct  namecache {
           LIST_ENTRY(namecache) nc_hash;  /* hash chain */
           TAILQ_ENTRY(namecache) nc_lru;  /* LRU chain */
           struct  vnode *nc_dvp;          /* vnode of parent of name */
           u_long  nc_dvpid;               /* capability number of nc_dvp */
           struct  vnode *nc_vp;           /* vnode the name refers to */
           u_long  nc_vpid;                /* capability number of nc_vp */
   #ifdef NCH_STATISTICS
           u_long  nc_nbr;                 /* a serial number */
           u_long  nc_hits;                /* how many times we got hit */
   #endif
           char    nc_nlen;                /* length of name */
           char    nc_name[NCHNAMLEN];     /* segment name */
   };
   
   #ifdef KERNEL
   extern u_long   nextvnodeid;
   extern u_long   numcache;
   extern u_long   numvnodes;
   
   int     namei __P((struct nameidata *ndp));
   int     lookup __P((struct nameidata *ndp));
   int     relookup __P((struct vnode *dvp, struct vnode **vpp,
               struct componentname *cnp));
   #endif
   
   /*
    * Stats on usefulness of namei caches.
    */
   struct  nchstats {
           long    ncs_goodhits;           /* hits that we can really use */
           long    ncs_neghits;            /* negative hits that we can use */
           long    ncs_badhits;            /* hits we must drop */
           long    ncs_falsehits;          /* hits with id mismatch */
           long    ncs_miss;               /* misses */
           long    ncs_long;               /* long names that ignore cache */
           long    ncs_pass2;              /* names found with passes == 2 */
           long    ncs_2passes;            /* number of times we attempt it */
   };
   
   extern struct nchstats nchstats;
   
   #endif /* !_SYS_NAMEI_H_ */

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