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

     /*      $NetBSD: namei.h,v 1.45.8.2 2007/02/17 23:27:51 tron Exp $      */
     
     /*
      * 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. 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) 8/20/94
     */
    
    #ifndef _SYS_NAMEI_H_
    #define _SYS_NAMEI_H_
    
    #include <sys/queue.h>
    
    #ifdef _KERNEL
    /*
     * 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.
             */
         /* kauth_cred_t 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.
             */
            size_t  ni_pathlen;             /* remaining chars in path */
            const 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  lwp *cn_lwp;    /* lwp requesting lookup */
                    kauth_cred_t cn_cred;   /* credentials */
                    /*
                     * Shared between lookup and commit routines.
                     */
                    char    *cn_pnbuf;      /* pathname buffer */
                    const 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;
    };
    
    /*
     * 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.cn_flags
    */
   #define LOCKLEAF        0x0004  /* lock inode on return */
   #define LOCKPARENT      0x0008  /* want parent vnode returned locked */
   #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    0x0000100       /* do not cross mount points */
   #define RDONLY          0x0000200       /* lookup with read-only semantics */
   #define HASBUF          0x0000400       /* has allocated pathname buffer */
   #define SAVENAME        0x0000800       /* save pathname buffer */
   #define SAVESTART       0x0001000       /* save starting directory */
   #define ISDOTDOT        0x0002000       /* current component name is .. */
   #define MAKEENTRY       0x0004000       /* entry is to be added to name cache */
   #define ISLASTCN        0x0008000       /* this is last component of pathname */
   #define ISSYMLINK       0x0010000       /* symlink needs interpretation */
   #define ISWHITEOUT      0x0020000       /* found whiteout */
   #define DOWHITEOUT      0x0040000       /* do whiteouts */
   #define REQUIREDIR      0x0080000       /* must be a directory */
   #define CREATEDIR       0x0200000       /* trailing slashes are ok */
   #define PARAMASK        0x03fff00       /* mask of parameter descriptors */
   /*
    * Initialization of an nameidata structure.
    */
   #define NDINIT(ndp, op, flags, segflg, namep, l) { \
           (ndp)->ni_cnd.cn_nameiop = op; \
           (ndp)->ni_cnd.cn_flags = flags; \
           (ndp)->ni_segflg = segflg; \
           (ndp)->ni_dirp = namep; \
           (ndp)->ni_cnd.cn_lwp = l; \
           (ndp)->ni_cnd.cn_cred = l->l_cred; \
   }
   #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.
    */
   
   #define NCHNAMLEN       31      /* maximum name segment length we bother with */
   
   struct  namecache {
           LIST_ENTRY(namecache) nc_hash;  /* hash chain */
           TAILQ_ENTRY(namecache) nc_lru;  /* LRU chain */
           LIST_ENTRY(namecache) nc_vhash; /* directory hash chain */
           LIST_ENTRY(namecache) nc_dvlist;
           struct  vnode *nc_dvp;          /* vnode of parent of name */
           LIST_ENTRY(namecache) nc_vlist;
           struct  vnode *nc_vp;           /* vnode the name refers to */
           int     nc_flags;               /* copy of componentname's ISWHITEOUT */
           char    nc_nlen;                /* length of name */
           char    nc_name[NCHNAMLEN];     /* segment name */
   };
   
   #ifdef _KERNEL
   #include <sys/mallocvar.h>
   #include <sys/pool.h>
   
   struct mount;
   
   extern struct pool pnbuf_pool;          /* pathname buffer pool */
   extern struct pool_cache pnbuf_cache;   /* pathname buffer cache */
   
   #define PNBUF_GET()     pool_cache_get(&pnbuf_cache, PR_WAITOK)
   #define PNBUF_PUT(pnb)  pool_cache_put(&pnbuf_cache, (pnb))
   
   typedef struct pathname_internal *pathname_t;
   
   int     namei(struct nameidata *);
   uint32_t namei_hash(const char *, const char **);
   int     lookup(struct nameidata *);
   int     relookup(struct vnode *, struct vnode **, struct componentname *);
   void    cache_purge1(struct vnode *, const struct componentname *, int);
   #define PURGE_PARENTS   1
   #define PURGE_CHILDREN  2
   #define cache_purge(vp) cache_purge1((vp), NULL, PURGE_PARENTS|PURGE_CHILDREN)
   int     cache_lookup(struct vnode *, struct vnode **, struct componentname *);
   int     cache_lookup_raw(struct vnode *, struct vnode **,
                            struct componentname *);
   int     cache_revlookup(struct vnode *, struct vnode **, char **, char *);
   void    cache_enter(struct vnode *, struct vnode *, struct componentname *);
   void    nchinit(void);
   void    nchreinit(void);
   void    cache_purgevfs(struct mount *);
   void    namecache_print(struct vnode *, void (*)(const char *, ...));
   
   int pathname_get(const char *, enum uio_seg, pathname_t *);
   const char *pathname_path(pathname_t);
   void pathname_put(pathname_t);
   #endif
   
   /*
    * Stats on usefulness of namei caches.
    * XXX: should be 64-bit counters.
    */
   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 */
           long    ncs_revhits;            /* reverse-cache hits */
           long    ncs_revmiss;            /* reverse-cache misses */
   };
   
   #ifdef _KERNEL
   extern struct nchstats nchstats;
   #endif
   #endif /* !_SYS_NAMEI_H_ */

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