sys/sys/namei.h

/*
 * Copyright (c) 1985, 1989, 1991 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.
 *
 *      from: @(#)namei.h       7.15 (Berkeley) 5/15/91
 *      $Id$
 */

#ifndef _NAMEI_H_
#define _NAMEI_H_

/*
 * Encapsulation of namei parameters.
 */
struct nameidata {
        /*
         * Arguments to namei.
         */
        caddr_t ni_dirp;                /* pathname pointer */
        enum    uio_seg ni_segflg;      /* location of pathname */
        u_long  ni_nameiop;             /* see below */
        /*
         * Arguments to lookup.
         */
        struct  ucred *ni_cred;         /* credentials */
        struct  vnode *ni_startdir;     /* starting directory */
        struct  vnode *ni_rootdir;      /* logical root directory */
        /*
         * Results
         */
        struct  vnode *ni_vp;           /* vnode of result */
        struct  vnode *ni_dvp;          /* vnode of intermediate directory */
        /*
         * Shared between namei, lookup routines, and commit routines.
         */
        char    *ni_pnbuf;              /* pathname buffer */
        long    ni_pathlen;             /* remaining chars in path */
        char    *ni_ptr;                /* current location in pathname */
        long    ni_namelen;             /* length of current component */
        char    *ni_next;               /* next location in pathname */
        u_long  ni_hash;                /* hash value of current component */
        u_char  ni_loopcnt;             /* count of symlinks encountered */
        u_char  ni_makeentry;           /* 1 => add entry to name cache */
        u_char  ni_isdotdot;            /* 1 => current component name is .. */
        u_char  ni_more;                /* 1 => symlink needs interpretation */
        /*
         * Side effects.
         */
        struct ufs_specific {           /* saved info for new dir entry */
                off_t   ufs_endoff;     /* end of useful directory contents */
                long    ufs_offset;     /* offset of free space in directory */
                long    ufs_count;      /* size of free slot in directory */
                ino_t   ufs_ino;        /* inode number of found directory */
                u_long  ufs_reclen;     /* size of found directory entry */
        } ni_ufs;
};

#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 modifiers
 */
#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    0x0100  /* do not cross mount points */
#define REMOTE          0x0200  /* lookup for remote filesystem servers */
#define HASBUF          0x0400  /* has allocated pathname buffer */
#define SAVENAME        0x0800  /* save pathanme buffer */
#define SAVESTART       0x1000  /* save starting directory */
#define PARAMASK        0xff00  /* mask of parameter descriptors */
#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 {
        struct  namecache *nc_forw;     /* hash chain, MUST BE FIRST */
        struct  namecache *nc_back;     /* hash chain, MUST BE FIRST */
        struct  namecache *nc_nxt;      /* LRU chain */
        struct  namecache **nc_prev;    /* 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 */
        char    nc_nlen;                /* length of name */
        char    nc_name[NCHNAMLEN];     /* segment name */
};

#ifdef KERNEL
u_long  nextvnodeid;
int     namei __P((struct nameidata *ndp, struct proc *p));
int     lookup __P((struct nameidata *ndp, struct proc *p));
#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 */
};
#endif /* !_NAMEI_H_ */