DragonFly On-Line Manual Pages

Search: Section:  

VOP_OLD_LOOKUP(9)     DragonFly Kernel Developer's Manual    VOP_OLD_LOOKUP(9)


NAME

     VOP_OLD_LOOKUP -- lookup a component of a pathname


SYNOPSIS

     #include <sys/param.h>
     #include <sys/vnode.h>
     #include <sys/namei.h>

     int
     VOP_OLD_LOOKUP(struct vnode *dvp, struct vnode **vpp,
         struct componentname *cnp);


DESCRIPTION

     This entry point looks up a single pathname component in a given
     directory.

     Its arguments are:

     dvp  the locked vnode of the directory to search

     vpp  the address of a variable where the resulting locked vnode should be
          stored

     cnp  the pathname component to be searched for

     Cnp is a pointer to a componentname structure defined as follows:

     struct componentname {
             /*
              * Arguments to lookup.
              */
             u_long  cn_nameiop;     /* namei operation */
             u_long  cn_flags;       /* flags to namei */
             struct  thread *cn_td;  /* process requesting lookup */
             struct  ucred *cn_cred; /* credentials */
             /*
              * Shared between lookup and commit routines.
              */
             char    *cn_nameptr;    /* pointer to looked up name */
             long    cn_namelen;     /* length of looked up component */
             long    cn_consume;     /* chars to consume in lookup() */
             int     cn_timeout;     /* if CNP_CACHETIMEOUT is set, in ticks */
             struct vnode *cn_notvp; /* used by NFS to check for collision */
     };

     Convert a component of a pathname into a pointer to a locked vnode.  This
     is a very central and rather complicated routine.  If the file system is
     not maintained in a strict tree hierarchy, this can result in a deadlock
     situation.

     The cnp->cn_nameiop argument is NAMEI_LOOKUP, NAMEI_CREATE, NAMEI_RENAME,
     or NAMEI_DELETE depending on the intended use of the object.  When
     NAMEI_CREATE, NAMEI_RENAME, or NAMEI_DELETE is specified, information
     usable in creating, renaming, or deleting a directory entry may be
     calculated.

     Overall outline of VOP_LOOKUP:

           Check accessibility of directory.  Look for name in cache, if
           found, then return name.  Search for name in directory, goto to
           found or notfound as appropriate.

     notfound:

           If creating or renaming and at end of pathname, return EJUSTRETURN,
           leaving info on available slots else return ENOENT.

     found:

           If at end of path and deleting, return information to allow delete.
           If at end of path and renaming, lock target inode and return info
           to allow rename.  If not at end, add name to cache; if at end and
           neither creating nor deleting, add name to cache.


LOCKS

     The directory, dvp should be locked on entry.  If an error (note: the
     return value EJUSTRETURN is not considered an error) is detected, it will
     be returned locked.  Otherwise, it will be unlocked unless CNP_LOCKPARENT
     is specified in cnp->cn_flags.  If an entry is found in the directory, it
     will be returned locked.


RETURN VALUES

     Zero is returned with *vpp set to the locked vnode of the file if the
     component is found.  If the component being searched for is ".", then the
     vnode just has an extra reference added to it with vref(9).  The caller
     must take care to release the locks appropriately in this case.

     If the component is not found and the operation is NAMEI_CREATE or
     NAMEI_RENAME the special return value EJUSTRETURN is returned.
     Otherwise, an appropriate error code is returned.


ERRORS

     [ENOTDIR]          The vnode dvp does not represent a directory.

     [ENOENT]           The component dvp was not found in this directory.

     [EACCES]           access for the specified operation is denied.

     [EJUSTRETURN]      a NAMEI_CREATE or NAMEI_RENAME operation would be
                        successful


SEE ALSO

     vnode(9), VOP_ACCESS(9), VOP_OLD_CREATE(9), VOP_OLD_MKDIR(9),
     VOP_OLD_MKNOD(9), VOP_OLD_RENAME(9), VOP_OLD_SYMLINK(9)


HISTORY

     The function VOP_OLD_LOOKUP appeared in 4.3BSD.


AUTHORS

     This man page was written by Doug Rabson, with some text from comments in
     sys/vfs/ufs/ufs_lookup.c.

DragonFly 3.9                  October 13, 2014                  DragonFly 3.9

Search: Section: