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

NAME
     VOP_GETATTR, VOP_SETATTR -- get and set attributes on a file or directory

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

     int
     VOP_GETATTR(struct vnode *vp, struct vattr *vap, struct ucred *cred,
         struct proc *p);

     int
     VOP_SETATTR(struct vnode *vp, struct vattr *vap, struct ucred *cred,
         struct proc *p);

DESCRIPTION
     These entry points manipulate various attributes of a file or directory,
     including file permissions, owner, group, size, access time and modifica-
     tion time.

     The arguments are:

     vp    the vnode of the file

     vap   the attributes of the file

     cred  the user credentials of the calling process

     p     the process

     Attributes which are not being modified by VOP_SETATTR(9) should be set
     to the value VNOVAL.

LOCKS
     VOP_GETATTR(9) expects the vnode to be locked on entry and will leave the
     vnode locked on return.

     VOP_SETATTR(9) expects the vnode to be locked on entry and will leave the
     vnode locked on return.

RETURN VALUES
     VOP_GETATTR(9) returns information about the file in *vap.
     VOP_SETATTR(9) returns zero if the attributes were changed successfully,
     otherwise an appropriate error is returned.

PSEUDOCODE
     int
     vop_getattr(struct vnode *vp, struct vattr *vap,
                 struct ucred *cred, struct proc *p)
     {
         /*
          * Fill in the contents of *vap with information from
          * the filesystem.
          */
         ...;

         return 0;
     }

     int
     vop_setattr(struct vnode *vp, struct vattr *vap,
                 struct ucred *cred, struct proc *p)
     {
         /*
          * Check for unsettable attributes.
          */
         if ((vap->va_type != VNON) || (vap->va_nlink != VNOVAL) ||
             (vap->va_fsid != VNOVAL) || (vap->va_fileid != VNOVAL) ||
             (vap->va_blocksize != VNOVAL) || (vap->va_rdev != VNOVAL) ||
             ((int)vap->va_bytes != VNOVAL) || (vap->va_gen != VNOVAL)) {
             return (EINVAL);
         }

         if (vap->va_flags != VNOVAL) {
             /*
              * Set the immutable and append flags of the file.
              */
         }

         if (vap->va_uid != (uid_t)VNOVAL || vap->va_gid != (gid_t)VNOVAL) {
             /*
              * Change owner and/or group of the file.
              */
         }

         if (vap->va_size != VNOVAL) {
             /*
              * Truncate the file to the specified size.
              */
         }

         if (vap->va_atime.tv_sec != VNOVAL || vap->va_mtime.tv_sec != VNOVAL) {
             /*
              * Change access and/or modification time of file.
              */
         }

         if (vap->va_mode != (mode_t)VNOVAL) {
             /*
              * Change permissions of file.
              */
         }

         return 0;
     }

ERRORS
     [EPERM]            The file is immutable

     [EACCES]           Permission denied

     [EROFS]            The filesystem is readonly

SEE ALSO
     vnode(9), VOP_ACCESS(9)

AUTHORS
     This man page was written by Doug Rabson.

DragonFly 3.5                    July 24, 1996                   DragonFly 3.5