DragonFly On-Line Manual Pages

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

NAME
     VOP_CREATE, VOP_MKNOD, VOP_MKDIR, VOP_SYMLINK -- create a file, socket,
     fifo, device, directory or symlink

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

     int
     VOP_CREATE(struct vnode *dvp, struct vnode **vpp,
	 struct componentname *cnp, struct vattr *vap);

     int
     VOP_MKNOD(struct vnode *dvp, struct vnode **vpp,
	 struct componentname *cnp, struct vattr *vap);

     int
     VOP_MKDIR(struct vnode *dvp, struct vnode **vpp,
	 struct componentname *cnp, struct vattr *vap);

     int
     VOP_SYMLINK(struct vnode *dvp, struct vnode **vpp,
	 struct componentname *cnp, struct vattr *vap, char *target);

DESCRIPTION
     These entry points create a new file, socket, fifo, device, directory or
     symlink in a given directory.

     The arguments are:

     dvp     the locked vnode of the directory

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

     cnp     the pathname component created

     vap     the attributes that the new object should be created with

     target  the pathname of the target of the symlink

     These entry points are called after VOP_LOOKUP(9) when an object is being
     created.  Normally, VOP_LOOKUP(9) will have set the SAVENAME flag in
     cnp->cn_flags to keep the memory pointed to by cnp->cn_pnbuf valid.  If
     an error is detected when creating the file, then this memory will be
     freed.  If the file is created successfully, then it will be freed unless
     the SAVESTART flag is specified in cnp.

LOCKS
     The directory, dvp will be locked on entry and must remain locked on
     return.  If the call is successful, the new object will be returned
     locked.

RETURN VALUES
     If successful, the vnode for the new object is placed in *vpp and zero is
     returned.	Otherwise, an appropriate error is returned.

PSEUDOCODE
     int
     vop_create(struct vnode *dvp,
		struct vnode **vpp,
		struct componentname *cnp
		struct vattr *vap)
     {
	 int mode = MAKEIMODE(vap->va_type, vap->va_mode);
	 struct vnode *vp;
	 int error;

	 *vpp = NULL;
	 if ((mode & IFMT) == 0)
	     mode |= IFREG;

	 error = SOMEFS_VALLOC(dvp, mode, cnp->cn_cred, &vp);
	 if (error) {
	     kfree(cnp->cn_pnbuf, M_NAMEI);
	     vput(dvp);
	     return error;
	 }

	 /*
	  * Update the permissions for the new vnode, including
	  * copying the group from the directory.
	  */
	 ...;

     #ifdef QUOTA
	 /*
	  * Possibly check quota information.
	  */
	 ...;
     #endif

	 /*
	  * Enter new vnode in directory, taking care that the vnode
	  * hits the disk before the directory contents are changed.
	  */
	 error = ...;

	 if (error)
	     goto bad;

	 if ((cnp->cn_flags & SAVESTART) == 0)
	     kfree(cnp->cn_pnbuf, M_NAMEI);
	 vput(dvp);
	 *vpp = vp;

	 return 0;

     bad:
	 /*
	  * Write error occurred trying to update the inode
	  * or the directory so must deallocate the inode.
	  */
	 kfree(cnp->cn_pnbuf, M_NAMEI);
	 vput(vp);

	 /*
	  * Deallocate filesystem resources for vp.
	  */
	 ...;

	 vput(dvp);

	 return error;
     }

ERRORS
     [ENOSPC]		The filesystem is full.

     [EDQUOT]		Quota exceeded.

SEE ALSO
     vnode(9), VOP_LOOKUP(9)

HISTORY
     The function VOP_CREATE appeared in 4.3BSD.

AUTHORS
     This man page was written by Doug Rabson.

DragonFly 3.9			 July 24, 1996			 DragonFly 3.9