freebsd-nq/share/man/man9/VOP_CREATE.9

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.Dd July 24, 1996
.Os
.Dt VOP_CREATE 9
.Sh NAME
.Nm VOP_CREATE ,
.Nm VOP_MKNOD ,
.Nm VOP_MKDIR ,
.Nm VOP_SYMLINK
.Nd create a file, socket, fifo, device, directory or symlink
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/vnode.h>
.Fd #include <sys/namei.h>
.Ft int
.Fn VOP_CREATE "struct vnode *dvp" "struct vnode **vpp" "struct componentname *cnp" "struct vattr *vap"
.Ft int
.Fn VOP_MKNOD "struct vnode *dvp" "struct vnode **vpp" "struct componentname *cnp" "struct vattr *vap"
.Ft int
.Fn VOP_MKDIR "struct vnode *dvp" "struct vnode **vpp" "struct componentname *cnp" "struct vattr *vap"
.Ft int
.Fn VOP_SYMLINK "struct vnode *dvp" "struct vnode **vpp" "struct componentname *cnp" "struct vattr *vap" "char *target"
.Sh DESCRIPTION
These entry points create a new file, socket, fifo, device, directory or symlink
in a given directory.
.Pp
The arguments are:
.Bl -tag -width target
.It Ar dvp
the locked vnode of the directory
.It Ar vpp
the address of a variable where the resulting locked vnode should be stored
.It Ar cnp
the pathname component created
.It Ar vap
the attributes that the new object should be created with
.It Ar target
the pathname of the target of the symlink
.El
.Pp
These entry points are called after
.Xr VOP_LOOKUP 9
when an object is being created.
Normally,
.Xr VOP_LOOKUP 9
will have set the
.Dv SAVENAME
flag in
.Fa cnp->cn_flags
to keep the memory pointed to by
.Fa 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
.Dv SAVESTART
flag is specified in
.Fa cnp .
.Sh LOCKS
The directory,
.Fa dvp
will be locked on entry and must remain locked on return.
If the call is successful, the new object will be returned locked,
unless the call is
.Xr VOP_MKNOD 9
or
.Xr VOP_SYMLINK 9
in which case the new object is not returned at all.
It is not clear why
.Xr VOP_MKNOD 9
and
.Xr VOP_SYMLINK 9
need a
.Fa *vpp
argument at all.
.Sh RETURN VALUES
If successful, the vnode for the new object is placed in
.Fa *vpp
and zero is returned.  Otherwise, an appropriate error is returned.
.Sh PSEUDOCODE
.Bd -literal
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) {
	free(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)
	free(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.
     */
    free(cnp->cn_pnbuf, M_NAMEI);
    vput(vp);

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

    vput(dvp);

    return error;
}
.Ed
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOSPC
The filesystem is full.
.It Bq Er EDQUOT
Quota exceeded.
.El
.Sh SEE ALSO
.Xr VOP_LOOKUP 9
.Sh HISTORY
The function
.Nm
appeared in
.Bx 4.3 .
.Sh SEE ALSO
.Xr vnode 9
.Sh AUTHORS
This man page was written by
.An Doug Rabson .