VERITAS File System 4.1 Administrator's Guide

Application Interface

Named Data Streams Programmatic Interface

Chapter 486

Named Data Streams Programmatic Interface

VxFS named data stream functionality is available only through the following application

programming interface (API) functions:

vxfs_nattr_link Links to a named data stream.

vxfs_nattr_open Open a named data stream.

vxfs_nattr_rename Renames a named data stream.

vxfs_nattr_unlink Removes a named data stream.

The vxfs_nattr_open() function works similar to the open() system call, except that the path

is interpreted as a named data stream to a ﬁle descriptor. If the vxfs_nattr_open() operation

completes successfully, the return value is the ﬁle descriptor associated with the named data

stream. The ﬁle descriptor can be used by other input/output functions to refer to that named

data stream. If the path of the named datastream is set to "." the ﬁle descriptor returned

points to the named data stream directory vnode.

The vxfs_nattr_link() function creates a new directory entry for the existing named data

stream and increments its link count by one. There is a pointer to an existing named data

stream in the named data stream namespace and a pointer to the new directory entry created

in the named data stream namespace.

The vxfs_nattr_unlink() function removes the named data stream at a speciﬁed path. The

calling function must have write permission to remove the directory entry for the named data

stream.

The vxfs_nattr_rename() function changes a speciﬁed namespace entry at path1 to a second

speciﬁed namespace at path2. The speciﬁed paths are resolved relative to a pointer to the

named data stream directory vnodes.

See the vxfs_nattr_open(3), vxfs_nattr_link(3), vxfs_nattr_unlink(3), and

vxfs_nattr_rename(3) manual pages for more information.

Listing Named Data Streams

The named data streams for a ﬁle can be listed by calling getdents() on the named data

stream directory inode. For example:

fd = open("foo", O_RDWR); /* open file foo */

afd = vxfs_nattr_open(fd, "attribute1",