Is there something like "v.report"? Can I mask vectors?

[spf at hoqaa.att.com]

Folks,
  I'm looking for the simplest way (in GRASS) to solve a problem of
the following sort:

Given a layer of townships (polygons), and a layer of roads (vectors),
compute the length of road in a given township.

I started out converting the polygons to raster regions and producing
a mask, and then converting the roads to raster and running r.report.

But this generates areas or cell counts, which are at best a crude way
to measure lengths.

It seems that vector displays are unaffected by masks, and I also cannot
find any tool to compute the length of vectors in a vector file.  If I
could mask the vector file and then run something like a "v.report" I
think I'd have it.  SO:

a) Is there a way to mask vector files?
b) Does someone have something like a "v.report"?
	(I found v.area, which must do the same calculation to get
	the perimeter values it reports).

Thanks!  Steve Frysinger