truncate: fix a minor nit + add a hole-punching testHEADmain

The struct spacectl_range we use is only really used in these three
lines of code, so re-scope it down to just the dealloc branch.  This is
marginally easier to reason about what might be necessary to replace in
porting our truncate(1) to other platforms.

While we're here, add a test for the -d flag to be sure it really does
punch a hole in the file.  The test also tries to confirm that it does
not disturb other segments of the file in the process, just to inspire
some confidence that it's not corrupting the file somehow.

Sponsored by:	Klara, Inc.
Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D51207

0 files changed, 0 insertions, 0 deletions