lockf: minor cosmetic cleanups, no functional change

Switch various flags from int -> bool.

kill(getpid(), foo) and raise(foo) are equivalent in this context, so
switch to the latter as a minor pre

lockf: minor cosmetic cleanups, no functional change

Switch various flags from int -> bool.

kill(getpid(), foo) and raise(foo) are equivalent in this context, so
switch to the latter as a minor preference for readability.

Use proper signal fences instead of volatile for our SIGALRM handler.

Reviewed by: kib (earlier version), des
Differential Revision: https://reviews.freebsd.org/D51027

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lockf: tests: add tests for the -p and -T features

Reviewed by: des
Differential Revision: https://reviews.freebsd.org/D51026

lockf: add a -T option to terminate the child upon early abort

This is useful to avoid having the command running twice in the face of
the admin terminating the process. Notably, if the -p option i

lockf: add a -T option to terminate the child upon early abort

This is useful to avoid having the command running twice in the face of
the admin terminating the process. Notably, if the -p option is not in
use (or can't be used, e.g., because we can't open the file for writing)
then this provides a nice alternative where one simply needs to send a
SIGTERM to the lockf(1) process associated with the lock file to clean
it all up.

Reviewed by: des
Differential Revision: https://reviews.freebsd.org/D51025

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lockf: switch to a SIGCHLD model for reaping child

A future change will add a -T flag to forward SIGTERM along to the
child before we cleanup and terminate ourselves. Using a SIGCHLD
handler to do

lockf: switch to a SIGCHLD model for reaping child

A future change will add a -T flag to forward SIGTERM along to the
child before we cleanup and terminate ourselves. Using a SIGCHLD
handler to do that with SIGTERM blocked only while the child is actively
being collected will enable us to safely do so without having to worry
that our pid is potentially invalid.

Add a test that concisely checks that the child's error is properly
bubbled up to the caller.

Reviewed by: des, kib
Differential Revision: https://reviews.freebsd.org/D51024

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lockf: add a -p mode to write the child's pid

If we're going to hold the lock, it can be useful to scribble down the
pid that we spawned off to quickly associate the lock back to the
process that's

lockf: add a -p mode to write the child's pid

If we're going to hold the lock, it can be useful to scribble down the
pid that we spawned off to quickly associate the lock back to the
process that's keeping it open.

Reviewed by: allanjude (previous version), des
Differential Revision: https://reviews.freebsd.org/D51014

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