Passing an array of arrays to run_command will cause each
array to be treated like a command piped to the following
command. Each argument is shell-quoted unless its passed by
reference.
The following situations could lead to the 'unknown error':
1) As commented, when the alarm triggered after the first
signal handler was installed and before the new alarm was
installed. In this case the $signalcount was increased,
and worse: the original signal handler was never called.
2) When $code died, since the call itself wasn't in an eval
block, we'd leave the eval block containing the inner alarm
signal handler. Then there's a time window from leaving the
signal block (and with that restoring the first installed
only-counting signal-handler) and reaching the code to
restore the previous alarm where the counting alarm handler
could get triggered by our own alarm set before running
$code. In this case at least the the old alarm would be
restored, but we'd still trigger the 'unknown error'.
The new code starts off by suspending the original alarm
before installing any signal handler, then installing the
timeout handler inside the first eval block. The $code is
then run inside another eval block to make sure we reach the
alarm(0) statement before restoring the old signal handler
and alarm timeout.
Added a generic function to split a host+port string to the
host and port part supporting the two most common ipv6
notations beside domains and ipv4: with brackets for the
address or a dot as port separator.
perl's IO::Socket::IP passes AI_ADDRCONFIG if no GetAddrInfoFlags are passed,
which is often useful but also causes it to error when explicitly trying to
bind to 127.0.0.1 when there are no _other_ IPv4 addresses present.
Instead of assuming a local address of 0.0.0.0, the next_*_port family
of functions now takes an optional packet family argument (AF_INET/AF_INET6),
used for ipv6 support.
