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From: Erik Cederstrand <erik@cederstrand.dk>
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Subject: time_t when used as timedelta
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Date: Tue, 9 Oct 2012 17:35:09 +0200
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Hi list,

I'm looking at this possible divide-by zero in dhclient: =
http://scan.freebsd.your.org/freebsd-head/WORLD/2012-10-07-amd64/report-nB=
hqE2.html.gz#EndPath

In this specific case, it's obvious from the intention of the code that =
ip->client->interval is always >0, but it's not obvious to me in the =
code. I could add an assert before the possible divide-by-zero:

assert(ip->client->interval > 0);

But looking at the code, I'm not sure it's very elegant. =
ip->client->interval is defined as time_t (see =
src/sbin/dhclient/dhcpd.h), which is a signed integer type, if I'm =
correct. However, some time_t members of struct client_state and struct =
client_config (see said header file) are assumed in the code to be =
positive and possibly non-null. Instead of plastering the code with =
asserts, is there something like an utime_t type? Or are there better =
ways to enforce the invariant?

Thanks,
Erik=