Date: Tue, 9 Oct 2012 17:35:09 +0200 From: Erik Cederstrand <erik@cederstrand.dk> To: FreeBSD Hackers <hackers@FreeBSD.org> Subject: time_t when used as timedelta Message-ID: <787F09EF-E3F7-467E-B023-B7846509D2A1@cederstrand.dk>
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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-nBhqE2.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
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