Date: Tue, 14 Jun 2011 04:00:24 GMT From: Robert Lorentz <robert.lorentz@gmail.com> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/157177: primes(1) prints non-prime for numbers > 2^32 Message-ID: <201106140400.p5E40OML033995@freefall.freebsd.org>
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The following reply was made to PR bin/157177; it has been noted by GNATS. From: Robert Lorentz <robert.lorentz@gmail.com> To: bug-followup@FreeBSD.org, kcwu@kcwu.csie.org Cc: Subject: Re: bin/157177: primes(1) prints non-prime for numbers > 2^32 Date: Mon, 13 Jun 2011 23:29:33 -0400 I regression tested this on FreeBSD 8.2-RELEASE against FreeBSD = 9.0-CURRENT r221981, using primegen-0.97 on amd64 platform and came up = with some interesting results. First off, from primes(1) man page, syntax is: primes [ low [high] ] So your bc line effectively says: primes 4294967296=20 Where low =3D 4294967296 and high is not explicitly stated. According = to the man page high defaults to 1000000000 where the last prime = possible is 999999937. Since 1,000,000,000 < 4,294,967,296, the correct = output of "primes 4294967296" should be nothing. In FreeBSD 8.2-RELEASE, primes correctly does output nothing. However on FreeBSD 9.0-CURRENT, primes incorrectly prints primes = starting at 4,294,967,296 and seems to go forever (not sure where it = will stop). This is contrary to what the manual page says and is a = problem. Your original problem I did regression test and confirm to be working in = 8.2-RELEASE and broken in 9.0-CURRENT. I isolated one of your examples = using: primes 4295360520 4295360522 | xargs -n 1 factor On FreeBSD 9.0-CURRENT: 4295360521: 65539 65539 On FreeBSD 8.2-RELEASE: No output=20 On FreeBSD 9.0-CURRENT I debugged the source in = /usr/ports/math/primegen/work/primegen-0.97 a bit and realized that if I = ran the compiled version in = /usr/ports/math/primegen/work/primegen-0.97/primes I got the correct = expected results. However, if I run the installed version in = /usr/games/primes, I get the incorrect results. The binaries in those = two places aren't the same (verified using md5). =20 This appears to be an issue with the port building, probably building in = 32 bit. If the inputs to primes are interpreted as 32bit then a "low" = of (2^32 + 1) is interpreted as 1, therefore being less than 1000000000, = therefore the code would continue to generate primes, and if this is the = case then I wouldn't be surprised that the prime generation code also = would misbehave.
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