Date: Tue, 30 Aug 2005 23:20:58 +0400 From: Solar Designer <solar@...nwall.com> To: john-users@...ts.openwall.com Subject: Re: trivial parallel processing (4 CPUs) I wrote: > Another problem is that standards such as the Single Unix Specification > do not require serialization of reads/writes from/to file descriptors. > Whenever two or more threads read off the same fd simultaneously, the > behavior is undefined. [...] A correction: this particular problem does not apply to the approach described by Michael because the concurrent reads actually happen via different fd's, not via duplicates of the same fd. Similarly, the hardening measure that I've put into Linux 2.4.x-ow kernels which would serialize concurrent reads off the same fd does not apply here. However, SUSv3 also says this: "The behavior of multiple concurrent reads on the same pipe, FIFO, or terminal device is unspecified." So we're back to the same conclusion. -- Alexander Peslyak <solar at openwall.com> GPG key ID: B35D3598 fp: 6429 0D7E F130 C13E C929 6447 73C3 A290 B35D 3598 http://www.openwall.com - bringing security into open computing environments Was I helpful? Please give your feedback here: http://rate.affero.net/solar
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