Eliminate temp filename based race condition from qsieve_factor#1201
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fredrik-johansson merged 1 commit intoflintlib:trunkfrom Jan 4, 2023
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The `qsieve_factor()` function uses a temporary file (with name `qs_inf->fname`) for internal operation. There were a few issues with this file: * The name is supposed to be random, yet a prior `srand()` call ensures that different threads will be using an identical "random" name. The ensuing race condition leads to crashes. * The pre-existence of another file with the same name is not verified. * The file is created in the current directory instead of some temporary space. Fix: resorting to standard temporary file approaches (`mkstemp` on POSIX and `GetTempFileName` on Windows).
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Looks like a reasonable fix. @wbhart is there a reason why the quadratic sieve uses files in the first place instead of doing everything in memory? |
Collaborator
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No, not really, apart from the fact that you don't know how much memory there is. Pari/GP used to use files and I just adopted the same technique. Bill Allombert subsequently switched it to using memory, which is defensible these days. |
Collaborator
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Indeed, #708 mentions this. Anyway, I will merge this as soon as CI is working again. |
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This was referenced Aug 5, 2023
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The
qsieve_factor()function uses a temporary file (with nameqs_inf->fname) for internal operation.There were a few issues with this file:
srand()call ensures that different threads will be using an identical "random" name. The ensuing race condition leads to crashes.Fix: resorting to standard temporary file approaches (
mkstempon POSIX andGetTempFileNameon Windows).