Timestamp: Prevent integer overflow on Darwin PPC 32-bit #511
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A Darwin PPC 32-bit user observes huge values numer == 1000000000 and denom == 18431683 returned from mach_timebase_info(). For these values, mach_absolute_time() * numer overflows uint64_t every 1000.82 seconds, and 1000000 * denom always overflows uint32_t, with the effect of making time run backwards at -11190660 times its usual speed. This bug was masked on Darwin x86 64-bit, where numer == denom == 1. Fix it by doing the conversion with double arithmetic instead. Closes mobile-shell#479. Signed-off-by: Anders Kaseorg <andersk@mit.edu>
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👍 |
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Can this be merged or is there still any blocking issue? |
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Have any of you tried this on Darwin/PPC? Once it's tested there I'll pull it. |
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Yep, both @gordon-morehouse and I have tested this and it works well. |
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Pulled. |
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Hand-me-down users the world over thank you! ;) |
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A Darwin PPC 32-bit user observes huge values
numer == 1000000000anddenom == 18431683returned frommach_timebase_info(). For these values,mach_absolute_time() * numeroverflowsuint64_tevery 1000.82 seconds, and1000000 * denomalways overflowsuint32_t, with the effect of making time run backwards at -11190660 times its usual speed.This bug was masked on Darwin x86 64-bit, where
numer == denom == 1.Fix it by doing the conversion with
doublearithmetic instead.Closes #479.