[release/6.0] Fallback to read/write if pread/pwrite fails #60280
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…/pwrite for unseekable files * Fallback to read/write only for known error ENXIO
…esAndSockets.cs Use Lazy for thread-safety Co-authored-by: Adam Sitnik <[email protected]>
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jeffhandley
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Oct 12, 2021
adamsitnik
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Oct 12, 2021
jeffhandley
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Tactics approved for 6.0 GA |
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Backport of #59846 to release/6.0.
Fixes #59754
Customer Impact
On Unix, Read/Write to certain special devices e.g:
/dev/ttyusing FIleStream stopped working on 6.0 given that we now use a different syscall for unseekable files.Our assumption was that such files always reported
CanSeekas false, but that turned out to not be true for/dev/ttyon macOS.This change catches the aforementioned error and fallbacks to the syscall that we previously used for seekable and non-seekable files.
Testing
Tested with many other devices that share similarities with
/dev/tty:e.g:
/dev/null,/dev/zero,/dev/console, named pipes and socket pairs.Risk
Low, we are affecting one edge case only which currently is in a regression state.