fix(readers): libnfc connection strings, double-close race, and NTP false wake#532
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wizzomafizzo merged 5 commits intomainfrom Feb 9, 2026
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…cores libnfc driver names require underscores (e.g. "pn532_i2c", "pn532_uart") but ConnectionString() normalization was stripping them, producing invalid strings like "pn532i2c:/dev/i2c-2" that libnfc cannot recognize. This caused all PN532 I2C and UART connections via libnfc to fail with "cannot open NFC device" after 10 retries. Fixes connection string translation in Open(), Detect(), and both auto-detect functions (detectSerialReaders, detectI2CReaders).
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On MiSTer (no RTC), the system boots at epoch (1970). When NTP syncs, the wall clock jumps ~56 years. SleepWakeMonitor was interpreting this as a wake-from-sleep event, triggering bulk reader reconnection and causing the "keeps disconnecting" bug. Now Check() skips wake detection when lastCheck was from an unreliable clock (year < 2024), since the elapsed time is meaningless in that case.
The libnfc reader had no mutex protecting its polling and pnd fields. When SleepWakeMonitor triggered reconnection, Close() could race with the polling goroutine, causing a double-close of the C library handle and crashing the service. Add syncutil.RWMutex to protect shared state, following the pattern already used by acr122pcsc and pn532 readers. Close() now nil-checks and nil-outs the device handle under lock before closing it, preventing the double-close race.
wizzomafizzo
changed the title
…methods Cover Connected, Info, Path, Close (nil device), ReaderID, and validateWriteParameters — all pure-logic paths that don't require the libnfc C library.
![sentry[bot]](https://avatars.githubusercontent.com/in/12637?s=60&v=4){kind=small}
…ng Close Capture r.pnd into a local variable under the mutex at the start of writeTag, matching the pattern already used by the polling goroutine. Previously, Close() could nil out r.pnd while writeTag was mid-operation, causing a panic on the next r.pnd method call.
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Summary
pn532_i2c,pn532_uart) butConnectionString()normalization was stripping them, producing invalid strings that libnfc cannot recognize. Extracts translation into testabletoLibnfcConnStr()with full regression coverage.SleepWakeMonitormisinterprets the ~56-year wall clock jump as wake-from-sleep, triggering bulk reader reconnection. Fixed by skipping wake detection when the previous timestamp was from an unreliable clock (year < 2024).pollingandpndfields. ConcurrentClose()calls could double-close the C library handle, crashing the service. Fixed by addingsyncutil.RWMutexprotection following the pattern used by acr122pcsc and pn532 readers.