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MIDI controller settings are silently lost on the next launch #3883

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@mcfnord

🤖 AI: MIDI controller settings do not survive a restart. Two independent defects produce the same symptom: the ini reader's range checks reject values that then reset to 0, and the JSON-RPC setter accepts values it never validates. All measured on main @ 8b667a3a, Qt 5.15.3, x86-64, QT_QPA_PLATFORM=offscreen.

1. --ctrlmidich count of 128 is rejected on reload (ini range check off by one)

CSettings::ReadFromFile range-checks nine MIDI keys against one shared 0..127 (src/settings.cpp:655). Four of those keys are counts rather than CC numbers, and both documented --ctrlmidich syntaxes legitimately produce 128:

  • legacy 1;0 sets iMidiFaderCount = qMin ( MAX_NUM_CHANNELS, 128 - iOffset ) = 128 (src/settings.cpp:285)
  • named 1;f0*128 sets iNum = qMin ( iNum, MAX_NUM_CHANNELS ) then qMin ( iNum, 128 - iFirst ) = 128 (src/settings.cpp:332)

128 is then written to the ini, and GetNumericIniSet's upper bound is inclusive (src/settings.cpp:144), so the stored value fails the check on read, the member keeps its default, and the count lands at 0. One launch with the flag to write the ini, one launch without it to read back:

key after --ctrlmidich "1;<t>0*128" after the next launch
midifadercount 128 0
midipancount 128 0
midisolocount 128 0
midimutecount 128 0

Control, identical procedure with *127 instead of *128: all four read back 127. A count of 0 maps no controllers, so a full-width MIDI map works for exactly one session and is gone from the next one, with nothing logged. Fix: split the shared range so offsets stay 0..127 and the four counts accept 0..128.

2. jamulusclient/setMidiSettings has no range validation, so values persist and then vanish on reload

The JSON-RPC setter writes every field straight to settings with no bounds check (src/clientrpc.cpp:421). Out-of-range values are accepted (the call returns {"result":"ok"}), saved to the ini on quit, and silently dropped by the reader's range checks on the next launch. One client driven over the JSON-RPC socket, quit, relaunched on the same ini:

field (valid range) set via RPC read back, same session in the ini after relaunch
midiChannel (0..16) 99 99 <midichannel>99</…> 0
midiFaderOffset (0..127) 5000 5000 <midifaderoffset>5000</…> 0
midiFaderCount (0..127) 200 200 <midifadercount>200</…> 0

midiChannel is checked at src/settings.cpp:636, the offsets and counts at src/settings.cpp:655, so all three fail on load and reset to the default 0 — the same silent-loss mechanism as case 1, reached through the RPC instead of the command line. Fix: validate the fields in setMidiSettings (reject or clamp) so a value the API accepts is one the reader will keep.


🤖 This message was written by AI and reviewed by @mcfnord.

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