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Improve event handling on macOS and Windows #117

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fb94b35
Improve win state handling
liamcmitchell Feb 24, 2026
2699d0f
Fix compiler warnings
liamcmitchell Feb 24, 2026
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83 changes: 55 additions & 28 deletions lib/devices.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -284,42 +284,69 @@ export class Devices extends EventEmitter {

state.hasCard = true;

// Try to connect to the card
try {
const readers = this._context!.listReaders();
const reader = readers.find((r) => r.name === readerName);
// Resolve reader with a short retry window for transient list churn.
const maxLookupAttempts = 3;
const lookupRetryDelayMs = 50;
let reader: Reader | undefined;

for (let attempt = 0; attempt < maxLookupAttempts; attempt++) {
if (!this._running || !this._context || !this._context.isValid) {
return;
}

const readers = this._context.listReaders();
reader = readers.find((r) => r.name === readerName);
if (reader) {
let nativeCard: Card;
try {
// First try with both T=0 and T=1 protocols
break;
}

if (attempt < maxLookupAttempts - 1) {
await new Promise((resolve) =>
setTimeout(resolve, lookupRetryDelayMs)
);
}
}

if (!reader) {
this.emit(
'error',
new Error(
`Reader not found while handling card insertion: ${readerName}`
)
);
return;
}

// Try to connect to the card
try {
let nativeCard: Card;
try {
// First try with both T=0 and T=1 protocols
nativeCard = await reader.connect(
this._SCARD_SHARE_SHARED,
this._SCARD_PROTOCOL_T0 | this._SCARD_PROTOCOL_T1
);
} catch (dualProtocolErr) {
// If dual protocol fails with unresponsive card error,
// fallback to T=0 only (issue #34)
if (isUnresponsiveCardError(dualProtocolErr as Error)) {
nativeCard = await reader.connect(
this._SCARD_SHARE_SHARED,
this._SCARD_PROTOCOL_T0 | this._SCARD_PROTOCOL_T1
this._SCARD_PROTOCOL_T0
);
} catch (dualProtocolErr) {
// If dual protocol fails with unresponsive card error,
// fallback to T=0 only (issue #34)
if (isUnresponsiveCardError(dualProtocolErr as Error)) {
nativeCard = await reader.connect(
this._SCARD_SHARE_SHARED,
this._SCARD_PROTOCOL_T0
);
} else {
// Re-throw if it's a different error
throw dualProtocolErr;
}
} else {
throw dualProtocolErr;
}
}

// Wrap the native card to add autoGetResponse support
const card = wrapCard(nativeCard);
state.card = card;
// Wrap the native card to add autoGetResponse support
const card = wrapCard(nativeCard);
state.card = card;

this.emit('card-inserted', {
reader: { name: readerName, state: eventState, atr: atr },
card: card,
});
}
this.emit('card-inserted', {
reader: { name: readerName, state: eventState, atr: atr },
card: card,
});
} catch (err) {
// Emit error but don't fail
this.emit('error', err as Error);
Expand Down
4 changes: 2 additions & 2 deletions src/async_workers.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -60,10 +60,10 @@ void WaitForChangeWorker::OnOK() {
}

deferred_.Resolve(changes);
} else if (result_ == SCARD_E_CANCELLED) {
} else if (result_ == static_cast<LONG>(SCARD_E_CANCELLED)) {
// Cancelled - resolve with null
deferred_.Resolve(env.Null());
} else if (result_ == SCARD_E_TIMEOUT) {
} else if (result_ == static_cast<LONG>(SCARD_E_TIMEOUT)) {
// Timeout - resolve with empty array
deferred_.Resolve(Napi::Array::New(env, 0));
} else {
Expand Down
6 changes: 3 additions & 3 deletions src/pcsc_context.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ Napi::Value PCSCContext::ListReaders(const Napi::CallbackInfo& info) {
DWORD readersLen = 0;
LONG result = SCardListReaders(context_, nullptr, nullptr, &readersLen);

if (result == SCARD_E_NO_READERS_AVAILABLE) {
if (result == static_cast<LONG>(SCARD_E_NO_READERS_AVAILABLE)) {
// No readers - return empty array
return Napi::Array::New(env, 0);
}
Expand Down Expand Up @@ -164,7 +164,7 @@ Napi::Value PCSCContext::WaitForChange(const Napi::CallbackInfo& info) {
DWORD readersLen = 0;
LONG result = SCardListReaders(context_, nullptr, nullptr, &readersLen);

if (result == SCARD_E_NO_READERS_AVAILABLE) {
if (result == static_cast<LONG>(SCARD_E_NO_READERS_AVAILABLE)) {
// Add PnP notification to detect when readers are attached
readerNames.push_back("\\\\?PnP?\\Notification");
currentStates.push_back(SCARD_STATE_UNAWARE);
Expand Down Expand Up @@ -200,7 +200,7 @@ Napi::Value PCSCContext::Cancel(const Napi::CallbackInfo& info) {
}

LONG result = SCardCancel(context_);
if (result != SCARD_S_SUCCESS && result != SCARD_E_INVALID_HANDLE) {
if (result != SCARD_S_SUCCESS && result != static_cast<LONG>(SCARD_E_INVALID_HANDLE)) {
Napi::Error::New(env, GetPCSCErrorString(result)).ThrowAsJavaScriptException();
}

Expand Down
88 changes: 70 additions & 18 deletions src/reader_monitor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -240,11 +240,11 @@ void ReaderMonitor::MonitorLoop() {
break;
}

if (result == SCARD_E_CANCELLED) {
if (result == static_cast<LONG>(SCARD_E_CANCELLED)) {
break;
}

if (result == SCARD_E_TIMEOUT) {
if (result == static_cast<LONG>(SCARD_E_TIMEOUT)) {
// Timeout - query fresh state to detect missed events (Issue #111)
// On Windows, dwEventState after timeout may just mirror dwCurrentState
// rather than reflecting actual hardware state. We must explicitly
Expand Down Expand Up @@ -322,6 +322,8 @@ void ReaderMonitor::MonitorLoop() {
// PnP notification - reader list changed
if (readerNames[i] == "\\\\?PnP?\\Notification") {
pnpTriggered = true;
const auto oldReaderStates = readerStates_;

// Get old reader names
std::vector<std::string> oldNames;
for (const auto& pair : readerStates_) {
Expand Down Expand Up @@ -351,12 +353,33 @@ void ReaderMonitor::MonitorLoop() {
EmitEvent("reader-detached", old, 0, {});
}
}
continue;

// Reconcile card presence for readers that still exist after PnP update.
// This minimizes missed insert/remove events that occurred during reader churn.
for (const auto& pair : readerStates_) {
const std::string& name = pair.first;
auto oldIt = oldReaderStates.find(name);
if (oldIt == oldReaderStates.end()) {
continue;
}

DWORD oldState = oldIt->second.lastState;
DWORD newState = pair.second.lastState;

bool wasPresent = (oldState & SCARD_STATE_PRESENT) != 0;
bool isPresent = (newState & SCARD_STATE_PRESENT) != 0;

if (!wasPresent && isPresent) {
EmitEvent("card-inserted", name, newState, pair.second.atr);
} else if (wasPresent && !isPresent) {
EmitEvent("card-removed", name, newState, {});
}
}

// Reader indices from this event batch may now be stale.
break;
}

// Skip reader state processing if PnP was triggered in this iteration
// The reader list has changed, so indices are no longer valid
// We'll pick up any card changes on the next iteration with fresh state
if (pnpTriggered) {
continue;
}
Expand Down Expand Up @@ -390,6 +413,10 @@ void ReaderMonitor::MonitorLoop() {
}
}
}

if (pnpTriggered) {
continue;
}
}
}

Expand All @@ -398,7 +425,7 @@ void ReaderMonitor::UpdateReaderList() {
DWORD readersLen = 0;
LONG result = SCardListReaders(context_, nullptr, nullptr, &readersLen);

if (result == SCARD_E_NO_READERS_AVAILABLE || readersLen == 0) {
if (result == static_cast<LONG>(SCARD_E_NO_READERS_AVAILABLE) || readersLen == 0) {
readerStates_.clear();
return;
}
Expand All @@ -423,25 +450,47 @@ void ReaderMonitor::UpdateReaderList() {
p += strlen(p) + 1;
}

// Get initial state for new readers
// Preserve previous state for readers that still exist
const auto previousStates = readerStates_;

// Get initial state for listed readers
std::vector<SCARD_READERSTATE> states(newNames.size());
for (size_t i = 0; i < newNames.size(); i++) {
states[i].szReader = newNames[i].c_str();
states[i].dwCurrentState = SCARD_STATE_UNAWARE;
}

SCardGetStatusChange(context_, 0, states.data(), states.size());
LONG stateResult = SCARD_S_SUCCESS;
if (!states.empty()) {
stateResult = SCardGetStatusChange(context_, 0, states.data(), states.size());
}

// Update reader states map (Issue #111 fix: use map keyed by name)
readerStates_.clear();
std::unordered_map<std::string, ReaderInfo> updatedStates;
for (size_t i = 0; i < newNames.size(); i++) {
ReaderInfo info;
info.lastState = states[i].dwEventState & ~SCARD_STATE_CHANGED;
if (states[i].cbAtr > 0) {
info.atr.assign(states[i].rgbAtr, states[i].rgbAtr + states[i].cbAtr);
const std::string& name = newNames[i];
ReaderInfo info = {};

auto previousIt = previousStates.find(name);
if (previousIt != previousStates.end()) {
info = previousIt->second;
} else {
info.lastState = SCARD_STATE_UNAWARE;
}
readerStates_[newNames[i]] = info;

if (stateResult == SCARD_S_SUCCESS) {
info.lastState = states[i].dwEventState & ~SCARD_STATE_CHANGED;
if (states[i].cbAtr > 0) {
info.atr.assign(states[i].rgbAtr, states[i].rgbAtr + states[i].cbAtr);
} else {
info.atr.clear();
}
}

updatedStates[name] = info;
}

readerStates_.swap(updatedStates);
}

void ReaderMonitor::EmitEvent(const std::string& eventType, const std::string& readerName,
Expand All @@ -450,9 +499,9 @@ void ReaderMonitor::EmitEvent(const std::string& eventType, const std::string& r
// before the callback executes (prevents memory leak)
auto data = std::make_shared<EventData>(EventData{eventType, readerName, state, atr});

// Call JavaScript callback on main thread
// Capture shared_ptr by value to extend lifetime until callback executes
tsfn_.BlockingCall(data.get(), [data](Napi::Env env, Napi::Function callback, EventData* ptr) {
// Call JavaScript callback on main thread without blocking monitor thread.
// Capture shared_ptr by value to extend lifetime until callback executes.
napi_status status = tsfn_.NonBlockingCall(data.get(), [data](Napi::Env env, Napi::Function callback, EventData* ptr) {
// Build event object
Napi::Object event = Napi::Object::New(env);
event.Set("type", Napi::String::New(env, ptr->eventType));
Expand All @@ -469,4 +518,7 @@ void ReaderMonitor::EmitEvent(const std::string& eventType, const std::string& r
callback.Call({event});
// shared_ptr automatically cleaned up when lambda is destroyed
});

// Ignore errors when queue is closing during shutdown.
(void)status;
}