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Fix process-wide signal handler override in JNI_OnLoad #632

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Fix process-wide signal handler override in JNI_OnLoad #632

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34 changes: 20 additions & 14 deletions src/main/c/Posix/SerialPort_Posix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,16 @@ static void enumeratePorts(void)
// Event listening threads
void* eventReadingThread1(void *serialPortPointer)
{
// Block signals that could be triggered by serial port operations in this thread only,
// avoiding process-wide signal handler changes that would interfere with the JVM
sigset_t signalMask;
sigemptyset(&signalMask);
sigaddset(&signalMask, SIGHUP);
sigaddset(&signalMask, SIGIO);
sigaddset(&signalMask, SIGTTOU);
sigaddset(&signalMask, SIGTTIN);
pthread_sigmask(SIG_BLOCK, &signalMask, NULL);

// Make this thread immediately and asynchronously cancellable
int oldValue;
serialPort *port = (serialPort*)(intptr_t)serialPortPointer;
Expand Down Expand Up @@ -185,6 +195,16 @@ void* eventReadingThread1(void *serialPortPointer)

void* eventReadingThread2(void *serialPortPointer)
{
// Block signals that could be triggered by serial port operations in this thread only,
// avoiding process-wide signal handler changes that would interfere with the JVM
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGHUP);
sigaddset(&mask, SIGIO);
sigaddset(&mask, SIGTTOU);
sigaddset(&mask, SIGTTIN);
pthread_sigmask(SIG_BLOCK, &mask, NULL);

// Make this thread immediately and asynchronously cancellable
int oldValue;
serialPort *port = (serialPort*)(intptr_t)serialPortPointer;
Expand Down Expand Up @@ -333,20 +353,6 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved)
eventFlagsField = (*env)->GetFieldID(env, serialCommClass, "eventFlags", "I");
if (checkJniError(env, __LINE__ - 1)) return JNI_ERR;

// Disable handling of various POSIX signals
sigset_t blockMask;
memset(&blockMask, 0, sizeof(blockMask));
struct sigaction ignoreAction = { 0 };
ignoreAction.sa_handler = SIG_IGN;
ignoreAction.sa_mask = blockMask;
sigaction(SIGIO, &ignoreAction, NULL);
sigaction(SIGHUP, &ignoreAction, NULL);
sigaction(SIGCONT, &ignoreAction, NULL);
sigaction(SIGUSR1, &ignoreAction, NULL);
sigaction(SIGUSR2, &ignoreAction, NULL);
sigaction(SIGTTOU, &ignoreAction, NULL);
sigaction(SIGTTIN, &ignoreAction, NULL);

// Initialize the critical section lock
pthread_mutex_init(&criticalSection, NULL);
classInitialized = 1;
Expand Down