How to handle EINTR in connect()?

Question

I'm trying to handle EINTR error from POSIX connect call. I'm running on OSX this connect code:

JNIEXPORT jint JNICALL Java_io_questdb_network_Net_connect
        (JNIEnv *e, jclass cl, jint fd, jlong sockAddr) {
    jboolean retry = 0;
    int result;
    do {
        result = connect((int) fd, (const struct sockaddr *) sockAddr, sizeof(struct sockaddr));
        retry |= result == -1 && errno == EINTR;
    } while (result == -1 && errno == EINTR);

    if (retry && errno == EISCONN) {
        return 0;
    }
    return result;
}

This is JNI code I call from Java. When I run the code under the profiler, I quite often get EINTR. Sometimes after running this connect() method, I get ENOTCONN on next send() call using the socket.

If I remove

if (retry && errno == EISCONN) {
        return 0;
}

I start to get EISCONN very often when calling this method.

How can I properly handle EINTR here so the socket is connected at the end of the call?

Answer 1

There is no need for the retry variable. Just do:

int result;
do {
    result = ...
} while (result == -1 && errno == EINTR); //on error result will be -1,
                                          //additional test for EINTR,
                                          //if both are true, try again

//the same goes for EISCONN
if (result == -1 && errno == EISCONN) {
    //already connected
    //usually an error, but we consider it as success
    return 0;
}

return result; //0 on success, -1 on error

The return value will be 0 if connect succeeded or if already connected, or -1 in all other error cases.

man connect

If the connection or binding succeeds, zero is returned. On error, -1 is returned, and errno is set to indicate the error.