ADDITIONAL SYSTEM INFORMATION :
Linux XXX 5.4.0-2-amd64 #1 SMP Debian 5.4.8-1 (2020-01-05) x86_64 GNU/Linux
openjdk version "11.0.6-ea" 2020-01-14
OpenJDK Runtime Environment (build 11.0.6-ea+7-post-Debian-1)
OpenJDK 64-Bit Server VM (build 11.0.6-ea+7-post-Debian-1, mixed mode, sharing)


A DESCRIPTION OF THE PROBLEM :
setting a signal handler and raise the signal SIGQUIT with kill(getpid(), SIGQUIT) will cause inside the signalhandler
(*jvm)->AttachCurrentThread(jvm, (void**) &env, NULL) return JNI_OK, but *env is NULL.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
compile and run the source code of main.c

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
*env not NULL
ACTUAL -
*env is NULL

---------- BEGIN SOURCE ----------
/*
 * File: main.c
 *
 * Created on 9. Januar 2020, 09:09
 */
#define _GNU_SOURCE

#include <signal.h>
#include <unistd.h>

#include <jni.h>
#include <stdlib.h>

static JavaVM *jvm;

#define SIG SIGQUIT

int signalHandler(int sig) {
    fprintf(stdout, "Signal received\n");
    JNIEnv *env;
    if ((*jvm)->AttachCurrentThread(jvm, (void**) &env, NULL) == JNI_OK) {
        if (*env == NULL) {
            //We should never reach this point here.
            fprintf(stderr, "Sucess, but env is NULL - This should never happen!\n");
            exit(1);
        } else {
            fprintf(stdout, "Sucess got env\n");
            exit(0);
        }
    } else {
        fprintf(stderr, "got no env\n");
        exit(2);
    }
}

int main() {
    fprintf(stdout, "Starting\n");
    jint res;
    JNIEnv *env;
    JavaVMInitArgs vm_args;
    vm_args.version = JNI_VERSION_10;
    vm_args.options = NULL;
    vm_args.nOptions = 0;
    vm_args.ignoreUnrecognized = JNI_TRUE;
    res = JNI_CreateJavaVM(&jvm, (void**) &env, &vm_args);
    if (res != JNI_OK) {
        fprintf(stderr, "Can*t create the Java VM\n");
        exit(-1);
    }
    
    signal(SIG, (__sighandler_t) & signalHandler);
    fprintf(stdout, "Will raise signal\n");
    kill(getpid(), SIG);
// raise(SIG); //Why does raise is differnt from kill here - the signal is not delivered -POSIX?
    fprintf(stdout, "Signal raised\n");
    sleep(2);
    exit(3);
}
---------- END SOURCE ----------

FREQUENCY : always