src/java.base/unix/native/libnio/ch/NativeThread.c

/*
 * Copyright (c) 2002, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

#include <sys/types.h>
#include <string.h>
#include "jni.h"
#include "jni_util.h"
#include "jvm.h"
#include "jlong.h"
#include "sun_nio_ch_NativeThread.h"
#include "nio_util.h"
#include <signal.h>
#include <pthread.h>

#ifdef __linux__
  /* Also defined in net/linux_close.c */
  #define INTERRUPT_SIGNAL (SIGRTMAX - 2)
#elif defined(_AIX)
  /* Also defined in net/aix_close.c */
  #define INTERRUPT_SIGNAL (SIGRTMAX - 1)
#elif defined(_ALLBSD_SOURCE)
  /* Also defined in net/bsd_close.c */
  #define INTERRUPT_SIGNAL SIGIO
#else
  #error "missing platform-specific definition here"
#endif

static void
nullHandler(int sig)
{
}

JNIEXPORT void JNICALL
Java_sun_nio_ch_NativeThread_init(JNIEnv *env, jclass cl)
{
    /* Install the null handler for INTERRUPT_SIGNAL.  This might overwrite the
     * handler previously installed by <platform>_close.c, but that's okay
     * since neither handler actually does anything.  We install our own
     * handler here simply out of paranoia; ultimately the two mechanisms
     * should somehow be unified, perhaps within the VM.
     */

    struct sigaction sa, osa;
    sa.sa_handler = nullHandler;
    sa.sa_flags = 0;
    sigemptyset(&sa.sa_mask);
    if (sigaction(INTERRUPT_SIGNAL, &sa, &osa) < 0)
        JNU_ThrowIOExceptionWithLastError(env, "sigaction");
}

JNIEXPORT jlong JNICALL
Java_sun_nio_ch_NativeThread_current0(JNIEnv *env, jclass cl)
{
    return (jlong)pthread_self();
}

JNIEXPORT void JNICALL
Java_sun_nio_ch_NativeThread_signal0(JNIEnv *env, jclass cl, jlong thread)
{
    int ret;
    ret = pthread_kill((pthread_t)thread, INTERRUPT_SIGNAL);
#ifdef MACOSX
    if (ret != 0 && ret != ESRCH)
#else
    if (ret != 0)
#endif
        JNU_ThrowIOExceptionWithLastError(env, "Thread signal failed");
}

JNIEXPORT jboolean JNICALL
Java_sun_nio_ch_NativeThread_supportPendingSignals0(JNIEnv *env, jclass cl) {
#if defined(_AIX)
    return JNI_TRUE;
#else
    return JNI_FALSE;
#endif
}