1 /*
   2  * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2012, 2013 SAP SE. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "jvm.h"
  28 #include "runtime/interfaceSupport.hpp"
  29 #include "runtime/osThread.hpp"
  30 
  31 #include <signal.h>
  32 
  33 
  34 // sun.misc.Signal ///////////////////////////////////////////////////////////
  35 // Signal code is mostly copied from classic vm, signals_md.c   1.4 98/08/23
  36 /*
  37  * This function is included primarily as a debugging aid. If Java is
  38  * running in a console window, then pressing <CTRL-\\> will cause
  39  * the current state of all active threads and monitors to be written
  40  * to the console window.
  41  */
  42 
  43 JVM_ENTRY_NO_ENV(void*, JVM_RegisterSignal(jint sig, void* handler))
  44   // Copied from classic vm
  45   // signals_md.c       1.4 98/08/23
  46   void* newHandler = handler == (void *)2
  47                    ? os::user_handler()
  48                    : handler;
  49   switch (sig) {
  50     /* The following are already used by the VM. */
  51     case SIGFPE:
  52     case SIGILL:
  53     case SIGSEGV:
  54 
  55     /* The following signal is used by the VM to dump thread stacks unless
  56        ReduceSignalUsage is set, in which case the user is allowed to set
  57        his own _native_ handler for this signal; thus, in either case,
  58        we do not allow JVM_RegisterSignal to change the handler. */
  59     case BREAK_SIGNAL:
  60       return (void *)-1;
  61 
  62     /* The following signals are used for Shutdown Hooks support. However, if
  63        ReduceSignalUsage (-Xrs) is set, Shutdown Hooks must be invoked via
  64        System.exit(), Java is not allowed to use these signals, and the the
  65        user is allowed to set his own _native_ handler for these signals and
  66        invoke System.exit() as needed. Terminator.setup() is avoiding
  67        registration of these signals when -Xrs is present.
  68        - If the HUP signal is ignored (from the nohup) command, then Java
  69          is not allowed to use this signal.
  70      */
  71 
  72     case SHUTDOWN1_SIGNAL:
  73     case SHUTDOWN2_SIGNAL:
  74     case SHUTDOWN3_SIGNAL:
  75       if (ReduceSignalUsage) return (void*)-1;
  76       if (os::Aix::is_sig_ignored(sig)) return (void*)1;
  77   }
  78 
  79   void* oldHandler = os::signal(sig, newHandler);
  80   if (oldHandler == os::user_handler()) {
  81       return (void *)2;
  82   } else {
  83       return oldHandler;
  84   }
  85 JVM_END
  86 
  87 
  88 JVM_ENTRY_NO_ENV(jboolean, JVM_RaiseSignal(jint sig))
  89   if (ReduceSignalUsage) {
  90     // do not allow SHUTDOWN1_SIGNAL,SHUTDOWN2_SIGNAL,SHUTDOWN3_SIGNAL,
  91     // BREAK_SIGNAL to be raised when ReduceSignalUsage is set, since
  92     // no handler for them is actually registered in JVM or via
  93     // JVM_RegisterSignal.
  94     if (sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
  95         sig == SHUTDOWN3_SIGNAL || sig == BREAK_SIGNAL) {
  96       return JNI_FALSE;
  97     }
  98   }
  99   else if ((sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
 100             sig == SHUTDOWN3_SIGNAL) && os::Aix::is_sig_ignored(sig)) {
 101     // do not allow SHUTDOWN1_SIGNAL to be raised when SHUTDOWN1_SIGNAL
 102     // is ignored, since no handler for them is actually registered in JVM
 103     // or via JVM_RegisterSignal.
 104     // This also applies for SHUTDOWN2_SIGNAL and SHUTDOWN3_SIGNAL
 105     return JNI_FALSE;
 106   }
 107 
 108   os::signal_raise(sig);
 109   return JNI_TRUE;
 110 JVM_END
 111