1 /*
   2  * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "runtime/interfaceSupport.hpp"
  28 #include "runtime/osThread.hpp"
  29 
  30 #include <signal.h>
  31 
  32 
  33 // sun.misc.Signal ///////////////////////////////////////////////////////////
  34 // Signal code is mostly copied from classic vm, signals_md.c   1.4 98/08/23
  35 /*
  36  * This function is included primarily as a debugging aid. If Java is
  37  * running in a console window, then pressing <CTRL-\\> will cause
  38  * the current state of all active threads and monitors to be written
  39  * to the console window.
  40  */
  41 
  42 JVM_ENTRY_NO_ENV(void*, JVM_RegisterSignal(jint sig, void* handler))
  43   // Copied from classic vm
  44   // signals_md.c       1.4 98/08/23
  45   void* newHandler = handler == (void *)2
  46                    ? os::user_handler()
  47                    : handler;
  48   switch (sig) {
  49     /* The following are already used by the VM. */
  50     case SIGFPE:
  51     case SIGILL:
  52     case SIGSEGV:
  53 
  54 #if defined(__APPLE__)
  55     /* On Darwin, memory access errors commonly results in SIGBUS instead
  56      * of SIGSEGV. */
  57     case SIGBUS:
  58 #endif
  59 
  60     /* The following signal is used by the VM to dump thread stacks unless
  61        ReduceSignalUsage is set, in which case the user is allowed to set
  62        his own _native_ handler for this signal; thus, in either case,
  63        we do not allow JVM_RegisterSignal to change the handler. */
  64     case BREAK_SIGNAL:
  65       return (void *)-1;
  66 
  67     /* The following signals are used for Shutdown Hooks support. However, if
  68        ReduceSignalUsage (-Xrs) is set, Shutdown Hooks must be invoked via
  69        System.exit(), Java is not allowed to use these signals, and the the
  70        user is allowed to set his own _native_ handler for these signals and
  71        invoke System.exit() as needed. Terminator.setup() is avoiding
  72        registration of these signals when -Xrs is present.
  73        - If the HUP signal is ignored (from the nohup) command, then Java
  74          is not allowed to use this signal.
  75      */
  76 
  77     case SHUTDOWN1_SIGNAL:
  78     case SHUTDOWN2_SIGNAL:
  79     case SHUTDOWN3_SIGNAL:
  80       if (ReduceSignalUsage) return (void*)-1;
  81       if (os::Bsd::is_sig_ignored(sig)) return (void*)1;
  82   }
  83 
  84   void* oldHandler = os::signal(sig, newHandler);
  85   if (oldHandler == os::user_handler()) {
  86       return (void *)2;
  87   } else {
  88       return oldHandler;
  89   }
  90 JVM_END
  91 
  92 
  93 JVM_ENTRY_NO_ENV(jboolean, JVM_RaiseSignal(jint sig))
  94   if (ReduceSignalUsage) {
  95     // do not allow SHUTDOWN1_SIGNAL,SHUTDOWN2_SIGNAL,SHUTDOWN3_SIGNAL,
  96     // BREAK_SIGNAL to be raised when ReduceSignalUsage is set, since
  97     // no handler for them is actually registered in JVM or via
  98     // JVM_RegisterSignal.
  99     if (sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
 100         sig == SHUTDOWN3_SIGNAL || sig == BREAK_SIGNAL) {
 101       return JNI_FALSE;
 102     }
 103   }
 104   else if ((sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
 105             sig == SHUTDOWN3_SIGNAL) && os::Bsd::is_sig_ignored(sig)) {
 106     // do not allow SHUTDOWN1_SIGNAL to be raised when SHUTDOWN1_SIGNAL
 107     // is ignored, since no handler for them is actually registered in JVM
 108     // or via JVM_RegisterSignal.
 109     // This also applies for SHUTDOWN2_SIGNAL and SHUTDOWN3_SIGNAL
 110     return JNI_FALSE;
 111   }
 112 
 113   os::signal_raise(sig);
 114   return JNI_TRUE;
 115 JVM_END
 116 
--- EOF ---