1/*
2 * Copyright (c) 1999, 2015, 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 "prims/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
42JVM_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    /* The following signal is used by the VM to dump thread stacks unless
55       ReduceSignalUsage is set, in which case the user is allowed to set
56       his own _native_ handler for this signal; thus, in either case,
57       we do not allow JVM_RegisterSignal to change the handler. */
58    case BREAK_SIGNAL:
59      return (void *)-1;
60
61    /* The following signals are used for Shutdown Hooks support. However, if
62       ReduceSignalUsage (-Xrs) is set, Shutdown Hooks must be invoked via
63       System.exit(), Java is not allowed to use these signals, and the the
64       user is allowed to set his own _native_ handler for these signals and
65       invoke System.exit() as needed. Terminator.setup() is avoiding
66       registration of these signals when -Xrs is present.
67       - If the HUP signal is ignored (from the nohup) command, then Java
68         is not allowed to use this signal.
69     */
70
71    case SHUTDOWN1_SIGNAL:
72    case SHUTDOWN2_SIGNAL:
73    case SHUTDOWN3_SIGNAL:
74      if (ReduceSignalUsage) return (void*)-1;
75      if (os::Linux::is_sig_ignored(sig)) return (void*)1;
76  }
77
78  void* oldHandler = os::signal(sig, newHandler);
79  if (oldHandler == os::user_handler()) {
80      return (void *)2;
81  } else {
82      return oldHandler;
83  }
84JVM_END
85
86
87JVM_ENTRY_NO_ENV(jboolean, JVM_RaiseSignal(jint sig))
88  if (ReduceSignalUsage) {
89    // do not allow SHUTDOWN1_SIGNAL,SHUTDOWN2_SIGNAL,SHUTDOWN3_SIGNAL,
90    // BREAK_SIGNAL to be raised when ReduceSignalUsage is set, since
91    // no handler for them is actually registered in JVM or via
92    // JVM_RegisterSignal.
93    if (sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
94        sig == SHUTDOWN3_SIGNAL || sig == BREAK_SIGNAL) {
95      return JNI_FALSE;
96    }
97  }
98  else if ((sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
99            sig == SHUTDOWN3_SIGNAL) && os::Linux::is_sig_ignored(sig)) {
100    // do not allow SHUTDOWN1_SIGNAL to be raised when SHUTDOWN1_SIGNAL
101    // is ignored, since no handler for them is actually registered in JVM
102    // or via JVM_RegisterSignal.
103    // This also applies for SHUTDOWN2_SIGNAL and SHUTDOWN3_SIGNAL
104    return JNI_FALSE;
105  }
106
107  os::signal_raise(sig);
108  return JNI_TRUE;
109JVM_END
110
111