1 /*
2 * Copyright (c) 1999, 2017, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 #include <stdatomic.h>
27
28 #include "vmDebug.h"
29
30 #include "JDWP.h"
31 #include "debugLoop.h"
32 #include "transport.h"
33 #include "util.h"
34
35 static _Atomic(jlong) lastDebuggerActivity = ATOMIC_VAR_INIT(0LL);
36 static _Atomic(jboolean) hasSeenDebuggerActivity = ATOMIC_VAR_INIT(JNI_FALSE);
37
38 // Reset the tracking variables.
vmDebug_onDisconnect()39 void vmDebug_onDisconnect()
40 {
41 atomic_store(&lastDebuggerActivity, 0LL);
42 atomic_store(&hasSeenDebuggerActivity, JNI_FALSE);
43 }
44
45 // Mark us as having seen actual debugger activity (so isDebuggerConnected can return true) and that
46 // we are currently doing something as the debugger.
vmDebug_notifyDebuggerActivityStart()47 void vmDebug_notifyDebuggerActivityStart()
48 {
49 atomic_store(&lastDebuggerActivity, 0LL);
50 atomic_store(&hasSeenDebuggerActivity, JNI_TRUE);
51 }
52
53 // Update the timestamp for the last debugger activity.
vmDebug_notifyDebuggerActivityEnd()54 void vmDebug_notifyDebuggerActivityEnd()
55 {
56 atomic_store(&lastDebuggerActivity, milliTime());
57 }
58
59 // For backwards compatibility we are only considered 'connected' as far as VMDebug is concerned if
60 // we have gotten at least one non-ddms JDWP packet.
61 static jboolean
isDebuggerConnected()62 isDebuggerConnected()
63 {
64 return transport_is_open() && atomic_load(&hasSeenDebuggerActivity);
65 }
66
67 static jboolean JNICALL
VMDebug_isDebuggerConnected(JNIEnv * env,jclass klass)68 VMDebug_isDebuggerConnected(JNIEnv* env, jclass klass)
69 {
70 return isDebuggerConnected();
71 }
72
73 static jboolean JNICALL
VMDebug_isDebuggingEnabled(JNIEnv * env,jclass klass)74 VMDebug_isDebuggingEnabled(JNIEnv* env, jclass klass)
75 {
76 // We are running the debugger so debugging is definitely enabled.
77 return JNI_TRUE;
78 }
79
80 static jlong JNICALL
VMDebug_lastDebuggerActivity(JNIEnv * env,jclass klass)81 VMDebug_lastDebuggerActivity(JNIEnv* env, jclass klass)
82 {
83 if (!isDebuggerConnected()) {
84 LOG_ERROR(("VMDebug.lastDebuggerActivity called without active debugger"));
85 return -1;
86 }
87 jlong last_time = atomic_load(&lastDebuggerActivity);
88 if (last_time == 0) {
89 LOG_MISC(("debugger is performing an action"));
90 return 0;
91 }
92
93 jlong cur_time = milliTime();
94
95 if (cur_time < last_time) {
96 LOG_ERROR(("Time seemed to go backwards: last was %lld, current is %lld",
97 last_time, cur_time));
98 return 0;
99 }
100 jlong res = cur_time - last_time;
101 LOG_MISC(("Debugger interval is %lld", res));
102 return res;
103 }
104
105 void
vmDebug_initalize(JNIEnv * env)106 vmDebug_initalize(JNIEnv* env)
107 {
108 WITH_LOCAL_REFS(env, 1) {
109 jclass vmdebug_class = JNI_FUNC_PTR(env,FindClass)(env, "dalvik/system/VMDebug");
110 if (vmdebug_class == NULL) {
111 // The VMDebug class isn't available. We don't need to do anything.
112 LOG_MISC(("dalvik.system.VMDebug does not seem to be available on this runtime."));
113 // Get rid of the ClassNotFoundException.
114 JNI_FUNC_PTR(env,ExceptionClear)(env);
115 goto finish;
116 }
117
118 JNINativeMethod methods[3];
119
120 // Take over the implementation of these three functions.
121 methods[0].name = "lastDebuggerActivity";
122 methods[0].signature = "()J";
123 methods[0].fnPtr = (void*)VMDebug_lastDebuggerActivity;
124
125 methods[1].name = "isDebuggingEnabled";
126 methods[1].signature = "()Z";
127 methods[1].fnPtr = (void*)VMDebug_isDebuggingEnabled;
128
129 methods[2].name = "isDebuggerConnected";
130 methods[2].signature = "()Z";
131 methods[2].fnPtr = (void*)VMDebug_isDebuggerConnected;
132
133 jint res = JNI_FUNC_PTR(env,RegisterNatives)(env,
134 vmdebug_class,
135 methods,
136 sizeof(methods) / sizeof(JNINativeMethod));
137 if (res != JNI_OK) {
138 EXIT_ERROR(JVMTI_ERROR_INTERNAL,
139 "RegisterNatives returned failure for VMDebug class");
140 }
141
142 finish: ;
143 } END_WITH_LOCAL_REFS(env);
144 }
145
146