1 /*
2 * Copyright (c) 2019, 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 package sun.tools;
27
28 import java.io.IOException;
29 import java.io.UncheckedIOException;
30 import java.nio.file.Files;
31 import java.nio.file.Paths;
32 import java.util.jar.Attributes;
33 import java.util.jar.JarFile;
34 import java.util.jar.Manifest;
35 import java.util.stream.Stream;
36
37 /**
38 * A helper class that retrieves the main class name for
39 * a running Java process using the proc filesystem (procfs)
40 */
41 public class ProcessHelper implements sun.tools.common.ProcessHelper {
42
43
44 private static final String CMD_PREFIX = "cmd:";
45 private static final ProcessHelper INSTANCE = new ProcessHelper();
46
47 public static ProcessHelper getInstance() {
48 return INSTANCE;
49 }
50
51 /**
52 * Gets the main class name for the given Java process by parsing the
53 * process command line.
54 * @param pid - process ID (pid)
55 * @return main class name or null if the process no longer exists or
56 * was started with a native launcher (e.g. jcmd etc)
57 */
58
59 public String getMainClass(String pid) {
60 String cmdLine = getCommandLine(pid);
61 if (cmdLine == null) {
62 return null;
63 }
64 if (cmdLine.startsWith(CMD_PREFIX)) {
65 cmdLine = cmdLine.substring(CMD_PREFIX.length());
66 }
67 String[] parts = cmdLine.split(" ");
68 String mainClass = null;
69
70 if(parts.length == 0) {
71 return null;
72 }
73
74 // Check the executable
75 String[] executablePath = parts[0].split("/");
76 if (executablePath.length > 0) {
77 String binaryName = executablePath[executablePath.length - 1];
78 if (!"java".equals(binaryName)) {
79 // Skip the process if it is not started with java launcher
80 return null;
81 }
82 }
83
84 // If -jar option is used then read the main class name from the manifest file.
85 // Otherwise, the main class name is either specified in -m or --module options or it
86 // is the first part that is not a Java option (doesn't start with '-' and is not a
87 // classpath or a module path).
88
89 for (int i = 1; i < parts.length && mainClass == null; i++) {
90 if (i < parts.length - 1) {
91 // Check if the module is executed with explicitly specified main class
92 if ((parts[i].equals("-m") || parts[i].equals("--module"))) {
93 return getMainClassFromModuleArg(parts[i + 1]);
94 }
95 // Check if the main class needs to be read from the manifest.mf in a JAR file
96 if (parts[i].equals("-jar")) {
97 return getMainClassFromJar(parts[i + 1], pid);
98 }
99 }
100 // If this is a classpath or a module path option then skip the next part
101 // (the classpath or the module path itself)
102 if (parts[i].equals("-cp") || parts[i].equals("-classpath") || parts[i].equals("--class-path") ||
103 parts[i].equals("-p") || parts[i].equals("--module-path")) {
104 i++;
105 continue;
106 }
107 // Skip all other Java options
108 if (parts[i].startsWith("-")) {
109 continue;
110 }
111 mainClass = parts[i];
112 }
113 return mainClass;
114
115 }
116
117 private String getMainClassFromModuleArg(String moduleArg) {
118 int pos = moduleArg.lastIndexOf("/");
119 return (pos > 0 && pos < moduleArg.length()-1) ? moduleArg.substring(pos + 1) : null;
120 }
121
122 private String getMainClassFromJar(String jar, String pid) {
123 if (!jar.startsWith("/")) {
124 String cwd = getCurrentWorkingDir(pid);
125 if (cwd != null) {
126 jar = cwd + "/" + jar;
127 }
128 }
129 try (JarFile jarFile = new JarFile(jar)) {
130 Manifest mf = jarFile.getManifest();
131 if (mf != null) {
132 Attributes mainAttributes = mf.getMainAttributes();
133 return mainAttributes.getValue("Main-Class");
134 }
135 } catch (IOException e) {
136 return null;
137 }
138 return null;
139 }
140
141 private static String getCurrentWorkingDir(String pid) {
142 return ("/proc/" + pid + "/cwd");
143 }
144
145 private static String getCommandLine(String pid) {
146 try (Stream<String> lines =
147 Files.lines(Paths.get("/proc/" + pid + "/cmdline"))) {
148 return lines.map(x -> x.replaceAll("\0", " ")).findFirst().orElse(null);
149 } catch (IOException | UncheckedIOException e) {
150 return null;
151 }
152 }
153 }
154
155