1 package org.sentrysoftware.jawk.jrt;
2
3 /*-
4 * ╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲
5 * Jawk
6 * ჻჻჻჻჻჻
7 * Copyright (C) 2006 - 2023 Sentry Software
8 * ჻჻჻჻჻჻
9 * This program is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation, either version 3 of the
12 * License, or (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Lesser Public License for more details.
18 *
19 * You should have received a copy of the GNU General Lesser Public
20 * License along with this program. If not, see
21 * <http://www.gnu.org/licenses/lgpl-3.0.html>.
22 * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
23 */
24
25 import java.io.IOException;
26 import java.io.InputStream;
27 import java.io.PrintStream;
28
29 /**
30 * Relay data from an input stream to an output stream.
31 * A thread is created to do the work.
32 * <p>
33 * Jawk uses data pumps to relay stdin, stdout, and stderr
34 * of a spawned process (by, for example, system() or
35 * "cmd" | getline) to the stdin, stdout, and/or stderr
36 * of the calling process (the interpreter itself).
37 *
38 * @author Danny Daglas
39 */
40 public class DataPump implements Runnable {
41
42 private InputStream is;
43 private PrintStream os;
44
45 /**
46 * Represents a data pump.
47 *
48 * @param in The input stream.
49 * @param out The output stream.
50 */
51 public DataPump(InputStream in, PrintStream out) {
52 this.is = in;
53 this.os = out;
54 //setDaemon(true);
55 }
56
57 /**
58 * Allocate the data pump and start the thread.
59 *
60 * @param desc A human-readable description of this data pump.
61 * It is part of the thread name, and, therefore, visible
62 * upon a VM thread dump.
63 * @param in The input stream.
64 * @param out The output stream.
65 */
66 public static void dump(String desc, InputStream in, PrintStream out) {
67 new Thread(new DataPump(in, out), desc).start();
68 }
69
70 /**
71 * {@inheritDoc}
72 *
73 * VM entry point for the thread. It performs the data
74 * relay.
75 */
76 @Override
77 public final void run() {
78 try {
79 byte[] b = new byte[4096];
80 int len;
81 while ((len = is.read(b, 0, b.length)) >= 0) {
82 os.write(b, 0, len);
83 }
84 } catch (IOException ioe) {
85 // ignore
86 }
87 try {
88 is.close();
89 } catch (IOException ioe) {}
90 }
91 }