001 /*
002 * Copyright 2006-2008 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package com.sun.tools.javac.processing;
027
028 import java.io.BufferedReader;
029 import java.io.FileNotFoundException;
030 import java.io.IOException;
031 import java.io.InputStream;
032 import java.io.InputStreamReader;
033 import java.net.MalformedURLException;
034 import java.net.URL;
035
036 /**
037 * Utility class to determine if a service can be found on the
038 * path that might be used to create a class loader.
039 *
040 * <p><b>This is NOT part of any API supported by Sun Microsystems.
041 * If you write code that depends on this, you do so at your own risk.
042 * This code and its internal interfaces are subject to change or
043 * deletion without notice.</b>
044 *
045 */
046 // based on sun.misc.Service
047 class ServiceProxy {
048 static class ServiceConfigurationError extends Error {
049 static final long serialVersionUID = 7732091036771098303L;
050
051 ServiceConfigurationError(String msg) {
052 super(msg);
053 }
054 }
055
056 private static final String prefix = "META-INF/services/";
057
058 private static void fail(Class<?> service, String msg)
059 throws ServiceConfigurationError {
060 throw new ServiceConfigurationError(service.getName() + ": " + msg);
061 }
062
063 private static void fail(Class<?> service, URL u, int line, String msg)
064 throws ServiceConfigurationError {
065 fail(service, u + ":" + line + ": " + msg);
066 }
067
068 /**
069 * Parse the content of the given URL as a provider-configuration file.
070 *
071 * @param service
072 * The service class for which providers are being sought;
073 * used to construct error detail strings
074 *
075 * @param url
076 * The URL naming the configuration file to be parsed
077 *
078 * @return true if the name of a service is found
079 *
080 * @throws ServiceConfigurationError
081 * If an I/O error occurs while reading from the given URL, or
082 * if a configuration-file format error is detected
083 */
084 private static boolean parse(Class<?> service, URL u) throws ServiceConfigurationError {
085 InputStream in = null;
086 BufferedReader r = null;
087 try {
088 in = u.openStream();
089 r = new BufferedReader(new InputStreamReader(in, "utf-8"));
090 int lc = 1;
091 String ln;
092 while ((ln = r.readLine()) != null) {
093 int ci = ln.indexOf('#');
094 if (ci >= 0) ln = ln.substring(0, ci);
095 ln = ln.trim();
096 int n = ln.length();
097 if (n != 0) {
098 if ((ln.indexOf(' ') >= 0) || (ln.indexOf('\t') >= 0))
099 fail(service, u, lc, "Illegal configuration-file syntax");
100 int cp = ln.codePointAt(0);
101 if (!Character.isJavaIdentifierStart(cp))
102 fail(service, u, lc, "Illegal provider-class name: " + ln);
103 for (int i = Character.charCount(cp); i < n; i += Character.charCount(cp)) {
104 cp = ln.codePointAt(i);
105 if (!Character.isJavaIdentifierPart(cp) && (cp != '.'))
106 fail(service, u, lc, "Illegal provider-class name: " + ln);
107 }
108 return true;
109 }
110 }
111 } catch (FileNotFoundException x) {
112 return false;
113 } catch (IOException x) {
114 fail(service, ": " + x);
115 } finally {
116 try {
117 if (r != null) r.close();
118 } catch (IOException y) {
119 fail(service, ": " + y);
120 }
121 try {
122 if (in != null) in.close();
123 } catch (IOException y) {
124 fail(service, ": " + y);
125 }
126 }
127 return false;
128 }
129
130 /**
131 * Return true if a description for at least one service is found in the
132 * service configuration files in the given URLs.
133 */
134 public static boolean hasService(Class<?> service, URL[] urls)
135 throws ServiceConfigurationError {
136 for (URL url: urls) {
137 try {
138 String fullName = prefix + service.getName();
139 URL u = new URL(url, fullName);
140 boolean found = parse(service, u);
141 if (found)
142 return true;
143 } catch (MalformedURLException e) {
144 // should not happen; ignore it if it does
145 }
146 }
147 return false;
148 }
149 }