duke@1: /*
duke@1:  * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.
duke@1:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@1:  *
duke@1:  * This code is free software; you can redistribute it and/or modify it
duke@1:  * under the terms of the GNU General Public License version 2 only, as
duke@1:  * published by the Free Software Foundation.  Sun designates this
duke@1:  * particular file as subject to the "Classpath" exception as provided
duke@1:  * by Sun in the LICENSE file that accompanied this code.
duke@1:  *
duke@1:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@1:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@1:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@1:  * version 2 for more details (a copy is included in the LICENSE file that
duke@1:  * accompanied this code).
duke@1:  *
duke@1:  * You should have received a copy of the GNU General Public License version
duke@1:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@1:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@1:  *
duke@1:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@1:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@1:  * have any questions.
duke@1:  */
duke@1: 
duke@1: package com.sun.tools.javac.processing;
duke@1: 
duke@1: import java.io.BufferedReader;
duke@1: import java.io.FileNotFoundException;
duke@1: import java.io.IOException;
duke@1: import java.io.InputStream;
duke@1: import java.io.InputStreamReader;
duke@1: import java.net.MalformedURLException;
duke@1: import java.net.URL;
duke@1: 
duke@1: /**
duke@1:  * Utility class to determine if a service can be found on the
duke@1:  * path that might be used to create a class loader.
duke@1:  *
duke@1:  * <p><b>This is NOT part of any API supported by Sun Microsystems.
duke@1:  * If you write code that depends on this, you do so at your own risk.
duke@1:  * This code and its internal interfaces are subject to change or
duke@1:  * deletion without notice.</b>
duke@1:  *
duke@1:  */
duke@1: // based on sun.misc.Service
duke@1: class ServiceProxy {
duke@1:     static class ServiceConfigurationError extends Error {
duke@1:         static final long serialVersionUID = 7732091036771098303L;
duke@1: 
duke@1:         ServiceConfigurationError(String msg) {
duke@1:             super(msg);
duke@1:         }
duke@1:     }
duke@1: 
duke@1:     private static final String prefix = "META-INF/services/";
duke@1: 
duke@1:     private static void fail(Class service, String msg)
duke@1:             throws ServiceConfigurationError {
duke@1:         throw new ServiceConfigurationError(service.getName() + ": " + msg);
duke@1:     }
duke@1: 
duke@1:     private static void fail(Class service, URL u, int line, String msg)
duke@1:             throws ServiceConfigurationError {
duke@1:         fail(service, u + ":" + line + ": " + msg);
duke@1:     }
duke@1: 
duke@1:     /**
duke@1:      * Parse the content of the given URL as a provider-configuration file.
duke@1:      *
duke@1:      * @param  service
duke@1:      *         The service class for which providers are being sought;
duke@1:      *         used to construct error detail strings
duke@1:      *
duke@1:      * @param  url
duke@1:      *         The URL naming the configuration file to be parsed
duke@1:      *
duke@1:      * @return true if the name of a service is found
duke@1:      *
duke@1:      * @throws ServiceConfigurationError
duke@1:      *         If an I/O error occurs while reading from the given URL, or
duke@1:      *         if a configuration-file format error is detected
duke@1:      */
duke@1:     private static boolean parse(Class service, URL u) throws ServiceConfigurationError {
duke@1:         InputStream in = null;
duke@1:         BufferedReader r = null;
duke@1:         try {
duke@1:             in = u.openStream();
duke@1:             r = new BufferedReader(new InputStreamReader(in, "utf-8"));
duke@1:             int lc = 1;
duke@1:             String ln;
duke@1:             while ((ln = r.readLine()) != null) {
duke@1:                 int ci = ln.indexOf('#');
duke@1:                 if (ci >= 0) ln = ln.substring(0, ci);
duke@1:                 ln = ln.trim();
duke@1:                 int n = ln.length();
duke@1:                 if (n != 0) {
duke@1:                     if ((ln.indexOf(' ') >= 0) || (ln.indexOf('\t') >= 0))
duke@1:                         fail(service, u, lc, "Illegal configuration-file syntax");
duke@1:                     int cp = ln.codePointAt(0);
duke@1:                     if (!Character.isJavaIdentifierStart(cp))
duke@1:                         fail(service, u, lc, "Illegal provider-class name: " + ln);
duke@1:                     for (int i = Character.charCount(cp); i < n; i += Character.charCount(cp)) {
duke@1:                         cp = ln.codePointAt(i);
duke@1:                         if (!Character.isJavaIdentifierPart(cp) && (cp != '.'))
duke@1:                             fail(service, u, lc, "Illegal provider-class name: " + ln);
duke@1:                     }
duke@1:                     return true;
duke@1:                 }
duke@1:             }
duke@1:         } catch (FileNotFoundException x) {
duke@1:             return false;
duke@1:         } catch (IOException x) {
duke@1:             fail(service, ": " + x);
duke@1:         } finally {
duke@1:             try {
duke@1:                 if (r != null) r.close();
duke@1:             } catch (IOException y) {
duke@1:                 fail(service, ": " + y);
duke@1:             }
duke@1:             try {
duke@1:                 if (in != null) in.close();
duke@1:             } catch (IOException y) {
duke@1:                 fail(service, ": " + y);
duke@1:             }
duke@1:         }
duke@1:         return false;
duke@1:     }
duke@1: 
duke@1:     /**
duke@1:      * Return true if a description for at least one service is found in the
duke@1:      * service configuration files in the given URLs.
duke@1:      */
duke@1:     public static boolean hasService(Class<?> service, URL[] urls)
duke@1:             throws ServiceConfigurationError {
duke@1:         for (URL url: urls) {
duke@1:             try {
duke@1:                 String fullName = prefix + service.getName();
duke@1:                 URL u = new URL(url, fullName);
duke@1:                 boolean found = parse(service, u);
duke@1:                 if (found)
duke@1:                     return true;
duke@1:             } catch (MalformedURLException e) {
duke@1:                 // should not happen; ignore it if it does
duke@1:             }
duke@1:         }
duke@1:         return false;
duke@1:     }
duke@1: }