1 /*

     2  * Copyright (c) 2016, 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 package jdk.internal.loader;

    26 

    27 import java.io.File;

    28 import java.nio.file.Path;

    29 import java.nio.file.Paths;

    30 

    31 import jdk.internal.module.Checks;

    32 

    33 /**

    34  * Helper class for Class#getResource, Module#getResourceAsStream, and other

    35  * methods that locate a resource in a module.

    36  */

    37 public final class ResourceHelper {

    38     private ResourceHelper() { }

    39 

    40     /**

    41      * Returns the <em>package name</em> for a resource or the empty package if

    42      * the resource name does not contain a slash.

    43      */

    44     public static String getPackageName(String name) {

    45         int index = name.lastIndexOf('/');

    46         if (index != -1) {

    47             return name.substring(0, index).replace("/", ".");

    48         } else {

    49             return "";

    50         }

    51     }

    52 

    53     /**

    54      * Returns true if the resource is a <em>simple resource</em>. Simple

    55      * resources can never be encapsulated. Resources ending in "{@code .class}"

    56      * or where the package name is not a legal package name can not be

    57      * encapsulated.

    58      */

    59     public static boolean isSimpleResource(String name) {

    60         int len = name.length();

    61         if (len > 6 && name.endsWith(".class")) {

    62             return true;

    63         }

    64         if (!Checks.isPackageName(getPackageName(name))) {

    65             return true;

    66         }

    67         return false;

    68     }

    69 

    70     /**

    71      * Converts a resource name to a file path. Returns {@code null} if the

    72      * resource name cannot be converted into a file path. Resource names

    73      * with empty elements, or elements that are "." or ".." are rejected,

    74      * as is a resource name that translates to a file path with a root

    75      * component.

    76      */

    77     public static Path toFilePath(String name) {

    78         // scan the resource name to eagerly reject obviously invalid names

    79         int next;

    80         int off = 0;

    81         while ((next = name.indexOf('/', off)) != -1) {

    82             int len = next - off;

    83             if (!mayTranslate(name, off, len)) {

    84                 return null;

    85             }

    86             off = next + 1;

    87         }

    88         int rem = name.length() - off;

    89         if (!mayTranslate(name, off, rem)) {

    90             return null;

    91         }

    92 

    93         // convert to file path

    94         Path path;

    95         if (File.separatorChar == '/') {

    96             path = Paths.get(name);

    97         } else {

    98             // not allowed to embed file separators

    99             if (name.contains(File.separator))

   100                 return null;

   101             path = Paths.get(name.replace('/', File.separatorChar));

   102         }

   103 

   104         // file path not allowed to have root component

   105         return (path.getRoot() == null) ? path : null;

   106     }

   107 

   108     /**

   109      * Returns {@code true} if the element in a resource name is a candidate

   110      * to translate to the element of a file path.

   111      */

   112     private static boolean mayTranslate(String name, int off, int len) {

   113         if (len <= 2) {

   114             if (len == 0)

   115                 return false;

   116             boolean starsWithDot = (name.charAt(off) == '.');

   117             if (len == 1 && starsWithDot)

   118                 return false;

   119             if (len == 2 && starsWithDot && (name.charAt(off+1) == '.'))

   120                 return false;

   121         }

   122         return true;

   123     }

   124 

   125 }