1 /*
   2  * Copyright (c) 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 
  26 package jdk.internal.util.jar;
  27 
  28 /**
  29  * Simple utility methods for checking Jar file attributes.
  30  */
  31 
  32 public class JarAttributes {
  33 
  34     // No can has instance!
  35     private JarAttributes() {}
  36 
  37     // Statics for hand-coded Boyer-Moore search
  38     private static final byte[] CLASSPATH_CHARS =
  39             {'C','L','A','S','S','-','P','A','T','H', ':', ' '};
  40 
  41     // The bad character shift for "class-path: "
  42     private static final byte[] CLASSPATH_LASTOCC;
  43 
  44     // The good suffix shift for "class-path: "
  45     private static final byte[] CLASSPATH_OPTOSFT;
  46 
  47     private static final byte[] MULTIRELEASE_CHARS =
  48             {'M','U','L','T','I','-','R','E','L','E', 'A', 'S', 'E', ':',
  49                     ' ', 'T', 'R', 'U', 'E'};
  50 
  51     // The bad character shift for "multi-release: true"
  52     private static final byte[] MULTIRELEASE_LASTOCC;
  53 
  54     // The good suffix shift for "multi-release: true"
  55     private static final byte[] MULTIRELEASE_OPTOSFT;
  56 
  57     static {
  58         CLASSPATH_LASTOCC = new byte[64];
  59         CLASSPATH_OPTOSFT = new byte[12];
  60         CLASSPATH_LASTOCC[(int)'C' - 32] = 1;
  61         CLASSPATH_LASTOCC[(int)'L' - 32] = 2;
  62         CLASSPATH_LASTOCC[(int)'S' - 32] = 5;
  63         CLASSPATH_LASTOCC[(int)'-' - 32] = 6;
  64         CLASSPATH_LASTOCC[(int)'P' - 32] = 7;
  65         CLASSPATH_LASTOCC[(int)'A' - 32] = 8;
  66         CLASSPATH_LASTOCC[(int)'T' - 32] = 9;
  67         CLASSPATH_LASTOCC[(int)'H' - 32] = 10;
  68         CLASSPATH_LASTOCC[(int)':' - 32] = 11;
  69         CLASSPATH_LASTOCC[(int)' ' - 32] = 12;
  70         for (int i = 0; i < 11; i++) {
  71             CLASSPATH_OPTOSFT[i] = 12;
  72         }
  73         CLASSPATH_OPTOSFT[11] = 1;
  74 
  75         MULTIRELEASE_LASTOCC = new byte[64];
  76         MULTIRELEASE_OPTOSFT = new byte[19];
  77         MULTIRELEASE_LASTOCC[(int)'M' - 32] = 1;
  78         MULTIRELEASE_LASTOCC[(int)'I' - 32] = 5;
  79         MULTIRELEASE_LASTOCC[(int)'-' - 32] = 6;
  80         MULTIRELEASE_LASTOCC[(int)'L' - 32] = 9;
  81         MULTIRELEASE_LASTOCC[(int)'A' - 32] = 11;
  82         MULTIRELEASE_LASTOCC[(int)'S' - 32] = 12;
  83         MULTIRELEASE_LASTOCC[(int)':' - 32] = 14;
  84         MULTIRELEASE_LASTOCC[(int)' ' - 32] = 15;
  85         MULTIRELEASE_LASTOCC[(int)'T' - 32] = 16;
  86         MULTIRELEASE_LASTOCC[(int)'R' - 32] = 17;
  87         MULTIRELEASE_LASTOCC[(int)'U' - 32] = 18;
  88         MULTIRELEASE_LASTOCC[(int)'E' - 32] = 19;
  89         for (int i = 0; i < 17; i++) {
  90             MULTIRELEASE_OPTOSFT[i] = 19;
  91         }
  92         MULTIRELEASE_OPTOSFT[17] = 6;
  93         MULTIRELEASE_OPTOSFT[18] = 1;
  94     }
  95 
  96     public static boolean hasClassPathAttribute(final byte[] manifestEntry) {
  97         return match(CLASSPATH_CHARS, manifestEntry,
  98                 CLASSPATH_LASTOCC, CLASSPATH_OPTOSFT) != -1;
  99     }
 100 
 101     public static boolean isMultiRelease(final byte[] manifest) {
 102         // is this a multi-release jar file
 103         int i = match(MULTIRELEASE_CHARS, manifest, MULTIRELEASE_LASTOCC,
 104                 MULTIRELEASE_OPTOSFT);
 105         if (i != -1) {
 106             i += MULTIRELEASE_CHARS.length;
 107             if (i < manifest.length) {
 108                 byte c = manifest[i++];
 109                 // Check that the value is followed by a newline
 110                 // and does not have a continuation
 111                 if (c == '\n' &&
 112                         (i == manifest.length || manifest[i] != ' ')) {
 113                     return true;
 114                 } else if (c == '\r') {
 115                     if (i == manifest.length) {
 116                         return true;
 117                     } else {
 118                         c = manifest[i++];
 119                         if (c == '\n') {
 120                             if (i == manifest.length || manifest[i] != ' ') {
 121                                 return true;
 122                             }
 123                         } else if (c != ' ') {
 124                             return true;
 125                         }
 126                     }
 127                 }
 128             }
 129         }
 130         return false;
 131     }
 132     /**
 133      * Returns true if the pattern {@code src} is found in {@code b}.
 134      * The {@code lastOcc} array is the precomputed bad character shifts.
 135      * Since there are no repeated substring in our search strings,
 136      * the good suffix shifts can be replaced with a comparison.
 137      */
 138     private static int match(byte[] src, byte[] b, byte[] lastOcc, byte[] optoSft) {
 139         int len = src.length;
 140         int last = b.length - len;
 141         int i = 0;
 142         next:
 143         while (i <= last) {
 144             for (int j = (len - 1); j >= 0; j--) {
 145                 byte c = b[i + j];
 146                 if (c >= ' ' && c <= 'z') {
 147                     if (c >= 'a') c -= 32; // Canonicalize
 148 
 149                     if (c != src[j]) {
 150                         // no match
 151                         int badShift = lastOcc[c - 32];
 152                         i += Math.max(j + 1 - badShift, optoSft[j]);
 153                         continue next;
 154                     }
 155                 } else {
 156                     // no match, character not valid for name
 157                     i += len;
 158                     continue next;
 159                 }
 160             }
 161             return i;
 162         }
 163         return -1;
 164     }
 165 }