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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.dx.dex.file;
     18 
     19 import com.android.dex.DexFormat;
     20 import com.android.dex.SizeOf;
     21 import com.android.dx.rop.cst.CstString;
     22 import com.android.dx.util.AnnotatedOutput;
     23 import com.android.dx.util.Hex;
     24 
     25 /**
     26  * File header section of a {@code .dex} file.
     27  */
     28 public final class HeaderItem extends IndexedItem {
     29     /**
     30      * Constructs an instance.
     31      */
     32     public HeaderItem() {
     33         // This space intentionally left blank.
     34     }
     35 
     36     /** {@inheritDoc} */
     37     @Override
     38     public ItemType itemType() {
     39         return ItemType.TYPE_HEADER_ITEM;
     40     }
     41 
     42     /** {@inheritDoc} */
     43     @Override
     44     public int writeSize() {
     45         return SizeOf.HEADER_ITEM;
     46     }
     47 
     48     /** {@inheritDoc} */
     49     @Override
     50     public void addContents(DexFile file) {
     51         // Nothing to do here.
     52     }
     53 
     54     /** {@inheritDoc} */
     55     @Override
     56     public void writeTo(DexFile file, AnnotatedOutput out) {
     57         int mapOff = file.getMap().getFileOffset();
     58         Section firstDataSection = file.getFirstDataSection();
     59         Section lastDataSection = file.getLastDataSection();
     60         int dataOff = firstDataSection.getFileOffset();
     61         int dataSize = lastDataSection.getFileOffset() +
     62             lastDataSection.writeSize() - dataOff;
     63 
     64         String magic = file.getDexOptions().getMagic();
     65 
     66         if (out.annotates()) {
     67             out.annotate(8, "magic: " + new CstString(magic).toQuoted());
     68             out.annotate(4, "checksum");
     69             out.annotate(20, "signature");
     70             out.annotate(4, "file_size:       " +
     71                          Hex.u4(file.getFileSize()));
     72             out.annotate(4, "header_size:     " + Hex.u4(SizeOf.HEADER_ITEM));
     73             out.annotate(4, "endian_tag:      " + Hex.u4(DexFormat.ENDIAN_TAG));
     74             out.annotate(4, "link_size:       0");
     75             out.annotate(4, "link_off:        0");
     76             out.annotate(4, "map_off:         " + Hex.u4(mapOff));
     77         }
     78 
     79         // Write the magic number.
     80         for (int i = 0; i < 8; i++) {
     81             out.writeByte(magic.charAt(i));
     82         }
     83 
     84         // Leave space for the checksum and signature.
     85         out.writeZeroes(24);
     86 
     87         out.writeInt(file.getFileSize());
     88         out.writeInt(SizeOf.HEADER_ITEM);
     89         out.writeInt(DexFormat.ENDIAN_TAG);
     90 
     91         /*
     92          * Write zeroes for the link size and data, as the output
     93          * isn't a staticly linked file.
     94          */
     95         out.writeZeroes(8);
     96 
     97         out.writeInt(mapOff);
     98 
     99         // Write out each section's respective header part.
    100         file.getStringIds().writeHeaderPart(out);
    101         file.getTypeIds().writeHeaderPart(out);
    102         file.getProtoIds().writeHeaderPart(out);
    103         file.getFieldIds().writeHeaderPart(out);
    104         file.getMethodIds().writeHeaderPart(out);
    105         file.getClassDefs().writeHeaderPart(out);
    106 
    107         if (out.annotates()) {
    108             out.annotate(4, "data_size:       " + Hex.u4(dataSize));
    109             out.annotate(4, "data_off:        " + Hex.u4(dataOff));
    110         }
    111 
    112         out.writeInt(dataSize);
    113         out.writeInt(dataOff);
    114     }
    115 }
    116