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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 package jdk.tools.jaotc.binformat.pecoff;
  25 
  26 import java.nio.ByteBuffer;
  27 
  28 import jdk.tools.jaotc.binformat.pecoff.PECoff.IMAGE_SECTION_HEADER;
  29 import jdk.tools.jaotc.binformat.pecoff.PECoffByteBuffer;
  30 
  31 final class PECoffSection {
  32     private final ByteBuffer section;
  33     private final byte[] data;
  34     private final boolean hasrelocations;
  35     private final int sectionIndex;
  36     private final int align;
  37 
  38     PECoffSection(String sectName, byte[] sectData0, int sectFlags0, int sectAlign, boolean hasRelocations, int sectIndex) {
  39 
  40         section = PECoffByteBuffer.allocate(IMAGE_SECTION_HEADER.totalsize);
  41 
  42         // If .oop.got section is empty, VM exits since .oop.got
  43         // symbol ends up as external forwarded reference.
  44         byte[] sectData = sectData0;
  45         if (sectData0.length == 0) {
  46             sectData = new byte[8];
  47         }
  48 
  49         // Copy only Max allowed bytes to Section Entry
  50         byte[] Name = sectName.getBytes();
  51         int max = Name.length <= IMAGE_SECTION_HEADER.Name.sz ? Name.length : IMAGE_SECTION_HEADER.Name.sz;
  52 
  53         assert (sectAlign < 1 || sectAlign > 1024 || (sectAlign & (sectAlign - 1)) != 0) : "section alignment is not valid: " + sectAlign;
  54         align = sectAlign;
  55 
  56         // Using 32 because IMAGE_SCN_ALIGN_*BYTES is value + 1
  57         int sectAlignBits = (32 - Integer.numberOfLeadingZeros(align)) << IMAGE_SECTION_HEADER.IMAGE_SCN_ALIGN_SHIFT;
  58         // Clear and set alignment bits
  59         int sectFlags = (sectFlags0 & ~IMAGE_SECTION_HEADER.IMAGE_SCN_ALIGN_MASK) | (sectAlignBits & IMAGE_SECTION_HEADER.IMAGE_SCN_ALIGN_MASK);
  60 
  61         section.put(Name, IMAGE_SECTION_HEADER.Name.off, max);
  62 
  63         section.putInt(IMAGE_SECTION_HEADER.VirtualSize.off, 0);
  64         section.putInt(IMAGE_SECTION_HEADER.VirtualAddress.off, 0);
  65         section.putInt(IMAGE_SECTION_HEADER.SizeOfRawData.off, sectData.length);
  66         section.putInt(IMAGE_SECTION_HEADER.PointerToLinenumbers.off, 0);
  67         section.putChar(IMAGE_SECTION_HEADER.NumberOfLinenumbers.off, (char) 0);
  68 
  69         section.putInt(IMAGE_SECTION_HEADER.Characteristics.off, sectFlags);
  70 
  71         data = sectData;
  72         hasrelocations = hasRelocations;
  73         sectionIndex = sectIndex;
  74     }
  75 
  76     long getSize() {
  77         return section.getInt(IMAGE_SECTION_HEADER.SizeOfRawData.off);
  78     }
  79 
  80     int getDataAlign() {
  81         return (align);
  82     }
  83 
  84     // Alignment requirements for the IMAGE_SECTION_HEADER structures
  85     static int getShdrAlign() {
  86         return (4);
  87     }
  88 
  89     byte[] getArray() {
  90         return section.array();
  91     }
  92 
  93     byte[] getDataArray() {
  94         return data;
  95     }
  96 
  97     void setOffset(long offset) {
  98         section.putInt(IMAGE_SECTION_HEADER.PointerToRawData.off, (int) offset);
  99     }
 100 
 101     long getOffset() {
 102         return (section.getInt(IMAGE_SECTION_HEADER.PointerToRawData.off));
 103     }
 104 
 105     void setReloff(int offset) {
 106         section.putInt(IMAGE_SECTION_HEADER.PointerToRelocations.off, offset);
 107     }
 108 
 109     void setRelcount(int count) {
 110         // If the number of relocs is larger than 65K, then set
 111         // the overflow bit. The real count will be written to
 112         // the first reloc entry for this section.
 113         if (count > 0xFFFF) {
 114             int flags;
 115             section.putChar(IMAGE_SECTION_HEADER.NumberOfRelocations.off, (char) 0xFFFF);
 116             flags = section.getInt(IMAGE_SECTION_HEADER.Characteristics.off);
 117             flags |= IMAGE_SECTION_HEADER.IMAGE_SCN_LNK_NRELOC_OVFL;
 118             section.putInt(IMAGE_SECTION_HEADER.Characteristics.off, flags);
 119         } else {
 120             section.putChar(IMAGE_SECTION_HEADER.NumberOfRelocations.off, (char) count);
 121         }
 122     }
 123 
 124     boolean hasRelocations() {
 125         return hasrelocations;
 126     }
 127 
 128     int getSectionId() {
 129         return sectionIndex;
 130     }
 131 
 132 }