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.
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.elf;
25
26 import java.nio.ByteBuffer;
27 import java.nio.ByteOrder;
28
29 import jdk.tools.jaotc.binformat.elf.Elf;
30 import jdk.tools.jaotc.binformat.elf.Elf.Elf64_Ehdr;
31 import jdk.tools.jaotc.binformat.elf.Elf.Elf64_Shdr;
32 import jdk.tools.jaotc.binformat.elf.Elf.Elf64_Rel;
33 import jdk.tools.jaotc.binformat.elf.Elf.Elf64_Rela;
34 import jdk.tools.jaotc.binformat.elf.Elf.Elf64_Sym;
35 import jdk.tools.jaotc.binformat.elf.ElfByteBuffer;
36
37 public class ElfSection {
38 String name;
39 ByteBuffer section;
40 byte [] data;
41 boolean hasrelocations;
42 int sectionIndex;
43
44 /**
45 * String holding section name strings
46 */
47 private static StringBuilder sectNameTab = new StringBuilder();
48
49 /**
50 * Keeps track of bytes in section string table since strTabContent.length()
51 * is number of chars, not bytes.
52 */
53 private static int shStrTabNrOfBytes = 0;
54
55 public ElfSection(String sectName, byte [] sectData, int sectFlags,
56 int sectType, boolean hasRelocations, int sectIndex) {
57
58 long align;
59
60 section = ElfByteBuffer.allocate(Elf64_Shdr.totalsize);
61
62 // Return all 0's for NULL section
63 if (sectIndex == 0) {
64 sectNameTab.append('\0');
65 shStrTabNrOfBytes += 1;
66 data = null;
67 hasrelocations = false;
68 sectionIndex = 0;
69 return;
70 }
71
72 section.putInt(Elf64_Shdr.sh_name.off, shStrTabNrOfBytes);
73 sectNameTab.append(sectName).append('\0');
74 shStrTabNrOfBytes += (sectName.getBytes().length + 1);
75 name = sectName;
76
77 section.putInt(Elf64_Shdr.sh_type.off, sectType);
78 section.putLong(Elf64_Shdr.sh_flags.off, sectFlags);
79 section.putLong(Elf64_Shdr.sh_addr.off, 0);
80 section.putLong(Elf64_Shdr.sh_offset.off, 0);
81
82 if (sectName.equals(".shstrtab")) {
83 section.putLong(Elf64_Shdr.sh_size.off, shStrTabNrOfBytes);
84 data = sectNameTab.toString().getBytes();
85 }
86 else {
87 data = sectData;
88 section.putLong(Elf64_Shdr.sh_size.off, sectData.length);
89 }
90
91 section.putLong(Elf64_Shdr.sh_entsize.off, 0);
92
93 // Determine the alignment and entrysize
94 // based on type of section
95 switch (sectType) {
96 case Elf64_Shdr.SHT_PROGBITS:
97 if ((sectFlags & Elf64_Shdr.SHF_EXECINSTR) != 0)
98 align = 16;
99 else
100 align = 4;
101 break;
102 case Elf64_Shdr.SHT_SYMTAB:
103 align = 8;
104 section.putLong(Elf64_Shdr.sh_entsize.off, Elf64_Sym.totalsize);
105 break;
106 case Elf64_Shdr.SHT_STRTAB:
107 align = 1;
108 break;
109 case Elf64_Shdr.SHT_RELA:
110 align = 8;
111 section.putLong(Elf64_Shdr.sh_entsize.off, Elf64_Rela.totalsize);
112 break;
113 case Elf64_Shdr.SHT_REL:
114 align = 8;
115 section.putLong(Elf64_Shdr.sh_entsize.off, Elf64_Rel.totalsize);
116 break;
117 case Elf64_Shdr.SHT_NOBITS:
118 align = 4;
119 break;
120 default:
121 align = 8;
122 break;
123 }
124 section.putLong(Elf64_Shdr.sh_addralign.off, align);
125
126 hasrelocations = hasRelocations;
127 sectionIndex = sectIndex;
128 }
129
130 public String getName() {
131 return name;
132 }
133
134 public long getSize() {
135 return section.getLong(Elf64_Shdr.sh_size.off);
136 }
137
138 public int getDataAlign() {
139 return ((int)section.getLong(Elf64_Shdr.sh_addralign.off));
140 }
141
142 // Alignment requirements for the Elf64_Shdr structures
143 public static int getShdrAlign() {
144 return (4);
145 }
146
147 public byte[] getArray() {
148 return section.array();
149 }
150
151 public byte[] getDataArray() {
152 return data;
153 }
154
155 public void setOffset(long offset) {
156 section.putLong(Elf64_Shdr.sh_offset.off, offset);
157 }
158
159 public void setLink(int link) {
160 section.putInt(Elf64_Shdr.sh_link.off, link);
161 }
162
163 public void setInfo(int info) {
164 section.putInt(Elf64_Shdr.sh_info.off, info);
165 }
166
167 public long getOffset() {
168 return (section.getLong(Elf64_Shdr.sh_offset.off));
169 }
170
171 public boolean hasRelocations() {
172 return hasrelocations;
173 }
174
175 public int getSectionId() {
176 return sectionIndex;
177 }
178
179 }
180
181