reloc.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 125 行

/**
 * $Id: Reloc.java,v 1.1 2003/11/25 11:54:01 epr Exp $
 */

package org.jnode.linker;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


public class Reloc {
	/**
	* Relocation item
	* typedef struct
	* {
	*   Elf32_Addr	r_address;		       relative to _start_ of section
	*	  Elf32_Word	r_symbol;		       ELF symbol info thingy
	* } Elf32_Reloc;
	**/
	public static final int R_386_32 = 1; /* ordinary absolute relocation */
	public static final int R_386_PC32 = 2; /* PC-relative relocation */
	public static final int R_386_GOT32 = 3; /* an offset into GOT */
	public static final int R_386_PLT32 = 4;
	/* a PC-relative offset into PLT */
	public static final int R_386_GOTOFF = 9; /* an offset from GOT base */
	public static final int R_386_GOTPC = 10;
	/* a PC-relative offset _to_ GOT */

	static final String[] typename =
		{
			null,
			"abs32",
			"pcrel32",
			"GOT32",
			"PLT32",
			null,
			null,
			null,
			null,
			"GOTOFF",
			"GOTPC" };

	private int r_address;
	private int r_symndx;
	private int r_type;
	private Elf elf;
	private Symbol symbol;

	public Reloc(Elf elf, InputStream in) {
		this.elf = elf;
		r_address = LoadUtil.little32(in);
		int v = LoadUtil.little32(in);
		r_symndx = v >> 8;
		r_type = v & 0xFF;
	}

	private Reloc(Elf elf, Symbol symbol, int address, int type) {
		this.elf = elf;
		this.r_address = address;
		this.r_type = type;
		this.symbol = symbol;
	}

	public static Reloc newAbsInstance(Elf elf, Symbol symbol, int address) {
		return new Reloc(elf, symbol, address, R_386_32);
	}

	public static Reloc newPcRelInstance(Elf elf, Symbol symbol, int address) {
		return new Reloc(elf, symbol, address, R_386_PC32);
	}

	public int store(OutputStream out) throws IOException {
		
		if (symbol != null) {
			r_symndx = elf.getIndexOfSymbol(symbol);
		}
		
		int v = (r_type & 0xFF) | (r_symndx << 8);
		int cnt = 0;
		cnt += StoreUtil.little32(out, r_address);
		cnt += StoreUtil.little32(out, v);
		return cnt;
	}

	public int getAddress() {
		return r_address;
	}
	public int getSymbolIndex() {
		if (symbol != null) {
			return elf.getIndexOfSymbol(symbol);
		} else {
			return r_symndx;
		}
	}
	public int getType() {
		return r_type;
	}
	public String getTypeName() {
		return typename[r_type];
	}
	public Symbol getSymbol() {
		if (symbol != null) {
			return symbol;
		} else {
			return elf.getSymbol(r_symndx);
		}
	}

	public boolean isAbs() {
		return (r_type == R_386_32);
	}
	public boolean isPcRel() {
		return (r_type == R_386_PC32);
	}

	public void print() {
		System.out.println("  ----- Reloc -----");
		System.out.println(
			"  r_address     : " + Integer.toHexString(r_address));
		System.out.println("  r_symbol      : " + getSymbol());
		System.out.println("  r_type        : " + getTypeName());
	}
}