Java tutorial
/* * Copyright 2016-present Facebook, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. You may obtain * a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. */ package com.facebook.buck.cxx.elf; import com.facebook.buck.model.Pair; import com.facebook.buck.util.MoreIterables; import com.facebook.buck.util.RichStream; import com.google.common.collect.ImmutableList; import java.nio.ByteBuffer; public class ElfVerDef { public final ImmutableList<Pair<Verdef, ImmutableList<Verdaux>>> entries; public ElfVerDef(ImmutableList<Pair<Verdef, ImmutableList<Verdaux>>> entries) { this.entries = entries; } public static ElfVerDef parse(ElfHeader.EIClass eiClass, ByteBuffer buffer) { ImmutableList.Builder<Pair<Verdef, ImmutableList<Verdaux>>> entries = ImmutableList.builder(); int vdPos = buffer.position(); while (buffer.hasRemaining()) { buffer.position(vdPos); Verdef verdef = Verdef.parse(eiClass, buffer); int vdaPos = vdPos + (int) verdef.vd_aux; ImmutableList.Builder<Verdaux> verdauxEntries = ImmutableList.builder(); for (int j = 0; j < verdef.vd_cnt; j++) { buffer.position(vdaPos); Verdaux verdaux = Verdaux.parse(eiClass, buffer); verdauxEntries.add(verdaux); vdaPos += (int) verdaux.vda_next; } entries.add(new Pair<>(verdef, verdauxEntries.build())); if (verdef.vd_next == 0) { break; } vdPos += verdef.vd_next; } return new ElfVerDef(entries.build()); } public void write(ElfHeader.EIClass eiClass, ByteBuffer buffer) { int vdPos = buffer.position(); for (Pair<Verdef, ImmutableList<Verdaux>> entry : entries) { Verdef verdef = entry.getFirst(); ImmutableList<Verdaux> verdauxEntries = entry.getSecond(); buffer.position(vdPos); verdef.write(eiClass, buffer); int vdaPos = vdPos + (int) verdef.vd_aux; for (Verdaux verdaux : verdauxEntries) { buffer.position(vdaPos); verdaux.write(eiClass, buffer); vdaPos += verdaux.vda_next; } vdPos += verdef.vd_next; } } public ElfVerDef compact() { return new ElfVerDef(RichStream.from(MoreIterables.enumerate(this.entries)).map(vdp -> { int verdefIndex = vdp.getFirst(); Verdef verdef = vdp.getSecond().getFirst(); ImmutableList<Verdaux> verdauxes = vdp.getSecond().getSecond(); return new Pair<>( new Verdef(verdef.vd_version, verdef.vd_flags, verdef.vd_ndx, verdauxes.size(), verdef.vd_hash, verdauxes.size() == 0 ? 0 : Verdef.BYTES, verdefIndex == entries.size() - 1 ? 0 : Verdef.BYTES + Verdaux.BYTES * verdauxes.size()), RichStream.from(MoreIterables.enumerate(verdauxes)) .map(vdxp -> new Verdaux(vdxp.getSecond().vda_name, vdxp.getFirst() == verdauxes.size() - 1 ? 0 : Verdaux.BYTES)) .toImmutableList()); }).toImmutableList()); } public static class Verdef { private static final int BYTES = 20; // CHECKSTYLE.OFF: MemberName public final int vd_version; public final int vd_flags; public final int vd_ndx; public final int vd_cnt; public final long vd_hash; public final long vd_aux; public final long vd_next; // CHECKSTYLE.ON: MemberName // CHECKSTYLE.OFF: ParameterName public Verdef(int vd_version, int vd_flags, int vd_ndx, int vd_cnt, long vd_hash, long vd_aux, long vd_next) { this.vd_version = vd_version; this.vd_flags = vd_flags; this.vd_ndx = vd_ndx; this.vd_cnt = vd_cnt; this.vd_hash = vd_hash; this.vd_aux = vd_aux; this.vd_next = vd_next; } // CHECKSTYLE.ON: ParameterName private static Verdef parse(ElfHeader.EIClass eiClass, ByteBuffer buffer) { if (eiClass == ElfHeader.EIClass.ELFCLASS32) { return new Verdef(Elf.Elf32.getElf32Half(buffer), Elf.Elf32.getElf32Half(buffer), Elf.Elf32.getElf32Half(buffer), Elf.Elf32.getElf32Half(buffer), Elf.Elf32.getElf32Word(buffer), Elf.Elf32.getElf32Word(buffer), Elf.Elf32.getElf32Word(buffer)); } else { return new Verdef(Elf.Elf64.getElf64Half(buffer), Elf.Elf64.getElf64Half(buffer), Elf.Elf64.getElf64Half(buffer), Elf.Elf64.getElf64Half(buffer), Elf.Elf64.getElf64Word(buffer), Elf.Elf64.getElf64Word(buffer), Elf.Elf64.getElf64Word(buffer)); } } private void write(ElfHeader.EIClass eiClass, ByteBuffer buffer) { if (eiClass == ElfHeader.EIClass.ELFCLASS32) { Elf.Elf32.putElf32Half(buffer, (short) vd_version); Elf.Elf32.putElf32Half(buffer, (short) vd_flags); Elf.Elf32.putElf32Half(buffer, (short) vd_ndx); Elf.Elf32.putElf32Half(buffer, (short) vd_cnt); Elf.Elf32.putElf32Word(buffer, (int) vd_hash); Elf.Elf32.putElf32Word(buffer, (int) vd_aux); Elf.Elf32.putElf32Word(buffer, (int) vd_next); } else { Elf.Elf64.putElf64Half(buffer, (short) vd_version); Elf.Elf64.putElf64Half(buffer, (short) vd_flags); Elf.Elf64.putElf64Half(buffer, (short) vd_ndx); Elf.Elf64.putElf64Half(buffer, (short) vd_cnt); Elf.Elf64.putElf64Word(buffer, (int) vd_hash); Elf.Elf64.putElf64Word(buffer, (int) vd_aux); Elf.Elf64.putElf64Word(buffer, (int) vd_next); } } } public static class Verdaux { private static final int BYTES = 8; // CHECKSTYLE.OFF: MemberName public final long vda_name; public final long vda_next; // CHECKSTYLE.ON: MemberName // CHECKSTYLE.OFF: ParameterName public Verdaux(long vda_name, long vda_next) { this.vda_name = vda_name; this.vda_next = vda_next; } // CHECKSTYLE.ON: ParameterName private static Verdaux parse(ElfHeader.EIClass eiClass, ByteBuffer buffer) { if (eiClass == ElfHeader.EIClass.ELFCLASS32) { return new Verdaux(Elf.Elf32.getElf32Word(buffer), Elf.Elf32.getElf32Word(buffer)); } else { return new Verdaux(Elf.Elf64.getElf64Word(buffer), Elf.Elf64.getElf64Word(buffer)); } } private void write(ElfHeader.EIClass eiClass, ByteBuffer buffer) { if (eiClass == ElfHeader.EIClass.ELFCLASS32) { Elf.Elf32.putElf32Word(buffer, (int) vda_name); Elf.Elf32.putElf32Word(buffer, (int) vda_next); } else { Elf.Elf64.putElf64Word(buffer, (int) vda_name); Elf.Elf64.putElf64Word(buffer, (int) vda_next); } } } }