| /* |
| * Copyright (C) 2007 The Android Open Source Project |
| * |
| * 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.android.dexgen.dex.file; |
| |
| import com.android.dexgen.util.AnnotatedOutput; |
| |
| import java.util.Collection; |
| |
| /** |
| * A section of a {@code .dex} file. Each section consists of a list |
| * of items of some sort or other. |
| */ |
| public abstract class Section { |
| /** {@code null-ok;} name of this part, for annotation purposes */ |
| private final String name; |
| |
| /** {@code non-null;} file that this instance is part of */ |
| private final DexFile file; |
| |
| /** {@code > 0;} alignment requirement for the final output; |
| * must be a power of 2 */ |
| private final int alignment; |
| |
| /** {@code >= -1;} offset from the start of the file to this part, or |
| * {@code -1} if not yet known */ |
| private int fileOffset; |
| |
| /** whether {@link #prepare} has been called successfully on this |
| * instance */ |
| private boolean prepared; |
| |
| /** |
| * Validates an alignment. |
| * |
| * @param alignment the alignment |
| * @throws IllegalArgumentException thrown if {@code alignment} |
| * isn't a positive power of 2 |
| */ |
| public static void validateAlignment(int alignment) { |
| if ((alignment <= 0) || |
| (alignment & (alignment - 1)) != 0) { |
| throw new IllegalArgumentException("invalid alignment"); |
| } |
| } |
| |
| /** |
| * Constructs an instance. The file offset is initially unknown. |
| * |
| * @param name {@code null-ok;} the name of this instance, for annotation |
| * purposes |
| * @param file {@code non-null;} file that this instance is part of |
| * @param alignment {@code > 0;} alignment requirement for the final output; |
| * must be a power of 2 |
| */ |
| public Section(String name, DexFile file, int alignment) { |
| if (file == null) { |
| throw new NullPointerException("file == null"); |
| } |
| |
| validateAlignment(alignment); |
| |
| this.name = name; |
| this.file = file; |
| this.alignment = alignment; |
| this.fileOffset = -1; |
| this.prepared = false; |
| } |
| |
| /** |
| * Gets the file that this instance is part of. |
| * |
| * @return {@code non-null;} the file |
| */ |
| public final DexFile getFile() { |
| return file; |
| } |
| |
| /** |
| * Gets the alignment for this instance's final output. |
| * |
| * @return {@code > 0;} the alignment |
| */ |
| public final int getAlignment() { |
| return alignment; |
| } |
| |
| /** |
| * Gets the offset from the start of the file to this part. This |
| * throws an exception if the offset has not yet been set. |
| * |
| * @return {@code >= 0;} the file offset |
| */ |
| public final int getFileOffset() { |
| if (fileOffset < 0) { |
| throw new RuntimeException("fileOffset not set"); |
| } |
| |
| return fileOffset; |
| } |
| |
| /** |
| * Sets the file offset. It is only valid to call this method once |
| * once per instance. |
| * |
| * @param fileOffset {@code >= 0;} the desired offset from the start of the |
| * file where this for this instance |
| * @return {@code >= 0;} the offset that this instance should be placed at |
| * in order to meet its alignment constraint |
| */ |
| public final int setFileOffset(int fileOffset) { |
| if (fileOffset < 0) { |
| throw new IllegalArgumentException("fileOffset < 0"); |
| } |
| |
| if (this.fileOffset >= 0) { |
| throw new RuntimeException("fileOffset already set"); |
| } |
| |
| int mask = alignment - 1; |
| fileOffset = (fileOffset + mask) & ~mask; |
| |
| this.fileOffset = fileOffset; |
| |
| return fileOffset; |
| } |
| |
| /** |
| * Writes this instance to the given raw data object. |
| * |
| * @param out {@code non-null;} where to write to |
| */ |
| public final void writeTo(AnnotatedOutput out) { |
| throwIfNotPrepared(); |
| align(out); |
| |
| int cursor = out.getCursor(); |
| |
| if (fileOffset < 0) { |
| fileOffset = cursor; |
| } else if (fileOffset != cursor) { |
| throw new RuntimeException("alignment mismatch: for " + this + |
| ", at " + cursor + |
| ", but expected " + fileOffset); |
| } |
| |
| if (out.annotates()) { |
| if (name != null) { |
| out.annotate(0, "\n" + name + ":"); |
| } else if (cursor != 0) { |
| out.annotate(0, "\n"); |
| } |
| } |
| |
| writeTo0(out); |
| } |
| |
| /** |
| * Returns the absolute file offset, given an offset from the |
| * start of this instance's output. This is only valid to call |
| * once this instance has been assigned a file offset (via {@link |
| * #setFileOffset}). |
| * |
| * @param relative {@code >= 0;} the relative offset |
| * @return {@code >= 0;} the corresponding absolute file offset |
| */ |
| public final int getAbsoluteOffset(int relative) { |
| if (relative < 0) { |
| throw new IllegalArgumentException("relative < 0"); |
| } |
| |
| if (fileOffset < 0) { |
| throw new RuntimeException("fileOffset not yet set"); |
| } |
| |
| return fileOffset + relative; |
| } |
| |
| /** |
| * Returns the absolute file offset of the given item which must |
| * be contained in this section. This is only valid to call |
| * once this instance has been assigned a file offset (via {@link |
| * #setFileOffset}). |
| * |
| * <p><b>Note:</b> Subclasses must implement this as appropriate for |
| * their contents.</p> |
| * |
| * @param item {@code non-null;} the item in question |
| * @return {@code >= 0;} the item's absolute file offset |
| */ |
| public abstract int getAbsoluteItemOffset(Item item); |
| |
| /** |
| * Prepares this instance for writing. This performs any necessary |
| * prerequisites, including particularly adding stuff to other |
| * sections. This method may only be called once per instance; |
| * subsequent calls will throw an exception. |
| */ |
| public final void prepare() { |
| throwIfPrepared(); |
| prepare0(); |
| prepared = true; |
| } |
| |
| /** |
| * Gets the collection of all the items in this section. |
| * It is not valid to attempt to change the returned list. |
| * |
| * @return {@code non-null;} the items |
| */ |
| public abstract Collection<? extends Item> items(); |
| |
| /** |
| * Does the main work of {@link #prepare}. |
| */ |
| protected abstract void prepare0(); |
| |
| /** |
| * Gets the size of this instance when output, in bytes. |
| * |
| * @return {@code >= 0;} the size of this instance, in bytes |
| */ |
| public abstract int writeSize(); |
| |
| /** |
| * Throws an exception if {@link #prepare} has not been |
| * called on this instance. |
| */ |
| protected final void throwIfNotPrepared() { |
| if (!prepared) { |
| throw new RuntimeException("not prepared"); |
| } |
| } |
| |
| /** |
| * Throws an exception if {@link #prepare} has already been called |
| * on this instance. |
| */ |
| protected final void throwIfPrepared() { |
| if (prepared) { |
| throw new RuntimeException("already prepared"); |
| } |
| } |
| |
| /** |
| * Aligns the output of the given data to the alignment of this instance. |
| * |
| * @param out {@code non-null;} the output to align |
| */ |
| protected final void align(AnnotatedOutput out) { |
| out.alignTo(alignment); |
| } |
| |
| /** |
| * Writes this instance to the given raw data object. This gets |
| * called by {@link #writeTo} after aligning the cursor of |
| * {@code out} and verifying that either the assigned file |
| * offset matches the actual cursor {@code out} or that the |
| * file offset was not previously assigned, in which case it gets |
| * assigned to {@code out}'s cursor. |
| * |
| * @param out {@code non-null;} where to write to |
| */ |
| protected abstract void writeTo0(AnnotatedOutput out); |
| |
| /** |
| * Returns the name of this section, for annotation purposes. |
| * |
| * @return {@code null-ok;} name of this part, for annotation purposes |
| */ |
| protected final String getName() { |
| return name; |
| } |
| } |