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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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package jdk.internal.jimage;

import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import java.util.Objects;

Implementation Note:This class needs to maintain JDK 8 source compatibility. It is used internally in the JDK to implement jimage/jrtfs access, but also compiled and delivered as part of the jrtfs.jar to support access to the jimage file provided by the shipped JDK by tools running on JDK 8.
/** * @implNote This class needs to maintain JDK 8 source compatibility. * * It is used internally in the JDK to implement jimage/jrtfs access, * but also compiled and delivered as part of the jrtfs.jar to support access * to the jimage file provided by the shipped JDK by tools running on JDK 8. */
public final class ImageHeader { public static final int MAGIC = 0xCAFEDADA; public static final int MAJOR_VERSION = 1; public static final int MINOR_VERSION = 0; private static final int HEADER_SLOTS = 7; private final int magic; private final int majorVersion; private final int minorVersion; private final int flags; private final int resourceCount; private final int tableLength; private final int locationsSize; private final int stringsSize; public ImageHeader(int resourceCount, int tableCount, int locationsSize, int stringsSize) { this(MAGIC, MAJOR_VERSION, MINOR_VERSION, 0, resourceCount, tableCount, locationsSize, stringsSize); } public ImageHeader(int magic, int majorVersion, int minorVersion, int flags, int resourceCount, int tableLength, int locationsSize, int stringsSize) { this.magic = magic; this.majorVersion = majorVersion; this.minorVersion = minorVersion; this.flags = flags; this.resourceCount = resourceCount; this.tableLength = tableLength; this.locationsSize = locationsSize; this.stringsSize = stringsSize; } public static int getHeaderSize() { return HEADER_SLOTS * 4; } static ImageHeader readFrom(IntBuffer buffer) { Objects.requireNonNull(buffer); if (buffer.capacity() != HEADER_SLOTS) { throw new InternalError( "jimage header not the correct size: " + buffer.capacity()); } int magic = buffer.get(0); int version = buffer.get(1); int majorVersion = version >>> 16; int minorVersion = version & 0xFFFF; int flags = buffer.get(2); int resourceCount = buffer.get(3); int tableLength = buffer.get(4); int locationsSize = buffer.get(5); int stringsSize = buffer.get(6); return new ImageHeader(magic, majorVersion, minorVersion, flags, resourceCount, tableLength, locationsSize, stringsSize); } public void writeTo(ImageStream stream) { Objects.requireNonNull(stream); stream.ensure(getHeaderSize()); writeTo(stream.getBuffer()); } public void writeTo(ByteBuffer buffer) { Objects.requireNonNull(buffer); buffer.putInt(magic); buffer.putInt(majorVersion << 16 | minorVersion); buffer.putInt(flags); buffer.putInt(resourceCount); buffer.putInt(tableLength); buffer.putInt(locationsSize); buffer.putInt(stringsSize); } public int getMagic() { return magic; } public int getMajorVersion() { return majorVersion; } public int getMinorVersion() { return minorVersion; } public int getFlags() { return flags; } public int getResourceCount() { return resourceCount; } public int getTableLength() { return tableLength; } public int getRedirectSize() { return tableLength * 4; } public int getOffsetsSize() { return tableLength * 4; } public int getLocationsSize() { return locationsSize; } public int getStringsSize() { return stringsSize; } public int getIndexSize() { return getHeaderSize() + getRedirectSize() + getOffsetsSize() + getLocationsSize() + getStringsSize(); } int getRedirectOffset() { return getHeaderSize(); } int getOffsetsOffset() { return getRedirectOffset() + getRedirectSize(); } int getLocationsOffset() { return getOffsetsOffset() + getOffsetsSize(); } int getStringsOffset() { return getLocationsOffset() + getLocationsSize(); } }