cc.shacocloud.mirage.loader.jar.CentralDirectoryFileHeader Maven / Gradle / Ivy

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mirage 的启动装载模块
There is a newer version: 2.1.0
package cc.shacocloud.mirage.loader.jar;

import cc.shacocloud.mirage.loader.data.RandomAccessData;
import org.jetbrains.annotations.Contract;
import org.jetbrains.annotations.NotNull;

import java.io.IOException;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.ValueRange;

/**
 * ZIP 文件中央目录文件头记录（CDFH）
 *
 * @see Zip File Format
 */

final class CentralDirectoryFileHeader implements FileHeader {
    
    private static final AsciiBytes SLASH = new AsciiBytes("/");
    
    private static final byte[] NO_EXTRA = {};
    
    private static final AsciiBytes NO_COMMENT = new AsciiBytes("");
    
    private byte[] header;
    
    private int headerOffset;
    
    private AsciiBytes name;
    
    private byte[] extra;
    
    private AsciiBytes comment;
    
    private long localHeaderOffset;
    
    CentralDirectoryFileHeader() {
    }
    
    CentralDirectoryFileHeader(byte[] header, int headerOffset, AsciiBytes name, byte[] extra, AsciiBytes comment,
                               long localHeaderOffset) {
        this.header = header;
        this.headerOffset = headerOffset;
        this.name = name;
        this.extra = extra;
        this.comment = comment;
        this.localHeaderOffset = localHeaderOffset;
    }
    
    void load(byte[] data, int dataOffset, RandomAccessData variableData, long variableOffset, JarEntryFilter filter)
            throws IOException {
        // Load fixed part
        this.header = data;
        this.headerOffset = dataOffset;
        long compressedSize = Bytes.littleEndianValue(data, dataOffset + 20, 4);
        long uncompressedSize = Bytes.littleEndianValue(data, dataOffset + 24, 4);
        long nameLength = Bytes.littleEndianValue(data, dataOffset + 28, 2);
        long extraLength = Bytes.littleEndianValue(data, dataOffset + 30, 2);
        long commentLength = Bytes.littleEndianValue(data, dataOffset + 32, 2);
        long localHeaderOffset = Bytes.littleEndianValue(data, dataOffset + 42, 4);
        // Load variable part
        dataOffset += 46;
        if (variableData != null) {
            data = variableData.read(variableOffset + 46, nameLength + extraLength + commentLength);
            dataOffset = 0;
        }
        this.name = new AsciiBytes(data, dataOffset, (int) nameLength);
        if (filter != null) {
            this.name = filter.apply(this.name);
        }
        this.extra = NO_EXTRA;
        this.comment = NO_COMMENT;
        if (extraLength > 0) {
            this.extra = new byte[(int) extraLength];
            System.arraycopy(data, (int) (dataOffset + nameLength), this.extra, 0, this.extra.length);
        }
        this.localHeaderOffset = getLocalHeaderOffset(compressedSize, uncompressedSize, localHeaderOffset, this.extra);
        if (commentLength > 0) {
            this.comment = new AsciiBytes(data, (int) (dataOffset + nameLength + extraLength), (int) commentLength);
        }
    }
    
    private long getLocalHeaderOffset(long compressedSize, long uncompressedSize, long localHeaderOffset, byte[] extra)
            throws IOException {
        if (localHeaderOffset != 0xFFFFFFFFL) {
            return localHeaderOffset;
        }
        int extraOffset = 0;
        while (extraOffset < extra.length - 2) {
            int id = (int) Bytes.littleEndianValue(extra, extraOffset, 2);
            int length = (int) Bytes.littleEndianValue(extra, extraOffset, 2);
            extraOffset += 4;
            if (id == 1) {
                int localHeaderExtraOffset = 0;
                if (compressedSize == 0xFFFFFFFFL) {
                    localHeaderExtraOffset += 4;
                }
                if (uncompressedSize == 0xFFFFFFFFL) {
                    localHeaderExtraOffset += 4;
                }
                return Bytes.littleEndianValue(extra, extraOffset + localHeaderExtraOffset, 8);
            }
            extraOffset += length;
        }
        throw new IOException("Zip64 扩展信息 未找到额外字段");
    }
    
    AsciiBytes getName() {
        return this.name;
    }
    
    @Override
    public boolean hasName(CharSequence name, char suffix) {
        return this.name.matches(name, suffix);
    }
    
    boolean isDirectory() {
        return this.name.endsWith(SLASH);
    }
    
    @Override
    public int getMethod() {
        return (int) Bytes.littleEndianValue(this.header, this.headerOffset + 10, 2);
    }
    
    long getTime() {
        long datetime = Bytes.littleEndianValue(this.header, this.headerOffset + 12, 4);
        return decodeMsDosFormatDateTime(datetime);
    }
    
    /**
     * 解码 MS-DOS 日期时间详细信息
     *
     * @see 微软文档
     */
    private long decodeMsDosFormatDateTime(long datetime) {
        int year = getChronoValue(((datetime >> 25) & 0x7f) + 1980, ChronoField.YEAR);
        int month = getChronoValue((datetime >> 21) & 0x0f, ChronoField.MONTH_OF_YEAR);
        int day = getChronoValue((datetime >> 16) & 0x1f, ChronoField.DAY_OF_MONTH);
        int hour = getChronoValue((datetime >> 11) & 0x1f, ChronoField.HOUR_OF_DAY);
        int minute = getChronoValue((datetime >> 5) & 0x3f, ChronoField.MINUTE_OF_HOUR);
        int second = getChronoValue((datetime << 1) & 0x3e, ChronoField.SECOND_OF_MINUTE);
        return ZonedDateTime.of(year, month, day, hour, minute, second, 0, ZoneId.systemDefault())
                .toInstant()
                .truncatedTo(ChronoUnit.SECONDS)
                .toEpochMilli();
    }
    
    long getCrc() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 16, 4);
    }
    
    @Override
    public long getCompressedSize() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 20, 4);
    }
    
    @Override
    public long getSize() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 24, 4);
    }
    
    byte[] getExtra() {
        return this.extra;
    }
    
    boolean hasExtra() {
        return this.extra.length > 0;
    }
    
    AsciiBytes getComment() {
        return this.comment;
    }
    
    @Override
    public long getLocalHeaderOffset() {
        return this.localHeaderOffset;
    }
    
    @Contract(" -> new")
    @Override
    public @NotNull CentralDirectoryFileHeader clone() {
        byte[] header = new byte[46];
        System.arraycopy(this.header, this.headerOffset, header, 0, header.length);
        return new CentralDirectoryFileHeader(header, 0, this.name, header, this.comment, this.localHeaderOffset);
    }
    
    static @NotNull CentralDirectoryFileHeader fromRandomAccessData(@NotNull RandomAccessData data, long offset, JarEntryFilter filter)
            throws IOException {
        CentralDirectoryFileHeader fileHeader = new CentralDirectoryFileHeader();
        byte[] bytes = data.read(offset, 46);
        fileHeader.load(bytes, 0, data, offset, filter);
        return fileHeader;
    }
    
    private static int getChronoValue(long value, @NotNull ChronoField field) {
        ValueRange range = field.range();
        return Math.toIntExact(Math.min(Math.max(value, range.getMinimum()), range.getMaximum()));
    }
    
}