added initial buggy version of executable jar plugin

executable-jar/executable-jar-common/build.gradle

@@ -0,0 +1,3 @@
+plugins {
+    id 'java-library'
+}

executable-jar/executable-jar-common/src/main/java/net/woggioni/executable/jar/Common.java

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+package net.woggioni.executable.jar;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.security.DigestInputStream;
+import java.security.MessageDigest;
+import java.util.AbstractMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Supplier;
+import java.util.zip.CRC32;
+import java.util.zip.ZipEntry;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import lombok.SneakyThrows;
+import java.io.IOException;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class Common {
+    final private static char[] hexArray = "0123456789ABCDEF".toCharArray();
+
+    public static String bytesToHex(byte[] bytes) {
+        char[] hexChars = new char[bytes.length * 2];
+        for (int j = 0; j < bytes.length; j++) {
+            int v = bytes[j] & 0xFF;
+            hexChars[j * 2] = hexArray[v >>> 4];
+            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
+        }
+        return new String(hexChars);
+    }
+
+    @SneakyThrows
+    public static byte[] computeSHA256Digest(Supplier<InputStream> streamSupplier) {
+        byte[] buffer = new byte[Constants.BUFFER_SIZE];
+        MessageDigest md = MessageDigest.getInstance("SHA-256");
+        return computeDigest(streamSupplier, md, buffer);
+    }
+
+    @SneakyThrows
+    public static byte[] computeDigest(Supplier<InputStream> streamSupplier, MessageDigest md, byte[] buffer) {
+        try(InputStream stream = new DigestInputStream(streamSupplier.get(), md)) {
+            while(stream.read(buffer) >= 0) {}
+        }
+        return md.digest();
+    }
+
+    @SneakyThrows
+    public static void computeSizeAndCrc32(
+            ZipEntry zipEntry,
+            InputStream inputStream,
+            byte[] buffer) {
+        CRC32 crc32 = new CRC32();
+        long sz = 0L;
+        while (true) {
+            int read = inputStream.read(buffer);
+            if (read < 0) break;
+            sz += read;
+            crc32.update(buffer, 0, read);
+        }
+        zipEntry.setSize(sz);
+        zipEntry.setCompressedSize(sz);
+        zipEntry.setCrc(crc32.getValue());
+    }
+
+    @SneakyThrows
+    public static void write2Stream(InputStream inputStream, OutputStream os,
+                                    byte[] buffer) {
+        while (true) {
+            int read = inputStream.read(buffer);
+            if (read < 0) break;
+            os.write(buffer, 0, read);
+        }
+    }
+
+    public static void write2Stream(InputStream inputStream, OutputStream os) {
+        write2Stream(inputStream, os, new byte[Constants.BUFFER_SIZE]);
+    }
+
+    public static Optional<Map.Entry<String, String>> splitExtension(String fileName) {
+        int index = fileName.lastIndexOf('.');
+        if (index == -1) {
+            return Optional.empty();
+        } else {
+            return Optional.of(
+                    new AbstractMap.SimpleEntry<>(fileName.substring(0, index), fileName.substring(index)));
+        }
+    }
+
+    /**
+     * Helper method to create an {@link InputStream} from a file without having to catch the possibly
+     * thrown {@link IOException}, use {@link FileInputStream#FileInputStream(File)} if you need to catch it.
+     * @param file the {@link File} to be opened
+     * @return an open {@link InputStream} instance reading from the file
+     */
+    @SneakyThrows
+    public static InputStream read(File file, boolean buffered) {
+        InputStream result = new FileInputStream(file);
+        return buffered ? new BufferedInputStream(result) : result;
+    }
+
+    /**
+     * Helper method to create an {@link OutputStream} from a file without having to catch the possibly
+     * thrown {@link IOException}, use {@link FileOutputStream#FileOutputStream(File)} if you need to catch it.
+     * @param file the {@link File} to be opened
+     * @return an open {@link OutputStream} instance writing to the file
+     */
+    @SneakyThrows
+    public static OutputStream write(File file, boolean buffered) {
+        OutputStream result = new FileOutputStream(file);
+        return buffered ? new BufferedOutputStream(result) : result;
+    }
+}

executable-jar/executable-jar-common/src/main/java/net/woggioni/executable/jar/Constants.java

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+package net.woggioni.executable.jar;
+
+import java.util.Calendar;
+import java.util.GregorianCalendar;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class Constants {
+    public static final String LIBRARIES_FOLDER = "LIB-INF";
+    public static final String METADATA_FOLDER = "META-INF";
+    public static final int BUFFER_SIZE = 0x10000;
+    public static final String DEFAULT_LAUNCHER = "net.woggioni.executable.jar.Launcher";
+
+    public static class ManifestAttributes {
+        public static final String MAIN_MODULE = "Executable-Jar-Main-Module";
+        public static final String MAIN_CLASS = "Executable-Jar-Main-Class";
+        public static final String ENTRY_HASH = "SHA-256-Digest";
+    }
+
+    /**
+     * This value is used as a default file timestamp for all the zip entries when
+     * <a href="https://docs.gradle.org/current/javadoc/org/gradle/api/tasks/bundling/AbstractArchiveTask.html#isPreserveFileTimestamps--">AbstractArchiveTask.isPreserveFileTimestamps</a>
+     * is true; its value is taken from Gradle's <a href="https://github.com/gradle/gradle/blob/master/subprojects/core/src/main/java/org/gradle/api/internal/file/archive/ZipCopyAction.java#L42-L57">ZipCopyAction<a/>
+     * for the reasons outlined there.
+     */
+    public static final long ZIP_ENTRIES_DEFAULT_TIMESTAMP =
+            new GregorianCalendar(1980, Calendar.FEBRUARY, 1, 0, 0, 0).getTimeInMillis();
+}