Turns out we don't actually need 30MB of bloated jars to make a single HTTP post to get a Google SSO auth token. Don't need them for Firebase either. And not for Apple SSO. Shoot while we're at it, might as well get rid of pi4j too since making a JNI wrapper for PiGPio is easy enough.

pigpio/lantern-pigpio/src/main/java/com/lanternsoftware/pigpio/PIGPIO.java

@@ -0,0 +1,54 @@
+package com.lanternsoftware.pigpio;
+
+import com.lanternsoftware.util.ResourceLoader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.nio.file.Files;
+
+public class PIGPIO {
+    protected static final Logger LOG = LoggerFactory.getLogger(PIGPIO.class);
+
+	private PIGPIO() {
+	}
+
+	static {
+		try {
+			String osArch = System.getProperty("os.arch").toLowerCase();
+			if (osArch.equals("arm"))
+				osArch = "armhf";
+			String path = "/lib/" + osArch + "/lantern-pigpio.so";
+			byte[] file = ResourceLoader.getByteArrayResource(PIGPIO.class, path);
+			String target = Files.createTempFile("lantern-pigpio", "so").toAbsolutePath().toString();
+			ResourceLoader.writeFile(target, file);
+			System.load(target);
+		} catch (IOException _e) {
+            LOG.error("Failed to load lantern-pigpio.so from resource", _e);
+		}
+	}
+
+	public static native int gpioInitialise();
+
+	public static native void gpioTerminate();
+
+	public static native int gpioSetMode(int gpio, int mode);
+
+	public static native int gpioGetMode(int gpio);
+
+	public static native int gpioSetPullUpDown(int gpio, int pud);
+
+	public static native int gpioRead(int gpio);
+
+	public static native int gpioWrite(int gpio, int level);
+
+	public static native int spiOpen(int spiChan, int baud, int spiFlags);
+
+	public static native int spiClose(int handle);
+
+	public static native int spiRead(int handle, byte[] buf, int offset, int count);
+
+	public static native int spiWrite(int handle, byte[] buf, int offset, int count);
+
+	public static native int spiXfer(int handle, byte[] txBuf, int txOffset, byte[] rxBuf, int rxOffset, int count);
+}

pigpio/lantern-pigpio/src/main/java/com/lanternsoftware/pigpio/PiGpioFactory.java

@@ -0,0 +1,51 @@
+package com.lanternsoftware.pigpio;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class PiGpioFactory {
+	private static final Logger LOG = LoggerFactory.getLogger(PIGPIO.class);
+	private static final Map<Integer, Spi> spiHandles = new HashMap<>();
+	private static boolean initialized = false;
+
+	public static Spi getSpiChannel(int _channel, int _baud, boolean _auxiliary) {
+		ensureInitialized();
+		int channelId = (0xff & _channel);
+		if (_auxiliary)
+			channelId |= 0x100;
+		Spi handle = spiHandles.get(channelId);
+		if (handle == null) {
+			int h = PIGPIO.spiOpen(_channel, _baud, _auxiliary ? 0x100 : 0);
+			if (h >= 0) {
+				handle = new Spi(h);
+				spiHandles.put(channelId, handle);
+			}
+			else {
+				LOG.error("Failed to get SPI handle");
+			}
+		}
+		return handle;
+	}
+
+	private static void ensureInitialized() {
+		if (initialized)
+			return;
+		int init = PIGPIO.gpioInitialise();
+		LOG.info("GPIO init: {}", init);
+		if (init < 0)
+			LOG.error("Failed to initialize PiGpio");
+		else
+			initialized = true;
+	}
+
+	public static void shutdown() {
+		for (Spi handle : spiHandles.values()) {
+			PIGPIO.spiClose(handle.getHandle());
+		}
+		spiHandles.clear();
+		PIGPIO.gpioTerminate();
+	}
+}

pigpio/lantern-pigpio/src/main/java/com/lanternsoftware/pigpio/Spi.java

@@ -0,0 +1,37 @@
+package com.lanternsoftware.pigpio;
+
+public class Spi {
+	private final int handle;
+
+	public Spi(int _handle) {
+		handle = _handle;
+	}
+
+	public int getHandle() {
+		return handle;
+	}
+
+	public int read(byte[] buf) {
+		return read(buf, 0, buf.length);
+	}
+
+	public int read(byte[] buf, int offset, int count) {
+		return PIGPIO.spiRead(handle, buf, offset, count);
+	}
+
+	public int write(byte[] buf) {
+		return write(buf, 0, buf.length);
+	}
+
+	public int write(byte[] buf, int offset, int count) {
+		return PIGPIO.spiWrite(handle, buf, offset, count);
+	}
+
+	public int transfer(byte[] txBuf, byte[] rxBuf) {
+		return transfer(txBuf, 0, rxBuf, 0, rxBuf.length);
+	}
+
+	public int transfer(byte[] txBuf, int txOffset, byte[] rxBuf, int rxOffset, int count) {
+		return PIGPIO.spiXfer(handle, txBuf, txOffset, rxBuf, rxOffset, count);
+	}
+}

pigpio/lantern-pigpio/src/main/native/Makefile

@@ -0,0 +1,54 @@
+ARCH        := armhf
+DEBUG	       = -O3
+CC           = $(CROSS_PREFIX)gcc
+AR           = $(CROSS_PREFIX)ar
+RANLIB       = $(CROSS_PREFIX)ranlib
+SIZE         = $(CROSS_PREFIX)size
+STRIP        = $(CROSS_PREFIX)strip
+SHLIB        = $(CC) -shared
+STRIPLIB     = $(STRIP) --strip-unneeded
+INCLUDE	     = -I. -Ipigpio                                              \
+               -I/$(JAVA_HOME)/include                                   \
+               -I/$(JAVA_HOME)/include/linux                             \
+               -I/usr/local/include -I/usr/local/include/linux
+
+CFLAGS      := $(DEBUG) -Wall $(INCLUDE) -Winline -pipe $(CARGS) -fPIC
+LIBS         =  -L lib/$(ARCH) -L pigpio -lpigpio -lrt
+
+TARGET=lantern-pigpio.so
+
+###############################################################################
+
+SRC	=   com_lanternsoftware_pigpio_PIGPIO.c
+
+OBJ =	$(SRC:.c=.o)
+
+all:	$(OBJ)
+	    @echo [LINK with DYNAMICALLY linked libraries]
+	    @$(CC) $(OBJ) -shared -o $(TARGET) $(INCLUDE) $(LIBS)
+
+.c.o:
+	@echo [COMPILE] $<
+	@$(CC) -c $(CFLAGS) $< -o $@
+
+clean:
+	rm -f $(OBJ) $(TARGET) *~ core tags Makefile.bak
+
+tags:	$(SRC)
+	@echo [ctags]
+	@ctags $(SRC)
+
+depend:
+	makedepend -Y $(SRC)
+
+install:	$(TARGET)
+	@echo [install]
+	install -m 0755 -d /usr/local/lib
+	install -m 0755 -d /usr/local/include
+	install -m 0644 $(TARGET)	/usr/local/lib
+
+uninstall:
+	@echo [uninstall]
+	rm -f /usr/local/lib/$(TARGET)
+
+com_lanternsoftware_pigpio_PIGPIO.o: com_lanternsoftware_pigpio_PIGPIO.h

pigpio/lantern-pigpio/src/main/native/com_lanternsoftware_pigpio_PIGPIO.c

@@ -0,0 +1,117 @@
+#include <jni.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <pigpio.h>
+#include "com_lanternsoftware_pigpio_PIGPIO.h"
+
+
+JavaVM *callback_jvm;
+
+JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved)
+{
+	JNIEnv *env;
+    if ((*jvm)->GetEnv(jvm, (void **)&env, JNI_VERSION_1_2))
+    {
+        return JNI_ERR;
+    }
+    callback_jvm = jvm;
+	return JNI_VERSION_1_2;
+}
+
+JNIEXPORT void JNICALL JNI_OnUnload(JavaVM *jvm, void *reserved)
+{
+	return;
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioInitialise
+  (JNIEnv *env, jclass class)
+{
+    gpioCfgSetInternals (gpioCfgGetInternals () | PI_CFG_NOSIGHANDLER);
+    return gpioInitialise();
+}
+
+JNIEXPORT void JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioTerminate(JNIEnv *env, jclass class)
+{
+    return gpioTerminate();
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioSetMode
+  (JNIEnv *env, jclass class, jint gpio, jint mode)
+{
+    return gpioSetMode((unsigned)gpio, (unsigned)mode);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioGetMode
+  (JNIEnv *env, jclass class, jint gpio)
+{
+    return gpioGetMode((unsigned)gpio);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioSetPullUpDown
+  (JNIEnv *env, jclass class, jint gpio, jint pud)
+{
+    return gpioSetPullUpDown((unsigned)gpio, (unsigned)pud);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioRead
+  (JNIEnv *env, jclass class, jint gpio)
+{
+    return gpioRead((unsigned)gpio);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioWrite
+  (JNIEnv *env, jclass class, jint gpio, jint level)
+{
+    return gpioWrite((unsigned)gpio, (unsigned)level);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiOpen
+  (JNIEnv *env, jclass class, jint spiChan, jint baud, jint spiFlags)
+{
+    return spiOpen((unsigned)spiChan, (unsigned)baud, (unsigned)spiFlags);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiClose
+  (JNIEnv *env, jclass class, jint handle)
+{
+    return spiClose((unsigned)handle);
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiRead
+  (JNIEnv *env, jclass class, jint handle, jbyteArray data, jint offset, jint count)
+{
+    jbyte *buffer = (*env)->GetByteArrayElements(env, data, 0);
+    jsize max_length = (*env)->GetArrayLength(env, data) - offset;
+    int length = (count > max_length) ? max_length : count;
+    jbyte *offsetBuffer = buffer + offset;
+	jint result = spiRead((unsigned)handle, (char *)offsetBuffer, (unsigned)length);
+	(*env)->ReleaseByteArrayElements(env, data, buffer, 0);
+	return result;
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiWrite
+  (JNIEnv *env, jclass class, jint handle, jbyteArray data, jint offset, jint count)
+{
+    jbyte *buffer = (*env)->GetByteArrayElements(env, data, 0);
+    jsize max_length = (*env)->GetArrayLength(env, data) - offset;
+    int length = (count > max_length) ? max_length : count;
+    jbyte *offsetBuffer = buffer + offset;
+	jint result = spiWrite((unsigned)handle, (char *)offsetBuffer, (unsigned)length);
+	(*env)->ReleaseByteArrayElements(env, data, buffer, JNI_ABORT);
+	return result;
+}
+
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiXfer
+  (JNIEnv *env, jclass class, jint handle, jbyteArray writeData, jint writeOffset, jbyteArray readData, jint readOffset, jint count)
+{
+    jbyte *writeBuffer = (*env)->GetByteArrayElements(env, writeData, 0);
+    jbyte *readBuffer = (*env)->GetByteArrayElements(env, readData, 0);
+    jsize max_length = (*env)->GetArrayLength(env, writeData) - writeOffset;
+    int length = (count > max_length) ? max_length : count;
+    jbyte *offsetWriteBuffer = writeBuffer + writeOffset;
+    jbyte *offsetReadBuffer = readBuffer + readOffset;
+    jint result = spiXfer((unsigned)handle, (char *)offsetWriteBuffer, (char *)offsetReadBuffer, (unsigned)length);
+	(*env)->ReleaseByteArrayElements(env, writeData, writeBuffer, JNI_ABORT);
+	(*env)->ReleaseByteArrayElements(env, readData, readBuffer, 0);
+	return result;
+}

pigpio/lantern-pigpio/src/main/native/com_lanternsoftware_pigpio_PIGPIO.h

@@ -0,0 +1,109 @@
+/* DO NOT EDIT THIS FILE - it is machine generated */
+#include <jni.h>
+/* Header for class com_lanternsoftware_pigpio_PIGPIO */
+
+#ifndef _Included_com_lanternsoftware_pigpio_PIGPIO
+#define _Included_com_lanternsoftware_pigpio_PIGPIO
+#ifdef __cplusplus
+extern "C" {
+#endif
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioInitialise
+ * Signature: ()I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioInitialise
+  (JNIEnv *, jclass);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioTerminate
+ * Signature: ()V
+ */
+JNIEXPORT void JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioTerminate
+  (JNIEnv *, jclass);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioSetMode
+ * Signature: (II)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioSetMode
+  (JNIEnv *, jclass, jint, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioGetMode
+ * Signature: (I)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioGetMode
+  (JNIEnv *, jclass, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioSetPullUpDown
+ * Signature: (II)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioSetPullUpDown
+  (JNIEnv *, jclass, jint, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioRead
+ * Signature: (I)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioRead
+  (JNIEnv *, jclass, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    gpioWrite
+ * Signature: (II)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_gpioWrite
+  (JNIEnv *, jclass, jint, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    spiOpen
+ * Signature: (III)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiOpen
+  (JNIEnv *, jclass, jint, jint, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    spiClose
+ * Signature: (I)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiClose
+  (JNIEnv *, jclass, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    spiRead
+ * Signature: (I[BII)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiRead
+  (JNIEnv *, jclass, jint, jbyteArray, jint, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    spiWrite
+ * Signature: (I[BII)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiWrite
+  (JNIEnv *, jclass, jint, jbyteArray, jint, jint);
+
+/*
+ * Class:     com_lanternsoftware_pigpio_PIGPIO
+ * Method:    spiXfer
+ * Signature: (I[BI[BII)I
+ */
+JNIEXPORT jint JNICALL Java_com_lanternsoftware_pigpio_PIGPIO_spiXfer
+  (JNIEnv *, jclass, jint, jbyteArray, jint, jbyteArray, jint, jint);
+
+#ifdef __cplusplus
+}
+#endif
+#endif