Add support for a static native library search path (#92)

- Add optional jssc.boot.library.path for native libs, helps with sandboxed environments
- Add unit tests for jssc.boot.library.path
- Bump maven-surefire-plugin to 3.0.0-M4

ant/build.xml

@@ -8,6 +8,7 @@
             <entry key="maven.nativelibdir.path" value="${maven.nativelibdir.path}"/>
             <entry key="maven.assembly.id" value="${maven.assembly.id}"/>
             <entry key="maven.test.skip" value="${maven.test.skip}"/>
+            <entry key="maven.exclude.tests" value="${maven.exclude.tests}"/>
         </propertyfile>
     </target>
 
@@ -193,6 +194,11 @@
             </and>
         </condition>
 
+        <!-- Skip ManualBootLibraryPathTest test if we're not building a native lib -->
+        <condition property="maven.exclude.tests" value="**/ManualBootLibraryPathTest.java" else="">
+            <equals arg1="${cmake.build.skip}" arg2="true"/>
+        </condition>
+
         <!-- Summarize host/target -->
         <echo level="info">Tests will run only if the TARGET and HOST match:${line.separator}${line.separator}</echo>
         <echo level="info">TARGET:   ${os.target.classifier}</echo>

pom.xml

@@ -68,7 +68,7 @@
     <plugin.osmaven.version>1.7.0</plugin.osmaven.version>
     <plugin.signature.version>1.1</plugin.signature.version>
     <plugin.source.version>3.0.1</plugin.source.version>
-    <plugin.surfire.version>3.0.0-M3</plugin.surfire.version>
+    <plugin.surfire.version>3.0.0-M4</plugin.surfire.version>
   </properties>
 
   <dependencies>
@@ -253,6 +253,12 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
         <version>${plugin.surfire.version}</version>
+        <configuration>
+          <reuseForks>false</reuseForks>
+          <excludes>
+            <exclude>${maven.exclude.tests}</exclude>
+          </excludes>
+        </configuration>
       </plugin>
 
       <plugin>

src/main/java/jssc/DefaultJniExtractorStub.java

@@ -0,0 +1,74 @@
+/**
+ * License: https://opensource.org/licenses/BSD-3-Clause
+ */
+package jssc;
+
+import org.scijava.nativelib.DefaultJniExtractor;
+import org.scijava.nativelib.NativeLibraryUtil;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * @author A. Tres Finocchiaro
+ *
+ * Stub <code>DefaultJniExtractor</code> class to allow native-lib-loader to conditionally
+ * use a statically defined native search path <code>bootPath</code> when provided.
+ */
+public class DefaultJniExtractorStub extends DefaultJniExtractor {
+    private File bootPath;
+
+    /**
+     * Default constructor
+     */
+    public DefaultJniExtractorStub(Class libraryJarClass) throws IOException {
+        super(libraryJarClass);
+    }
+
+    /**
+     * Force native-lib-loader to first look in the location defined as <code>bootPath</code>
+     * prior to extracting a native library, useful for sandboxed environments.
+     *  <code>
+     *  NativeLoader.setJniExtractor(new DefaultJniExtractorStub(null, "/opt/nativelibs")));
+     *  NativeLoader.loadLibrary("mylibrary");
+     *  </code>
+     */
+    public DefaultJniExtractorStub(Class libraryJarClass, String bootPath) throws IOException {
+        this(libraryJarClass);
+
+        if(bootPath != null) {
+            File bootTest = new File(bootPath);
+            if(bootTest.exists()) {
+                // assume a static, existing directory will contain the native libs
+                this.bootPath = bootTest;
+            } else {
+                System.err.println("WARNING " + DefaultJniExtractorStub.class.getCanonicalName() + ": Boot path " + bootPath + " not found, falling back to default extraction behavior.");
+            }
+        }
+    }
+
+    /**
+     * If a <code>bootPath</code> was provided to the constructor and exists,
+     * calculate the <code>File</code> path without any extraction logic.
+     *
+     * If a <code>bootPath</code> was NOT provided or does NOT exist, fallback on
+     * the default extraction behavior.
+     */
+    @Override
+    public File extractJni(String libPath, String libName) throws IOException {
+        // Lie and pretend it's already extracted at the bootPath location
+        if(bootPath != null) {
+            return new File(bootPath, NativeLibraryUtil.getPlatformLibraryName(libName));
+        }
+        // Fallback on default behavior
+        return super.extractJni(libPath, libName);
+    }
+
+    @Override
+    public void extractRegistered() throws IOException {
+        if(bootPath != null) {
+            return; // no-op
+        }
+        super.extractRegistered();
+    }
+}

src/main/java/jssc/SerialNativeInterface.java

@@ -85,6 +85,13 @@ else if(osName.equals("SunOS"))
         else if(osName.equals("Mac OS X") || osName.equals("Darwin"))
             osType = OS_MAC_OS_X;
         try {
+            /**
+             * JSSC includes a small, platform-specific shared library and uses native-lib-loader for extraction.
+             * - First, native-lib-loader will attempt to load this library from the system library path.
+             * - Next, it will fallback to <code>jssc.boot.library.path</code>
+             * - Finally it will attempt to extract the library from from the jssc.jar file, and load it.
+             */
+            NativeLoader.setJniExtractor(new DefaultJniExtractorStub(null, System.getProperty("jssc.boot.library.path")));
             NativeLoader.loadLibrary("jssc");
         } catch (IOException ioException) {
             throw new UnsatisfiedLinkError("Could not load the jssc library: " + ioException.getMessage());

src/test/java/jssc/bootpath/ManualBootLibraryPathFailedTest.java

@@ -0,0 +1,31 @@
+package jssc.bootpath;
+
+import jssc.SerialNativeInterface;
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+/**
+ * Tests if a valid <code>jssc.boot.library.path</code> which does NOT contain a native library
+ * will predictably fail.  This test can be run regardless of whether or not a native binary was
+ * created during the build process.
+ *
+ * TODO: This MUST be in its own class to run in a separate JVM (https://stackoverflow.com/questions/68657855)
+ * - JUnit does NOT currently offer JVM unloading between methods.
+ * - maven-surefire-plugin DOES offer JVM unloading between classes using <code>reuseForks=false</code>
+ * - Unloading is needed due to NativeLoader.loadLibrary(...) calls System.loadLibrary(...) which is static
+ */
+public class ManualBootLibraryPathFailedTest {
+    @Test
+    public void testBootPathOverride() {
+        String nativeLibDir = "/"; // This should be valid on all platforms
+        System.setProperty("jssc.boot.library.path", nativeLibDir);
+        try {
+            SerialNativeInterface.getNativeLibraryVersion();
+            fail("Library loading should fail if path provided exists but does not contain a native library");
+        } catch (UnsatisfiedLinkError ignore) {
+            assertTrue("Library loading failed as expected with an invalid jssc.boot.library.path", true);
+        }
+    }
+}

src/test/java/jssc/bootpath/ManualBootLibraryPathTest.java

@@ -0,0 +1,35 @@
+package jssc.bootpath;
+
+import jssc.SerialNativeInterface;
+import org.junit.Test;
+import org.scijava.nativelib.NativeLibraryUtil;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.fail;
+
+/**
+ * Tests if a valid <code>jssc.boot.library.path</code> which DOES contain a native library
+ * will predictably pass.  This test can ONLY be run regardless if a native binary was created
+ * during the build process.  See also <code>maven.exclude.tests</code>.
+ *
+ * TODO: This MUST be in its own class to run in a separate JVM (https://stackoverflow.com/questions/68657855)
+ * - JUnit does NOT currently offer JVM unloading between methods.
+ * - maven-surefire-plugin DOES offer JVM unloading between classes using <code>reuseForks=false</code>
+ * - Unloading is needed due to NativeLoader.loadLibrary(...) calls System.loadLibrary(...) which is static
+ */
+public class ManualBootLibraryPathTest {
+    @Test
+    public void testBootPathOverride() {
+        String nativeLibDir = NativeLibraryUtil.getPlatformLibraryPath(System.getProperty("user.dir") + "/target/cmake/natives/");
+        System.setProperty("jssc.boot.library.path", nativeLibDir);
+        try {
+            final String nativeLibraryVersion = SerialNativeInterface.getNativeLibraryVersion();
+            assertThat(nativeLibraryVersion, is(not(nullValue())));
+            assertThat(nativeLibraryVersion, is(not("")));
+        } catch (UnsatisfiedLinkError linkError) {
+            linkError.printStackTrace();
+            fail("Should be able to call method!");
+        }
+    }
+}