Implement support for service providers

build.sbt

@@ -42,6 +42,14 @@ lazy val jarjar = project
         .value
         .map(_.data).mkString(System.getProperty("path.separator"))
     )
+
+    assemblyMergeStrategy  := {
+      case PathList("module-info.class") => MergeStrategy.discard
+      case x if x.endsWith("/module-info.class") => MergeStrategy.discard
+      case x =>
+        val oldStrategy = (ThisBuild / assemblyMergeStrategy).value
+        oldStrategy(x)
+    }
   })
 
 lazy val core = project

jarjar/src/main/java/com/eed3si9n/jarjar/ResourceProcessor.java

@@ -16,22 +16,67 @@
 
 package com.eed3si9n.jarjar;
 
-import com.eed3si9n.jarjar.util.*;
+import com.eed3si9n.jarjar.util.EntryStruct;
+import com.eed3si9n.jarjar.util.JarProcessor;
+
 import java.io.IOException;
-import java.util.*;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.stream.Collectors;
 
 class ResourceProcessor implements JarProcessor
 {
+    private final static String META_INF_SERVICES = "META-INF/services/";
     private PackageRemapper pr;
 
     public ResourceProcessor(PackageRemapper pr) {
         this.pr = pr;
     }
 
     public boolean process(EntryStruct struct) throws IOException {
-        if (!struct.name.endsWith(".class"))
-            struct.name = pr.mapPath(struct.name);
+        switch (identify(struct)) {
+            case CLASS_FILE:
+                break;
+            case SERVICE_PROVIDER_CONFIGURATION:
+                struct.name = remapService(struct.name);
+                struct.data = remapServiceProviders(struct.data);
+                break;
+            case OTHER:
+                struct.name = pr.mapPath(struct.name);
+                break;
+        }
         return true;
     }
+
+    private String remapService(String serviceFile) {
+        int idx = serviceFile.lastIndexOf('/');
+        return META_INF_SERVICES + pr.mapValue(serviceFile.substring(idx + 1));
+    }
+
+    private byte[] remapServiceProviders(byte[] providers) {
+        // Provider configuration is encoded in UTF-8
+        // The file can also have comments and whitespaces
+        String s = new String(providers, StandardCharsets.UTF_8);
+
+        String mapped = Arrays.stream(s.split(System.lineSeparator()))
+            .map(l -> (String) pr.mapValue(l.split("#")[0].trim()))
+            .collect(Collectors.joining(System.lineSeparator()));
+        return mapped.getBytes(StandardCharsets.UTF_8);
+    }
+
+    private Resource identify(EntryStruct struct) {
+        if (struct.name.endsWith(".class"))
+            return Resource.CLASS_FILE;
+        // https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/ServiceLoader.html
+        if (struct.name.startsWith(META_INF_SERVICES) && !struct.name.equals(META_INF_SERVICES))
+            return Resource.SERVICE_PROVIDER_CONFIGURATION;
+        return Resource.OTHER;
+    }
+
+    private enum Resource {
+        CLASS_FILE,
+        SERVICE_PROVIDER_CONFIGURATION,
+        OTHER
+    }
 }
 

jarjar/src/main/java/com/eed3si9n/jarjar/RulesFileParser.java

@@ -34,7 +34,7 @@ public static List<PatternElement> parse(String value) throws IOException {
 
     private static String stripComment(String in) {
       int p = in.indexOf("#");
-      return p < 0 ? in : in.substring(0, p);
+      return p < 0 ? in.trim() : in.substring(0, p).trim();
     }
 
     private static List<PatternElement> parse(Reader r) throws IOException {

jarjar/src/test/java/com/eed3si9n/jarjar/ResourceProcessorTest.java

@@ -0,0 +1,72 @@
+package com.eed3si9n.jarjar;
+
+import com.eed3si9n.jarjar.util.EntryStruct;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+
+import static org.junit.Assert.*;
+
+public class ResourceProcessorTest {
+
+    private ResourceProcessor processor;
+
+    @Before
+    public void setUp() throws Exception {
+        String rules = "rule org.example.** something.shaded.@0";
+        List<Rule> parsed = (List<Rule>)(List<?>) RulesFileParser.parse(rules);
+        processor = new ResourceProcessor(new PackageRemapper(parsed, true));
+    }
+
+    @Test
+    public void testClassFile() throws IOException {
+        EntryStruct entryStruct = new EntryStruct();
+        entryStruct.name = "org/example/Object.class";
+        entryStruct.data = new byte[]{0x10};
+
+        assertTrue(processor.process(entryStruct));
+        assertEquals(entryStruct.name, "org/example/Object.class");
+        assertArrayEquals(entryStruct.data, new byte[]{0x10});
+    }
+
+    @Test
+    public void testServiceProviderConfig() throws IOException {
+        String original = "org.example.Impl     # comment" + System.lineSeparator()
+                        + "org.example.AnotherImpl" + System.lineSeparator()
+                        + System.lineSeparator()
+                        + "     org.another.Impl";
+        String expected = "something.shaded.org.example.Impl" + System.lineSeparator()
+                        + "something.shaded.org.example.AnotherImpl" + System.lineSeparator()
+                        + System.lineSeparator()
+                        + "org.another.Impl";
+        EntryStruct entryStruct = new EntryStruct();
+        entryStruct.name = "META-INF/services/org.example.Service";
+        entryStruct.data = original.getBytes(StandardCharsets.UTF_8);
+
+        assertTrue(processor.process(entryStruct));
+        assertEquals(entryStruct.name, "META-INF/services/something.shaded.org.example.Service");
+        assertArrayEquals(entryStruct.data, expected.getBytes(StandardCharsets.UTF_8));
+    }
+
+    @Test
+    public void testOtherResource() throws IOException {
+        EntryStruct entryStruct = new EntryStruct();
+        entryStruct.name = "org/example/file.txt";
+        entryStruct.data = new byte[]{0x10};
+
+        assertTrue(processor.process(entryStruct));
+        assertEquals(entryStruct.name, "something/shaded/org/example/file.txt");
+        assertArrayEquals(entryStruct.data, new byte[]{0x10});
+
+        EntryStruct entryStruct2 = new EntryStruct();
+        entryStruct2.name = "another_org/example/file.txt";
+        entryStruct2.data = new byte[]{0x10};
+
+        assertTrue(processor.process(entryStruct2));
+        assertEquals(entryStruct2.name, "another_org/example/file.txt");
+        assertArrayEquals(entryStruct.data, new byte[]{0x10});
+    }
+}

project/plugins.sbt

@@ -2,3 +2,4 @@ addSbtPlugin("com.eed3si9n" % "sbt-nocomma" % "0.1.0")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.3")
 addSbtPlugin("org.scala-sbt" % "sbt-contraband" % "0.4.6")
 addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.0.1")
+addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "1.1.0")