1 files changed, 41 insertions, 6 deletions

diff --git a/java/com/google/turbine/binder/CtSymClassBinder.java b/java/com/google/turbine/binder/CtSymClassBinder.java
index a6f1b3d..1d7ece7 100644
--- a/java/com/google/turbine/binder/CtSymClassBinder.java
+++ b/java/com/google/turbine/binder/CtSymClassBinder.java
@@ -16,11 +16,15 @@
 
 package com.google.turbine.binder;
 
+import static com.google.common.base.Ascii.toUpperCase;
 import static com.google.common.base.StandardSystemProperty.JAVA_HOME;
+import static java.util.Objects.requireNonNull;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Supplier;
 import com.google.common.base.Suppliers;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.primitives.Ints;
 import com.google.turbine.binder.bound.ModuleInfo;
 import com.google.turbine.binder.bytecode.BytecodeBinder;
 import com.google.turbine.binder.bytecode.BytecodeBoundClass;
@@ -32,6 +36,7 @@ import com.google.turbine.binder.sym.ClassSymbol;
 import com.google.turbine.binder.sym.ModuleSymbol;
 import com.google.turbine.zip.Zip;
 import java.io.IOException;
+import java.lang.reflect.Method;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -40,12 +45,13 @@ import java.util.Map;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Constructs a platform {@link ClassPath} from the current JDK's ct.sym file. */
-public class CtSymClassBinder {
+public final class CtSymClassBinder {
 
   @Nullable
   public static ClassPath bind(String version) throws IOException {
-    Path javaHome = Paths.get(JAVA_HOME.value());
-    Path ctSym = javaHome.resolve("lib/ct.sym");
+    String javaHome = JAVA_HOME.value();
+    requireNonNull(javaHome, "attempted to use --release, but JAVA_HOME is not set");
+    Path ctSym = Paths.get(javaHome).resolve("lib/ct.sym");
     if (!Files.exists(ctSym)) {
       throw new IllegalStateException("lib/ct.sym does not exist in " + javaHome);
     }
@@ -59,7 +65,9 @@ public class CtSymClassBinder {
           }
         };
     // ct.sym contains directories whose names are the concatentation of a list of target versions
-    // (e.g. 789) and which contain interface class files with a .sig extension.
+    // formatted as a single character 0-9 or A-Z (e.g. 789A) and which contain interface class
+    // files with a .sig extension.
+    String releaseString = formatReleaseVersion(version);
     for (Zip.Entry ze : new Zip.ZipIterable(ctSym)) {
       String name = ze.name();
       if (!name.endsWith(".sig")) {
@@ -70,10 +78,13 @@ public class CtSymClassBinder {
         continue;
       }
       // check if the directory matches the desired release
-      // TODO(cushon): what happens when version numbers contain more than one digit?
-      if (!ze.name().substring(0, idx).contains(version)) {
+      if (!ze.name().substring(0, idx).contains(releaseString)) {
         continue;
       }
+      if (isAtLeastJDK12()) {
+        // JDK >= 12 includes the module name as a prefix
+        idx = name.indexOf('/', idx + 1);
+      }
       if (name.substring(name.lastIndexOf('/') + 1).equals("module-info.sig")) {
         ModuleInfo moduleInfo = BytecodeBinder.bindModuleInfo(name, toByteArrayOrDie(ze));
         modules.put(new ModuleSymbol(moduleInfo.name()), moduleInfo);
@@ -122,4 +133,28 @@ public class CtSymClassBinder {
           }
         });
   }
+
+  @VisibleForTesting
+  static String formatReleaseVersion(String version) {
+    Integer n = Ints.tryParse(version);
+    if (n == null || n <= 4 || n >= 36) {
+      throw new IllegalArgumentException("invalid release version: " + version);
+    }
+    return toUpperCase(Integer.toString(n, 36));
+  }
+
+  private static boolean isAtLeastJDK12() {
+    int major;
+    try {
+      Method versionMethod = Runtime.class.getMethod("version");
+      Object version = versionMethod.invoke(null);
+      major = (int) version.getClass().getMethod("major").invoke(version);
+    } catch (ReflectiveOperationException e) {
+      // `Runtime.version()` was added in JDK 9
+      return false;
+    }
+    return major >= 12;
+  }
+
+  private CtSymClassBinder() {}
 }