src/java.base/share/classes/jdk/internal/module/ModuleInfo.java

@@ -87,22 +87,28 @@
      * that represent the non-standard class file attributes that are read from
      * the class file.
      */
     public static final class Attributes {
         private final ModuleDescriptor descriptor;
+        private final ModuleTarget target;
         private final ModuleHashes recordedHashes;
         private final ModuleResolution moduleResolution;
         Attributes(ModuleDescriptor descriptor,
+                   ModuleTarget target,
                    ModuleHashes recordedHashes,
                    ModuleResolution moduleResolution) {
             this.descriptor = descriptor;
+            this.target = target;
             this.recordedHashes = recordedHashes;
             this.moduleResolution = moduleResolution;
         }
         public ModuleDescriptor descriptor() {
             return descriptor;
         }
+        public ModuleTarget target() {
+            return target;
+        }
         public ModuleHashes recordedHashes() {
             return recordedHashes;
         }
         public ModuleResolution moduleResolution() {
             return moduleResolution;

@@ -219,12 +225,12 @@
         Set<String> attributes = new HashSet<>();
 
         Builder builder = null;
         Set<String> allPackages = null;
         String mainClass = null;
-        String[] osValues = null;
-        ModuleHashes hashes = null;
+        ModuleTarget moduleTarget = null;
+        ModuleHashes moduelHashes = null;
         ModuleResolution moduleResolution = null;
 
         for (int i = 0; i < attributes_count ; i++) {
             int name_index = in.readUnsignedShort();
             String attribute_name = cpool.getUtf8(name_index);

@@ -249,16 +255,16 @@
                 case MODULE_MAIN_CLASS :
                     mainClass = readModuleMainClassAttribute(in, cpool);
                     break;
 
                 case MODULE_TARGET :
-                    osValues = readModuleTargetAttribute(in, cpool);
+                    moduleTarget = readModuleTargetAttribute(in, cpool);
                     break;
 
                 case MODULE_HASHES :
                     if (parseHashes) {
-                        hashes = readModuleHashesAttribute(in, cpool);
+                        moduelHashes = readModuleHashesAttribute(in, cpool);
                     } else {
                         in.skipBytes(length);
                     }
                     break;
 

@@ -280,19 +286,14 @@
         // the Module attribute is required
         if (builder == null) {
             throw invalidModuleDescriptor(MODULE + " attribute not found");
         }
 
-        // ModuleMainClass and ModuleTarget attributes
+        // ModuleMainClass  attribute
         if (mainClass != null) {
             builder.mainClass(mainClass);
         }
-        if (osValues != null) {
-            if (osValues[0] != null) builder.osName(osValues[0]);
-            if (osValues[1] != null) builder.osArch(osValues[1]);
-            if (osValues[2] != null) builder.osVersion(osValues[2]);
-        }
 
         // If the ModulePackages attribute is not present then the packageFinder
         // is used to find the set of packages
         boolean usedPackageFinder = false;
         if (allPackages == null && packageFinder != null) {

@@ -321,11 +322,14 @@
             }
             builder.packages(allPackages);
         }
 
         ModuleDescriptor descriptor = builder.build();
-        return new Attributes(descriptor, hashes, moduleResolution);
+        return new Attributes(descriptor,
+                              moduleTarget,
+                              moduelHashes,
+                              moduleResolution);
     }
 
     /**
      * Reads the Module attribute, returning the ModuleDescriptor.Builder to
      * build the corresponding ModuleDescriptor.

@@ -420,11 +424,15 @@
                 int exports_to_count = in.readUnsignedShort();
                 if (exports_to_count > 0) {
                     Set<String> targets = new HashSet<>(exports_to_count);
                     for (int j=0; j<exports_to_count; j++) {
                         int exports_to_index = in.readUnsignedShort();
-                        targets.add(cpool.getModuleName(exports_to_index));
+                        String target = cpool.getModuleName(exports_to_index);
+                        if (!targets.add(target)) {
+                            throw invalidModuleDescriptor(pkg + " exported to "
+                                                          + target + " more than once");
+                        }
                     }
                     builder.exports(mods, pkg, targets);
                 } else {
                     builder.exports(mods, pkg);
                 }

@@ -456,11 +464,15 @@
                 int open_to_count = in.readUnsignedShort();
                 if (open_to_count > 0) {
                     Set<String> targets = new HashSet<>(open_to_count);
                     for (int j=0; j<open_to_count; j++) {
                         int opens_to_index = in.readUnsignedShort();
-                        targets.add(cpool.getModuleName(opens_to_index));
+                        String target = cpool.getModuleName(opens_to_index);
+                        if (!targets.add(target)) {
+                            throw invalidModuleDescriptor(pkg + " opened to "
+                                                          + target + " more than once");
+                        }
                     }
                     builder.opens(mods, pkg, targets);
                 } else {
                     builder.opens(mods, pkg);
                 }

@@ -484,11 +496,14 @@
                 int with_count = in.readUnsignedShort();
                 List<String> providers = new ArrayList<>(with_count);
                 for (int j=0; j<with_count; j++) {
                     index = in.readUnsignedShort();
                     String pn = cpool.getClassName(index);
-                    providers.add(pn);
+                    if (!providers.add(pn)) {
+                        throw invalidModuleDescriptor(sn + " provides " + pn
+                                                      + " more than once");
+                    }
                 }
                 builder.provides(sn, providers);
             }
         }
 

@@ -526,28 +541,25 @@
     }
 
     /**
      * Reads the ModuleTarget attribute
      */
-    private String[] readModuleTargetAttribute(DataInput in, ConstantPool cpool)
+    private ModuleTarget readModuleTargetAttribute(DataInput in, ConstantPool cpool)
         throws IOException
     {
-        String[] values = new String[3];
+        String osName = null;
+        String osArch = null;
 
         int name_index = in.readUnsignedShort();
         if (name_index != 0)
-            values[0] = cpool.getUtf8(name_index);
+            osName = cpool.getUtf8(name_index);
 
         int arch_index = in.readUnsignedShort();
         if (arch_index != 0)
-            values[1] = cpool.getUtf8(arch_index);
-
-        int version_index = in.readUnsignedShort();
-        if (version_index != 0)
-            values[2] = cpool.getUtf8(version_index);
+            osArch = cpool.getUtf8(arch_index);
 
-        return values;
+        return new ModuleTarget(osName, osArch);
     }
 
 
     /**
      * Reads the ModuleHashes attribute