Index: src/org/netbeans/core/modules/Module.java
===================================================================
RCS file: /cvs/core/src/org/netbeans/core/modules/Module.java,v
--- src/org/netbeans/core/modules/Module.java	11 Aug 2004 10:07:40 -0000	1.55
+++ src/org/netbeans/core/modules/Module.java	12 Mar 2005 09:01:50 -0000
@@ -110,6 +110,8 @@ public final class Module extends Module
     private Properties localizedProps;
     /** public packages, may be null */
     private PackageExport[] publicPackages;
+    /** Set<String> of names of friend modules or null */
+    private Set/*<String>*/ friendNames;
     
     /** Map from extension JARs to sets of JAR that load them via Class-Path.
      * Used only for debugging purposes, so that a warning is printed if two
@@ -380,6 +382,14 @@ public final class Module extends Module
         return publicPackages;
     }
     
+    /** Checks whether we use friends attribute and if so, then
+     * whether the name of module is listed there.
+     */
+    public boolean isDeclaredAsFriend (Module module) {
+        if (friendNames == null) return true;
+        return friendNames.contains (module.getCodeName());
+    }
+    
     /** Parse information from the current manifest.
      * Includes code name, specification version, and dependencies.
      * If anything is in an invalid format, throws an exception with
@@ -481,6 +491,23 @@ public final class Module extends Module
                 Util.err.log(ErrorManager.WARNING, "Warning: module " + codeNameBase + " does not declare OpenIDE-Module-Public-Packages in its manifest, so all packages are considered public by default: http://www.netbeans.org/download/dev/javadoc/OpenAPIs/org/openide/doc-files/upgrade.html#3.4-public-packages");
                 publicPackages = null;
             }
+            
+            {
+                // friends 
+                String friends = attr.getValue("OpenIDE-Module-Friends"); // NOI18N
+                if (friends != null) {
+                    StringTokenizer tok = new StringTokenizer(friends, ", "); // NOI18N
+                    HashSet set = new HashSet ();
+                    while (tok.hasMoreTokens()) {
+                        String piece = tok.nextToken();
+                        set.add(piece.intern ());
+                    }
+                    if (set.isEmpty()) throw new IllegalArgumentException("Illegal OpenIDE-Module-Friends: " + friends); // NOI18N
+                    this.friendNames = set;
+                }
+            }
+            
+            
             // Dependencies
             Set dependencies = new HashSet(20); // Set<Dependency>
             // First convert IDE/1 -> org.openide/1, so we never have to deal with
Index: src/org/netbeans/core/modules/ModuleManager.java
===================================================================
RCS file: /cvs/core/src/org/netbeans/core/modules/ModuleManager.java,v
--- src/org/netbeans/core/modules/ModuleManager.java	14 Aug 2004 00:28:23 -0000	1.64
+++ src/org/netbeans/core/modules/ModuleManager.java	12 Mar 2005 09:01:51 -0000
@@ -555,6 +555,14 @@ public final class ModuleManager {
                     return false;
                 }
                 //Util.err.log("friend");
+            } else {
+                // We have to verify that the caller is friend of this module
+                if (!parent.isDeclaredAsFriend (m)) {
+                    if (Util.err.isLoggable(ErrorManager.INFORMATIONAL)) {
+                        Util.err.log("Refusing to load public package " + pkg + " for " + m + " from parent module " + parent + " as the caller is not listed as a friend module"); // NOI18N
+                    }
+                    return false;
+                }
             }
             //Util.err.log("exported");
         }
Index: test/unit/src/org/netbeans/core/modules/ModuleManagerTest.java
===================================================================
RCS file: /cvs/core/test/unit/src/org/netbeans/core/modules/ModuleManagerTest.java,v
--- test/unit/src/org/netbeans/core/modules/ModuleManagerTest.java	8 Feb 2005 10:12:29 -0000	1.39
+++ test/unit/src/org/netbeans/core/modules/ModuleManagerTest.java	12 Mar 2005 09:01:52 -0000
@@ -1653,6 +1653,50 @@ public class ModuleManagerTest extends S
             mgr.mutexPrivileged().exitWriteAccess();
         }
     }
+
+    public void testPublicPackagesCanBeExportedToSelectedFriendsOnlyIssue54123 () throws Exception {
+        ModuleManager mgr = new ModuleManager(new FakeModuleInstaller(), new FakeEvents());
+        mgr.mutexPrivileged().enterWriteAccess();
+        try {
+            addOpenide(mgr);
+            Module m1 = mgr.create(new File(jars, "api-mod-export-friend.jar"), null, false, false, false);
+            Module m2 = mgr.create(new File(jars, "uses-api-friend.jar"), null, false, false, false);
+            Module m3 = mgr.create(new File(jars, "uses-and-exports-api.jar"), null, false, false, false);
+            Module m4 = mgr.create(new File(jars, "uses-api-directly.jar"), null, false, false, false);
+            assertEquals("api-mod-export-api.jar had no problems", Collections.EMPTY_SET, m1.getProblems());
+            assertEquals("uses-api-friend.jar had no problems", Collections.EMPTY_SET, m2.getProblems());
+            assertEquals("uses-and-exports-api.jar had no problems", Collections.EMPTY_SET, m3.getProblems());
+            assertEquals("uses-api-directly.jar had no problems", Collections.EMPTY_SET, m4.getProblems());
+            mgr.enable(new HashSet(Arrays.asList(new Module[] {m1, m2, m3, m4})));
+            m2.getClassLoader().loadClass("usesapi.UsesPublicClass").newInstance();
+            try {
+                m2.getClassLoader().loadClass("usesapi.UsesImplClass").newInstance();
+                fail ("Even friends modules cannot access implementation classes");
+            } catch (NoClassDefFoundError ex) {
+                // ok
+            }
+            
+            try {
+                m4.getClassLoader().loadClass("usesapi.UsesPublicClass").newInstance();
+                fail ("m4 is not friend and should not be allowed to load the class");
+            } catch (NoClassDefFoundError ex) {
+                // ok
+            }
+            try {
+                m4.getClassLoader().loadClass("usesapi.UsesImplClass").newInstance();
+                fail ("m4 is not friend and should not be allowed to load the implementation either");
+            } catch (NoClassDefFoundError ex) {
+                // ok
+            }
+            mgr.disable(new HashSet(Arrays.asList(new Module[] {m1, m2, m3, m4})));
+            mgr.delete(m4);
+            mgr.delete(m3);
+            mgr.delete(m2);
+            mgr.delete(m1);
+        } finally {
+            mgr.mutexPrivileged().exitWriteAccess();
+        }
+    }
     
     public void testModuleInterdependencies() throws Exception {
         FakeModuleInstaller installer = new FakeModuleInstaller();
Index: test/unit/src/org/netbeans/core/modules/build.xml
===================================================================
RCS file: /cvs/core/test/unit/src/org/netbeans/core/modules/build.xml,v
--- test/unit/src/org/netbeans/core/modules/build.xml	29 Oct 2004 15:18:42 -0000	1.24
+++ test/unit/src/org/netbeans/core/modules/build.xml	12 Mar 2005 09:01:52 -0000
@@ -159,6 +159,10 @@ Microsystems, Inc. All Rights Reserved.
             <param name="sourcedir" value="jars/exposes-api"/>
         </antcall>
         <antcall target="create-jar">
+            <param name="name" value="api-mod-export-friend"/>
+            <param name="sourcedir" value="jars/exposes-api"/>
+        </antcall>
+        <antcall target="create-jar">
             <param name="name" value="uses-api-simple-dep"/>
             <param name="sourcedir" value="jars/uses-api"/>
             <param name="cp" value="${jars}/api-mod-export-api.jar"/>
@@ -202,6 +206,10 @@ Microsystems, Inc. All Rights Reserved.
         </antcall>
         <antcall target="create-jar">
             <param name="name" value="look-for-myself"/>
+        </antcall>
+        <antcall target="create-jar">
+            <param name="name" value="uses-api-friend"/>
+            <param name="sourcedir" value="jars/uses-api"/>
         </antcall>
         <!-- Don't use <jar>! It will add Created-By: Ant 1.nnn, which screws up results. -->
         <zip zipfile="jars/little-manifest.jar" compress="false">
Index: test/unit/src/org/netbeans/core/modules/jars/api-mod-export-friend.mf
===================================================================
RCS file: test/unit/src/org/netbeans/core/modules/jars/api-mod-export-friend.mf
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ test/unit/src/org/netbeans/core/modules/jars/api-mod-export-friend.mf	12 Mar 2005 09:01:52 -0000
@@ -0,0 +1,8 @@ 
+Manifest-Version: 1.0
+OpenIDE-Module: org.netbeans.modules.foo
+OpenIDE-Module-Public-Packages: org.netbeans.api.foo.*
+OpenIDE-Module-Friends: org.netbeans.core/1, usesapifriend
+OpenIDE-Module-Specification-Version: 1.0
+OpenIDE-Module-Implementation-Version: today
+OpenIDE-Module-IDE-Dependencies: IDE/1 > 2.2
+
Index: test/unit/src/org/netbeans/core/modules/jars/uses-api-friend.mf
===================================================================
RCS file: test/unit/src/org/netbeans/core/modules/jars/uses-api-friend.mf
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ test/unit/src/org/netbeans/core/modules/jars/uses-api-friend.mf	12 Mar 2005 09:01:52 -0000
@@ -0,0 +1,5 @@ 
+Manifest-Version: 1.0
+OpenIDE-Module: usesapifriend
+OpenIDE-Module-Module-Dependencies: org.netbeans.modules.foo > 1.0
+OpenIDE-Module-IDE-Dependencies: IDE/1 > 5.0
+