fix: modifiable and ordered permissions, sorted user attributes

core/src/main/java/io/roastedroot/zerofs/PosixAttributeProvider.java

@@ -13,6 +13,10 @@
 import java.nio.file.attribute.PosixFilePermission;
 import java.nio.file.attribute.PosixFilePermissions;
 import java.nio.file.attribute.UserPrincipal;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
@@ -31,7 +35,7 @@ final class PosixAttributeProvider extends AttributeProvider {
 
     private static final GroupPrincipal DEFAULT_GROUP = createGroupPrincipal("group");
     private static final Set<PosixFilePermission> DEFAULT_PERMISSIONS =
-            Set.copyOf(PosixFilePermissions.fromString("rw-r--r--"));
+            immutablePermissions(PosixFilePermissions.fromString("rw-r--r--"));
 
     @Override
     public String name() {
@@ -74,7 +78,7 @@ public Set<String> fixedAttributes() {
         if (userProvidedPermissions != null) {
             if (userProvidedPermissions instanceof String) {
                 permissions =
-                        Set.copyOf(
+                        immutablePermissions(
                                 PosixFilePermissions.fromString((String) userProvidedPermissions));
             } else if (userProvidedPermissions instanceof Set) {
                 permissions = toPermissions((Set<?>) userProvidedPermissions);
@@ -140,7 +144,14 @@ private static Set<PosixFilePermission> toPermissions(Set<?> set) {
             }
         }
 
-        return Set.copyOf((Set<PosixFilePermission>) copy);
+        return immutablePermissions((Set<PosixFilePermission>) copy);
+    }
+
+    private static Set<PosixFilePermission> immutablePermissions(
+            Collection<PosixFilePermission> permissions) {
+        Set<PosixFilePermission> result = EnumSet.noneOf(PosixFilePermission.class);
+        result.addAll(permissions);
+        return Collections.unmodifiableSet(result);
     }
 
     @Override
@@ -201,7 +212,7 @@ public void setTimes(
 
         @Override
         public void setPermissions(Set<PosixFilePermission> perms) throws IOException {
-            lookupFile().setAttribute("posix", "permissions", Set.copyOf(perms));
+            lookupFile().setAttribute("posix", "permissions", immutablePermissions(perms));
         }
 
         @Override
@@ -248,7 +259,7 @@ public GroupPrincipal group() {
 
         @Override
         public Set<PosixFilePermission> permissions() {
-            return permissions;
+            return new LinkedHashSet<>(permissions);
         }
     }
 }

core/src/main/java/io/roastedroot/zerofs/UserDefinedAttributeProvider.java

@@ -4,6 +4,7 @@
 import java.nio.ByteBuffer;
 import java.nio.file.attribute.FileAttributeView;
 import java.nio.file.attribute.UserDefinedFileAttributeView;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -49,7 +50,7 @@ private static Set<String> userDefinedAttributes(File file) {
         for (String attribute : file.getAttributeNames("user")) {
             builder.add(attribute);
         }
-        return Set.copyOf(builder);
+        return Collections.unmodifiableSet(builder);
     }
 
     @Override

core/src/test/java/io/roastedroot/zerofs/PosixAttributeProviderTest.java

@@ -10,6 +10,8 @@
 import java.nio.file.attribute.PosixFileAttributes;
 import java.nio.file.attribute.PosixFilePermission;
 import java.nio.file.attribute.PosixFilePermissions;
+import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -107,4 +109,22 @@ public void testAttributes() {
         assertEquals(createGroupPrincipal("group"), attrs.group());
         assertEquals(0, attrs.fileKey());
     }
+
+    @Test
+    public void testAttributes_permissionsAreModifiable() {
+        Set<PosixFilePermission> permissions = provider.readAttributes(file).permissions();
+        permissions.add(PosixFilePermission.OWNER_EXECUTE);
+        assertEquals(PosixFilePermissions.fromString("rwxr--r--"), permissions);
+    }
+
+    @Test
+    public void testAttributes_permissionsInEnumOrder() {
+        provider.set(file, "posix", "permissions", new HashSet<>(allPermissions()), false);
+        assertEquals(
+                allPermissions(), new ArrayList<>(provider.readAttributes(file).permissions()));
+    }
+
+    private static List<PosixFilePermission> allPermissions() {
+        return List.of(PosixFilePermission.values());
+    }
 }

core/src/test/java/io/roastedroot/zerofs/UserDefinedAttributeProviderTest.java

@@ -59,6 +59,19 @@ public void testSetOnCreate() {
         assertSetFailsOnCreate("anything", new byte[0]);
     }
 
+    @Test
+    public void testView_listIsSorted() throws IOException {
+        UserDefinedFileAttributeView view = provider.view(fileLookup(), NO_INHERITED_VIEWS);
+        List<String> names =
+                List.of(
+                        "alpha", "bravo", "charlie", "delta", "echo", "foxtrot", "golf", "hotel",
+                        "india", "juliett");
+        for (String name : names) {
+            view.write(name, ByteBuffer.wrap(new byte[] {1}));
+        }
+        assertEquals(names, view.list());
+    }
+
     @Test
     public void testView() throws IOException {
         UserDefinedFileAttributeView view = provider.view(fileLookup(), NO_INHERITED_VIEWS);