LibCore: Restore support for multiple symbolic classes

Reverts recent change introduced to support implicit symbolic permission
which broke the parser when multiple classes are specified.
The state machine must assume it's dealing with classes until an
operation character is consumed.

Tests/LibCore/TestLibCoreFilePermissionsMask.cpp

@@ -44,6 +44,13 @@ TEST_CASE(file_permission_mask_from_symbolic_notation)
     EXPECT_EQ(mask.value().apply(0), 0555);
     EXPECT_EQ(mask.value().apply(0664), 0555);
 
+    mask = Core::FilePermissionsMask::from_symbolic_notation("ugo=rx"sv);
+    EXPECT(!mask.is_error());
+    EXPECT_EQ(mask.value().clear_mask(), 0777);
+    EXPECT_EQ(mask.value().write_mask(), 0555);
+    EXPECT_EQ(mask.value().apply(0), 0555);
+    EXPECT_EQ(mask.value().apply(0664), 0555);
+
     mask = Core::FilePermissionsMask::from_symbolic_notation("u+rw,g=rx,o-rwx"sv);
     EXPECT(!mask.is_error());
     EXPECT_EQ(mask.value().clear_mask(), 0077);
@@ -51,6 +58,20 @@ TEST_CASE(file_permission_mask_from_symbolic_notation)
     EXPECT_EQ(mask.value().apply(0), 0650);
     EXPECT_EQ(mask.value().apply(0177), 0750);
 
+    mask = Core::FilePermissionsMask::from_symbolic_notation("+r"sv);
+    EXPECT(!mask.is_error());
+    EXPECT_EQ(mask.value().clear_mask(), 0);
+    EXPECT_EQ(mask.value().write_mask(), 0444);
+    EXPECT_EQ(mask.value().apply(0), 0444);
+    EXPECT_EQ(mask.value().apply(0123), 0567);
+
+    mask = Core::FilePermissionsMask::from_symbolic_notation("=rx"sv);
+    EXPECT(!mask.is_error());
+    EXPECT_EQ(mask.value().clear_mask(), 0777);
+    EXPECT_EQ(mask.value().write_mask(), 0555);
+    EXPECT_EQ(mask.value().apply(0), 0555);
+    EXPECT_EQ(mask.value().apply(0664), 0555);
+
     mask = Core::FilePermissionsMask::from_symbolic_notation("z+rw"sv);
     EXPECT(mask.is_error());
 

Userland/Libraries/LibCore/FilePermissionsMask.cpp

@@ -14,14 +14,14 @@ namespace Core {
 
 enum State {
     Classes,
-    Operation,
     Mode
 };
 
 enum ClassFlag {
     Other = 1,
     Group = 2,
-    User = 4
+    User = 4,
+    All = 7
 };
 
 enum Operation {
@@ -56,43 +56,32 @@ ErrorOr<FilePermissionsMask> FilePermissionsMask::from_symbolic_notation(StringV
     for (auto ch : string) {
         switch (state) {
         case State::Classes: {
-            // one or more [ugoa] terminated by one operator [+-=]
-            if (ch == 'u') {
+            // zero or more [ugoa] terminated by one operator [+-=]
+            if (ch == 'u')
                 classes |= ClassFlag::User;
-                state = State::Operation;
-                break;
-            } else if (ch == 'g') {
+            else if (ch == 'g')
                 classes |= ClassFlag::Group;
-                state = State::Operation;
-                break;
-            } else if (ch == 'o') {
+            else if (ch == 'o')
                 classes |= ClassFlag::Other;
-                state = State::Operation;
-                break;
-            } else if (ch == 'a') {
-                classes = ClassFlag::User | ClassFlag::Group | ClassFlag::Other;
-                state = State::Operation;
-                break;
+            else if (ch == 'a')
+                classes = ClassFlag::All;
+            else {
+                if (ch == '+')
+                    operation = Operation::Add;
+                else if (ch == '-')
+                    operation = Operation::Remove;
+                else if (ch == '=')
+                    operation = Operation::Assign;
+                else
+                    return Error::from_string_literal("invalid operation: expected '+', '-' or '='"sv);
+
+                // if an operation was specified without a class, assume all
+                if (classes == 0)
+                    classes = ClassFlag::All;
+
+                state = State::Mode;
             }
-        }
-            [[fallthrough]];
-        case State::Operation: {
-            if (ch == '+')
-                operation = Operation::Add;
-            else if (ch == '-')
-                operation = Operation::Remove;
-            else if (ch == '=')
-                operation = Operation::Assign;
-            else if (classes == 0)
-                return Error::from_string_literal("invalid access class: expected 'u', 'g', 'o' or 'a' "sv);
-            else
-                return Error::from_string_literal("invalid operation: expected '+', '-' or '='"sv);
-
-            // if an operation was specified without a class, assume all
-            if (classes == 0)
-                classes = ClassFlag::User | ClassFlag::Group | ClassFlag::Other;
 
-            state = State::Mode;
             break;
         }