Update the fix for #99 and some more tests

planus/src/table_reader.rs

@@ -101,21 +101,23 @@ impl<'buf> Table<'buf> {
             error_kind,
         };
 
-        let offset = self
-            .vtable
-            .get(2 * vtable_offset..2 * (vtable_offset + 2))
-            .ok_or_else(|| make_error(ErrorKind::InvalidOffset))?;
-
-        let tag_offset = u16::from_le_bytes(offset[..2].try_into().unwrap()) as usize;
-        let value_offset = u16::from_le_bytes(offset[2..].try_into().unwrap()) as usize;
-
-        let tag = u8::from_buffer(self.object, tag_offset).map_err(make_error)?;
-        if tag_offset != 0 && value_offset != 0 && tag != 0 {
-            T::from_buffer(self.object, value_offset, tag)
-                .map(Some)
-                .map_err(make_error)
-        } else {
+        if let Some(offset) = self.vtable.get(2 * vtable_offset..2 * (vtable_offset + 2)) {
+            let tag_offset = u16::from_le_bytes(offset[..2].try_into().unwrap()) as usize;
+            let value_offset = u16::from_le_bytes(offset[2..].try_into().unwrap()) as usize;
+            let tag = u8::from_buffer(self.object, tag_offset).map_err(make_error)?;
+            if tag_offset != 0 && value_offset != 0 && tag != 0 {
+                T::from_buffer(self.object, value_offset, tag)
+                    .map(Some)
+                    .map_err(make_error)
+            } else {
+                Ok(None)
+            }
+        } else if self.vtable.len() <= 2 * vtable_offset {
             Ok(None)
+        } else {
+            Err(make_error(ErrorKind::InvalidVtableLength {
+                length: self.vtable.len() as u16 + 4,
+            }))
         }
     }
 

test/rust/test_files/issue_99.fbs

@@ -0,0 +1,9 @@
+table Table {}
+
+union Union {
+  t: Table
+}
+
+table Root {
+  f: Union;
+}

test/rust/test_files/issue_99/deserialize/bad-file.txt

@@ -0,0 +1,14 @@
+RootRef {
+    f: Err(
+        Error {
+            source_location: ErrorLocation {
+                type_: "Root",
+                method: "f",
+                byte_offset: 10,
+            },
+            error_kind: InvalidVtableLength {
+                length: 6,
+            },
+        },
+    ),
+}

test/rust/test_files/issue_99/deserialize/issue-99.txt

@@ -0,0 +1 @@
+RootRef

test/rust/test_files/issue_99/serialize/non_null.dbg.txt

@@ -0,0 +1,4 @@
+Root {
+    f_type: t,
+    f: Table,
+}

test/rust/test_files/issue_99/serialize/non_null.dump.txt

@@ -0,0 +1,6 @@
+obj    @ 0x04..0x0d
+vtable @ 0x10..0x18
+field[0] @ 0x0c..0x0d:
+  01
+field[1] @ 0x08..0x0c:
+  10 00 00 00

test/rust/test_files/issue_99/serialize/non_null.json

@@ -0,0 +1 @@
+{"f": {"T": {}}}

test/rust/test_files/issue_99/serialize/null.dbg.txt

@@ -0,0 +1,4 @@
+Root {
+    f_type: NONE,
+    f: None,
+}

test/rust/test_files/issue_99/serialize/null.dump.txt

@@ -0,0 +1,2 @@
+obj    @ 0x04..0x08
+vtable @ 0x08..0x0c

test/rust/test_files/issue_99/serialize/null.json

@@ -0,0 +1 @@
+{"f": null}