Dynamic (#77)

tests/dynamic_fixtures/java/fileio_negative.java

@@ -0,0 +1,28 @@
+// File I/O — negative fixture.
+// Safe: normalizes the path and checks it stays within the base directory, so
+// the traversal payload cannot escape `testfiles/` to reach the planted canary.
+// Entry: Entry.readFile(String)  Cap: FILE_IO
+// Expected verdict: NotConfirmed
+
+import java.io.*;
+import java.nio.file.*;
+
+public class Entry {
+    public static void readFile(String userPath) throws Exception {
+        // Same base the harness plants the canary one level above; the
+        // containment check is what makes this safe.
+        Path base = Paths.get(System.getProperty("user.dir"), "testfiles").toRealPath();
+        Path resolved = base.resolve(userPath).normalize();
+        if (!resolved.startsWith(base)) {
+            System.out.println("Access denied");
+            return;
+        }
+        try {
+            byte[] data = Files.readAllBytes(resolved);
+            int len = Math.min(data.length, 100);
+            System.out.write(data, 0, len);
+        } catch (IOException e) {
+            System.out.println("File not found");
+        }
+    }
+}