Another, more angry, test about tampering with the input.

Author: giomasce

cmstestsuite/Tests.py

@@ -230,4 +230,9 @@
          languages=(LANG_C,),
          checks=[CheckOverallScore(0, 100)]),
 
+    Test('delete-write-input',
+         task=batch_fileio_managed, filename='delete-write-input.%l',
+         languages=(LANG_C,),
+         checks=[CheckOverallScore(0, 100)]),
+
 ]

cmstestsuite/code/delete-write-input.c

@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <unistd.h>
+
+/*
+ * This returns the wrong result, but deletes and writes again the
+ * input file so that a wrong result appears as a correct one. CMS is
+ * expected not to be fooled by this cheat attempt.
+ *
+ * CMS can counter this attack by rewriting the input file again
+ * before calling the checker. This test is here to check that this is
+ * done.
+ */
+
+int userfunc(int x) {
+    unlink("input.txt");
+    FILE *fin = fopen("input.txt", "w");
+    fprintf(fin, "%d\n", x+1);
+    fclose(fin);
+    return x+1;
+}