1 files changed, 27 insertions, 0 deletions

diff --git a/tests/test_memcpy_overlap.c b/tests/test_memcpy_overlap.c
new file mode 100644
index 0000000..f8c6639
--- /dev/null
+++ b/tests/test_memcpy_overlap.c
@@ -0,0 +1,27 @@
+#include "common.h"
+
+#include <string.h>
+
+/* fortify-headers' memcpy traps when src/dst overlap (but not when src == dst).
+ * This test exercises that overlap-detection branch, which is unique to this
+ * implementation. The pointer offset is hidden behind a volatile so -Wrestrict
+ * cannot see the overlap at compile time. */
+
+int main(int argc, char** argv) {
+  static char buffer[16] = "0123456789ABCDE";
+  volatile int off = 2; /* hidden from the compiler so -Wrestrict won't see */
+  char *p = buffer;
+  char *q = p + off;
+
+  /* dst == src: must NOT trap */
+  memcpy(p, p, 8);
+  puts(buffer);
+
+  /* Overlapping src/dst (dst < src): must trap */
+  CHK_FAIL_START
+  memcpy(p, q, 8);
+  CHK_FAIL_END
+
+  puts(buffer);
+  return ret;
+}