tests: Add a test to check invalid PKCS7 signature attaching

Add a test for the invalid PKCS7 signature attaching. This test
generates 1K of zero bytes as an invalid signature to attach.

Signed-off-by: Ivan Hu <ivan.hu@canonical.com>
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>

tests/Makefile.am

@@ -42,7 +42,8 @@ TESTS = sign-verify.sh \
 	sign-missing-cert.sh \
 	sign-missing-key.sh \
 	verify-missing-image.sh \
-	verify-missing-cert.sh
+	verify-missing-cert.sh \
+	sign-invalidattach-verify.sh
 
 EXTRA_DIST = $(test_lds) test.S $(TESTS) $(check_SCRIPTS)
 CLEANFILES = $(test_key) $(test_cert) $(test_image)

tests/sign-invalidattach-verify.sh

@@ -0,0 +1,15 @@
+#!/bin/bash -e
+
+. "$srcdir/common.sh"
+
+invsig="test.invsig"
+dd if=/dev/zero of="$invsig" bs=1 count=1k
+tmp_image=test.pecoff
+cp "$image" "$tmp_image"
+
+set +e
+"$sbattach" --attach "$invsig" "$tmp_image"
+rc=$?
+set -e
+
+test $rc -eq 1