[DTrace-devel] [PATCH 2/2] test: add a test for libctf bug 30264

[Nick Alcock]

If present, this bug breaks offsetof (and anything else requiring
reliable offset info, like, oh, say, *any access*) to fields of
unnamed structs/unions at nonzero offsets within their containing
struct/union.

(We just check offsetof, because it's simpler than doing full access
checks.  We check only the in-kernel CTF, because the D language does
not support unnamed struct/union fields at all.)

Signed-off-by: Nick Alcock <nick.alcock at oracle.com>
---
 .../types/tst.nested-unnamed-structs.d        | 32 +++++++++++++++++++
 .../types/tst.nested-unnamed-structs.x        |  7 ++++
 2 files changed, 39 insertions(+)
 create mode 100644 test/unittest/types/tst.nested-unnamed-structs.d
 create mode 100755 test/unittest/types/tst.nested-unnamed-structs.x

diff --git a/test/unittest/types/tst.nested-unnamed-structs.d b/test/unittest/types/tst.nested-unnamed-structs.d
new file mode 100644
index 0000000000000..a2b174434574d
--- /dev/null
+++ b/test/unittest/types/tst.nested-unnamed-structs.d
@@ -0,0 +1,32 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+/*
+ * ASSERTION:
+ *	Check for the absence of a libctf bug breaking offsets of
+ *	members of nested unnamed structs in the kernel.
+ *	See https://sourceware.org/bugzilla/show_bug.cgi?id=30264
+ *
+ */
+
+#pragma D option quiet
+
+BEGIN {
+	printf("offset is %i\n", offsetof(struct rds`rds_message, atomic));
+}
+
+BEGIN
+/ offsetof(struct rds`rds_message, atomic) == 0 /
+{
+	exit(1);
+}
+
+BEGIN
+/ offsetof(struct rds`rds_message, atomic) != 0 /
+{
+	exit(0);
+}
diff --git a/test/unittest/types/tst.nested-unnamed-structs.x b/test/unittest/types/tst.nested-unnamed-structs.x
new file mode 100755
index 0000000000000..47e579ed00f60
--- /dev/null
+++ b/test/unittest/types/tst.nested-unnamed-structs.x
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+if ! $(grep -q '^rds ' /proc/modules); then
+    exit 1
+fi
+
+exit 0
-- 
2.39.1.268.g9de2f9a303