btrace(8): prohibit use of argN builtins in BEGIN/END.

The argN builtins are undefined for BEGIN and END special probes.
Similar to bpftrace, produce an error from the parser.

Adds a regress test, as well.

ok mpi@

3 files changed, 17 insertions, 3 deletions

diff --git a/regress/usr.sbin/btrace/Makefile b/regress/usr.sbin/btrace/Makefile
index 29f90cef4b9..e1d39991082 100644
--- a/regress/usr.sbin/btrace/Makefile
+++ b/regress/usr.sbin/btrace/Makefile
@@ -1,11 +1,11 @@
-# $OpenBSD: Makefile,v 1.27 2023/08/13 09:49:47 mpi Exp $
+# $OpenBSD: Makefile,v 1.28 2023/08/28 21:23:46 dv Exp $
 
 BTRACE?=		 /usr/sbin/btrace
 ALLOWDT!=		sysctl -n kern.allowdt 2>/dev/null
 
 # scripts that don't need /dev/dt
-BT_LANG_SCRIPTS=	arithm beginend boolean comments delete exit \
-			histempty if \
+BT_LANG_SCRIPTS=	arithm beginend beginend-argn boolean comments delete \
+			exit histempty if \
 			map mapclear mapempty mapsyntax mapzero map-unnamed \
 			maxoperand min+max+sum multismts nsecs+var \
 			precedence print read-map-after-clear staticv-empty \
diff --git a/regress/usr.sbin/btrace/beginend-argn.bt b/regress/usr.sbin/btrace/beginend-argn.bt
new file mode 100644
index 00000000000..7260ad40121
--- /dev/null
+++ b/regress/usr.sbin/btrace/beginend-argn.bt
@@ -0,0 +1,8 @@
+// Test catching invalid use of argN in BEGIN and END contexts.
+BEGIN {
+	print(arg0);
+}
+
+END {
+	print(arg0);
+}
diff --git a/regress/usr.sbin/btrace/beginend-argn.ok b/regress/usr.sbin/btrace/beginend-argn.ok
new file mode 100644
index 00000000000..3c0fb6780e0
--- /dev/null
+++ b/regress/usr.sbin/btrace/beginend-argn.ok
@@ -0,0 +1,6 @@
+beginend-argn.bt:3:11: the arg0 builtin cannot be used with BEGIN or END probes:
+	print(arg0);
+                 ^
+beginend-argn.bt:7:11: the arg0 builtin cannot be used with BEGIN or END probes:
+	print(arg0);
+                 ^