Add support for unnamed map.

The following is now possible but won't print anything by default:

# btrace -e 'profile:hz:99 { @[kstack] = count() }'

ok patrick@, tobhe@

3 files changed, 20 insertions, 5 deletions

diff --git a/usr.sbin/btrace/bt_parse.y b/usr.sbin/btrace/bt_parse.y
index ee85b1bb83d..0be86d1a01b 100644
--- a/usr.sbin/btrace/bt_parse.y
+++ b/usr.sbin/btrace/bt_parse.y
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bt_parse.y,v 1.8 2020/01/28 16:39:51 mpi Exp $	*/
+/*	$OpenBSD: bt_parse.y,v 1.9 2020/03/19 15:52:30 mpi Exp $	*/
 
 /*
  * Copyright (c) 2019 - 2020 Martin Pieuchot <mpi@openbsd.org>
@@ -41,13 +41,16 @@
 
 #include "bt_parser.h"
 
+/* Name for the default map @[], hopefully nobody will use this one ;) */
+#define UNNAMED_MAP	"___unnamed_map_doesnt_have_any_name"
+
 /* Number of rules to evaluate. */
 struct bt_ruleq		g_rules = TAILQ_HEAD_INITIALIZER(g_rules);
 
 /* Number of probes except BEGIN/END. */
 int		 	g_nprobes;
 
-/* List of global variables. */
+/* List of global variables, including maps. */
 SLIST_HEAD(, bt_var)	 g_variables;
 
 struct bt_rule	*br_new(struct bt_probe *, struct bt_filter *, struct bt_stmt *,
@@ -203,6 +206,7 @@ term		: '(' term ')'			{ $$ = $2; }
 		;
 
 gvar		: '@' STRING			{ $$ = $2; }
+		| '@'				{ $$ = UNNAMED_MAP; }
 
 map		: gvar '[' arg ']'		{ $$ = bm_get($1, $3); }
 		;
@@ -406,6 +410,14 @@ bs_append(struct bt_stmt *ds0, struct bt_stmt *ds1)
 	return ds0;
 }
 
+const char *
+bv_name(struct bt_var *bv)
+{
+	if (strncmp(bv->bv_name, UNNAMED_MAP, strlen(UNNAMED_MAP)) == 0)
+		return "";
+	return bv->bv_name;
+}
+
 /* Return the global variable corresponding to `vname'. */
 struct bt_var *
 bv_find(const char *vname)
diff --git a/usr.sbin/btrace/bt_parser.h b/usr.sbin/btrace/bt_parser.h
index 9c18fce9bb2..9b87673fcf5 100644
--- a/usr.sbin/btrace/bt_parser.h
+++ b/usr.sbin/btrace/bt_parser.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bt_parser.h,v 1.4 2020/01/28 16:39:51 mpi Exp $	*/
+/*	$OpenBSD: bt_parser.h,v 1.5 2020/03/19 15:52:30 mpi Exp $	*/
 
 /*
  * Copyright (c) 2019 Martin Pieuchot <mpi@openbsd.org>
@@ -165,6 +165,8 @@ int			 btparse(const char *, size_t, const char *, int);
 #define ba_new(v, t)	 ba_new0((void *)(v), (t))
 struct bt_arg		*ba_new0(void *, enum bt_argtype);
 
+const char		*bv_name(struct bt_var *);
+
 void			 bm_insert(struct bt_var *, struct bt_arg *,
 			     struct bt_arg *);
 
diff --git a/usr.sbin/btrace/map.c b/usr.sbin/btrace/map.c
index 1c4581b9824..d4064d2df18 100644
--- a/usr.sbin/btrace/map.c
+++ b/usr.sbin/btrace/map.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: map.c,v 1.3 2020/01/28 16:39:51 mpi Exp $ */
+/*	$OpenBSD: map.c,v 1.4 2020/03/19 15:52:30 mpi Exp $ */
 
 /*
  * Copyright (c) 2020 Martin Pieuchot <mpi@openbsd.org>
@@ -207,7 +207,8 @@ map_print(struct bt_var *bv, size_t top)
 		}
 		if (mcur == NULL)
 			break;
-		printf("@map[%s]: %s\n", mcur->mkey, ba2str(mcur->mval, NULL));
+		printf("@%s[%s]: %s\n", bv_name(bv), mcur->mkey,
+		    ba2str(mcur->mval, NULL));
 		bprev = mcur->mval;
 	}
 }