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@

diff --git a/regress/usr.sbin/btrace/Makefile b/regress/usr.sbin/btrace/Makefile
index 29f90ce..e1d3999 100644 (file)
--- 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 (file)
index 0000000..7260ad4
--- /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 (file)
index 0000000..3c0fb67
--- /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);
+                 ^

diff --git a/usr.sbin/btrace/bt_parse.y b/usr.sbin/btrace/bt_parse.y
index 959f6e4..b2c3bef 100644 (file)
--- a/usr.sbin/btrace/bt_parse.y
+++ b/usr.sbin/btrace/bt_parse.y
@@ -1,4 +1,4 @@
-/*     $OpenBSD: bt_parse.y,v 1.50 2023/08/13 13:19:23 dv Exp $        */
+/*     $OpenBSD: bt_parse.y,v 1.51 2023/08/28 21:23:46 dv Exp $        */
 
 /*
  * Copyright (c) 2019-2021 Martin Pieuchot <mpi@openbsd.org>
@@ -109,7 +109,8 @@ typedef struct {
 static void     yyerror(const char *, ...);
 static int      yylex(void);
 
-static int pflag;
+static int      pflag = 0;             /* probe parsing context flag */
+static int      beflag = 0;            /* BEGIN/END parsing context flag */
 %}
 
 %token <v.i>           ERROR ENDFILT
@@ -137,7 +138,7 @@ grammar     : /* empty */
        | grammar error
        ;
 
-rule   : plist filter action           { br_new($1, $2, $3); }
+rule   : plist filter action           { br_new($1, $2, $3); beflag = 0; }
        ;
 
 beginend: BEGIN        | END ;
@@ -147,7 +148,7 @@ plist       : plist ',' probe               { $$ = bp_append($1, $3); }
        ;
 
 probe  : { pflag = 1; } pname          { $$ = $2; pflag = 0; }
-       | beginend                      { $$ = bp_new(NULL, NULL, NULL, $1); }
+       | { beflag = 1; } beginend      { $$ = bp_new(NULL, NULL, NULL, $2); }
        ;
 
 pname  : STRING ':' STRING ':' STRING  { $$ = bp_new($1, $3, $5, 0); }
@@ -962,6 +963,12 @@ again:
                                yylval.v.string = kwp->word;
                                return STRING;
                        }
+               } else if (beflag) {
+                       /* Interpret tokens in a BEGIN/END context. */
+                       if (kwp->type >= B_AT_BI_ARG0 &&
+                           kwp->type <= B_AT_BI_ARG9)
+                               yyerror("the %s builtin cannot be used with "
+                                   "BEGIN or END probes", kwp->word);
                }
                yylval.v.i = kwp->type;
                return kwp->token;