do{} while(n--) loops end at n=-1 but programmers sometimes assume that
they end at n=0. This checker sends a warning in these scenarios.
Signed-off-by: Harshvardhan Jha <harshvardhan.jha@xxxxxxxxxx>
---
check_do_while_loop_limit.c | 67 +++++++++++++++++++++++++++++++++++++
check_list.h | 1 +
2 files changed, 68 insertions(+)
create mode 100644 check_do_while_loop_limit.c
diff --git a/check_do_while_loop_limit.c b/check_do_while_loop_limit.c
new file mode 100644
index 00000000..9a492725
--- /dev/null
+++ b/check_do_while_loop_limit.c
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2021 Harshvardhan Jha.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
+ */
+
+#include "smatch.h"
+#include "smatch_slist.h"
+#include "smatch_extra.h"
+
+static int my_id;
+
+STATE(post_minus);
+
+static bool is_post_minus(struct expression *expr)
+{
+ expr = strip_expr(expr);
+ if (!expr)
+ return false;
+ if (expr->type != EXPR_POSTOP)
+ return false;
+ if (expr->op != SPECIAL_DECREMENT)
+ return false;
+ return true;
+}
+
+static void match_post_loop(struct expression *expr)
+{
+ struct statement *stmt;
+
+ expr = strip_expr(expr);
+ stmt = expr_get_parent_stmt(expr);
+
+ if (!stmt)
+ return;
+ if (stmt->type != STMT_ITERATOR)
+ return;
+ if (!is_post_minus(stmt->iterator_post_condition))
+ return;
+ if (is_post_minus(stmt->iterator_post_condition))
+ set_state_expr(my_id, stmt->iterator_post_condition->left, &post_minus);
+}
+
+static void match_condition(struct expression *expr)
+{
+ if (get_state_expr(my_id, expr) != &post_minus)
+ return;
+ sm_warning("do while ends on '%s == -1'",expr_to_str(expr));
+}
+
+void check_do_while_loop_limit(int id)
+{
+ my_id = id;
+ add_hook(&match_post_loop, CONDITION_HOOK);
+ add_hook(&match_condition, CONDITION_HOOK);
+}
diff --git a/check_list.h b/check_list.h
index a57715ea..4d18a173 100644
--- a/check_list.h
+++ b/check_list.h
@@ -171,6 +171,7 @@ CK(check_syscall_arg_type)
CK(check_trinity_generator)
CK(register_param_bits_set)
CK(register_param_bits_clear)
+CK(check_do_while_loop_limit)
/* <- your test goes here */
/* CK(register_template) */
--
2.32.0
