[PATCH] check_do_while_loop_limit: implements checker for do_while loops

[PATCH] check_do_while_loop_limit: implements checker for do_while loops

[Harshvardhan Jha]

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@oracle.com>
---
 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..cc04dfa5
--- /dev/null
+++ b/check_do_while_loop_limit.c
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2021 Oracle.
+ *
+ * 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

Re: [PATCH] check_do_while_loop_limit: implements checker for do_while loops

[Dan Carpenter]

On Mon, Jul 26, 2021 at 07:24:12PM +0530, Harshvardhan Jha wrote:
> 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@oracle.com>

Thanks a lot!  Applied.

regards,
dan carpenter

Re: [PATCH] check_do_while_loop_limit: implements checker for do_while loops

[Dan Carpenter]

On Mon, Jul 26, 2021 at 07:13:19PM +0530, Harshvardhan Jha wrote:
> 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@oracle.com>
> ---
>  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 should be copyright Oracle (Harshvardhan has been working for
Oracle as an intern this summer).

> + *
> + * 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));
                                                 ^
Add a space after the comma.

> +}

regards,
dan carpenter

[PATCH] check_do_while_loop_limit: implements checker for do_while loops

[Harshvardhan Jha]

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@oracle.com>
---
 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