From dad9097fc1dc5e62fe9207b17341dd248c869815 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 26 Apr 2012 15:20:17 +0300
Subject: [PATCH] *new* or_vs_and: complain about if (x != 3 || x != 4) { ...

Sometimes people type:
	if (x != 3 || x != 4) { ...
when:
	if (x != 3 && x != 4) { ...
was intended.

This is a fairly common mistake but other people have found most of these
bugs in the kernel.  This test currently finds 2 bugs and 0 false
positives.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 check_list.h      |   1 +
 check_or_vs_and.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+)
 create mode 100644 check_or_vs_and.c

diff --git a/check_list.h b/check_list.h
index 20fbd714..0cc8991e 100644
--- a/check_list.h
+++ b/check_list.h
@@ -72,6 +72,7 @@ CK(check_pointer_math)
 CK(check_bit_shift)
 CK(check_macro_side_effects)
 CK(check_bool_implications)
+CK(check_or_vs_and)
 
 /* <- your test goes here */
 /* CK(register_template) */
diff --git a/check_or_vs_and.c b/check_or_vs_and.c
new file mode 100644
index 00000000..0db557cb
--- /dev/null
+++ b/check_or_vs_and.c
@@ -0,0 +1,103 @@
+/*
+ * sparse/check_or_vs_and.c
+ *
+ * Copyright (C) 2012 Oracle.
+ *
+ * Licensed under the Open Software License version 1.1
+ *
+ */
+
+#include "smatch.h"
+
+static int my_id;
+
+static int expr_equiv(struct expression *one, struct expression *two)
+{
+	struct symbol *one_sym, *two_sym;
+	char *one_name = NULL;
+	char *two_name = NULL;
+	int ret = 0;
+
+	one_name = get_variable_from_expr_complex(one, &one_sym);
+	if (!one_name || !one_sym)
+		goto free;
+	two_name = get_variable_from_expr_complex(two, &two_sym);
+	if (!two_name || !two_sym)
+		goto free;
+	if (one_sym != two_sym)
+		goto free;
+	if (strcmp(one_name, two_name) == 0)
+		ret = 1;
+free:
+	free_string(one_name);
+	free_string(two_name);
+	return ret;
+}
+
+static int inconsistent_check(struct expression *left, struct expression *right)
+{
+	long long val;
+
+	if (get_value(left->left, &val)) {
+		if (get_value(right->left, &val))
+			return expr_equiv(left->right, right->right);
+		if (get_value(right->right, &val))
+			return expr_equiv(left->right, right->left);
+		return 0;
+	}
+	if (get_value(left->right, &val)) {
+		if (get_value(right->left, &val))
+			return expr_equiv(left->left, right->right);
+		if (get_value(right->right, &val))
+			return expr_equiv(left->left, right->left);
+		return 0;
+	}
+
+	return 0;
+}
+
+static void check_or(struct expression *expr)
+{
+	if (expr->left->type != EXPR_COMPARE ||
+			expr->left->op != SPECIAL_NOTEQUAL)
+		return;
+	if (expr->right->type != EXPR_COMPARE ||
+			expr->right->op != SPECIAL_NOTEQUAL)
+		return;
+	if (!inconsistent_check(expr->left, expr->right))
+		return;
+
+	sm_msg("warn: was && intended here instead of ||?");
+}
+
+static void check_and(struct expression *expr)
+{
+	if (expr->left->type != EXPR_COMPARE ||
+			expr->left->op != SPECIAL_EQUAL)
+		return;
+	if (expr->right->type != EXPR_COMPARE ||
+			expr->right->op != SPECIAL_EQUAL)
+		return;
+	if (!inconsistent_check(expr->left, expr->right))
+		return;
+
+	sm_msg("warn: was || intended here instead of &&?");
+}
+
+static void match_logic(struct expression *expr)
+{
+	if (expr->type != EXPR_LOGICAL)
+		return;
+
+	if (expr->op == SPECIAL_LOGICAL_OR)
+		check_or(expr);
+	if (expr->op == SPECIAL_LOGICAL_AND)
+		check_and(expr);
+}
+
+void check_or_vs_and(int id)
+{
+	my_id = id;
+
+	add_hook(&match_logic, LOGIC_HOOK);
+}
-- 
2.11.4.GIT