CERT C: Rule EXP32-C

Do not access a volatile object through a nonvolatile reference

expand all in page

Description

Rule Definition

Do not access a volatile object through a nonvolatile reference.¹

Polyspace Implementation

The rule checker checks for Cast to pointer that removes volatile qualification.

Examples

expand all

Cast to pointer that removes `volatile` qualification

Issue

Polyspace^® flags both implicit and explicit conversions that violate this rule.

Risk

This rule forbids casts from a pointer to a volatile object to a pointer that does not point to a volatile object. Such casts violate type qualification.

Example - Casts That Remove Qualifiers

void foo(void) {
    volatile unsigned short *pvi;    /* pointer to volatile  */
    unsigned short          *pi;

    pi  = (unsigned short *)  pvi;   /* Non-compliant */

}

In this example, the variable pvi has a volatile qualifier in its type. The rule is violated when the variable is cast to a type that does not have the volatile qualifier.

Check Information

Group: Rule 03. Expressions (EXP)

Version History

Introduced in R2019a

¹ This software has been created by MathWorks incorporating portions of: the “SEI CERT-C Website,” © 2017 Carnegie Mellon University, the SEI CERT-C++ Web site © 2017 Carnegie Mellon University, ”SEI CERT C Coding Standard – Rules for Developing safe, Reliable and Secure systems – 2016 Edition,” © 2016 Carnegie Mellon University, and “SEI CERT C++ Coding Standard – Rules for Developing safe, Reliable and Secure systems in C++ – 2016 Edition” © 2016 Carnegie Mellon University, with special permission from its Software Engineering Institute.

ANY MATERIAL OF CARNEGIE MELLON UNIVERSITY AND/OR ITS SOFTWARE ENGINEERING INSTITUTE CONTAINED HEREIN IS FURNISHED ON AN "AS-IS" BASIS. CARNEGIE MELLON UNIVERSITY MAKES NO WARRANTIES OF ANY KIND, EITHER EXPRESSED OR IMPLIED, AS TO ANY MATTER INCLUDING, BUT NOT LIMITED TO, WARRANTY OF FITNESS FOR PURPOSE OR MERCHANTABILITY, EXCLUSIVITY, OR RESULTS OBTAINED FROM USE OF THE MATERIAL. CARNEGIE MELLON UNIVERSITY DOES NOT MAKE ANY WARRANTY OF ANY KIND WITH RESPECT TO FREEDOM FROM PATENT, TRADEMARK, OR COPYRIGHT INFRINGEMENT.

This software and associated documentation has not been reviewed nor is it endorsed by Carnegie Mellon University or its Software Engineering Institute.