A preprocessing directive of the form:
# define identifier replacement-list new-line
defines an object-like macro that causes each subsequent instance of the macro name to be replaced by the replacement list of preprocessing tokens that constitute the remainder of the directive [[ISO/IEC 9899-1999]].
Compliant Solution
#define JOIN(x, y) JOIN_AGAIN(x, y) #define JOIN_AGAIN(x, y) x ## y
JOIN(x, y) calls JOIN_AGAIN(x, y) so that, if x or y is a macro, they are expanded before the ## operator pastes them together.
Risk Assessment
Recommendation |
Severity |
Likelihood |
Remediation Cost |
Priority |
Level |
|---|---|---|---|---|---|
DCL03-A |
1 (low) |
1 (unlikely) |
1 (high) |
P1 |
L3 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
References
[Saks 08] Dan Saks, Stephen C. Dewhurst. Presentation. Sooner Rather Than Later: Static Programming Techniques for C++.
[[ISO/IEC 9899-1999]] Section 6.10.3, "Macro replacement," Section 6.10.3.3, "The ## operator," and Section 6.10.3.4, "Rescanning and further replacement"
PRE04-A. Do not reuse a standard header file name 01. Preprocessor (PRE) PRE06-A. Enclose header file in an inclusion sandwich