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The C Standard, 5.1.1.2, paragraph 4 [ISO/IEC 9899:20112024], says
If a character sequence that matches the syntax of a universal character name is produced by token concatenation (6.10.35.3), the behavior is undefined.
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Creating a universal character name through token concatenation results in undefined behavior. See undefined behavior 3.
Rule | Severity | Likelihood | Detectable | Remediation CostRepairable | Priority | Level |
|---|---|---|---|---|---|---|
PRE30-C | Low | Unlikely | Yes | MediumNo | P2 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| universal-character-name-concatenation | Fully implemented | ||||||||||
| CertC-PRE30 | Fully implemented | |||||||||||
| CodeSonar |
| LANG.PREPROC.PASTE LANG.PREPROC.PASTEHASH | Macro uses ## operator## follows # operator | ||||||||||
| Cppcheck |
| preprocessorErrorDirective | |||||||||||
| Cppcheck Premium |
| preprocessorErrorDirective | |||||||||||
| Helix QAC |
| C0905 C++0064,C++0080 | Fully implemented | ||||||||||
| Klocwork |
| MISRA.DEFINE.SHARP | Fully implemented | ||||||||||
| LDRA tool suite |
| 573 S | Fully implemented | ||||||||||
| Parasoft C/C++test |
| CERT_C-PRE30-a | Avoid token concatenation that may produce universal character names | ||||||||||
| Universal CERT C: Rule PRE30-C | Checks for universal character name from token concatenation | (rule fully covered) | ||||||||||
| RuleChecker |
| universal-character-name-concatenation | Fully checked | You create a universal character name by joining tokens with ## operator
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Bibliography
| [ISO/IEC 10646-2003] | |
| [ISO/IEC 9899:20112024] | Subclause 5.1.1.2, "Translation Phases" |
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