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The header stdio.h defines the BUFSIZ macro, which expands to an integer constant expression that is the size of the buffer used by the setbuf() function. This noncompliant code example defeats the purpose of defining BUFSIZ as a constant by assuming its value in the following expression:
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|---|---|---|---|---|
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#include <stdio.h>
/* ... */
nblocks = 1 + ((nbytes - 1) >> 9); /* BUFSIZ = 512 = 2^9 */
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This compliant solution uses the identifier assigned to the constant value in the expression.:
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|---|---|---|---|---|
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#include <stdio.h>
/* ... */
nblocks = 1 + (nbytes - 1) / BUFSIZ;
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Assuming the value of an expression diminishes the maintainability of code and can produce unexpected behavior under any circumstances in which the constant changes.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
EXP07-C |
Low |
Unlikely |
Medium | P2 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Axivion Bauhaus Suite |
| CertC-EXP07 | |||||||
| Helix QAC |
| C3120, C3121, C3122, C3123, C3131, C3132 | |||||||
| LDRA tool suite |
| 201 S | Fully implemented |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
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Related Guidelines
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References
| Wiki Markup |
|---|
\[[Plum 85|AA. Bibliography#Plum 85]\] Rule 1-5
\[[ISO/IEC 9899:1999|AA. Bibliography#ISO/IEC 9899-1999]\] Section 6.10, "Preprocessing directives," and Section 5.1.1, "Translation environment" |
Bibliography
| [Plum 1985] | Rule 1-5 |
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EXP06-C. Operands to the sizeof operator should not contain side effects 03. Expressions (EXP)