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Although failures are frequently indicated by a return value of 0, some common conventions may conflict in the future with code in which the test for nonzero is not explicit. In this case, defaulting the test for nonzero welcomes bugs if and when a developer modifies foovalidateUser() to return an error code or −1 rather than 0 to indicate a failure (all of which are also common conventions).
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Code that does not conform to the common practices presented is difficult to maintain. Bugs can easily arise when modifying helper functions that evaluate true/false or success/failure. Bugs can also easily arise when modifying code that tests for equality using a comparison function that obeys the same conventions as standard library functions such as strcmp.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
EXP20-C | Medium | Probable | Low | P12 | L1 |
Automated Detection
Tool | Version | Checker | Description | ||||||
| Astrée |
| Supported indirectly via MISRA C:2004 Rule 13.2. | |||||||
| Axivion Bauhaus Suite |
| CertC-EXP20 | Fully implemented | ||||||
| Helix QAC |
| C3344, C4116 | |||||||
| LDRA tool suite |
| 114 S | Partially implemented |
3344
4116
| Parasoft C/C++test |
| CERT_C-EXP20-a | Avoid comparing values with TRUE macro/enum constant using equality operators ("==", "!=") | ||||||
| PC-lint Plus |
| 697 | Partially supported: reports comparisons of Boolean values to constants other than 0 |
Bibliography
| [StackOvflw 2009] | "Should I Return TRUE/FALSE Values from a C Function?" |
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