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Mixing bitwise and relational operators in the same full expression can be a sign of a logic error in the expression where a logical operator is usually the intended operator. Do not use the bitwise AND (&), bitwise OR (|), or bitwise XOR (^) operators with an operand of type _Bool, or the result of a relational-expression or equality-expression. If the bitwise operator is intended, it should be indicated with use of a parenthesized expression.

Noncompliant Code Example

In this noncompliant code example, a bitwise & operator is used with the results of an equality-expression:

if (!(getuid() & geteuid() == 0)) { 
  /* ... */ 
} 

Compliant Solution

This compliant solution uses the && operator for the logical operation within the conditional expression:

if (!(getuid() && geteuid() == 0)) {
  /* ... */
}

Risk Assessment

Rule

Severity

Likelihood

Remediation Cost

Priority

Level

EXP46-C

Low

Likely

Low

P9

L2

Automated Detection

Tool

Version

Checker

Description

Coverity

2017.07

CONSTANT_EXPRESSION_RESULT

Can detect the specific instance where bitwise operator is used in place of logical operator, or vice versa. The behavior might be desirable in some situations, so further verification is necessary

PRQA QA-C
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3344,4502 

Related Guidelines

ISO/IEC TR 24772:2013Likely Incorrect Expression [KOA]
MITRE CWECWE-480, Use of incorrect operator

Bibliography

[Hatton 1995]Section 2.7.2, "Errors of Omission and Addition"

 


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