DCL05-A. Use typedefs to improve code readability

Use type definitions (typedef) to improve code readability.

Non-Compliant Code Example

The following declaration of the signal() function is difficult to read and comprehend.

void (*signal(int, void (*)(int)))(int);

Compliant Solution

This compliant solution makes use of type definitions to specify the same type as in the non-compliant code example.

typedef void (*SighandlerType)(int signum);
extern SighandlerType signal(
  int signum, 
  SighandlerType handler
);

Risk Assessment

Code readability is important for discovering and eliminating vulnerabilities.

Automated Detection

The LDRA tool suite V 7.6.0 is able to detect violations of this recommendation.

Compass/ROSE could detect violations of this recommendation...typedefs are well represented in ROSE's AST. To detect violations, we first have to rigorously define what constitutes a 'too complicated type'. Most could concede that a pointer to a simple type is not too complicated, but a function type is. I think a reasonable definition of 'too complicated' would be any type that has two pointers, two arrays, one array + one pointer, or one function.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

References

[[ISO/IEC 9899:1999]] Section 6.7.7, "Type definitions"
[[ISO/IEC PDTR 24772]] "BRS Leveraging human experience"

DCL04-A. Do not declare more than one variable per declaration      02. Declarations and Initialization (DCL)       DCL06-A. Use meaningful symbolic constants to represent literal values in program logic