SEI CERT C Coding Standard

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changes.mady.by.user Carol J. Lallier

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changes.mady.by.user Carol J. Lallier

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Code Block
if (/* arguments will cause a domain error */) {
  /* handleHandle domain error */
}
else {
  /* performPerform computation */
}

Range Checking

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Code Block
#include <math.h>
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
#include <fenv.h>
#endif

/* ... */

#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
  feclearexcept(FE_ALL_EXCEPT);
#endif
errno = 0;

/* callCall the function */

#if !defined(math_errhandling) \
  || (math_errhandling & MATH_ERRNO)
if (errno != 0) {
  /* handleHandle range error */
}
#endif
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
if (fetestexcept(FE_INVALID
               | FE_DIVBYZERO
               | FE_OVERFLOW
               | FE_UNDERFLOW) != 0) {
  /* handleHandle range error */
}
#endif

See FLP03-C. Detect and handle floating-point errors for more details on how to detect floating-point errors.

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Code Block
bgColor#ccccff
langc
double x;
double result;

if (isless(x, 0)) {
  /* handleHandle domain error */
}

result = sqrt(x);

...

Code Block
bgColor#ccccff
langc
#include <math.h>
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
#include <fenv.h>
#endif

/* ... */

#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
  feclearexcept(FE_ALL_EXCEPT);
#endif
errno = 0;

double x;
double result;

result = sinh(x);

#if !defined(math_errhandling) \
  || (math_errhandling & MATH_ERRNO)
if (errno != 0) {
  /* handleHandle range error */
}
#endif
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
if (fetestexcept(FE_INVALID
               | FE_DIVBYZERO
               | FE_OVERFLOW
               | FE_UNDERFLOW) != 0)
{
  /* handleHandle range error */
}
#endif

Anchor
Power
Power

...

Code Block
bgColor#ccccff
langc
#include <math.h>
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
#include <fenv.h>
#endif

/* ... */

#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
  feclearexcept(FE_ALL_EXCEPT);
#endif
errno = 0;

/* callCall the function */

double x;
double y;
double result;

if (((x == 0.f) && islessequal(y, 0)) || (isless(x, 0))) {
  /* handleHandle domain error */
}

result = pow(x, y);

#if !defined(math_errhandling) \
  || (math_errhandling & MATH_ERRNO)
if (errno != 0) {
  /* handleHandle range error */
}
#endif
#if defined(math_errhandling) \
  && (math_errhandling & MATH_ERREXCEPT)
if (fetestexcept(FE_INVALID
               | FE_DIVBYZERO
               | FE_OVERFLOW
               | FE_UNDERFLOW) != 0)
{
  /* handleHandle range error */
}
#endif

Risk Assessment

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CERT C++ Secure Coding StandardFLP32-CPP. Prevent or detect domain and range errors in math functions
MITRE CWECWE-682, Incorrect calculation

Bibliography

[ISO/IEC 9899:2011]Section 7.3, "Complex Arithmetic <complex.h>"
Section 7.12, "Mathematics <math.h>"
[Plum 1985]Rule 2-2
[Plum 1989]Topic 2.10, "conv—Conversions and Overflow"

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