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Typically, converting an integer to a smaller type results in truncation of the high-order bits.
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Noncompliant Code Example (Unsigned to Signed)
Type range errors, including loss of data (truncation) and loss of sign (sign errors), can occur when converting from an unsigned type to a signed type. The following non-compliant noncompliant code example results in a truncation error on most implementations.
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| Code Block | ||
|---|---|---|
| ||
unsigned long int ul = ULONG_MAX;
signed char sc;
if (ul <= SCHAR_MAX) {
sc = (signed char)ul; /* use cast to eliminate warning */
}
else {
/* handle error condition */
}
|
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Noncompliant Code Example (Signed to Unsigned)
Type range errors, including loss of data (truncation) and loss of sign (sign errors), can occur when converting from a signed type to an unsigned type. The following code results in a loss of sign.
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NOTE: While unsigned types can usually represent all positive values of the corresponding signed type, this relationship is not guaranteed by the C99 standard.
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Noncompliant Code Example (Signed, Loss of Precision)
A loss of data (truncation) can occur when converting from a signed type to a signed type with less precision. The following code can result in truncation.
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Conversions from signed types with greater precision to signed types with lesser precision require both the upper and lower bounds to be checked.
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Noncompliant Code Example (Unsigned, Loss of Precision)
A loss of data (truncation) can occur when converting from an unsigned type to an unsigned type with less precision. The following code results in a truncation error on most implementations.
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Fortify SCA Version 5.0 with CERT C Rule Pack is able to can detect violations of this rule.
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