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This recommendation depends on C11 Annex K being implemented. The following code can be added to remove this dependency:

#ifndef __STDC_LIB_EXT1__
  typedef int errno_t;
#endif

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This noncompliant code example nevertheless complies with ERR30-C. Set errno to zero before calling a library function known to set errno, and check errno only after the function returns a value indicating failureTake care when reading errno.

Compliant Solution (POSIX)

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Failing to test for error conditions can lead to vulnerabilities of varying severity. Declaring functions that return an errno with a return type of errno_t will not eliminate this problem but may reduce errors caused by programmers' misunderstanding the purpose of a return value.

Automated Detection

Related Vulnerabilities

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

Related Guidelines

Bibliography

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