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Noncompliant Code Example

Wiki MarkupThe standard {{strncpy()}} function does not guarantee that the resulting string is null terminated \[ [ISO/IEC 9899:1999|AA. Bibliography#ISO/IEC 9899-1999]\]. If there is no null character in the first {{n}} characters of the {{source}} array, the result may not be null terminated.

char *source;
char a[NTBS_SIZE];
/* ... */
if (source) {
  errno_t err = strncpy(a, source, 5);
  if (err != 0) {
    /* Handle error */
  }
}
else {
  /* handle NULL string condition */
}

Compliant Solution (strncpy_s())

Wiki MarkupThe {{strncpy_s()}} function copies up to {{n}} characters from the source array to a destination array \ [[TR 24731|AA. Bibliography#ISO/IEC TR 24731-1-2007]\]. If no null character was copied from the source array, then the {{n{}}}th position in the destination array is set to a null character, guaranteeing that the resulting string is null-terminated.

char *source;
char a[NTBS_SIZE];
/* ... */
if (source) {
  errno_t err = strncpy_s(a, sizeof(a), source, 5);
  if (err != 0) {
    /* Handle error */
  }
}
else {
  /* handle NULL string condition */
}

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