PVS-Studio warning V666 for Scilab

void CreCommon(f,var)
     FILE *f;
     VARPTR var;
{
  ....
  if ( strncmp(var->fexternal,"cintf",4)==0 )
  ....
}

This suspicious code was found in Scilab project by PVS-Studio static code analyzer.
Warning message is:
V666 Consider inspecting third argument of the function 'strncmp'. It is possible that the value does not correspond with the length of a string which was passed with the second argument. crerhs.c 119

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