ruby_vsnprintf   2154 include/ruby/ruby.h int ruby_vsnprintf(char *str, size_t n, char const *fmt, va_list ap);
ruby_vsnprintf      7 include/ruby/subst.h #define vsnprintf ruby_vsnprintf
ruby_vsnprintf   1296 sprintf.c          ret = ruby_vsnprintf(str, n, fmt, ap);