pub fn read_fpcalc(stdout: &str) -> Result<Fingerprint, String>Expand description
Reads fpcalc’s two lines: DURATION= and FINGERPRINT=.
The duration it states is preferred over the caller’s, because it is the
length of what was decoded rather than the length a header claims.
Decimal fractions are truncated to whole seconds; malformed fractions,
signs and values outside u32 are refused instead of accepting a prefix.