in sgx_tstd/src/net/ip_addr.rs [1681:1762]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// If there are no alignment requirements, write the IP address directly to `f`.
// Otherwise, write it to a local buffer and then use `f.pad`.
if f.precision().is_none() && f.width().is_none() {
let segments = self.segments();
// Special case for :: and ::1; otherwise they get written with the
// IPv4 formatter
if self.is_unspecified() {
f.write_str("::")
} else if self.is_loopback() {
f.write_str("::1")
} else if let Some(ipv4) = self.to_ipv4() {
match segments[5] {
// IPv4 Compatible address
0 => write!(f, "::{}", ipv4),
// IPv4 Mapped address
0xffff => write!(f, "::ffff:{}", ipv4),
_ => unreachable!(),
}
} else {
#[derive(Copy, Clone, Default)]
struct Span {
start: usize,
len: usize,
}
// Find the inner 0 span
let zeroes = {
let mut longest = Span::default();
let mut current = Span::default();
for (i, &segment) in segments.iter().enumerate() {
if segment == 0 {
if current.len == 0 {
current.start = i;
}
current.len += 1;
if current.len > longest.len {
longest = current;
}
} else {
current = Span::default();
}
}
longest
};
/// Write a colon-separated part of the address
#[inline]
fn fmt_subslice(f: &mut fmt::Formatter<'_>, chunk: &[u16]) -> fmt::Result {
if let Some((first, tail)) = chunk.split_first() {
write!(f, "{:x}", first)?;
for segment in tail {
f.write_char(':')?;
write!(f, "{:x}", segment)?;
}
}
Ok(())
}
if zeroes.len > 1 {
fmt_subslice(f, &segments[..zeroes.start])?;
f.write_str("::")?;
fmt_subslice(f, &segments[zeroes.start + zeroes.len..])
} else {
fmt_subslice(f, &segments)
}
}
} else {
const LONGEST_IPV6_ADDR: &str = "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff";
let mut buf = DisplayBuffer::<{ LONGEST_IPV6_ADDR.len() }>::new();
// Buffer is long enough for the longest possible IPv6 address, so this should never fail.
write!(buf, "{}", self).unwrap();
f.pad(buf.as_str())
}
}