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Write short form hostname #922

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Write short form hostname #922

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fd6bf73
Write short form hostname
gabriel-samfira May 11, 2023
84f851d
Add --short command line option
gabriel-samfira May 12, 2023
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7 changes: 5 additions & 2 deletions src/cli/multi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,11 @@ pub struct CliMulti {
#[arg(long)]
check_in: bool,
/// The file into which the hostname should be written
#[arg(long = "hostname", value_name = "path")]
#[arg(group = "hostname", long = "hostname", value_name = "path")]
hostname_file: Option<String>,
/// Parse the hostname retrieved from metadata as a short hostname
#[arg(long = "short", requires = "hostname")]
short_hostname: bool,
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I think I prefer your original idea of having --short-hostname=/etc/hostname. Rather than adding a mode switch that controls the behavior of another option, let's just support --hostname and --short-hostname as two output switches that operate independently.

/// The directory into which network units are written
#[arg(long = "network-units", value_name = "path")]
network_units_dir: Option<String>,
Expand Down Expand Up @@ -64,7 +67,7 @@ impl CliMulti {

// write hostname if configured to do so
self.hostname_file
.map_or(Ok(()), |x| metadata.write_hostname(x))
.map_or(Ok(()), |x| metadata.write_hostname(x, self.short_hostname))
.context("writing hostname")?;

// write network units if configured to do so
Expand Down
46 changes: 28 additions & 18 deletions src/providers/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -238,18 +238,20 @@ pub trait MetadataProvider {
Ok(())
}

fn write_hostname(&self, hostname_file_path: String) -> Result<()> {
fn write_hostname(&self, hostname_file_path: String, short: bool) -> Result<()> {
if let Some(mut hostname) = self.hostname()? {
if let Some(maxlen) = max_hostname_len()? {
// Get the short form hostname (i.e. without the domain name).
// The domain name is usually set as a search domain via DHCP, and
// it can optionally be added as a canonical hostname to /etc/hosts
// as well, as the first value after the local IP address.
//
// Example:
// 127.0.0.1 example.local example
if let Some(idx) = hostname.find('.') {
hostname.truncate(idx);
if short {
// Get the short form hostname (i.e. without the domain name).
// The domain name is usually set as a search domain via DHCP, and
// it can optionally be added as a canonical hostname to /etc/hosts
// as well, as the first value after the local IP address.
//
// Example:
// 127.0.0.1 example.local example
if let Some(idx) = hostname.find('.') {
hostname.truncate(idx);
}
}
if hostname.len() > maxlen {
// Value exceeds the system's maximum hostname length.
Expand All @@ -262,6 +264,9 @@ pub trait MetadataProvider {
maxlen
);
hostname.truncate(maxlen);
if let Some(idx) = hostname.find('.') {
hostname.truncate(idx);
}
}
}

Expand Down Expand Up @@ -316,11 +321,11 @@ mod tests {
}

// write specified hostname to a file, then read it back
fn try_write_hostname(hostname: &str) -> String {
fn try_write_hostname(hostname: &str, short: bool) -> String {
let mut temp = NamedTempFile::new().unwrap();
let provider = HostnameMock(hostname.into());
provider
.write_hostname(temp.path().to_str().unwrap().into())
.write_hostname(temp.path().to_str().unwrap().into(), short)
.unwrap();
let mut ret = String::new();
temp.read_to_string(&mut ret).unwrap();
Expand All @@ -337,30 +342,35 @@ mod tests {
.take(maxlen * 2)
.collect::<String>();
// simple hostname
assert_eq!(try_write_hostname("hostname7"), "hostname7");
assert_eq!(try_write_hostname("hostname7", false), "hostname7");
// simple FQDN
assert_eq!(
try_write_hostname("hostname7.example.com"),
try_write_hostname("hostname7.example.com", false),
"hostname7.example.com"
);
// short form hostname
assert_eq!(
try_write_hostname("hostname7.example.com", true),
"hostname7"
);
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Let's at least also test short hostnames where the input value doesn't have an FQDN.

// truncated simple hostname
assert_eq!(
try_write_hostname(&long_string[0..maxlen + 10]),
try_write_hostname(&long_string[0..maxlen + 10], false),
long_string[0..maxlen]
);
// truncated FQDN
assert_eq!(
try_write_hostname(&format!("{}.example.com", &long_string[0..maxlen + 5])),
try_write_hostname(&format!("{}.example.com", &long_string[0..maxlen + 5]), false),
long_string[0..maxlen]
);
// truncate to first dot
assert_eq!(
try_write_hostname(&format!("{}.example.com", &long_string[0..maxlen - 5])),
try_write_hostname(&format!("{}.example.com", &long_string[0..maxlen - 5]), false),
long_string[0..maxlen - 5]
);
// truncate to first dot even if we could truncate to second dot
assert_eq!(
try_write_hostname(&format!("{}.example.com", &long_string[0..maxlen - 10])),
try_write_hostname(&format!("{}.example.com", &long_string[0..maxlen - 10]), false),
long_string[0..maxlen - 10]
);
}
Expand Down