tail: improve GNU compatibility

src/uu/tail/src/args.rs

@@ -45,6 +45,10 @@ pub mod options {
  pub static MAX_UNCHANGED_STATS: &str = "max-unchanged-stats";
  pub static ARG_FILES: &str = "files";
  pub static PRESUME_INPUT_PIPE: &str = "-presume-input-pipe"; // NOTE: three hyphens is correct
+ pub static B_GNU_COMPAT: &str = "b-gnu-compat";
+ pub static L_GNU_COMPAT: &str = "l-gnu-compat";
+ pub static K_GNU_COMPAT: &str = "k-gnu-compat";
+ pub static M_GNU_COMPAT: &str = "m-gnu-compat";
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -79,6 +83,14 @@ impl FilterMode {
  }
  Err(e) => return Err(UUsageError::new(1, format!("invalid number of lines: {e}"))),
  }
+ } else if matches.get_flag(options::B_GNU_COMPAT) {
+ Self::Bytes(Signum::Negative(10 * 512))
+ } else if matches.get_flag(options::L_GNU_COMPAT) {
+ Self::Lines(Signum::Negative(10), b'\n')
+ } else if matches.get_flag(options::K_GNU_COMPAT) {
+ Self::Bytes(Signum::Negative(10 * 1024))
+ } else if matches.get_flag(options::M_GNU_COMPAT) {
+ Self::Bytes(Signum::Negative(10 * 1024 * 1024))
  } else if zero_term {
  Self::default_zero()
  } else {
@@ -208,6 +220,62 @@ impl Settings {
  .map(|v| v.map(|string| Input::from(string.clone())).collect())
  .unwrap_or_default();
 
+ if !inputs.is_empty() {
+ const DEFAULT_MODE: char = 'l';
+ const DEFAULT_INTVAL: u64 = 10;
+ let mut name = inputs[0].display_name.to_string();
+ let mut default_mode = false;
+ if let Some(mut mode) = name.chars().last() {
+ if mode == 'l' || mode == 'c' || mode == 'b' || mode == 'k' || mode == 'm' {
+ name.pop();
+ } else {
+ mode = DEFAULT_MODE;
+ default_mode = true;
+ }
+ if let Some(sign) = name.chars().next() {
+ let mut intval_opt: Option<u64> = None;
+ let mut signum_opt: Option<Signum> = None;
+ if sign == '+' || sign == '-' {
+ name.remove(0);
+ intval_opt = if let Ok(intval) = name.parse::<u64>() {
+ Some(intval)
+ } else if !default_mode && name.is_empty() {
+ Some(DEFAULT_INTVAL)
+ } else {
+ None
+ };
+ }
+ if let Some(intval) = intval_opt {
+ let multiplier: u64 = if mode == 'b' {
+ mode = 'c';
+ 512
+ } else if mode == 'k' {
+ mode = 'c';
+ 1024
+ } else if mode == 'm' {
+ mode = 'c';
+ 1024 * 1024
+ } else {
+ 1
+ };
+ signum_opt = if sign == '+' {
+ Some(Signum::Positive(multiplier * intval))
+ } else {
+ Some(Signum::Negative(multiplier * intval))
+ };
+ }
+ if let Some(signum) = signum_opt {
+ if mode == 'c' {
+ settings.mode = FilterMode::Bytes(signum);
+ } else {
+ settings.mode = FilterMode::Lines(signum, b'\n');
+ }
+ inputs.remove(0);
+ }
+ }
+ }
+ }
+
  // apply default and add '-' to inputs if none is present
  if inputs.is_empty() {
  inputs.push_front(Input::default());
@@ -366,6 +434,14 @@ pub fn uu_app() -> Command {
  pub static POLLING_HELP: &str =
  "Disable 'ReadDirectoryChanges' support and use polling instead";
 
+ let overrides = [
+ options::BYTES,
+ options::LINES,
+ options::B_GNU_COMPAT,
+ options::K_GNU_COMPAT,
+ options::L_GNU_COMPAT,
+ options::M_GNU_COMPAT,
+ ];
  Command::new(uucore::util_name())
  .version(crate_version!())
  .about(ABOUT)
@@ -376,7 +452,7 @@ pub fn uu_app() -> Command {
  .short('c')
  .long(options::BYTES)
  .allow_hyphen_values(true)
- .overrides_with_all([options::BYTES, options::LINES])
+ .overrides_with_all(overrides)
  .help("Number of bytes to print"),
  )
  .arg(
@@ -394,7 +470,7 @@ pub fn uu_app() -> Command {
  .short('n')
  .long(options::LINES)
  .allow_hyphen_values(true)
- .overrides_with_all([options::BYTES, options::LINES])
+ .overrides_with_all(overrides)
  .help("Number of lines to print"),
  )
  .arg(
@@ -479,6 +555,34 @@ pub fn uu_app() -> Command {
  .num_args(1..)
  .value_hint(clap::ValueHint::FilePath),
  )
+ .arg(
+ Arg::new(options::B_GNU_COMPAT)
+ .short('b')
+ .action(ArgAction::SetTrue)
+ .overrides_with_all(overrides)
+ .hide(true),
+ )
+ .arg(
+ Arg::new(options::K_GNU_COMPAT)
+ .short('k')
+ .action(ArgAction::SetTrue)
+ .overrides_with_all(overrides)
+ .hide(true),
+ )
+ .arg(
+ Arg::new(options::L_GNU_COMPAT)
+ .short('l')
+ .action(ArgAction::SetTrue)
+ .overrides_with_all(overrides)
+ .hide(true),
+ )
+ .arg(
+ Arg::new(options::M_GNU_COMPAT)
+ .short('m')
+ .action(ArgAction::SetTrue)
+ .overrides_with_all(overrides)
+ .hide(true),
+ )
 }
 
 #[cfg(test)]

src/uu/tail/src/parse.rs

@@ -36,7 +36,7 @@ pub fn parse_obsolete(src: &str) -> Option<Result<impl Iterator<Item = OsString>
  let mut multiplier = None;
  let mut c = last_char;
  loop {
- // not that here, we only match lower case 'k', 'c', and 'm'
+ // not that here, we only match lower case 'k', 'c', 'm', and 'l'
  match c {
  // we want to preserve order
  // this also saves us 1 heap allocation
@@ -53,6 +53,7 @@ pub fn parse_obsolete(src: &str) -> Option<Result<impl Iterator<Item = OsString>
  'b' => multiplier = Some(512),
  'k' => multiplier = Some(1024),
  'm' => multiplier = Some(1024 * 1024),
+ 'l' => {}
  '\0' => {}
  _ => return Some(Err(ParseError::Syntax)),
  }