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cmp Feat: change data type bytes limit to u64/u128 ignore initial u64 #183

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d0c0611
feat: u64 for --bytes and --ignore-initial
Mar 1, 2026
884edb2
fix: removed 32-bit conditional compiling
Mar 1, 2026
2e9d395
fix: clippy warning
Mar 2, 2026
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8 changes: 7 additions & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ unicode-width = "0.2.0"
pretty_assertions = "1.4.0"
assert_cmd = "2.0.14"
predicates = "3.1.0"
tempfile = "3.10.1"
tempfile = "3.26.0"

[profile.release]
lto = "thin"
Expand All @@ -40,3 +40,9 @@ panic = "abort"
[profile.dist]
inherits = "release"
lto = "thin"

[features]
# default = ["cmp_bytes_limit_128_bit"]
# allows to set the --bytes limit from u64 to u128, if limits larger than Exabyte are required.
cmp_bytes_limit_128_bit = []

101 changes: 54 additions & 47 deletions src/cmp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,15 +20,23 @@ use std::os::unix::fs::MetadataExt;
#[cfg(target_os = "windows")]
use std::os::windows::fs::MetadataExt;

/// for --bytes, so really large number limits can be expressed, like 1Y.
#[cfg(not(feature = "cmp_bytes_limit_128_bit"))]
pub type Bytes = u64;
#[cfg(feature = "cmp_bytes_limit_128_bit")]
pub type Bytes = u128;
// ignore initial is currently limited to u64, as take(skip) is used.
pub type IgnInit = u64;

#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Params {
executable: OsString,
from: OsString,
to: OsString,
print_bytes: bool,
skip_a: Option<usize>,
skip_b: Option<usize>,
max_bytes: Option<usize>,
skip_a: Option<IgnInit>,
skip_b: Option<IgnInit>,
max_bytes: Option<Bytes>,
verbose: bool,
quiet: bool,
}
Expand Down Expand Up @@ -66,13 +74,13 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
};
let executable_str = executable.to_string_lossy().to_string();

let parse_skip = |param: &str, skip_desc: &str| -> Result<usize, String> {
let parse_skip = |param: &str, skip_desc: &str| -> Result<IgnInit, String> {
let suffix_start = param
.find(|b: char| !b.is_ascii_digit())
.unwrap_or(param.len());
let mut num = match param[..suffix_start].parse::<usize>() {
let mut num = match param[..suffix_start].parse::<IgnInit>() {
Ok(num) => num,
Err(e) if *e.kind() == std::num::IntErrorKind::PosOverflow => usize::MAX,
Err(e) if *e.kind() == std::num::IntErrorKind::PosOverflow => IgnInit::MAX,
Err(_) => {
return Err(format!(
"{executable_str}: invalid --ignore-initial value '{skip_desc}'"
Expand All @@ -83,33 +91,24 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
if suffix_start != param.len() {
// Note that GNU cmp advertises supporting up to Y, but fails if you try
// to actually use anything beyond E.
let multiplier: usize = match &param[suffix_start..] {
let multiplier: IgnInit = match &param[suffix_start..] {
"kB" => 1_000,
"K" => 1_024,
"MB" => 1_000_000,
"M" => 1_048_576,
"GB" => 1_000_000_000,
"G" => 1_073_741_824,
// This only generates a warning when compiling for target_pointer_width < 64
#[allow(unused_variables)]
suffix @ ("TB" | "T" | "PB" | "P" | "EB" | "E") => {
#[cfg(target_pointer_width = "64")]
match suffix {
"TB" => 1_000_000_000_000,
"T" => 1_099_511_627_776,
"PB" => 1_000_000_000_000_000,
"P" => 1_125_899_906_842_624,
"EB" => 1_000_000_000_000_000_000,
"E" => 1_152_921_504_606_846_976,
_ => unreachable!(),
}
#[cfg(not(target_pointer_width = "64"))]
usize::MAX
}
"ZB" => usize::MAX, // 1_000_000_000_000_000_000_000,
"Z" => usize::MAX, // 1_180_591_620_717_411_303_424,
"YB" => usize::MAX, // 1_000_000_000_000_000_000_000_000,
"Y" => usize::MAX, // 1_208_925_819_614_629_174_706_176,
"TB" => 1_000_000_000_000,
"T" => 1_099_511_627_776,
"PB" => 1_000_000_000_000_000,
"P" => 1_125_899_906_842_624,
"EB" => 1_000_000_000_000_000_000,
"E" => 1_152_921_504_606_846_976,
// TODO setting usize:MAX does not mimic GNU cmp behavior, it should be an error.
"ZB" => IgnInit::MAX, // 1_000_000_000_000_000_000_000,
"Z" => IgnInit::MAX, // 1_180_591_620_717_411_303_424,
"YB" => IgnInit::MAX, // 1_000_000_000_000_000_000_000_000,
"Y" => IgnInit::MAX, // 1_208_925_819_614_629_174_706_176,
_ => {
return Err(format!(
"{executable_str}: invalid --ignore-initial value '{skip_desc}'"
Expand All @@ -119,7 +118,7 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu

num = match num.overflowing_mul(multiplier) {
(n, false) => n,
_ => usize::MAX,
_ => IgnInit::MAX,
}
}

Expand Down Expand Up @@ -173,9 +172,10 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
let (_, arg) = param_str.split_once('=').unwrap();
arg.to_string()
};
let max_bytes = match max_bytes.parse::<usize>() {
let max_bytes = match max_bytes.parse::<Bytes>() {
Ok(num) => num,
Err(e) if *e.kind() == std::num::IntErrorKind::PosOverflow => usize::MAX,
// TODO limit to MAX is dangerous, this should become an error like in GNU cmp.
Err(e) if *e.kind() == std::num::IntErrorKind::PosOverflow => Bytes::MAX,
Err(_) => {
return Err(format!(
"{executable_str}: invalid --bytes value '{max_bytes}'"
Expand Down Expand Up @@ -233,7 +233,7 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
}

// Do as GNU cmp, and completely disable printing if we are
// outputing to /dev/null.
// outputting to /dev/null.
#[cfg(not(target_os = "windows"))]
if is_stdout_dev_null() {
params.quiet = true;
Expand Down Expand Up @@ -285,7 +285,7 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu

fn prepare_reader(
path: &OsString,
skip: &Option<usize>,
skip: &Option<IgnInit>,
params: &Params,
) -> Result<Box<dyn BufRead>, String> {
let mut reader: Box<dyn BufRead> = if path == "-" {
Expand All @@ -304,6 +304,8 @@ fn prepare_reader(
};

if let Some(skip) = skip {
// cast as u64 must remain, because value of IgnInit data type could be changed.
#[allow(clippy::unnecessary_cast)]
if let Err(e) = io::copy(&mut reader.by_ref().take(*skip as u64), &mut io::sink()) {
return Err(format_failure_to_read_input_file(
&params.executable,
Expand All @@ -326,7 +328,7 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
let mut from = prepare_reader(&params.from, &params.skip_a, params)?;
let mut to = prepare_reader(&params.to, &params.skip_b, params)?;

let mut offset_width = params.max_bytes.unwrap_or(usize::MAX);
let mut offset_width = params.max_bytes.unwrap_or(Bytes::MAX);

if let (Ok(a_meta), Ok(b_meta)) = (fs::metadata(&params.from), fs::metadata(&params.to)) {
#[cfg(not(target_os = "windows"))]
Expand All @@ -341,7 +343,7 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
return Ok(Cmp::Different);
}

let smaller = cmp::min(a_size, b_size) as usize;
let smaller = cmp::min(a_size, b_size) as Bytes;
offset_width = cmp::min(smaller, offset_width);
}

Expand All @@ -350,8 +352,8 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
// Capacity calc: at_byte width + 2 x 3-byte octal numbers + 2 x 4-byte value + 4 spaces
let mut output = Vec::<u8>::with_capacity(offset_width + 3 * 2 + 4 * 2 + 4);

let mut at_byte = 1;
let mut at_line = 1;
let mut at_byte: Bytes = 1;
let mut at_line: u64 = 1;
let mut start_of_line = true;
let mut stdout = BufWriter::new(io::stdout().lock());
let mut compare = Cmp::Equal;
Expand Down Expand Up @@ -401,8 +403,8 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
if from_buf[..consumed] == to_buf[..consumed] {
let last = from_buf[..consumed].last().unwrap();

at_byte += consumed;
at_line += from_buf[..consumed].iter().filter(|&c| *c == b'\n').count();
at_byte += consumed as Bytes;
at_line += (from_buf[..consumed].iter().filter(|&c| *c == b'\n').count()) as u64;

start_of_line = *last == b'\n';

Expand Down Expand Up @@ -590,7 +592,7 @@ fn format_visible_byte(byte: u8) -> String {
fn format_verbose_difference(
from_byte: u8,
to_byte: u8,
at_byte: usize,
at_byte: Bytes,
offset_width: usize,
output: &mut Vec<u8>,
params: &Params,
Expand Down Expand Up @@ -655,7 +657,7 @@ fn format_verbose_difference(
}

#[inline]
fn report_eof(at_byte: usize, at_line: usize, start_of_line: bool, eof_on: &str, params: &Params) {
fn report_eof(at_byte: Bytes, at_line: u64, start_of_line: bool, eof_on: &str, params: &Params) {
if params.quiet {
return;
}
Expand Down Expand Up @@ -707,7 +709,7 @@ fn is_posix_locale() -> bool {
}

#[inline]
fn report_difference(from_byte: u8, to_byte: u8, at_byte: usize, at_line: usize, params: &Params) {
fn report_difference(from_byte: u8, to_byte: u8, at_byte: Bytes, at_line: u64, params: &Params) {
if params.quiet {
return;
}
Expand Down Expand Up @@ -804,7 +806,7 @@ mod tests {
from: os("foo"),
to: os("bar"),
skip_a: Some(1),
skip_b: Some(usize::MAX),
skip_b: Some(IgnInit::MAX),
..Default::default()
}),
parse_params(
Expand Down Expand Up @@ -982,7 +984,7 @@ mod tests {
executable: os("cmp"),
from: os("foo"),
to: os("bar"),
max_bytes: Some(usize::MAX),
max_bytes: Some(Bytes::MAX),
..Default::default()
}),
parse_params(
Expand All @@ -999,6 +1001,7 @@ mod tests {
);

// Failure case
// TODO This is actually fine in GNU cmp. --bytes does not have a unit parser yet.
assert_eq!(
Err("cmp: invalid --bytes value '1K'".to_string()),
parse_params(
Expand Down Expand Up @@ -1044,8 +1047,8 @@ mod tests {
executable: os("cmp"),
from: os("foo"),
to: os("bar"),
skip_a: Some(usize::MAX),
skip_b: Some(usize::MAX),
skip_a: Some(IgnInit::MAX),
skip_b: Some(IgnInit::MAX),
..Default::default()
}),
parse_params(
Expand Down Expand Up @@ -1116,8 +1119,12 @@ mod tests {
.enumerate()
{
let values = [
1_000usize.checked_pow((i + 1) as u32).unwrap_or(usize::MAX),
1024usize.checked_pow((i + 1) as u32).unwrap_or(usize::MAX),
(1_000 as IgnInit)
.checked_pow((i + 1) as u32)
.unwrap_or(IgnInit::MAX),
(1024 as IgnInit)
.checked_pow((i + 1) as u32)
.unwrap_or(IgnInit::MAX),
];
for (j, v) in values.iter().enumerate() {
assert_eq!(
Expand Down
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