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Merge pull request #100 from kov/cmp-mem
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cmp: print verbose diffs as we find them
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@oSoMoN
oSoMoN authored Oct 8, 2024
2 parents 0bf04b4 + a316262 commit 933230e
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Showing 2 changed files with 93 additions and 99 deletions.
190 changes: 92 additions & 98 deletions src/cmp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use std::ffi::OsString;
use std::io::{BufRead, BufReader, BufWriter, Read, Write};
use std::iter::Peekable;
use std::process::ExitCode;
use std::{fs, io};
use std::{cmp, fs, io};

#[cfg(not(target_os = "windows"))]
use std::os::fd::{AsRawFd, FromRawFd};
Expand Down Expand Up @@ -320,10 +320,35 @@ 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);

if let (Ok(a_meta), Ok(b_meta)) = (fs::metadata(&params.from), fs::metadata(&params.to)) {
#[cfg(not(target_os = "windows"))]
let (a_size, b_size) = (a_meta.size(), b_meta.size());

#[cfg(target_os = "windows")]
let (a_size, b_size) = (a_meta.file_size(), b_meta.file_size());

// If the files have different sizes, we already know they are not identical. If we have not
// been asked to show even the first difference, we can quit early.
if params.quiet && a_size != b_size {
return Ok(Cmp::Different);
}

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

let offset_width = 1 + offset_width.checked_ilog10().unwrap_or(1) as usize;

// 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 start_of_line = true;
let mut verbose_diffs = vec![];
let mut stdout = BufWriter::new(io::stdout().lock());
let mut compare = Cmp::Equal;
loop {
// Fill up our buffers.
let from_buf = match from.fill_buf() {
Expand Down Expand Up @@ -360,10 +385,6 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
&params.to.to_string_lossy()
};

if params.verbose {
report_verbose_diffs(verbose_diffs, params)?;
}

report_eof(at_byte, at_line, start_of_line, eof_on, params);
return Ok(Cmp::Different);
}
Expand Down Expand Up @@ -395,8 +416,24 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
// first one runs out.
for (&from_byte, &to_byte) in from_buf.iter().zip(to_buf.iter()) {
if from_byte != to_byte {
compare = Cmp::Different;

if params.verbose {
verbose_diffs.push((at_byte, from_byte, to_byte));
format_verbose_difference(
from_byte,
to_byte,
at_byte,
offset_width,
&mut output,
params,
)?;
stdout.write_all(output.as_slice()).map_err(|e| {
format!(
"{}: error printing output: {e}",
params.executable.to_string_lossy()
)
})?;
output.clear();
} else {
report_difference(from_byte, to_byte, at_byte, at_line, params);
return Ok(Cmp::Different);
Expand All @@ -422,12 +459,7 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
to.consume(consumed);
}

if params.verbose && !verbose_diffs.is_empty() {
report_verbose_diffs(verbose_diffs, params)?;
return Ok(Cmp::Different);
}

Ok(Cmp::Equal)
Ok(compare)
}

// Exit codes are documented at
Expand All @@ -450,21 +482,6 @@ pub fn main(opts: Peekable<ArgsOs>) -> ExitCode {
return ExitCode::SUCCESS;
}

// If the files have different sizes, we already know they are not identical. If we have not
// been asked to show even the first difference, we can quit early.
if params.quiet {
if let (Ok(a_meta), Ok(b_meta)) = (fs::metadata(&params.from), fs::metadata(&params.to)) {
#[cfg(not(target_os = "windows"))]
if a_meta.size() != b_meta.size() {
return ExitCode::from(1);
}
#[cfg(target_os = "windows")]
if a_meta.file_size() != b_meta.file_size() {
return ExitCode::from(1);
}
}
}

match cmp(&params) {
Ok(Cmp::Equal) => ExitCode::SUCCESS,
Ok(Cmp::Different) => ExitCode::from(1),
Expand Down Expand Up @@ -533,99 +550,76 @@ fn format_byte(byte: u8) -> String {
// This function has been optimized to not use the Rust fmt system, which
// leads to a massive speed up when processing large files: cuts the time
// for comparing 2 ~36MB completely different files in half on an M1 Max.
fn report_verbose_diffs(diffs: Vec<(usize, u8, u8)>, params: &Params) -> Result<(), String> {
#[inline]
fn format_verbose_difference(
from_byte: u8,
to_byte: u8,
at_byte: usize,
offset_width: usize,
output: &mut Vec<u8>,
params: &Params,
) -> Result<(), String> {
assert!(!params.quiet);

let mut stdout = BufWriter::new(io::stdout().lock());
if let Some((offset, _, _)) = diffs.last() {
// Obtain the width of the first column from the last byte offset.
let width = format!("{}", offset).len();

let mut at_byte_buf = itoa::Buffer::new();
let mut from_oct = [0u8; 3]; // for octal conversions
let mut to_oct = [0u8; 3];

// Capacity calc: at_byte width + 2 x 3-byte octal numbers + 4-byte value + up to 2 byte value + 4 spaces
let mut output = Vec::<u8>::with_capacity(width + 3 * 2 + 4 + 2 + 4);

if params.print_bytes {
for (at_byte, from_byte, to_byte) in diffs {
output.clear();

// "{:>width$} {:>3o} {:4} {:>3o} {}",
let at_byte_str = at_byte_buf.format(at_byte);
let at_byte_padding = width - at_byte_str.len();
let mut at_byte_buf = itoa::Buffer::new();
let mut from_oct = [0u8; 3]; // for octal conversions
let mut to_oct = [0u8; 3];

for _ in 0..at_byte_padding {
output.push(b' ')
}

output.extend_from_slice(at_byte_str.as_bytes());

output.push(b' ');
if params.print_bytes {
// "{:>width$} {:>3o} {:4} {:>3o} {}",
let at_byte_str = at_byte_buf.format(at_byte);
let at_byte_padding = offset_width.saturating_sub(at_byte_str.len());

output.extend_from_slice(format_octal(from_byte, &mut from_oct).as_bytes());
for _ in 0..at_byte_padding {
output.push(b' ')
}

output.push(b' ');
output.extend_from_slice(at_byte_str.as_bytes());

let from_byte_str = format_byte(from_byte);
let from_byte_padding = 4 - from_byte_str.len();
output.push(b' ');

output.extend_from_slice(from_byte_str.as_bytes());
output.extend_from_slice(format_octal(from_byte, &mut from_oct).as_bytes());

for _ in 0..from_byte_padding {
output.push(b' ')
}
output.push(b' ');

output.push(b' ');
let from_byte_str = format_byte(from_byte);
let from_byte_padding = 4 - from_byte_str.len();

output.extend_from_slice(format_octal(to_byte, &mut to_oct).as_bytes());
output.extend_from_slice(from_byte_str.as_bytes());

output.push(b' ');
for _ in 0..from_byte_padding {
output.push(b' ')
}

output.extend_from_slice(format_byte(to_byte).as_bytes());
output.push(b' ');

output.push(b'\n');
output.extend_from_slice(format_octal(to_byte, &mut to_oct).as_bytes());

stdout.write_all(output.as_slice()).map_err(|e| {
format!(
"{}: error printing output: {e}",
params.executable.to_string_lossy()
)
})?;
}
} else {
for (at_byte, from_byte, to_byte) in diffs {
output.clear();
output.push(b' ');

// "{:>width$} {:>3o} {:>3o}"
let at_byte_str = at_byte_buf.format(at_byte);
let at_byte_padding = width - at_byte_str.len();
output.extend_from_slice(format_byte(to_byte).as_bytes());

for _ in 0..at_byte_padding {
output.push(b' ')
}
output.push(b'\n');
} else {
// "{:>width$} {:>3o} {:>3o}"
let at_byte_str = at_byte_buf.format(at_byte);
let at_byte_padding = offset_width - at_byte_str.len();

output.extend_from_slice(at_byte_str.as_bytes());
for _ in 0..at_byte_padding {
output.push(b' ')
}

output.push(b' ');
output.extend_from_slice(at_byte_str.as_bytes());

output.extend_from_slice(format_octal(from_byte, &mut from_oct).as_bytes());
output.push(b' ');

output.push(b' ');
output.extend_from_slice(format_octal(from_byte, &mut from_oct).as_bytes());

output.extend_from_slice(format_octal(to_byte, &mut to_oct).as_bytes());
output.push(b' ');

output.push(b'\n');
output.extend_from_slice(format_octal(to_byte, &mut to_oct).as_bytes());

stdout.write_all(output.as_slice()).map_err(|e| {
format!(
"{}: error printing output: {e}",
params.executable.to_string_lossy()
)
})?;
}
}
output.push(b'\n');
}

Ok(())
Expand Down
2 changes: 1 addition & 1 deletion tests/integration.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -616,7 +616,7 @@ mod cmp {
.code(predicate::eq(1))
.failure()
.stderr(predicate::str::is_empty())
.stdout(predicate::eq("4 40 144 d\n8 40 150 h\n"));
.stdout(predicate::eq(" 4 40 144 d\n 8 40 150 h\n"));
Ok(())
}

Expand Down

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