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Make error message consistent with GNU diff's implementation when fai…
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…ling to read input file(s)
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@oSoMoN
oSoMoN committed Apr 30, 2024
1 parent 61314ea commit c72564e
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Showing 3 changed files with 93 additions and 16 deletions.
33 changes: 29 additions & 4 deletions src/main.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
// files that was distributed with this source code.

use crate::params::{parse_params, Format};
use regex::Regex;
use std::env;
use std::ffi::OsString;
use std::fs;
Expand All @@ -18,6 +19,22 @@ mod params;
mod unified_diff;
mod utils;

fn report_failure_to_read_input_file(
executable: &OsString,
filepath: &OsString,
error: &std::io::Error,
) {
// std::io::Error's display trait outputs "{detail} (os error {code})"
// but we want only the {detail} (error string) part
let error_code_re = Regex::new(r"\ \(os\ error\ \d+\)$").unwrap();
eprintln!(
"{}: {}: {}",
executable.to_string_lossy(),
filepath.to_string_lossy(),
error_code_re.replace(error.to_string().as_str(), ""),
);
}

// Exit codes are documented at
// https://www.gnu.org/software/diffutils/manual/html_node/Invoking-diff.html.
// An exit status of 0 means no differences were found,
Expand Down Expand Up @@ -45,6 +62,7 @@ fn main() -> ExitCode {
maybe_report_identical_files();
return ExitCode::SUCCESS;
}

// read files
fn read_file_contents(filepath: &OsString) -> io::Result<Vec<u8>> {
if filepath == "-" {
Expand All @@ -54,20 +72,27 @@ fn main() -> ExitCode {
fs::read(filepath)
}
}
let mut io_error = false;
let from_content = match read_file_contents(&params.from) {
Ok(from_content) => from_content,
Err(e) => {
eprintln!("Failed to read from-file: {e}");
return ExitCode::from(2);
report_failure_to_read_input_file(&params.executable, &params.from, &e);
io_error = true;
vec![]
}
};
let to_content = match read_file_contents(&params.to) {
Ok(to_content) => to_content,
Err(e) => {
eprintln!("Failed to read to-file: {e}");
return ExitCode::from(2);
report_failure_to_read_input_file(&params.executable, &params.to, &e);
io_error = true;
vec![]
}
};
if io_error {
return ExitCode::from(2);
}

// run diff
let result: Vec<u8> = match params.format {
Format::Normal => normal_diff::diff(&from_content, &to_content, &params),
Expand Down
55 changes: 49 additions & 6 deletions src/params.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ pub enum Format {

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Params {
pub executable: OsString,
pub from: OsString,
pub to: OsString,
pub format: Format,
Expand All @@ -27,6 +28,7 @@ pub struct Params {
impl Default for Params {
fn default() -> Self {
Self {
executable: OsString::default(),
from: OsString::default(),
to: OsString::default(),
format: Format::default(),
Expand All @@ -43,10 +45,13 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
let mut opts = opts.into_iter().peekable();
// parse CLI

let Some(exe) = opts.next() else {
let Some(executable) = opts.next() else {
return Err("Usage: <exe> <from> <to>".to_string());
};
let mut params = Params::default();
let mut params = Params {
executable,
..Default::default()
};
let mut from = None;
let mut to = None;
let mut format = None;
Expand All @@ -63,7 +68,10 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
} else if to.is_none() {
to = Some(param);
} else {
return Err(format!("Usage: {} <from> <to>", exe.to_string_lossy()));
return Err(format!(
"Usage: {} <from> <to>",
params.executable.to_string_lossy()
));
}
continue;
}
Expand Down Expand Up @@ -155,22 +163,31 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
} else if to.is_none() {
to = Some(param);
} else {
return Err(format!("Usage: {} <from> <to>", exe.to_string_lossy()));
return Err(format!(
"Usage: {} <from> <to>",
params.executable.to_string_lossy()
));
}
}
params.from = if let Some(from) = from {
from
} else if let Some(param) = opts.next() {
param
} else {
return Err(format!("Usage: {} <from> <to>", exe.to_string_lossy()));
return Err(format!(
"Usage: {} <from> <to>",
params.executable.to_string_lossy()
));
};
params.to = if let Some(to) = to {
to
} else if let Some(param) = opts.next() {
param
} else {
return Err(format!("Usage: {} <from> <to>", exe.to_string_lossy()));
return Err(format!(
"Usage: {} <from> <to>",
params.executable.to_string_lossy()
));
};

// diff DIRECTORY FILE => diff DIRECTORY/FILE FILE
Expand Down Expand Up @@ -301,6 +318,7 @@ mod tests {
fn basics() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
..Default::default()
Expand All @@ -309,6 +327,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
..Default::default()
Expand All @@ -325,6 +344,7 @@ mod tests {
for arg in ["-e", "--ed"] {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Ed,
Expand All @@ -342,6 +362,7 @@ mod tests {
params.extend(["foo", "bar"]);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Context,
Expand All @@ -362,6 +383,7 @@ mod tests {
params.extend(["foo", "bar"]);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Context,
Expand Down Expand Up @@ -399,6 +421,7 @@ mod tests {
params.extend(["foo", "bar"]);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Unified,
Expand All @@ -419,6 +442,7 @@ mod tests {
params.extend(["foo", "bar"]);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Unified,
Expand Down Expand Up @@ -452,6 +476,7 @@ mod tests {
fn context_count() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Unified,
Expand All @@ -466,6 +491,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Unified,
Expand All @@ -480,6 +506,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Unified,
Expand All @@ -494,6 +521,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format: Format::Context,
Expand All @@ -511,6 +539,7 @@ mod tests {
fn report_identical_files() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
..Default::default()
Expand All @@ -519,6 +548,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
report_identical_files: true,
Expand All @@ -528,6 +558,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
report_identical_files: true,
Expand All @@ -549,6 +580,7 @@ mod tests {
fn brief() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
..Default::default()
Expand All @@ -557,6 +589,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
brief: true,
Expand All @@ -566,6 +599,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
brief: true,
Expand All @@ -582,6 +616,7 @@ mod tests {
fn expand_tabs() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
..Default::default()
Expand All @@ -591,6 +626,7 @@ mod tests {
for option in ["-t", "--expand-tabs"] {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
expand_tabs: true,
Expand All @@ -608,6 +644,7 @@ mod tests {
fn tabsize() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
..Default::default()
Expand All @@ -616,6 +653,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
tabsize: 0,
Expand All @@ -629,6 +667,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
tabsize: 42,
Expand Down Expand Up @@ -686,6 +725,7 @@ mod tests {
fn double_dash() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("-g"),
to: os("-h"),
..Default::default()
Expand All @@ -697,6 +737,7 @@ mod tests {
fn default_to_stdin() {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("-"),
..Default::default()
Expand All @@ -705,6 +746,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("-"),
to: os("bar"),
..Default::default()
Expand All @@ -713,6 +755,7 @@ mod tests {
);
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("-"),
to: os("-"),
..Default::default()
Expand Down
21 changes: 15 additions & 6 deletions tests/integration.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,21 +36,30 @@ fn cannot_read_files() -> Result<(), Box<dyn std::error::Error>> {
cmd.assert()
.code(predicate::eq(2))
.failure()
.stderr(predicate::str::starts_with("Failed to read from-file"));
.stderr(predicate::str::ends_with(format!(
": {}: No such file or directory\n",
&nopath.as_os_str().to_string_lossy()
)));

let mut cmd = Command::cargo_bin("diffutils")?;
cmd.arg(file.path()).arg(&nopath);
cmd.assert()
.code(predicate::eq(2))
.failure()
.stderr(predicate::str::starts_with("Failed to read to-file"));
.stderr(predicate::str::ends_with(format!(
": {}: No such file or directory\n",
&nopath.as_os_str().to_string_lossy()
)));

let mut cmd = Command::cargo_bin("diffutils")?;
cmd.arg(&nopath).arg(&nopath);
cmd.assert()
.code(predicate::eq(2))
.failure()
.stderr(predicate::str::starts_with("Failed to read from-file"));
cmd.assert().code(predicate::eq(2)).failure().stderr(
predicate::str::contains(format!(
": {}: No such file or directory\n",
&nopath.as_os_str().to_string_lossy()
))
.count(2),
);

Ok(())
}
Expand Down

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