fix: panic on write to /dev/full

* fixes issue #165
* simpler format of io errors (remove (os error 2))

Author: Gunter Schmidt

Cargo.lock

@@ -3,7 +3,7 @@
 // For the full copyright and license information, please view the LICENSE-*
 // files that was distributed with this source code.
 
-use crate::utils::format_failure_to_read_input_file;
+use crate::utils::{format_failure_to_read_input_file, format_io_error};
 use std::env::{self, ArgsOs};
 use std::ffi::OsString;
 use std::io::{BufRead, BufReader, BufWriter, Read, Write};
@@ -441,7 +441,7 @@ pub fn cmp(params: &Params) -> Result<Cmp, String> {
                     })?;
                     output.clear();
                 } else {
-                    report_difference(from_byte, to_byte, at_byte, at_line, params);
+                    report_difference(from_byte, to_byte, at_byte, at_line, params)?;
                     return Ok(Cmp::Different);
                 }
             }
@@ -707,9 +707,15 @@ 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: usize,
+    at_line: usize,
+    params: &Params,
+) -> Result<(), String> {
     if params.quiet {
-        return;
+        return Ok(());
     }
 
     let term = if is_posix_locale() && !params.print_bytes {
@@ -734,7 +740,16 @@ fn report_difference(from_byte: u8, to_byte: u8, at_byte: usize, at_line: usize,
             format_visible_byte(to_byte)
         );
     }
-    println!();
+    // Instead of println!(), which panics in case of error (> /dev/full).
+    let mut stdout = io::stdout();
+    if let Err(e) = writeln!(stdout) {
+        return Err(format_io_error(&e));
+    };
+    if let Err(e) = stdout.flush() {
+        return Err(format_io_error(&e));
+    };
+
+    Ok(())
 }
 
 #[cfg(test)]

src/cmp.rs

@@ -4,7 +4,7 @@
 // files that was distributed with this source code.
 
 use crate::params::{parse_params, Format};
-use crate::utils::report_failure_to_read_input_file;
+use crate::utils::{format_io_error, report_failure_to_read_input_file};
 use crate::{context_diff, ed_diff, normal_diff, side_diff, unified_diff};
 use std::env::ArgsOs;
 use std::ffi::OsString;
@@ -107,8 +107,8 @@ pub fn main(opts: Peekable<ArgsOs>) -> ExitCode {
                     uucore::error::set_exit_code(1);
                 }
             }
-            Err(err) => {
-                eprintln!("{err}");
+            Err(error) => {
+                eprintln!("{}", format_io_error(&error));
                 return ExitCode::FAILURE;
             }
         }

src/diff.rs

@@ -3,7 +3,6 @@
 // For the full copyright and license information, please view the LICENSE-*
 // files that was distributed with this source code.
 
-use regex::Regex;
 use std::{ffi::OsString, io::Write};
 use unicode_width::UnicodeWidthStr;
 
@@ -78,15 +77,19 @@ pub fn format_failure_to_read_input_file(
 ) -> String {
     // 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();
     format!(
         "{}: {}: {}",
         executable.to_string_lossy(),
         filepath.to_string_lossy(),
-        error_code_re.replace(error.to_string().as_str(), ""),
+        format_io_error(&error),
     )
 }
 
+pub fn format_io_error(error: &dyn std::error::Error) -> String {
+    let s = error.to_string();
+    s.split(" (os error").next().unwrap_or(&s).to_string()
+}
+
 pub fn report_failure_to_read_input_file(
     executable: &OsString,
     filepath: &OsString,