From 6b6bd31ee5effa13bdd8710a00c6a9cf7eb534d8 Mon Sep 17 00:00:00 2001
From: Toggy Smith <git@toggysmith.com>
Date: Sat, 11 Jul 2026 15:56:37 +0100
Subject: [PATCH 1/2] fix: panics on redirect to /dev/full

This fixes several panics that would occur when the stdout was
redirected to /dev/full. This also introduces a new macro for
this purpose, named `safe_println!()`, that does not panic in
this situation, which can presumably be reused elsewhere this
issue may reoccur in the future.
---
 src/cmp.rs    |  3 ++-
 src/diff.rs   |  2 +-
 src/macros.rs | 12 ++++++++++++
 src/main.rs   |  8 ++++----
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/cmp.rs b/src/cmp.rs
index 0175466e..50a5325a 100644
--- a/src/cmp.rs
+++ b/src/cmp.rs
@@ -4,6 +4,7 @@
 // files that was distributed with this source code.
 
 use crate::utils::format_failure_to_read_input_file;
+use crate::safe_println;
 use std::env::{self, ArgsOs};
 use std::ffi::OsString;
 use std::io::{BufRead, BufReader, BufWriter, Read, Write};
@@ -721,7 +722,7 @@ fn report_difference(
             format_visible_byte(to_byte)
         );
     }
-    println!();
+    safe_println!();
 }
 
 #[cfg(test)]
diff --git a/src/diff.rs b/src/diff.rs
index f4c0614c..c0e5b8f5 100644
--- a/src/diff.rs
+++ b/src/diff.rs
@@ -91,7 +91,7 @@ pub fn main(opts: Peekable<ArgsOs>) -> ExitCode {
             params.to.to_string_lossy()
         );
     } else {
-        io::stdout().write_all(&result).unwrap();
+        let _ = io::stdout().write_all(&result);
     }
     if result.is_empty() {
         maybe_report_identical_files();
diff --git a/src/macros.rs b/src/macros.rs
index 90a4eaaf..18bef119 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -23,3 +23,15 @@ macro_rules! assert_diff_eq {
         assert_eq!(actual, $expected);
     }};
 }
+
+/// A safe version of println!() that does not panic if stdout is redirected to /dev/full
+#[macro_export]
+macro_rules! safe_println {
+    () => {
+        let _ = ::std::io::Write::write_all(&mut ::std::io::stdout(), b"\n");
+    };
+    ($($arg:tt)*) => {
+        let _ = ::std::io::Write::write_fmt(&mut ::std::io::stdout(), format_args!($($arg)*))
+            .and_then(|_| ::std::io::Write::write_all(&mut ::std::io::stdout(), b"\n"));
+    };
+}
diff --git a/src/main.rs b/src/main.rs
index d0adb692..13efd173 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -40,10 +40,10 @@ fn name(binary_path: &Path) -> &OsStr {
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 
 fn usage(name: &str) {
-    println!("{name} {VERSION} (multi-call binary)\n");
-    println!("Usage: {name} [function [arguments...]]\n");
-    println!("Currently defined functions:\n");
-    println!("    cmp, diff\n");
+    safe_println!("{name} {VERSION} (multi-call binary)\n");
+    safe_println!("Usage: {name} [function [arguments...]]\n");
+    safe_println!("Currently defined functions:\n");
+    safe_println!("    cmp, diff\n");
 }
 
 fn second_arg_error(name: &OsStr) -> ! {

From 6e4e3592ba9bbb0be6c856bdd061390d44f655de Mon Sep 17 00:00:00 2001
From: Toggy Smith <git@toggysmith.com>
Date: Sat, 11 Jul 2026 16:00:35 +0100
Subject: [PATCH 2/2] refactor: run cargo fmt

---
 src/cmp.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/cmp.rs b/src/cmp.rs
index 50a5325a..50c01632 100644
--- a/src/cmp.rs
+++ b/src/cmp.rs
@@ -3,8 +3,8 @@
 // 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::safe_println;
+use crate::utils::format_failure_to_read_input_file;
 use std::env::{self, ArgsOs};
 use std::ffi::OsString;
 use std::io::{BufRead, BufReader, BufWriter, Read, Write};