diff panics (broken-pipe unwrap) when its stdout is closed early

Bắt đầu với các lần ghi đầu ra được xác định trong src/diff.rs:94 và src/side_diff.rs:353-356, sau đó tái hiện cả trường hợp thông thường và trường hợp song song bằng các lệnh seq, sed và head được cung cấp. Xác minh rằng đầu ra vào pipe đã đóng không còn gây panic hoặc in ra lỗi, đồng thời cả hai chế độ đều kết thúc với trạng thái SIGPIPE mong đợi như GNU diff.

Summary

When diff's standard output is a pipe whose reader closes early (e.g. diff … | head), uutils diff aborts with a panic (exit 134, core dump)
instead of dying cleanly to SIGPIPE like GNU (exit 141). The output is written with a bare .unwrap() on the write_all/push_output result; the BrokenPipe error is unwrapped and, under panic="abort", aborts the process. This affects every output mode: the normal/context/unified/ed path writes the buffered result in src/diff.rs:94, and the side-by-side (-y) path writes each line in src/side_diff.rs:353-356.

Steps to reproduce

$ seq 1 100000 > b1; seq 1 100000 | sed 's/5/X/' > b2
$ diffutils diff b1 b2 | head -1
thread 'main' panicked at src/diff.rs:94:41:
called `Result::unwrap()` on an `Err` value: Os { code: 32, kind: BrokenPipe, message: "Broken pipe" }
$ echo "${PIPESTATUS[0]}"
134

Side-by-side mode hits the sibling site src/side_diff.rs:353:

$ diffutils diff -y b1 b2 | head -1
thread 'main' panicked at src/side_diff.rs:353:87:
called `Result::unwrap()` on an `Err` value: Os { code: 32, kind: BrokenPipe, message: "Broken pipe" }
$ echo "${PIPESTATUS[0]}"
134

Expected behavior

Match GNU: a closed output pipe terminates the program via SIGPIPE (exit 141) with no error message and no core dump.

$ /usr/bin/diff b1 b2 | head -1
1c1
$ echo "${PIPESTATUS[0]}"
141
$ /usr/bin/diff -y b1 b2 | head -1
1                            <      1
$ echo "${PIPESTATUS[0]}"
141

Root cause

The full diff output (normal/context/unified/ed) is buffered and written once:

// src/diff.rs:94
io::stdout().write_all(&result).unwrap();

Side-by-side writes each line straight to the locked stdout and unwraps every
write:

// src/side_diff.rs:353-356
push_output(...).unwrap();   // and the sibling unwraps at :354, :356

Any write_all/push_output error — BrokenPipe in the common pipe-closed case — is unwrapped and aborts.

Found by our static analysis tooling.