From d4ccc5e1d71bf8e031288e595af10d75e4798212 Mon Sep 17 00:00:00 2001
From: Daniel Hofstetter <daniel.hofstetter@42dh.com>
Date: Wed, 22 Jun 2022 09:37:16 +0200
Subject: [PATCH] paste: handle list ending with unescaped backslash

---
 src/uu/paste/src/paste.rs   | 14 +++++++++++---
 tests/by-util/test_paste.rs | 31 +++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/src/uu/paste/src/paste.rs b/src/uu/paste/src/paste.rs
index 682e66a5da9..bd9f0a10f81 100644
--- a/src/uu/paste/src/paste.rs
+++ b/src/uu/paste/src/paste.rs
@@ -11,7 +11,7 @@ use clap::{crate_version, Arg, Command};
 use std::fs::File;
 use std::io::{stdin, stdout, BufRead, BufReader, Read, Write};
 use std::path::Path;
-use uucore::error::{FromIo, UResult};
+use uucore::error::{FromIo, UResult, USimpleError};
 
 static ABOUT: &str = "Write lines consisting of the sequentially corresponding lines from each
 FILE, separated by TABs, to standard output.";
@@ -89,6 +89,16 @@ fn paste(filenames: Vec<String>, serial: bool, delimiters: &str) -> UResult<()>
         files.push(file);
     }
 
+    if delimiters.ends_with('\\') && !delimiters.ends_with("\\\\") {
+        return Err(USimpleError::new(
+            1,
+            format!(
+                "delimiter list ends with an unescaped backslash: {}",
+                delimiters
+            ),
+        ));
+    }
+
     let delimiters: Vec<char> = unescape(delimiters).chars().collect();
     let mut delim_count = 0;
     let stdout = stdout();
@@ -152,10 +162,8 @@ fn paste(filenames: Vec<String>, serial: bool, delimiters: &str) -> UResult<()>
 }
 
 // Unescape all special characters
-// TODO: this will need work to conform to GNU implementation
 fn unescape(s: &str) -> String {
     s.replace("\\n", "\n")
         .replace("\\t", "\t")
         .replace("\\\\", "\\")
-        .replace('\\', "")
 }
diff --git a/tests/by-util/test_paste.rs b/tests/by-util/test_paste.rs
index 6d539e45e52..0da730982e2 100644
--- a/tests/by-util/test_paste.rs
+++ b/tests/by-util/test_paste.rs
@@ -103,6 +103,37 @@ fn test_multi_stdin() {
     }
 }
 
+#[test]
+fn test_delimiter_list_ending_with_escaped_backslash() {
+    for d in ["-d", "--delimiters"] {
+        let (at, mut ucmd) = at_and_ucmd!();
+        let mut ins = vec![];
+        for (i, _in) in ["a\n", "b\n"].iter().enumerate() {
+            let file = format!("in{}", i);
+            at.write(&file, _in);
+            ins.push(file);
+        }
+        ucmd.args(&[d, "\\\\"])
+            .args(&ins)
+            .succeeds()
+            .stdout_is("a\\b\n");
+    }
+}
+
+#[test]
+fn test_delimiter_list_ending_with_unescaped_backslash() {
+    for d in ["-d", "--delimiters"] {
+        new_ucmd!()
+            .args(&[d, "\\"])
+            .fails()
+            .stderr_contains("delimiter list ends with an unescaped backslash: \\");
+        new_ucmd!()
+            .args(&[d, "_\\"])
+            .fails()
+            .stderr_contains("delimiter list ends with an unescaped backslash: _\\");
+    }
+}
+
 #[test]
 fn test_data() {
     for example in EXAMPLE_DATA {