paste: handle list ending with unescaped backslash

src/uu/paste/src/paste.rs

@@ -12,7 +12,7 @@ use std::fmt::Display;
 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};
 use uucore::{format_usage, help_about, help_usage};
 
 const ABOUT: &str = help_about!("paste.md");
@@ -129,6 +129,16 @@ fn paste(
         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 mut delim_length = 1;
@@ -222,10 +232,8 @@ fn paste(
 }
 
 // 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('\\', "")
 }

tests/by-util/test_paste.rs

@@ -156,6 +156,37 @@ 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 {