From 4fb4511da39b460c145eff58b8e1b9dfa73382b0 Mon Sep 17 00:00:00 2001
From: Hanif Bin Ariffin <hanif.ariffin.4326@gmail.com>
Date: Thu, 29 Jul 2021 21:59:30 +0800
Subject: [PATCH] Fixed empty backslash

Signed-off-by: Hanif Bin Ariffin <hanif.ariffin.4326@gmail.com>
---
 src/uu/tr/src/operation.rs | 15 +++++++++++++--
 src/uu/tr/src/tr.rs        |  8 ++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/uu/tr/src/operation.rs b/src/uu/tr/src/operation.rs
index 595dcc529..660ab4883 100644
--- a/src/uu/tr/src/operation.rs
+++ b/src/uu/tr/src/operation.rs
@@ -235,9 +235,20 @@ impl Sequence {
             (
                 l,
                 if let Some(input) = a.strip_prefix('\\') {
-                    char::from_u32(u32::from_str_radix(&input, 8).unwrap()).unwrap()
+                    if input.is_empty() {
+                        '\\'
+                    } else {
+                        char::from_u32(
+                            u32::from_str_radix(&input, 8)
+                                .expect("We only matched against 0-7 so it should not fail"),
+                        )
+                        .expect("Cannot convert octal value to character")
+                    }
                 } else {
-                    input.chars().next().unwrap()
+                    input
+                        .chars()
+                        .next()
+                        .expect("We recognized a character so this should not fail")
                 },
             )
         })
diff --git a/src/uu/tr/src/tr.rs b/src/uu/tr/src/tr.rs
index 99d7b5132..eb02eb962 100644
--- a/src/uu/tr/src/tr.rs
+++ b/src/uu/tr/src/tr.rs
@@ -112,6 +112,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             return 1;
         }
     };
+
+    if set2.len() == 1 && set2[0] == '\\' {
+        show_error!(
+            "{}",
+            "warning: an unescaped backslash at end of string is not portable"
+        );
+    }
+
     if delete_flag {
         if squeeze_flag {
             let mut delete_buffer = vec![];