From 985b4848e69a4354a3c449f8bd08df0243c89a93 Mon Sep 17 00:00:00 2001
From: Devel <Denislav08@proton.me>
Date: Mon, 27 Jul 2026 02:38:28 +0300
Subject: [PATCH 1/4] truncate: check if there's a number after the
 positive/negative sign in -s flag

---
 src/uu/truncate/src/truncate.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/uu/truncate/src/truncate.rs b/src/uu/truncate/src/truncate.rs
index bdb2af011ab..5951dba7d8e 100644
--- a/src/uu/truncate/src/truncate.rs
+++ b/src/uu/truncate/src/truncate.rs
@@ -360,6 +360,13 @@ fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ParseSizeError
     // Get the modifier character from the size string, if any. For
     // example, if the argument is "+123", then the modifier is '+'.
     if let Some(c) = size_string.chars().next() {
+        // Check if there's a non-numerical string after the positive/negative sign
+        if (size_string.starts_with('+') || size_string.starts_with('-'))
+            && !size_string.chars().nth(1).unwrap_or(c).is_ascii_digit()
+        {
+            return Err(ParseSizeError::ParseFailure(format!("'{size_string}'")));
+        }
+
         if is_modifier(c) {
             size_string = &size_string[1..];
         }
@@ -378,6 +385,9 @@ fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ParseSizeError
                 _ => TruncateMode::Absolute,
             })
     } else {
+        if size_string.is_empty() {
+            return Err(ParseSizeError::ParseFailure("''".to_string()));
+        }
         Err(ParseSizeError::ParseFailure(size_string.to_string()))
     }
 }

From a15703aa5fafcaff904bd5445f0eaf01cf89bb93 Mon Sep 17 00:00:00 2001
From: Devel <Denislav08@proton.me>
Date: Mon, 27 Jul 2026 02:47:34 +0300
Subject: [PATCH 2/4] test_truncate: add test_empty_size and
 test_sign_as_a_size

---
 tests/by-util/test_truncate.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tests/by-util/test_truncate.rs b/tests/by-util/test_truncate.rs
index d44723c36b6..743c6271823 100644
--- a/tests/by-util/test_truncate.rs
+++ b/tests/by-util/test_truncate.rs
@@ -491,3 +491,19 @@ fn test_truncate_non_utf8_paths() {
     // Test that truncate can handle non-UTF-8 filenames
     ts.ucmd().arg("-s").arg("10").arg(file_name).succeeds();
 }
+
+#[test]
+fn test_empty_size() {
+    new_ucmd!()
+        .args(&["-s", "", "asd"])
+        .fails()
+        .stderr_is("truncate: Invalid number: ''\n");
+}
+
+#[test]
+fn test_sign_as_a_size() {
+    new_ucmd!()
+        .args(&["-s", "+", "asd"])
+        .fails()
+        .stderr_is("truncate: Invalid number: '+'\n");
+}

From b79dfdbed53ee2b612b5c52c2730bcc6ff032f66 Mon Sep 17 00:00:00 2001
From: Devel <Denislav08@proton.me>
Date: Mon, 27 Jul 2026 16:19:48 +0300
Subject: [PATCH 3/4] truncate: simplify empty argument and negative/postive
 sign checks

---
 src/uu/truncate/src/truncate.rs | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/uu/truncate/src/truncate.rs b/src/uu/truncate/src/truncate.rs
index 5951dba7d8e..7db36a887d3 100644
--- a/src/uu/truncate/src/truncate.rs
+++ b/src/uu/truncate/src/truncate.rs
@@ -361,9 +361,7 @@ fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ParseSizeError
     // example, if the argument is "+123", then the modifier is '+'.
     if let Some(c) = size_string.chars().next() {
         // Check if there's a non-numerical string after the positive/negative sign
-        if (size_string.starts_with('+') || size_string.starts_with('-'))
-            && !size_string.chars().nth(1).unwrap_or(c).is_ascii_digit()
-        {
+        if (matches!(c, '+' | '-')) && !size_string.chars().nth(1).unwrap_or(c).is_ascii_digit() {
             return Err(ParseSizeError::ParseFailure(format!("'{size_string}'")));
         }
 
@@ -385,10 +383,7 @@ fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ParseSizeError
                 _ => TruncateMode::Absolute,
             })
     } else {
-        if size_string.is_empty() {
-            return Err(ParseSizeError::ParseFailure("''".to_string()));
-        }
-        Err(ParseSizeError::ParseFailure(size_string.to_string()))
+        Err(ParseSizeError::ParseFailure("''".to_string()));
     }
 }
 

From e6ce4e64f6e7037479589d8388ac0fa6ab025f6a Mon Sep 17 00:00:00 2001
From: Devel <Denislav08@proton.me>
Date: Mon, 27 Jul 2026 16:21:50 +0300
Subject: [PATCH 4/4] typo

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

diff --git a/src/uu/truncate/src/truncate.rs b/src/uu/truncate/src/truncate.rs
index 7db36a887d3..6e28c0108f8 100644
--- a/src/uu/truncate/src/truncate.rs
+++ b/src/uu/truncate/src/truncate.rs
@@ -383,7 +383,7 @@ fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ParseSizeError
                 _ => TruncateMode::Absolute,
             })
     } else {
-        Err(ParseSizeError::ParseFailure("''".to_string()));
+        Err(ParseSizeError::ParseFailure("''".to_string()))
     }
 }