From 129cfe12b826377a5eeb24577c492bcb0da02033 Mon Sep 17 00:00:00 2001
From: Jeffrey Finkelstein <jeffrey.finkelstein@protonmail.com>
Date: Sun, 23 Jan 2022 11:14:48 -0500
Subject: [PATCH] truncate: create non-existent file by default

Fix the behavior of truncate when given a non-existent file so that it
correctly creates the file before truncating it (unless the
`--no-create` option is also given).
---
 src/uu/truncate/src/truncate.rs | 13 ++++++++++---
 tests/by-util/test_truncate.rs  | 25 +++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/uu/truncate/src/truncate.rs b/src/uu/truncate/src/truncate.rs
index d9ffb31f7..b615cf495 100644
--- a/src/uu/truncate/src/truncate.rs
+++ b/src/uu/truncate/src/truncate.rs
@@ -278,9 +278,16 @@ fn truncate_size_only(
         Err(e) => crash!(1, "Invalid number: {}", e.to_string()),
     };
     for filename in &filenames {
-        let fsize = usize::try_from(metadata(filename)?.len()).unwrap();
-        let tsize = mode.to_size(fsize);
-        file_truncate(filename, create, tsize)?;
+        let fsize = match metadata(filename) {
+            Ok(m) => m.len(),
+            Err(_) => 0,
+        };
+        let tsize = mode.to_size(fsize as usize);
+        match file_truncate(filename, create, tsize) {
+            Ok(_) => continue,
+            Err(e) if e.kind() == ErrorKind::NotFound && !create => continue,
+            Err(e) => return Err(e),
+        }
     }
     Ok(())
 }
diff --git a/tests/by-util/test_truncate.rs b/tests/by-util/test_truncate.rs
index 4b2e9e502..bb76e8b94 100644
--- a/tests/by-util/test_truncate.rs
+++ b/tests/by-util/test_truncate.rs
@@ -321,3 +321,28 @@ fn test_truncate_bytes_size() {
         }
     }
 }
+
+/// Test that truncating a non-existent file creates that file.
+#[test]
+fn test_new_file() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let filename = "new_file_that_does_not_exist_yet";
+    ucmd.args(&["-s", "8", filename])
+        .succeeds()
+        .no_stdout()
+        .no_stderr();
+    assert!(at.file_exists(filename));
+    assert_eq!(at.read_bytes(filename), vec![b'\0'; 8]);
+}
+
+/// Test for not creating a non-existent file.
+#[test]
+fn test_new_file_no_create() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let filename = "new_file_that_does_not_exist_yet";
+    ucmd.args(&["-s", "8", "-c", filename])
+        .succeeds()
+        .no_stdout()
+        .no_stderr();
+    assert!(!at.file_exists(filename));
+}