Use libc::UTIME_NOW in touch when updating time to now (#9870)

* Use libc::UTIME_NOW in touch when updating time to now

* Explicit libc import to satisfy clippy

* Fix location of cfg in touch

* Add cfg gate to libc import to satisfy clippy on windows

* Change cfg gates in touch near libc::UTIME_NOW from unix to linux

---------

Co-authored-by: Sylvestre Ledru <sylvestre@debian.org>

src/uu/touch/src/touch.rs

@@ -3,7 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore (ToDO) filetime datetime lpszfilepath mktime DATETIME datelike timelike
+// spell-checker:ignore (ToDO) filetime datetime lpszfilepath mktime DATETIME datelike timelike UTIME
 // spell-checker:ignore (FORMATS) MMDDhhmm YYYYMMDDHHMM YYMMDDHHMM YYYYMMDDHHMMS
 
 pub mod error;
@@ -23,6 +23,8 @@ use std::io::{Error, ErrorKind};
 use std::path::{Path, PathBuf};
 use uucore::display::Quotable;
 use uucore::error::{FromIo, UResult, USimpleError};
+#[cfg(target_os = "linux")]
+use uucore::libc;
 use uucore::parser::shortcut_value_parser::ShortcutValueParser;
 use uucore::translate;
 use uucore::{format_usage, show};
@@ -377,7 +379,19 @@ pub fn touch(files: &[InputFile], opts: &Options) -> Result<(), TouchError> {
             (atime, mtime)
         }
         Source::Now => {
-            let now = datetime_to_filetime(&Local::now());
+            let now: FileTime;
+            #[cfg(target_os = "linux")]
+            {
+                if opts.date.is_none() {
+                    now = FileTime::from_unix_time(0, libc::UTIME_NOW as u32);
+                } else {
+                    now = datetime_to_filetime(&Local::now());
+                }
+            }
+            #[cfg(not(target_os = "linux"))]
+            {
+                now = datetime_to_filetime(&Local::now());
+            }
             (now, now)
         }
         &Source::Timestamp(ts) => (ts, ts),

tests/by-util/test_touch.rs

@@ -1052,3 +1052,10 @@ fn test_touch_non_utf8_paths() {
     scene.ucmd().arg(non_utf8_name).succeeds().no_output();
     assert!(std::fs::metadata(at.plus(non_utf8_name)).is_ok());
 }
+
+#[test]
+#[cfg(target_os = "linux")]
+fn test_touch_dev_full() {
+    let (_, mut ucmd) = at_and_ucmd!();
+    ucmd.args(&["/dev/full"]).succeeds().no_output();
+}