From fe207640e24b25ec3cade4384da8b156265418b2 Mon Sep 17 00:00:00 2001
From: Aleksandar Janicijevic <ajanicij@yahoo.com>
Date: Sat, 17 Apr 2021 04:08:10 -0400
Subject: [PATCH] touch: dealing with DST in touch -m -t (#2073)

---
 src/uu/touch/src/touch.rs   | 23 ++++++++++++++++++++++-
 tests/by-util/test_touch.rs | 19 +++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/uu/touch/src/touch.rs b/src/uu/touch/src/touch.rs
index f0c3c12d2..b158fdc0e 100644
--- a/src/uu/touch/src/touch.rs
+++ b/src/uu/touch/src/touch.rs
@@ -18,6 +18,7 @@ use filetime::*;
 use std::fs::{self, File};
 use std::io::Error;
 use std::path::Path;
+use std::process;
 
 static VERSION: &str = env!("CARGO_PKG_VERSION");
 static ABOUT: &str = "Update the access and modification times of each FILE to the current time.";
@@ -261,7 +262,27 @@ fn parse_timestamp(s: &str) -> FileTime {
     };
 
     match time::strptime(&ts, format) {
-        Ok(tm) => local_tm_to_filetime(to_local(tm)),
+        Ok(tm) => {
+            let mut local = to_local(tm);
+            local.tm_isdst = -1;
+            let ft = local_tm_to_filetime(local);
+
+            // We have to check that ft is valid time. Due to daylight saving
+            // time switch, local time can jump from 1:59 AM to 3:00 AM,
+            // in which case any time between 2:00 AM and 2:59 AM is not valid.
+            // Convert back to local time and see if we got the same value back.
+            let ts = time::Timespec {
+                sec: ft.unix_seconds(),
+                nsec: 0,
+            };
+            let tm2 = time::at(ts);
+            if tm.tm_hour != tm2.tm_hour {
+                show_error!("invalid date format {}", s);
+                process::exit(1);
+            }
+
+            ft
+        }
         Err(e) => panic!("Unable to parse timestamp\n{}", e),
     }
 }
diff --git a/tests/by-util/test_touch.rs b/tests/by-util/test_touch.rs
index 9921c16b5..9f2c079b0 100644
--- a/tests/by-util/test_touch.rs
+++ b/tests/by-util/test_touch.rs
@@ -29,6 +29,7 @@ fn set_file_times(at: &AtPath, path: &str, atime: FileTime, mtime: FileTime) {
 fn str_to_filetime(format: &str, s: &str) -> FileTime {
     let mut tm = time::strptime(s, format).unwrap();
     tm.tm_utcoff = time::now().tm_utcoff;
+    tm.tm_isdst = -1; // Unknown flag DST
     let ts = tm.to_timespec();
     FileTime::from_unix_time(ts.sec as i64, ts.nsec as u32)
 }
@@ -352,3 +353,21 @@ fn test_touch_set_date() {
     assert_eq!(atime, start_of_year);
     assert_eq!(mtime, start_of_year);
 }
+
+#[test]
+fn test_touch_mtime_dst_succeeds() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let file = "test_touch_set_mtime_dst_succeeds";
+
+    ucmd.args(&["-m", "-t", "202103140300", file])
+        .succeeds()
+        .no_stderr();
+
+    assert!(at.file_exists(file));
+
+    let target_time = str_to_filetime("%Y%m%d%H%M", "202103140300");
+    let (_, mtime) = get_file_times(&at, file);
+    eprintln!("target_time: {:?}", target_time);
+    eprintln!("mtime: {:?}", mtime);
+    assert!(target_time == mtime);
+}