touch -d with relative day is ahead of its time

[ysthakur]

By a day, to be exact, but only sometimes. I looked at the tests for touch and none of them seem to make sure that stuff like -d yesterday has the right output, which is why this hasn't been detected yet, I guess.

The shell I'm using is Nushell, but I can reproduce in Zsh. OS is Ubuntu (WSL).

I ran touch -d yesterday at around 10:40 pm ET, both the uutils one and the GNU one. The GNU one correctly set the file's times to yesterday, but the uutils one set the file's times to the current time.

> cargo run -p uu_touch -- -d yesterday testing/foo
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.07s
     Running `target/debug/touch -d yesterday testing/foo`
> ^touch -d yesterday testing/bar
> ls -al testing | select name accessed modified
╭─#─┬────name─────┬────accessed────┬────modified────╮
│ 0 │ testing/foo │ 13 seconds ago │ 13 seconds ago │
│ 1 │ testing/bar │ a day ago      │ a day ago      │
╰───┴─────────────┴────────────────┴────────────────╯

Curiously enough, when I ran it at around 5:47 pm ET, I couldn't reproduce it:

> cargo run -p uu_touch -- -d yesterday testing/foo
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.09s
     Running `target/debug/touch -d yesterday testing/foo`
> ^touch -d yesterday testing/bar
> ls -al testing | select name accessed modified
╭─#─┬────name─────┬─accessed──┬─modified──╮
│ 0 │ testing/foo │ a day ago │ a day ago │
│ 1 │ testing/bar │ a day ago │ a day ago │
╰───┴─────────────┴───────────┴───────────╯

-d "1 month ago" also had the same problem when I ran it at around 5:50 pm ET.

> cargo run -p uu_touch -- -d "1 month ago" testing/foo
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.09s
     Running `target/debug/touch -d '1 month ago' testing/foo`
> (ls -al testing/foo).0.accessed
Wed, 10 Jul 2024 17:49:09 -0400 (a month ago)
> ^touch -d "1 month ago" testing/bar
> (ls -al testing/bar).0.accessed
Tue, 9 Jul 2024 17:49:31 -0400 (a month ago)

But when I ran it at around 10:45 pm ET, I couldn't reproduce the problem with -d "1 month ago":

> cargo run -p uu_touch -- -d "1 month ago" testing/foo
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.08s
     Running `target/debug/touch -d '1 month ago' testing/foo`
> ^touch -d "1 month ago" testing/bar
> ls -al testing | select name accessed modified
╭─#─┬────name─────┬──accessed───┬──modified───╮
│ 0 │ testing/foo │ a month ago │ a month ago │
│ 1 │ testing/bar │ a month ago │ a month ago │
╰───┴─────────────┴─────────────┴─────────────╯

I suspect that this is a problem with using DateTime<Local>s or something. The -d yesterday bug happened when I ran it after UTC midnight but before my local midnight. It didn't happen when I ran it after my local midnight but before UTC midnight. The -d "1 month ago" behavior was the opposite. Perhaps if uutils uses DateTime<Utc>, that'll help?

[ysthakur]

Update: I mentioned this in Discord but the problem with "+1 month", at least, appears to be a bug in the parse_datetime crate. When you pass in a relative time with months, parse_relative_time_at_date creates a Duration object assuming that each month is 30 days (https://github.com/uutils/parse_datetime/blob/main/src/parse_relative_time.rs#L109). This causes problems when a month isn't 30 days.

I don't know why exactly "yesterday" doesn't work properly either, but maybe it's a similar problem.