Make ctime() return in expected formatting (#29)

This *should* be returning with local timezone, using `iana-time-zone` to determine that. However on my system it only ever returns UTC. That's probably a bug in iana-time-zone, or my system config, tho.

In any case the expected formatting seems to match:

;ctime()
=> "Sat Oct 07 17:23:43 2023 UTC"

Cargo.toml

@@ -77,6 +77,8 @@ pwhash = "1.0.0" # For MOO's hokey "crypt" function, which is unix's crypt(3) ba
 md5 = "0.7.0" # For MOO's "string_hash"
 rand = "0.8.5"
 onig = "6.4.0"
+chrono-tz = "0.8.3"
+iana-time-zone = "0.1.57"
 
 ## Compiler grammar/parser
 pest = "2.7.1"

crates/kernel/Cargo.toml

@@ -39,6 +39,8 @@ pwhash.workspace = true
 md5.workspace = true
 rand.workspace = true
 onig.workspace = true
+chrono-tz.workspace = true
+iana-time-zone.workspace = true
 
 ## Error declaration/ handling
 thiserror.workspace = true

crates/kernel/src/builtins/bf_server.rs

@@ -2,7 +2,9 @@ use std::sync::Arc;
 use std::time::{Duration, SystemTime};
 
 use async_trait::async_trait;
-use chrono::{DateTime, Local};
+use chrono::{DateTime, Local, TimeZone};
+use chrono_tz::{OffsetName, Tz};
+use iana_time_zone::get_timezone;
 use metrics_macros::increment_counter;
 use tokio::sync::oneshot;
 use tracing::{debug, error, info, warn};
@@ -298,8 +300,17 @@ async fn bf_ctime<'a>(bf_args: &mut BfCallState<'a>) -> Result<BfRet, Error> {
     };
 
     let date_time: DateTime<Local> = chrono::DateTime::from(time);
-
-    Ok(Ret(v_string(date_time.to_rfc2822())))
+    let tz_str = get_timezone().unwrap();
+    let tz: Tz = tz_str.parse().unwrap();
+    let offset = tz.offset_from_local_date(&date_time.date_naive()).unwrap();
+    let abbreviation = offset.abbreviation();
+    let datetime_str = format!(
+        "{} {}",
+        date_time.format("%a %b %d %H:%M:%S %Y"),
+        abbreviation
+    );
+
+    Ok(Ret(v_string(datetime_str.to_string())))
 }
 bf_declare!(ctime, bf_ctime);
 async fn bf_raise<'a>(bf_args: &mut BfCallState<'a>) -> Result<BfRet, Error> {