feat: Add timezone host functions.

Allow clocks-timezone feature to be enabled.

Author: cdmurph32

Cargo.lock

@@ -413,6 +413,8 @@ itertools = "0.14.0"
 base64 = "0.22.1"
 termcolor = "1.4.1"
 flate2 = "1.0.30"
+chrono = "0.4.26"
+chrono-tz = "0.8.3"
 
 # =============================================================================
 #

Cargo.toml

@@ -420,6 +420,8 @@ wasmtime_option_group! {
         pub cli: Option<bool>,
         /// Enable WASI APIs marked as: @unstable(feature = cli-exit-with-code)
         pub cli_exit_with_code: Option<bool>,
+        /// Enable WASI APIs marked as: @unstable(feature = clocks-timezone)
+        pub clocks_timezone: Option<bool>,
         /// Deprecated alias for `cli`
         pub common: Option<bool>,
         /// Enable support for WASI neural network imports (experimental)

crates/cli-flags/src/lib.rs

@@ -1,3 +1,5 @@
+use test_programs::wasi::clocks::{timezone, wall_clock};
+
 fn main() {
     let a = std::time::Instant::now();
     let b = std::time::Instant::now();
@@ -7,4 +9,7 @@ fn main() {
     let d = std::time::SystemTime::now();
     let _ = c.duration_since(std::time::UNIX_EPOCH).unwrap();
     let _ = d.duration_since(std::time::UNIX_EPOCH).unwrap();
+
+    let wall_time = wall_clock::now();
+    let _ = timezone::display(wall_time);
 }

crates/test-programs/src/bin/cli_default_clocks.rs

@@ -25,7 +25,7 @@ wit_bindgen::generate!({
         "../wasi-tls/wit/deps/tls",
     ],
     world: "wasmtime:test/test",
-    features: ["cli-exit-with-code", "tls"],
+    features: ["cli-exit-with-code", "tls", "clocks-timezone"],
     generate_all,
 });
 
@@ -48,6 +48,7 @@ pub mod proxy {
             "wasi:clocks/[email protected]": crate::wasi::clocks::monotonic_clock,
             "wasi:clocks/[email protected]": crate::wasi::clocks::wall_clock,
         },
+        features: ["clocks-timezone"],
     });
 }
 

crates/test-programs/src/lib.rs

@@ -67,6 +67,7 @@ pub mod bindings {
             "poll",
             "[method]outgoing-datagram-stream.send",
         ],
+        features: ["clocks-timezone"],
         generate_all,
         disable_custom_section_link_helpers: true,
     });
@@ -90,6 +91,7 @@ pub mod bindings {
         ],
         generate_all,
         disable_custom_section_link_helpers: true,
+        features: ["clocks-timezone"],
     });
 
     #[cfg(feature = "proxy")]
@@ -111,6 +113,7 @@ pub mod bindings {
         raw_strings,
         runtime_path: "crate::bindings::wit_bindgen_rt_shim",
         skip: ["poll", "[method]outgoing-datagram-stream.send"],
+        features: ["clocks-timezone"],
         generate_all,
         disable_custom_section_link_helpers: true,
     });

crates/wasi-preview1-component-adapter/src/lib.rs

@@ -29,6 +29,8 @@ cap-rand = { workspace = true }
 cap-fs-ext = { workspace = true }
 cap-net-ext = { workspace = true }
 cap-time-ext = { workspace = true }
+chrono = { workspace = true }
+chrono-tz = { workspace = true }
 io-lifetimes = { workspace = true }
 fs-set-times = { workspace = true }
 bitflags = { workspace = true }

crates/wasi/Cargo.toml

@@ -1,6 +1,9 @@
+use crate::p2::bindings::clocks::timezone::TimezoneDisplay;
 use cap_std::time::{Duration, Instant, SystemClock, SystemTime};
 use cap_std::{AmbientAuthority, ambient_authority};
 use cap_time_ext::{MonotonicClockExt as _, SystemClockExt as _};
+use chrono::{DateTime, TimeZone};
+use chrono_tz::{OffsetComponents, TZ_VARIANTS, Tz};
 use wasmtime::component::{HasData, ResourceTable};
 
 pub(crate) struct WasiClocks;
@@ -12,13 +15,15 @@ impl HasData for WasiClocks {
 pub struct WasiClocksCtx {
     pub wall_clock: Box<dyn HostWallClock + Send>,
     pub monotonic_clock: Box<dyn HostMonotonicClock + Send>,
+    pub timezone: Box<dyn HostTimezone + Send>,
 }
 
 impl Default for WasiClocksCtx {
     fn default() -> Self {
         Self {
             wall_clock: wall_clock(),
             monotonic_clock: monotonic_clock(),
+            timezone: timezone(),
         }
     }
 }
@@ -42,6 +47,11 @@ pub trait HostMonotonicClock: Send {
     fn now(&self) -> u64;
 }
 
+pub trait HostTimezone: Send {
+    fn display(&self, datetime: Duration) -> TimezoneDisplay;
+    fn utc_offset(&self, datetime: Duration) -> i32;
+}
+
 pub struct WallClock {
     /// The underlying system clock.
     clock: cap_std::time::SystemClock,
@@ -123,6 +133,10 @@ pub fn wall_clock() -> Box<dyn HostWallClock + Send> {
     Box::new(WallClock::default())
 }
 
+pub fn timezone() -> Box<dyn HostTimezone + Send> {
+    Box::new(Timezone::default())
+}
+
 pub(crate) struct Datetime {
     pub seconds: u64,
     pub nanoseconds: u32,
@@ -141,3 +155,56 @@ impl TryFrom<SystemTime> for Datetime {
         })
     }
 }
+
+pub struct Timezone {
+    // The underlying system timezone.
+    timezone: cap_time_ext::Timezone,
+}
+
+impl Default for Timezone {
+    fn default() -> Self {
+        Self::new(ambient_authority())
+    }
+}
+
+impl Timezone {
+    pub fn new(ambient_authority: AmbientAuthority) -> Self {
+        Self {
+            timezone: cap_time_ext::Timezone::new(ambient_authority),
+        }
+    }
+
+    fn timezone_from_duration(&self, datetime: Duration) -> Option<TimezoneDisplay> {
+        let name = self.timezone.timezone_name().ok()?;
+        let tz: Tz = TZ_VARIANTS.into_iter().find(|tz| tz.to_string() == name)?;
+        let naive_datetime = DateTime::from_timestamp(datetime.as_secs() as i64, 0)?.naive_utc();
+        let tz_offset = tz.offset_from_local_datetime(&naive_datetime).single()?;
+        let utc_offset = tz_offset.base_utc_offset().num_hours() as i32;
+        let in_daylight_saving_time = !tz_offset.dst_offset().is_zero();
+        Some(TimezoneDisplay {
+            utc_offset,
+            name,
+            in_daylight_saving_time,
+        })
+    }
+}
+
+impl HostTimezone for Timezone {
+    fn display(&self, datetime: Duration) -> TimezoneDisplay {
+        match self.timezone_from_duration(datetime) {
+            None => TimezoneDisplay {
+                utc_offset: 0,
+                name: "UTC".to_string(),
+                in_daylight_saving_time: false,
+            },
+            Some(timezone_display) => timezone_display,
+        }
+    }
+
+    fn utc_offset(&self, datetime: Duration) -> i32 {
+        match self.timezone_from_duration(datetime) {
+            None => 0,
+            Some(timezone_display) => timezone_display.utc_offset,
+        }
+    }
+}

crates/wasi/src/clocks.rs

@@ -1,5 +1,5 @@
 use crate::cli::{StdinStream, StdoutStream, WasiCliCtx};
-use crate::clocks::{HostMonotonicClock, HostWallClock, WasiClocksCtx};
+use crate::clocks::{HostMonotonicClock, HostTimezone, HostWallClock, WasiClocksCtx};
 use crate::filesystem::{Dir, WasiFilesystemCtx};
 use crate::random::WasiRandomCtx;
 use crate::sockets::{SocketAddrCheck, SocketAddrUse, WasiSocketsCtx};
@@ -366,6 +366,14 @@ impl WasiCtxBuilder {
         self
     }
 
+    /// Configures `wasi:clocks/timezone` to use the `clock` specified.
+    ///
+    /// By default the host's timezone is used.
+    pub fn timezone(&mut self, clock: impl HostTimezone + 'static) -> &mut Self {
+        self.clocks.timezone = Box::new(clock);
+        self
+    }
+
     /// Allow all network addresses accessible to the host.
     ///
     /// This method will inherit all network addresses meaning that any address

crates/wasi/src/ctx.rs

@@ -32,7 +32,7 @@ pub mod runtime;
 pub mod sockets;
 mod view;
 
-pub use self::clocks::{HostMonotonicClock, HostWallClock};
+pub use self::clocks::{HostMonotonicClock, HostTimezone, HostWallClock};
 pub use self::ctx::{WasiCtx, WasiCtxBuilder};
 pub use self::error::{I32Exit, TrappableError};
 pub use self::filesystem::{DirPerms, FilePerms, OpenMode};