Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 99 insertions, 0 deletions

diff --git a/third_party/rust/time/src/util.rs b/third_party/rust/time/src/util.rs
new file mode 100644
index 0000000000..857f5f20b0
--- /dev/null
+++ b/third_party/rust/time/src/util.rs
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+//! Utility functions.
+
+pub use time_core::util::{days_in_year, is_leap_year, weeks_in_year};
+
+use crate::Month;
+
+/// Whether to adjust the date, and in which direction. Useful when implementing arithmetic.
+pub(crate) enum DateAdjustment {
+    /// The previous day should be used.
+    Previous,
+    /// The next day should be used.
+    Next,
+    /// The date should be used as-is.
+    None,
+}
+
+/// Get the number of days in the month of a given year.
+///
+/// ```rust
+/// # use time::{Month, util};
+/// assert_eq!(util::days_in_year_month(2020, Month::February), 29);
+/// ```
+pub const fn days_in_year_month(year: i32, month: Month) -> u8 {
+    use Month::*;
+    match month {
+        January | March | May | July | August | October | December => 31,
+        April | June | September | November => 30,
+        February if is_leap_year(year) => 29,
+        February => 28,
+    }
+}
+
+#[cfg(feature = "local-offset")]
+/// Utility functions relating to the local UTC offset.
+pub mod local_offset {
+    use core::sync::atomic::{AtomicBool, Ordering};
+
+    /// Whether obtaining the local UTC offset is required to be sound.
+    static LOCAL_OFFSET_IS_SOUND: AtomicBool = AtomicBool::new(true);
+
+    /// The soundness of obtaining the local UTC offset.
+    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    pub enum Soundness {
+        /// Obtaining the local UTC offset is required to be sound. Undefined behavior will never
+        /// occur. This is the default.
+        Sound,
+        /// Obtaining the local UTC offset is allowed to invoke undefined behavior. **Setting this
+        /// value is strongly discouraged.** To do so, you must comply with the safety requirements
+        /// of [`time::local_offset::set_soundness`](set_soundness).
+        Unsound,
+    }
+
+    /// Set whether obtaining the local UTC offset is allowed to invoke undefined behavior. **Use of
+    /// this function is heavily discouraged.**
+    ///
+    /// # Safety
+    ///
+    /// If this method is called with [`Soundness::Sound`], the call is always sound. If this method
+    /// is called with [`Soundness::Unsound`], the following conditions apply.
+    ///
+    /// - If the operating system provides a thread-safe environment, the call is sound.
+    /// - If the process is single-threaded, the call is sound.
+    /// - If the process is multi-threaded, no other thread may mutate the environment in any way at
+    ///   the same time a call to a method that obtains the local UTC offset. This includes adding,
+    ///   removing, or modifying an environment variable.
+    ///
+    /// The first two conditions are automatically checked by `time`, such that you do not need to
+    /// declare your code unsound. Currently, the only known operating systems that does _not_
+    /// provide a thread-safe environment are some Unix-like OS's. All other operating systems
+    /// should succeed when attempting to obtain the local UTC offset.
+    ///
+    /// Note that you must not only verify this safety condition for your code, but for **all** code
+    /// that will be included in the final binary. Notably, it applies to both direct and transitive
+    /// dependencies and to both Rust and non-Rust code. **For this reason it is not possible to
+    /// soundly pass [`Soundness::Unsound`] to this method if you are writing a library that may
+    /// used by others.**
+    ///
+    /// If using this method is absolutely necessary, it is recommended to keep the time between
+    /// setting the soundness to [`Soundness::Unsound`] and setting it back to [`Soundness::Sound`]
+    /// as short as possible.
+    ///
+    /// The following methods currently obtain the local UTC offset:
+    ///
+    /// - [`OffsetDateTime::now_local`](crate::OffsetDateTime::now_local)
+    /// - [`UtcOffset::local_offset_at`](crate::UtcOffset::local_offset_at)
+    /// - [`UtcOffset::current_local_offset`](crate::UtcOffset::current_local_offset)
+    pub unsafe fn set_soundness(soundness: Soundness) {
+        LOCAL_OFFSET_IS_SOUND.store(soundness == Soundness::Sound, Ordering::SeqCst);
+    }
+
+    /// Obtains the soundness of obtaining the local UTC offset. If it is [`Soundness::Unsound`],
+    /// it is allowed to invoke undefined behavior when obtaining the local UTC offset.
+    pub fn get_soundness() -> Soundness {
+        match LOCAL_OFFSET_IS_SOUND.load(Ordering::SeqCst) {
+            false => Soundness::Unsound,
+            true => Soundness::Sound,
+        }
+    }
+}