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pub(crate) fn get_timezone_inner() -> Result<String, crate::GetTimezoneError> {
get_timezone().ok_or(crate::GetTimezoneError::OsError)
}
#[inline]
fn get_timezone() -> Option<String> {
// The longest name in the IANA time zone database is 25 ASCII characters long.
const MAX_LEN: usize = 32;
let mut buf = [0; MAX_LEN];
// Get system time zone, and borrow its name.
let tz = system_time_zone::SystemTimeZone::new()?;
let name = tz.name()?;
// If the name is encoded in UTF-8, copy it directly.
let name = if let Some(name) = name.as_utf8() {
name
} else {
// Otherwise convert the name to UTF-8.
name.to_utf8(&mut buf)?
};
if name.is_empty() || name.len() >= MAX_LEN {
// The name should not be empty, or excessively long.
None
} else {
Some(name.to_owned())
}
}
mod system_time_zone {
//! create a safe wrapper around `CFTimeZoneRef`
use core_foundation_sys::base::{CFRelease, CFTypeRef};
use core_foundation_sys::timezone::{CFTimeZoneCopySystem, CFTimeZoneGetName, CFTimeZoneRef};
pub(crate) struct SystemTimeZone(CFTimeZoneRef);
impl Drop for SystemTimeZone {
fn drop(&mut self) {
// SAFETY: `SystemTimeZone` is only ever created with a valid `CFTimeZoneRef`.
unsafe { CFRelease(self.0 as CFTypeRef) };
}
}
impl SystemTimeZone {
pub(crate) fn new() -> Option<Self> {
// SAFETY: No invariants to uphold. We'll release the pointer when we don't need it anymore.
let v: CFTimeZoneRef = unsafe { CFTimeZoneCopySystem() };
if v.is_null() {
None
} else {
Some(SystemTimeZone(v))
}
}
/// Get the time zone name as a [super::string_ref::StringRef].
///
/// The lifetime of the `StringRef` is bound to our lifetime. Mutable
/// access is also prevented by taking a reference to `self`.
pub(crate) fn name(&self) -> Option<super::string_ref::StringRef<'_, Self>> {
// SAFETY: `SystemTimeZone` is only ever created with a valid `CFTimeZoneRef`.
let string = unsafe { CFTimeZoneGetName(self.0) };
if string.is_null() {
None
} else {
// SAFETY: here we ensure that `string` is a valid pointer.
Some(unsafe { super::string_ref::StringRef::new(string, self) })
}
}
}
}
mod string_ref {
//! create safe wrapper around `CFStringRef`
use std::convert::TryInto;
use core_foundation_sys::base::{Boolean, CFRange};
use core_foundation_sys::string::{
kCFStringEncodingUTF8, CFStringGetBytes, CFStringGetCStringPtr, CFStringGetLength,
CFStringRef,
};
pub(crate) struct StringRef<'a, T> {
string: CFStringRef,
// We exclude mutable access to the parent by taking a reference to the
// parent (rather than, for example, just using a marker to enforce the
// parent's lifetime).
_parent: &'a T,
}
impl<'a, T> StringRef<'a, T> {
// SAFETY: `StringRef` must be valid pointer
pub(crate) unsafe fn new(string: CFStringRef, _parent: &'a T) -> Self {
Self { string, _parent }
}
pub(crate) fn as_utf8(&self) -> Option<&'a str> {
// SAFETY: `StringRef` is only ever created with a valid `CFStringRef`.
let v = unsafe { CFStringGetCStringPtr(self.string, kCFStringEncodingUTF8) };
if !v.is_null() {
// SAFETY: `CFStringGetCStringPtr()` returns NUL-terminated strings.
let v = unsafe { std::ffi::CStr::from_ptr(v) };
if let Ok(v) = v.to_str() {
return Some(v);
}
}
None
}
pub(crate) fn to_utf8<'b>(&self, buf: &'b mut [u8]) -> Option<&'b str> {
// SAFETY: `StringRef` is only ever created with a valid `CFStringRef`.
let length = unsafe { CFStringGetLength(self.string) };
let mut buf_bytes = 0;
let range = CFRange {
location: 0,
length,
};
let converted_bytes = unsafe {
// SAFETY: `StringRef` is only ever created with a valid `CFStringRef`.
CFStringGetBytes(
self.string,
range,
kCFStringEncodingUTF8,
b'\0',
false as Boolean,
buf.as_mut_ptr(),
buf.len() as isize,
&mut buf_bytes,
)
};
if converted_bytes != length {
return None;
}
let len = buf_bytes.try_into().ok()?;
let s = buf.get(..len)?;
std::str::from_utf8(s).ok()
}
}
}