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Use core-foundation-sys instead of core-foundation #50

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merged 1 commit into from Aug 11, 2022
Merged

Use core-foundation-sys instead of core-foundation #50

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2 changes: 1 addition & 1 deletion Cargo.toml
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Expand Up @@ -18,7 +18,7 @@ fallback = []
android_system_properties = "0.1.4"

[target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
core-foundation = "0.9"
core-foundation-sys = "0.8.3"

[target.'cfg(target_os = "windows")'.dependencies]
winapi = { version = "0.3.9", features = ["activation", "combaseapi", "objbase", "roapi", "winerror", "winstring"] }
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42 changes: 39 additions & 3 deletions src/tz_macos.rs
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@@ -1,5 +1,41 @@
use core_foundation_sys::base::{CFRelease, CFTypeRef};
use core_foundation_sys::string::{kCFStringEncodingUTF8, CFStringGetCStringPtr};
use core_foundation_sys::timezone::{CFTimeZoneCopySystem, CFTimeZoneGetName};

pub(crate) fn get_timezone_inner() -> Result<String, crate::GetTimezoneError> {
Ok(core_foundation::timezone::CFTimeZone::system()
.name()
.to_string())
unsafe {
Dropping::new(CFTimeZoneCopySystem())
.and_then(|tz| Dropping::new(CFTimeZoneGetName(tz.0)))
.and_then(|name| {
let name = CFStringGetCStringPtr(name.0, kCFStringEncodingUTF8);
if name.is_null() {
None
} else {
Some(name)
}
})
.and_then(|name| std::ffi::CStr::from_ptr(name).to_str().ok())
.map(|name| name.to_owned())
Comment on lines +17 to +18
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This bit makes me a bit scared with the Dropping type and the CStr being dropped while a borrowed &str is taken from name. Is the .map(|name| name.to_owned()) a use after free?

To be sure, I'd probably restructure all of these combinators to use short circuit return to make sure the Dropping and CStr wrappers are dropped in the right order.

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Hm, I am not exactly sure. An implementation that's guaranteed to be sane should be:

pub(crate) fn get_timezone_inner() -> Result<String, crate::GetTimezoneError> {
    unsafe {
        if let Some(tz) = Dropping::new(CFTimeZoneCopySystem()) {
            if let Some(name) = Dropping::new(CFTimeZoneGetName(tz.0)) {
                let name = CFStringGetCStringPtr(name.0, kCFStringEncodingUTF8);
                if !name.is_null() {
                    if let Ok(name) = std::ffi::CStr::from_ptr(name).to_str() {
                        return Ok(name.to_owned());
                    }
                }
            }
        }
    }
    Err(crate::GetTimezoneError::OsError)
}

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to be double sure I'd promote the std::ffi::CStr::from_ptr(name) to a named binding before the if let instead of a temporary in the if let.

.ok_or(crate::GetTimezoneError::OsError)
}
}

struct Dropping<T>(*const T);

impl<T> Drop for Dropping<T> {
#[inline]
fn drop(&mut self) {
unsafe { CFRelease(self.0 as CFTypeRef) };
}
}

impl<T> Dropping<T> {
#[inline]
unsafe fn new(v: *const T) -> Option<Self> {
if v.is_null() {
None
} else {
Some(Self(v))
}
}
}