diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/libstd/sys/vxworks/weak.rs | 56 |
1 files changed, 0 insertions, 56 deletions
diff --git a/src/libstd/sys/vxworks/weak.rs b/src/libstd/sys/vxworks/weak.rs deleted file mode 100644 index 4c6fddefd3f..00000000000 --- a/src/libstd/sys/vxworks/weak.rs +++ /dev/null @@ -1,56 +0,0 @@ -//! Support for "weak linkage" to symbols on Unix -//! -//! Some I/O operations we do in libstd require newer versions of OSes but we -//! need to maintain binary compatibility with older releases for now. In order -//! to use the new functionality when available we use this module for -//! detection. -//! -//! One option to use here is weak linkage, but that is unfortunately only -//! really workable on Linux. Hence, use dlsym to get the symbol value at -//! runtime. This is also done for compatibility with older versions of glibc, -//! and to avoid creating dependencies on GLIBC_PRIVATE symbols. It assumes that -//! we've been dynamically linked to the library the symbol comes from, but that -//! is currently always the case for things like libpthread/libc. -//! -//! A long time ago this used weak linkage for the __pthread_get_minstack -//! symbol, but that caused Debian to detect an unnecessarily strict versioned -//! dependency on libc6 (#23628). - -use crate::ffi::CStr; -use crate::marker; -use crate::mem; -use crate::sync::atomic::{AtomicUsize, Ordering}; - -pub struct Weak<F> { - name: &'static str, - addr: AtomicUsize, - _marker: marker::PhantomData<F>, -} - -impl<F> Weak<F> { - pub const fn new(name: &'static str) -> Weak<F> { - Weak { name, addr: AtomicUsize::new(1), _marker: marker::PhantomData } - } - - pub fn get(&self) -> Option<F> { - assert_eq!(mem::size_of::<F>(), mem::size_of::<usize>()); - unsafe { - if self.addr.load(Ordering::SeqCst) == 1 { - self.addr.store(fetch(self.name), Ordering::SeqCst); - } - match self.addr.load(Ordering::SeqCst) { - 0 => None, - addr => Some(mem::transmute_copy::<usize, F>(&addr)), - } - } - } -} - -unsafe fn fetch(name: &str) -> usize { - let name = match CStr::from_bytes_with_nul(name.as_bytes()) { - Ok(cstr) => cstr, - Err(..) => return 0, - }; - assert!(false, "FIXME: fetch"); - libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) as usize -} |
