1 files changed, 149 insertions, 0 deletions
diff --git a/vendor/rustix/src/backend/linux_raw/param/init.rs b/vendor/rustix/src/backend/linux_raw/param/init.rs
new file mode 100644
index 000000000..46aae009a
--- /dev/null
+++ b/vendor/rustix/src/backend/linux_raw/param/init.rs
@@ -0,0 +1,149 @@
+//! Linux auxv `init` function, for "use-explicitly-provided-auxv" mode.
+//!
+//! # Safety
+//!
+//! This uses raw pointers to locate and read the kernel-provided auxv array.
+#![allow(unsafe_code)]
+
+use crate::backend::c;
+#[cfg(feature = "param")]
+use crate::ffi::CStr;
+use core::ffi::c_void;
+use core::ptr::{null_mut, read, NonNull};
+use core::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
+use linux_raw_sys::elf::*;
+use linux_raw_sys::general::{
+    AT_CLKTCK, AT_EXECFN, AT_HWCAP, AT_HWCAP2, AT_NULL, AT_PAGESZ, AT_SYSINFO_EHDR,
+};
+#[cfg(feature = "runtime")]
+use linux_raw_sys::general::{AT_ENTRY, AT_PHDR, AT_PHENT, AT_PHNUM};
+
+#[cfg(feature = "param")]
+#[inline]
+pub(crate) fn page_size() -> usize {
+    unsafe { PAGE_SIZE.load(Ordering::Relaxed) }
+}
+
+#[cfg(feature = "param")]
+#[inline]
+pub(crate) fn clock_ticks_per_second() -> u64 {
+    unsafe { CLOCK_TICKS_PER_SECOND.load(Ordering::Relaxed) as u64 }
+}
+
+#[cfg(feature = "param")]
+#[inline]
+pub(crate) fn linux_hwcap() -> (usize, usize) {
+    unsafe {
+        (
+            HWCAP.load(Ordering::Relaxed),
+            HWCAP2.load(Ordering::Relaxed),
+        )
+    }
+}
+
+#[cfg(feature = "param")]
+#[inline]
+pub(crate) fn linux_execfn() -> &'static CStr {
+    let execfn = unsafe { EXECFN.load(Ordering::Relaxed) };
+
+    // SAFETY: We initialize `EXECFN` to a valid `CStr` pointer, and we assume
+    // the `AT_EXECFN` value provided by the kernel points to a valid C string.
+    unsafe { CStr::from_ptr(execfn.cast()) }
+}
+
+#[cfg(feature = "runtime")]
+#[inline]
+pub(crate) fn exe_phdrs() -> (*const c_void, usize, usize) {
+    unsafe {
+        (
+            PHDR.load(Ordering::Relaxed).cast(),
+            PHENT.load(Ordering::Relaxed),
+            PHNUM.load(Ordering::Relaxed),
+        )
+    }
+}
+
+/// `AT_SYSINFO_EHDR` isn't present on all platforms in all configurations, so
+/// if we don't see it, this function returns a null pointer.
+#[inline]
+pub(in super::super) fn sysinfo_ehdr() -> *const Elf_Ehdr {
+    unsafe { SYSINFO_EHDR.load(Ordering::Relaxed) }
+}
+
+#[cfg(feature = "runtime")]
+#[inline]
+pub(crate) fn entry() -> usize {
+    unsafe { ENTRY.load(Ordering::Relaxed) }
+}
+
+static mut PAGE_SIZE: AtomicUsize = AtomicUsize::new(0);
+static mut CLOCK_TICKS_PER_SECOND: AtomicUsize = AtomicUsize::new(0);
+static mut HWCAP: AtomicUsize = AtomicUsize::new(0);
+static mut HWCAP2: AtomicUsize = AtomicUsize::new(0);
+static mut SYSINFO_EHDR: AtomicPtr<Elf_Ehdr> = AtomicPtr::new(null_mut());
+// Initialize `EXECFN` to a valid `CStr` pointer so that we don't need to check
+// for null on every `execfn` call.
+static mut EXECFN: AtomicPtr<c::c_char> = AtomicPtr::new(b"\0".as_ptr() as _);
+// Use `dangling` so that we can always treat it like an empty slice.
+#[cfg(feature = "runtime")]
+static mut PHDR: AtomicPtr<Elf_Phdr> = AtomicPtr::new(NonNull::dangling().as_ptr());
+#[cfg(feature = "runtime")]
+static mut PHENT: AtomicUsize = AtomicUsize::new(0);
+#[cfg(feature = "runtime")]
+static mut PHNUM: AtomicUsize = AtomicUsize::new(0);
+#[cfg(feature = "runtime")]
+static mut ENTRY: AtomicUsize = AtomicUsize::new(0);
+
+/// When "use-explicitly-provided-auxv" is enabled, we export a function to be
+/// called during initialization, and passed a pointer to the original
+/// environment variable block set up by the OS.
+pub(crate) unsafe fn init(envp: *mut *mut u8) {
+    init_from_envp(envp);
+}
+
+/// # Safety
+///
+/// This must be passed a pointer to the environment variable buffer
+/// provided by the kernel, which is followed in memory by the auxv array.
+unsafe fn init_from_envp(mut envp: *mut *mut u8) {
+    while !(*envp).is_null() {
+        envp = envp.add(1);
+    }
+    init_from_auxp(envp.add(1).cast())
+}
+
+/// Process auxv entries from the auxv array pointed to by `auxp`.
+///
+/// # Safety
+///
+/// This must be passed a pointer to an auxv array.
+///
+/// The buffer contains `Elf_aux_t` elements, though it need not be aligned;
+/// function uses `read_unaligned` to read from it.
+unsafe fn init_from_auxp(mut auxp: *const Elf_auxv_t) {
+    loop {
+        let Elf_auxv_t { a_type, a_val } = read(auxp);
+
+        match a_type as _ {
+            AT_PAGESZ => PAGE_SIZE.store(a_val as usize, Ordering::Relaxed),
+            AT_CLKTCK => CLOCK_TICKS_PER_SECOND.store(a_val as usize, Ordering::Relaxed),
+            AT_HWCAP => HWCAP.store(a_val as usize, Ordering::Relaxed),
+            AT_HWCAP2 => HWCAP2.store(a_val as usize, Ordering::Relaxed),
+            AT_EXECFN => EXECFN.store(a_val.cast::<c::c_char>(), Ordering::Relaxed),
+            AT_SYSINFO_EHDR => SYSINFO_EHDR.store(a_val.cast::<Elf_Ehdr>(), Ordering::Relaxed),
+
+            #[cfg(feature = "runtime")]
+            AT_PHDR => PHDR.store(a_val.cast::<Elf_Phdr>(), Ordering::Relaxed),
+            #[cfg(feature = "runtime")]
+            AT_PHNUM => PHNUM.store(a_val as usize, Ordering::Relaxed),
+            #[cfg(feature = "runtime")]
+            AT_PHENT => PHENT.store(a_val as usize, Ordering::Relaxed),
+            #[cfg(feature = "runtime")]
+            AT_ENTRY => ENTRY.store(a_val as usize, Ordering::Relaxed),
+
+            AT_NULL => break,
+            _ => (),
+        }
+        auxp = auxp.add(1);
+    }
+}