1 files changed, 102 insertions, 0 deletions
diff --git a/library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs b/library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs
new file mode 100644
index 000000000..29fcc8cb0
--- /dev/null
+++ b/library/stdarch/crates/std_detect/src/detect/os/freebsd/auxvec.rs
@@ -0,0 +1,102 @@
+//! Parses ELF auxiliary vectors.
+#![cfg_attr(
+    any(
+        target_arch = "aarch64",
+        target_arch = "arm",
+        target_arch = "powerpc64",
+        target_arch = "riscv64"
+    ),
+    allow(dead_code)
+)]
+
+/// Key to access the CPU Hardware capabilities bitfield.
+pub(crate) const AT_HWCAP: usize = 25;
+/// Key to access the CPU Hardware capabilities 2 bitfield.
+pub(crate) const AT_HWCAP2: usize = 26;
+
+/// Cache HWCAP bitfields of the ELF Auxiliary Vector.
+///
+/// If an entry cannot be read all the bits in the bitfield are set to zero.
+/// This should be interpreted as all the features being disabled.
+#[derive(Debug, Copy, Clone)]
+pub(crate) struct AuxVec {
+    pub hwcap: usize,
+    pub hwcap2: usize,
+}
+
+/// ELF Auxiliary Vector
+///
+/// The auxiliary vector is a memory region in a running ELF program's stack
+/// composed of (key: usize, value: usize) pairs.
+///
+/// The keys used in the aux vector are platform dependent. For FreeBSD, they are
+/// defined in [sys/elf_common.h][elf_common_h]. The hardware capabilities of a given
+/// CPU can be queried with the  `AT_HWCAP` and `AT_HWCAP2` keys.
+///
+/// Note that run-time feature detection is not invoked for features that can
+/// be detected at compile-time.
+///
+/// [elf_common.h]: https://svnweb.freebsd.org/base/release/12.0.0/sys/sys/elf_common.h?revision=341707
+pub(crate) fn auxv() -> Result<AuxVec, ()> {
+    if let Ok(hwcap) = archauxv(AT_HWCAP) {
+        if let Ok(hwcap2) = archauxv(AT_HWCAP2) {
+            if hwcap != 0 && hwcap2 != 0 {
+                return Ok(AuxVec { hwcap, hwcap2 });
+            }
+        }
+    }
+    Err(())
+}
+
+/// Tries to read the `key` from the auxiliary vector.
+fn archauxv(key: usize) -> Result<usize, ()> {
+    use core::mem;
+
+    #[derive(Copy, Clone)]
+    #[repr(C)]
+    pub struct Elf_Auxinfo {
+        pub a_type: usize,
+        pub a_un: unnamed,
+    }
+    #[derive(Copy, Clone)]
+    #[repr(C)]
+    pub union unnamed {
+        pub a_val: libc::c_long,
+        pub a_ptr: *mut libc::c_void,
+        pub a_fcn: Option<unsafe extern "C" fn() -> ()>,
+    }
+
+    let mut auxv: [Elf_Auxinfo; 27] = [Elf_Auxinfo {
+        a_type: 0,
+        a_un: unnamed { a_val: 0 },
+    }; 27];
+
+    let mut len: libc::c_uint = mem::size_of_val(&auxv) as libc::c_uint;
+
+    unsafe {
+        let mut mib = [
+            libc::CTL_KERN,
+            libc::KERN_PROC,
+            libc::KERN_PROC_AUXV,
+            libc::getpid(),
+        ];
+
+        let ret = libc::sysctl(
+            mib.as_mut_ptr(),
+            mib.len() as u32,
+            &mut auxv as *mut _ as *mut _,
+            &mut len as *mut _ as *mut _,
+            0 as *mut libc::c_void,
+            0,
+        );
+
+        if ret != -1 {
+            for i in 0..auxv.len() {
+                if auxv[i].a_type == key {
+                    return Ok(auxv[i].a_un.a_val as usize);
+                }
+            }
+        }
+    }
+    return Ok(0);
+}