| //! Linux auxv support, using libc. |
| //! |
| //! # 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; |
| #[cfg(not(feature = "runtime"))] |
| use core::ptr::null; |
| use linux_raw_sys::elf::*; |
| |
| // `getauxval` wasn't supported in glibc until 2.16. Also this lets us use |
| // `*mut` as the return type to preserve strict provenance. |
| #[cfg(not(feature = "runtime"))] |
| weak!(fn getauxval(c::c_ulong) -> *mut c::c_void); |
| |
| // With the "runtime" feature, go ahead and depend on `getauxval` existing so |
| // that we never fail. |
| #[cfg(feature = "runtime")] |
| extern "C" { |
| fn getauxval(type_: c::c_ulong) -> *mut c::c_void; |
| } |
| |
| #[cfg(feature = "runtime")] |
| const AT_PHDR: c::c_ulong = 3; |
| #[cfg(feature = "runtime")] |
| const AT_PHENT: c::c_ulong = 4; |
| #[cfg(feature = "runtime")] |
| const AT_PHNUM: c::c_ulong = 5; |
| #[cfg(feature = "runtime")] |
| const AT_ENTRY: c::c_ulong = 9; |
| const AT_HWCAP: c::c_ulong = 16; |
| const AT_HWCAP2: c::c_ulong = 26; |
| const AT_SECURE: c::c_ulong = 23; |
| const AT_EXECFN: c::c_ulong = 31; |
| const AT_SYSINFO_EHDR: c::c_ulong = 33; |
| |
| // Declare `sysconf` ourselves so that we don't depend on all of libc just for |
| // this. |
| extern "C" { |
| fn sysconf(name: c::c_int) -> c::c_long; |
| } |
| |
| #[cfg(target_os = "android")] |
| const _SC_PAGESIZE: c::c_int = 39; |
| #[cfg(target_os = "linux")] |
| const _SC_PAGESIZE: c::c_int = 30; |
| #[cfg(target_os = "android")] |
| const _SC_CLK_TCK: c::c_int = 6; |
| #[cfg(target_os = "linux")] |
| const _SC_CLK_TCK: c::c_int = 2; |
| |
| #[test] |
| fn test_abi() { |
| const_assert_eq!(self::_SC_PAGESIZE, ::libc::_SC_PAGESIZE); |
| const_assert_eq!(self::_SC_CLK_TCK, ::libc::_SC_CLK_TCK); |
| const_assert_eq!(self::AT_HWCAP, ::libc::AT_HWCAP); |
| const_assert_eq!(self::AT_HWCAP2, ::libc::AT_HWCAP2); |
| const_assert_eq!(self::AT_EXECFN, ::libc::AT_EXECFN); |
| const_assert_eq!(self::AT_SECURE, ::libc::AT_SECURE); |
| const_assert_eq!(self::AT_SYSINFO_EHDR, ::libc::AT_SYSINFO_EHDR); |
| #[cfg(feature = "runtime")] |
| const_assert_eq!(self::AT_PHDR, ::libc::AT_PHDR); |
| #[cfg(feature = "runtime")] |
| const_assert_eq!(self::AT_PHNUM, ::libc::AT_PHNUM); |
| #[cfg(feature = "runtime")] |
| const_assert_eq!(self::AT_ENTRY, ::libc::AT_ENTRY); |
| } |
| |
| #[cfg(feature = "param")] |
| #[inline] |
| pub(crate) fn page_size() -> usize { |
| unsafe { sysconf(_SC_PAGESIZE) as usize } |
| } |
| |
| #[cfg(feature = "param")] |
| #[inline] |
| pub(crate) fn clock_ticks_per_second() -> u64 { |
| unsafe { sysconf(_SC_CLK_TCK) as u64 } |
| } |
| |
| #[cfg(feature = "param")] |
| #[inline] |
| pub(crate) fn linux_hwcap() -> (usize, usize) { |
| #[cfg(not(feature = "runtime"))] |
| unsafe { |
| if let Some(libc_getauxval) = getauxval.get() { |
| let hwcap = libc_getauxval(AT_HWCAP) as usize; |
| let hwcap2 = libc_getauxval(AT_HWCAP2) as usize; |
| (hwcap, hwcap2) |
| } else { |
| (0, 0) |
| } |
| } |
| |
| #[cfg(feature = "runtime")] |
| unsafe { |
| let hwcap = getauxval(AT_HWCAP) as usize; |
| let hwcap2 = getauxval(AT_HWCAP2) as usize; |
| (hwcap, hwcap2) |
| } |
| } |
| |
| #[cfg(feature = "param")] |
| #[inline] |
| pub(crate) fn linux_execfn() -> &'static CStr { |
| #[cfg(not(feature = "runtime"))] |
| unsafe { |
| if let Some(libc_getauxval) = getauxval.get() { |
| CStr::from_ptr(libc_getauxval(AT_EXECFN).cast()) |
| } else { |
| cstr!("") |
| } |
| } |
| |
| #[cfg(feature = "runtime")] |
| unsafe { |
| CStr::from_ptr(getauxval(AT_EXECFN).cast()) |
| } |
| } |
| |
| #[cfg(feature = "runtime")] |
| #[inline] |
| pub(crate) fn linux_secure() -> bool { |
| unsafe { getauxval(AT_SECURE) as usize != 0 } |
| } |
| |
| #[cfg(feature = "runtime")] |
| #[inline] |
| pub(crate) fn exe_phdrs() -> (*const c::c_void, usize, usize) { |
| unsafe { |
| let phdr = getauxval(AT_PHDR) as *const c::c_void; |
| let phent = getauxval(AT_PHENT) as usize; |
| let phnum = getauxval(AT_PHNUM) as usize; |
| (phdr, phent, phnum) |
| } |
| } |
| |
| /// `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 { |
| #[cfg(not(feature = "runtime"))] |
| unsafe { |
| if let Some(libc_getauxval) = getauxval.get() { |
| libc_getauxval(AT_SYSINFO_EHDR) as *const Elf_Ehdr |
| } else { |
| null() |
| } |
| } |
| |
| #[cfg(feature = "runtime")] |
| unsafe { |
| getauxval(AT_SYSINFO_EHDR) as *const Elf_Ehdr |
| } |
| } |
| |
| #[cfg(feature = "runtime")] |
| #[inline] |
| pub(crate) fn entry() -> usize { |
| unsafe { getauxval(AT_ENTRY) as usize } |
| } |