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std_detect: Move cfgs into getauxval helper function

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Taiki Endo 2025-03-26 00:49:20 +09:00 • committed by Amanieu d'Antras
parent 0965a880c2
commit 5b9cdf26df
1 changed files with 35 additions and 94 deletions
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129
library/stdarch/crates/std_detect/src/detect/os/linux/auxvec.rs
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@ -74,68 +74,8 @@ pub(crate) struct AuxVec {
/// [auxvec_h]: https://github.com/torvalds/linux/blob/master/include/uapi/linux/auxvec.h
/// [auxv_docs]: https://docs.rs/auxv/0.3.3/auxv/
pub(crate) fn auxv() -> Result<AuxVec, ()> {
#[cfg(all(
feature = "std_detect_dlsym_getauxval",
not(all(
target_os = "linux",
any(target_env = "gnu", target_env = "musl", target_env = "ohos"),
)),
// TODO: libc crate currently doesn't provide getauxval on 32-bit Android.
not(all(target_os = "android", target_pointer_width = "64")),
))]
{
// Try to call a dynamically-linked getauxval function.
if let Ok(hwcap) = getauxval(AT_HWCAP) {
// Targets with only AT_HWCAP:
#[cfg(any(
target_arch = "riscv32",
target_arch = "riscv64",
target_arch = "mips",
target_arch = "mips64"
))]
{
// Zero could indicate that no features were detected, but it's also used to
// indicate an error. In either case, try the fallback.
if hwcap != 0 {
return Ok(AuxVec { hwcap });
}
}
// Targets with AT_HWCAP and AT_HWCAP2:
#[cfg(any(
target_arch = "aarch64",
target_arch = "arm",
target_arch = "powerpc",
target_arch = "powerpc64",
target_arch = "s390x",
))]
{
if let Ok(hwcap2) = getauxval(AT_HWCAP2) {
// Zero could indicate that no features were detected, but it's also used to
// indicate an error. In particular, on many platforms AT_HWCAP2 will be
// legitimately zero, since it contains the most recent feature flags. Use the
// fallback only if no features were detected at all.
if hwcap != 0 || hwcap2 != 0 {
return Ok(AuxVec { hwcap, hwcap2 });
}
}
}
// Intentionnaly not used
let _ = hwcap;
}
}
#[cfg(not(all(
feature = "std_detect_dlsym_getauxval",
not(all(
target_os = "linux",
any(target_env = "gnu", target_env = "musl", target_env = "ohos"),
)),
// TODO: libc crate currently doesn't provide getauxval on 32-bit Android.
not(all(target_os = "android", target_pointer_width = "64")),
)))]
{
// Try to call a getauxval function.
if let Ok(hwcap) = getauxval(AT_HWCAP) {
// Targets with only AT_HWCAP:
#[cfg(any(
target_arch = "riscv32",
@ -145,7 +85,6 @@ pub(crate) fn auxv() -> Result<AuxVec, ()> {
target_arch = "loongarch64",
))]
{
let hwcap = unsafe { libc::getauxval(AT_HWCAP as libc::c_ulong) as usize };
// Zero could indicate that no features were detected, but it's also used to indicate
// an error. In either case, try the fallback.
if hwcap != 0 {
@ -162,16 +101,19 @@ pub(crate) fn auxv() -> Result<AuxVec, ()> {
target_arch = "s390x",
))]
{
let hwcap = unsafe { libc::getauxval(AT_HWCAP as libc::c_ulong) as usize };
let hwcap2 = unsafe { libc::getauxval(AT_HWCAP2 as libc::c_ulong) as usize };
// Zero could indicate that no features were detected, but it's also used to indicate
// an error. In particular, on many platforms AT_HWCAP2 will be legitimately zero,
// since it contains the most recent feature flags. Use the fallback only if no
// features were detected at all.
if hwcap != 0 || hwcap2 != 0 {
return Ok(AuxVec { hwcap, hwcap2 });
if let Ok(hwcap2) = getauxval(AT_HWCAP2) {
// Zero could indicate that no features were detected, but it's also used to indicate
// an error. In particular, on many platforms AT_HWCAP2 will be legitimately zero,
// since it contains the most recent feature flags. Use the fallback only if no
// features were detected at all.
if hwcap != 0 || hwcap2 != 0 {
return Ok(AuxVec { hwcap, hwcap2 });
}
}
}
// Intentionnaly not used
let _ = hwcap;
}
#[cfg(feature = "std_detect_file_io")]
@ -187,32 +129,31 @@ pub(crate) fn auxv() -> Result<AuxVec, ()> {
}
/// Tries to read the `key` from the auxiliary vector by calling the
/// dynamically-linked `getauxval` function. If the function is not linked,
/// this function return `Err`.
#[cfg(any(
test,
all(
feature = "std_detect_dlsym_getauxval",
not(all(
target_os = "linux",
any(target_env = "gnu", target_env = "musl", target_env = "ohos"),
)),
// TODO: libc crate currently doesn't provide getauxval on 32-bit Android.
not(all(target_os = "android", target_pointer_width = "64")),
)
))]
/// `getauxval` function. If the function is not linked, this function return `Err`.
fn getauxval(key: usize) -> Result<usize, ()> {
use libc;
pub type F = unsafe extern "C" fn(usize) -> usize;
unsafe {
let ptr = libc::dlsym(libc::RTLD_DEFAULT, c"getauxval".as_ptr());
if ptr.is_null() {
return Err(());
type F = unsafe extern "C" fn(libc::c_ulong) -> libc::c_ulong;
cfg_if::cfg_if! {
if #[cfg(all(
feature = "std_detect_dlsym_getauxval",
not(all(
target_os = "linux",
any(target_env = "gnu", target_env = "musl", target_env = "ohos"),
)),
// TODO: libc crate currently doesn't provide getauxval on 32-bit Android.
not(all(target_os = "android", target_pointer_width = "64")),
))] {
let ffi_getauxval: F = unsafe {
let ptr = libc::dlsym(libc::RTLD_DEFAULT, c"getauxval".as_ptr());
if ptr.is_null() {
return Err(());
}
core::mem::transmute(ptr)
};
} else {
let ffi_getauxval: F = libc::getauxval;
}
let ffi_getauxval: F = core::mem::transmute(ptr);
Ok(ffi_getauxval(key))
}
Ok(unsafe { ffi_getauxval(key as libc::c_ulong) as usize })
}
/// Tries to read the auxiliary vector from the `file`. If this fails, this