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#[cfg(feature = "std")]
extern crate std;
use core::fmt;
// This private alias mirrors `std::io::RawOsError`:
cfg_if::cfg_if!(
if #[cfg(target_os = "uefi")] {
// See the UEFI spec for more information:
type RawOsError = usize;
type NonZeroRawOsError = core::num::NonZeroUsize;
const UEFI_ERROR_FLAG: RawOsError = 1 << (RawOsError::BITS - 1);
} else {
type RawOsError = i32;
type NonZeroRawOsError = core::num::NonZeroI32;
}
);
/// A small and `no_std` compatible error type
///
/// The [`Error::raw_os_error()`] will indicate if the error is from the OS, and
/// if so, which error code the OS gave the application. If such an error is
/// encountered, please consult with your system documentation.
///
/// *If this crate's `"std"` Cargo feature is enabled*, then:
/// - [`getrandom::Error`][Error] implements
// note: on non-UEFI targets OS errors are represented as negative integers,
// while on UEFI targets OS errors have the highest bit set to 1.
#[derive(Copy, Clone, Eq, PartialEq)]
pub struct Error(NonZeroRawOsError);
impl Error {
/// This target/platform is not supported by `getrandom`.
pub const UNSUPPORTED: Error = Self::new_internal(0);
/// The platform-specific `errno` returned a non-positive value.
pub const ERRNO_NOT_POSITIVE: Error = Self::new_internal(1);
/// Encountered an unexpected situation which should not happen in practice.
pub const UNEXPECTED: Error = Self::new_internal(2);
/// Internal errors can be in the range of 2^16..2^17
const INTERNAL_START: RawOsError = 1 << 16;
/// Custom errors can be in the range of 2^17..(2^17 + 2^16)
const CUSTOM_START: RawOsError = 1 << 17;
/// Creates a new instance of an `Error` from a negative error code.
#[cfg(not(target_os = "uefi"))]
#[allow(dead_code)]
pub(super) fn from_neg_error_code(code: RawOsError) -> Self {
if code < 0 {
let code = NonZeroRawOsError::new(code).expect("`code` is negative");
Self(code)
} else {
Error::UNEXPECTED
}
}
/// Creates a new instance of an `Error` from an UEFI error code.
#[cfg(target_os = "uefi")]
#[allow(dead_code)]
pub(super) fn from_uefi_code(code: RawOsError) -> Self {
if code & UEFI_ERROR_FLAG != 0 {
let code = NonZeroRawOsError::new(code).expect("The highest bit of `code` is set to 1");
Self(code)
} else {
Self::UNEXPECTED
}
}
/// Extract the raw OS error code (if this error came from the OS)
///
/// This method is identical to [`std::io::Error::raw_os_error()`][1], except
/// that it works in `no_std` contexts. On most targets this method returns
/// `Option<i32>`, but some platforms (e.g. UEFI) may use a different primitive
/// type like `usize`. Consult with the [`RawOsError`] docs for more information.
///
/// If this method returns `None`, the error value can still be formatted via
/// the `Display` implementation.
///
#[inline]
pub fn raw_os_error(self) -> Option<RawOsError> {
let code = self.0.get();
// note: in this method we need to cover only backends which rely on
// `Error::{from_error_code, from_errno, from_uefi_code}` methods,
// on all other backends this method always returns `None`.
#[cfg(target_os = "uefi")]
{
if code & UEFI_ERROR_FLAG != 0 {
Some(code)
} else {
None
}
}
#[cfg(not(target_os = "uefi"))]
{
// On most targets `std` expects positive error codes while retrieving error strings:
// - `libc`-based targets use `strerror_r` which expects positive error codes.
// - Hermit relies on the `hermit-abi` crate, which expects positive error codes:
// - WASIp1 uses the same conventions as `libc`:
//
// The only exception is Solid, `std` expects negative system error codes, see:
if code >= 0 {
None
} else if cfg!(not(target_os = "solid_asp3")) {
code.checked_neg()
} else {
Some(code)
}
}
}
/// Creates a new instance of an `Error` from a particular custom error code.
pub const fn new_custom(n: u16) -> Error {
// SAFETY: code > 0 as CUSTOM_START > 0 and adding `n` won't overflow `RawOsError`.
let code = Error::CUSTOM_START + (n as RawOsError);
Error(unsafe { NonZeroRawOsError::new_unchecked(code) })
}
/// Creates a new instance of an `Error` from a particular internal error code.
pub(crate) const fn new_internal(n: u16) -> Error {
// SAFETY: code > 0 as INTERNAL_START > 0 and adding `n` won't overflow `RawOsError`.
let code = Error::INTERNAL_START + (n as RawOsError);
Error(unsafe { NonZeroRawOsError::new_unchecked(code) })
}
fn internal_desc(&self) -> Option<&'static str> {
let desc = match *self {
Error::UNSUPPORTED => "getrandom: this target is not supported",
Error::ERRNO_NOT_POSITIVE => "errno: did not return a positive value",
Error::UNEXPECTED => "unexpected situation",
#[cfg(any(
target_os = "ios",
target_os = "visionos",
target_os = "watchos",
target_os = "tvos",
))]
Error::IOS_RANDOM_GEN => "SecRandomCopyBytes: iOS Security framework failure",
#[cfg(all(windows, target_vendor = "win7"))]
Error::WINDOWS_RTL_GEN_RANDOM => "RtlGenRandom: Windows system function failure",
#[cfg(all(feature = "wasm_js", getrandom_backend = "wasm_js"))]
Error::WEB_CRYPTO => "Web Crypto API is unavailable",
#[cfg(target_os = "vxworks")]
Error::VXWORKS_RAND_SECURE => "randSecure: VxWorks RNG module is not initialized",
#[cfg(any(
getrandom_backend = "rdrand",
all(target_arch = "x86_64", target_env = "sgx")
))]
Error::FAILED_RDRAND => "RDRAND: failed multiple times: CPU issue likely",
#[cfg(any(
getrandom_backend = "rdrand",
all(target_arch = "x86_64", target_env = "sgx")
))]
Error::NO_RDRAND => "RDRAND: instruction not supported",
#[cfg(getrandom_backend = "rndr")]
Error::RNDR_FAILURE => "RNDR: Could not generate a random number",
#[cfg(getrandom_backend = "rndr")]
Error::RNDR_NOT_AVAILABLE => "RNDR: Register not supported",
_ => return None,
};
Some(desc)
}
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut dbg = f.debug_struct("Error");
if let Some(errno) = self.raw_os_error() {
dbg.field("os_error", &errno);
#[cfg(feature = "std")]
dbg.field("description", &std::io::Error::from_raw_os_error(errno));
} else if let Some(desc) = self.internal_desc() {
dbg.field("internal_code", &self.0.get());
dbg.field("description", &desc);
} else {
dbg.field("unknown_code", &self.0.get());
}
dbg.finish()
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(errno) = self.raw_os_error() {
cfg_if! {
if #[cfg(feature = "std")] {
std::io::Error::from_raw_os_error(errno).fmt(f)
} else {
write!(f, "OS Error: {}", errno)
}
}
} else if let Some(desc) = self.internal_desc() {
f.write_str(desc)
} else {
write!(f, "Unknown Error: {}", self.0.get())
}
}
}