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// Copyright 2018 Developers of the Rand project.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use core::fmt;
use core::num::NonZeroU32;
/// 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.
///
/// Internally this type is a NonZeroU32, with certain values reserved for
/// certain purposes, see [`Error::INTERNAL_START`] and [`Error::CUSTOM_START`].
#[derive(Copy, Clone, Eq, PartialEq)]
pub struct Error(NonZeroU32);
impl Error {
#[deprecated(since = "0.1.7")]
/// Unknown error.
pub const UNKNOWN: Error = UNSUPPORTED;
#[deprecated(since = "0.1.7")]
/// System entropy source is unavailable.
pub const UNAVAILABLE: Error = UNSUPPORTED;
/// Codes below this point represent OS Errors (i.e. positive i32 values).
/// Codes at or above this point, but below [`Error::CUSTOM_START`] are
/// reserved for use by the `rand` and `getrandom` crates.
pub const INTERNAL_START: u32 = 1 << 31;
/// Codes at or above this point can be used by users to define their own
/// custom errors.
pub const CUSTOM_START: u32 = (1 << 31) + (1 << 30);
/// Extract the raw OS error code (if this error came from the OS)
///
/// This method is identical to `std::io::Error::raw_os_error()`, except
/// that it works in `no_std` contexts. If this method returns `None`, the
/// error value can still be formatted via the `Display` implementation.
#[inline]
pub fn raw_os_error(self) -> Option<i32> {
if self.0.get() < Self::INTERNAL_START {
Some(self.0.get() as i32)
} else {
None
}
}
/// Extract the bare error code.
///
/// This code can either come from the underlying OS, or be a custom error.
/// Use [`Error::raw_os_error()`] to disambiguate.
#[inline]
pub fn code(self) -> NonZeroU32 {
self.0
}
}
cfg_if! {
if #[cfg(unix)] {
fn os_err_desc(errno: i32, buf: &mut [u8]) -> Option<&str> {
let buf_ptr = buf.as_mut_ptr() as *mut libc::c_char;
if unsafe { libc::strerror_r(errno, buf_ptr, buf.len()) } != 0 {
return None;
}
// Take up to trailing null byte
let n = buf.len();
let idx = buf.iter().position(|&b| b == 0).unwrap_or(n);
core::str::from_utf8(&buf[..idx]).ok()
}
} else if #[cfg(target_os = "wasi")] {
fn os_err_desc(errno: i32, _buf: &mut [u8]) -> Option<&str> {
core::num::NonZeroU16::new(errno as u16)
.and_then(wasi::wasi_unstable::error_str)
}
} else {
fn os_err_desc(_errno: i32, _buf: &mut [u8]) -> Option<&str> {
None
}
}
}
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);
let mut buf = [0u8; 128];
if let Some(desc) = os_err_desc(errno, &mut buf) {
dbg.field("description", &desc);
}
} else if let Some(desc) = internal_desc(*self) {
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() {
let mut buf = [0u8; 128];
match os_err_desc(errno, &mut buf) {
Some(desc) => f.write_str(desc),
None => write!(f, "OS Error: {}", errno),
}
} else if let Some(desc) = internal_desc(*self) {
f.write_str(desc)
} else {
write!(f, "Unknown Error: {}", self.0.get())
}
}
}
impl From<NonZeroU32> for Error {
fn from(code: NonZeroU32) -> Self {
Self(code)
}
}
// TODO: Convert to a function when min_version >= 1.33
macro_rules! internal_error {
($n:expr) => {
Error(unsafe { NonZeroU32::new_unchecked(Error::INTERNAL_START + $n as u16 as u32) })
};
}
/// Internal Error constants
pub(crate) const UNSUPPORTED: Error = internal_error!(0);
pub(crate) const ERRNO_NOT_POSITIVE: Error = internal_error!(1);
pub(crate) const UNKNOWN_IO_ERROR: Error = internal_error!(2);
pub(crate) const SEC_RANDOM_FAILED: Error = internal_error!(3);
pub(crate) const RTL_GEN_RANDOM_FAILED: Error = internal_error!(4);
pub(crate) const FAILED_RDRAND: Error = internal_error!(5);
pub(crate) const NO_RDRAND: Error = internal_error!(6);
pub(crate) const BINDGEN_CRYPTO_UNDEF: Error = internal_error!(7);
pub(crate) const BINDGEN_GRV_UNDEF: Error = internal_error!(8);
pub(crate) const STDWEB_NO_RNG: Error = internal_error!(9);
pub(crate) const STDWEB_RNG_FAILED: Error = internal_error!(10);
pub(crate) const RAND_SECURE_FATAL: Error = internal_error!(11);
fn internal_desc(error: Error) -> Option<&'static str> {
match error {
UNSUPPORTED => Some("getrandom: this target is not supported"),
ERRNO_NOT_POSITIVE => Some("errno: did not return a positive value"),
UNKNOWN_IO_ERROR => Some("Unknown std::io::Error"),
SEC_RANDOM_FAILED => Some("SecRandomCopyBytes: call failed"),
RTL_GEN_RANDOM_FAILED => Some("RtlGenRandom: call failed"),
FAILED_RDRAND => Some("RDRAND: failed multiple times: CPU issue likely"),
NO_RDRAND => Some("RDRAND: instruction not supported"),
BINDGEN_CRYPTO_UNDEF => Some("wasm-bindgen: self.crypto is undefined"),
BINDGEN_GRV_UNDEF => Some("wasm-bindgen: crypto.getRandomValues is undefined"),
STDWEB_NO_RNG => Some("stdweb: no randomness source available"),
STDWEB_RNG_FAILED => Some("stdweb: failed to get randomness"),
RAND_SECURE_FATAL => Some("randSecure: random number generator module is not initialized"),
_ => None,
}
}
#[cfg(test)]
mod tests {
use super::Error;
use core::mem::size_of;
#[test]
fn test_size() {
assert_eq!(size_of::<Error>(), 4);
assert_eq!(size_of::<Result<(), Error>>(), 4);
}
}
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