1 files changed, 178 insertions, 0 deletions
diff --git a/getrandom/src/error.rs b/getrandom/src/error.rs
new file mode 100644
index 0000000..b2cb9a8
--- /dev/null
+++ b/getrandom/src/error.rs
@@ -0,0 +1,178 @@
+// 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);
+    }
+}