getrandom/
error.rs

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1// Copyright 2018 Developers of the Rand project.
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8use core::{fmt, num::NonZeroU32};
9
10/// A small and `no_std` compatible error type
11///
12/// The [`Error::raw_os_error()`] will indicate if the error is from the OS, and
13/// if so, which error code the OS gave the application. If such an error is
14/// encountered, please consult with your system documentation.
15///
16/// Internally this type is a NonZeroU32, with certain values reserved for
17/// certain purposes, see [`Error::INTERNAL_START`] and [`Error::CUSTOM_START`].
18///
19/// *If this crate's `"std"` Cargo feature is enabled*, then:
20/// - [`getrandom::Error`][Error] implements
21///   [`std::error::Error`](https://doc.rust-lang.org/std/error/trait.Error.html)
22/// - [`std::io::Error`](https://doc.rust-lang.org/std/io/struct.Error.html) implements
23///   [`From<getrandom::Error>`](https://doc.rust-lang.org/std/convert/trait.From.html).
24#[derive(Copy, Clone, Eq, PartialEq)]
25pub struct Error(NonZeroU32);
26
27const fn internal_error(n: u16) -> Error {
28    // SAFETY: code > 0 as INTERNAL_START > 0 and adding n won't overflow a u32.
29    let code = Error::INTERNAL_START + (n as u32);
30    Error(unsafe { NonZeroU32::new_unchecked(code) })
31}
32
33impl Error {
34    /// This target/platform is not supported by `getrandom`.
35    pub const UNSUPPORTED: Error = internal_error(0);
36    /// The platform-specific `errno` returned a non-positive value.
37    pub const ERRNO_NOT_POSITIVE: Error = internal_error(1);
38    /// Call to iOS [`SecRandomCopyBytes`](https://developer.apple.com/documentation/security/1399291-secrandomcopybytes) failed.
39    pub const IOS_SEC_RANDOM: Error = internal_error(3);
40    /// Call to Windows [`RtlGenRandom`](https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom) failed.
41    pub const WINDOWS_RTL_GEN_RANDOM: Error = internal_error(4);
42    /// RDRAND instruction failed due to a hardware issue.
43    pub const FAILED_RDRAND: Error = internal_error(5);
44    /// RDRAND instruction unsupported on this target.
45    pub const NO_RDRAND: Error = internal_error(6);
46    /// The environment does not support the Web Crypto API.
47    pub const WEB_CRYPTO: Error = internal_error(7);
48    /// Calling Web Crypto API `crypto.getRandomValues` failed.
49    pub const WEB_GET_RANDOM_VALUES: Error = internal_error(8);
50    /// On VxWorks, call to `randSecure` failed (random number generator is not yet initialized).
51    pub const VXWORKS_RAND_SECURE: Error = internal_error(11);
52    /// Node.js does not have the `crypto` CommonJS module.
53    pub const NODE_CRYPTO: Error = internal_error(12);
54    /// Calling Node.js function `crypto.randomFillSync` failed.
55    pub const NODE_RANDOM_FILL_SYNC: Error = internal_error(13);
56    /// Called from an ES module on Node.js. This is unsupported, see:
57    /// <https://docs.rs/getrandom#nodejs-es-module-support>.
58    pub const NODE_ES_MODULE: Error = internal_error(14);
59
60    /// Codes below this point represent OS Errors (i.e. positive i32 values).
61    /// Codes at or above this point, but below [`Error::CUSTOM_START`] are
62    /// reserved for use by the `rand` and `getrandom` crates.
63    pub const INTERNAL_START: u32 = 1 << 31;
64
65    /// Codes at or above this point can be used by users to define their own
66    /// custom errors.
67    pub const CUSTOM_START: u32 = (1 << 31) + (1 << 30);
68
69    /// Extract the raw OS error code (if this error came from the OS)
70    ///
71    /// This method is identical to [`std::io::Error::raw_os_error()`][1], except
72    /// that it works in `no_std` contexts. If this method returns `None`, the
73    /// error value can still be formatted via the `Display` implementation.
74    ///
75    /// [1]: https://doc.rust-lang.org/std/io/struct.Error.html#method.raw_os_error
76    #[inline]
77    pub fn raw_os_error(self) -> Option<i32> {
78        if self.0.get() < Self::INTERNAL_START {
79            match () {
80                #[cfg(target_os = "solid_asp3")]
81                // On SOLID, negate the error code again to obtain the original
82                // error code.
83                () => Some(-(self.0.get() as i32)),
84                #[cfg(not(target_os = "solid_asp3"))]
85                () => Some(self.0.get() as i32),
86            }
87        } else {
88            None
89        }
90    }
91
92    /// Extract the bare error code.
93    ///
94    /// This code can either come from the underlying OS, or be a custom error.
95    /// Use [`Error::raw_os_error()`] to disambiguate.
96    #[inline]
97    pub const fn code(self) -> NonZeroU32 {
98        self.0
99    }
100}
101
102cfg_if! {
103    if #[cfg(unix)] {
104        fn os_err(errno: i32, buf: &mut [u8]) -> Option<&str> {
105            let buf_ptr = buf.as_mut_ptr() as *mut libc::c_char;
106            if unsafe { libc::strerror_r(errno, buf_ptr, buf.len()) } != 0 {
107                return None;
108            }
109
110            // Take up to trailing null byte
111            let n = buf.len();
112            let idx = buf.iter().position(|&b| b == 0).unwrap_or(n);
113            core::str::from_utf8(&buf[..idx]).ok()
114        }
115    } else {
116        fn os_err(_errno: i32, _buf: &mut [u8]) -> Option<&str> {
117            None
118        }
119    }
120}
121
122impl fmt::Debug for Error {
123    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
124        let mut dbg = f.debug_struct("Error");
125        if let Some(errno) = self.raw_os_error() {
126            dbg.field("os_error", &errno);
127            let mut buf = [0u8; 128];
128            if let Some(err) = os_err(errno, &mut buf) {
129                dbg.field("description", &err);
130            }
131        } else if let Some(desc) = internal_desc(*self) {
132            dbg.field("internal_code", &self.0.get());
133            dbg.field("description", &desc);
134        } else {
135            dbg.field("unknown_code", &self.0.get());
136        }
137        dbg.finish()
138    }
139}
140
141impl fmt::Display for Error {
142    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
143        if let Some(errno) = self.raw_os_error() {
144            let mut buf = [0u8; 128];
145            match os_err(errno, &mut buf) {
146                Some(err) => err.fmt(f),
147                None => write!(f, "OS Error: {}", errno),
148            }
149        } else if let Some(desc) = internal_desc(*self) {
150            f.write_str(desc)
151        } else {
152            write!(f, "Unknown Error: {}", self.0.get())
153        }
154    }
155}
156
157impl From<NonZeroU32> for Error {
158    fn from(code: NonZeroU32) -> Self {
159        Self(code)
160    }
161}
162
163fn internal_desc(error: Error) -> Option<&'static str> {
164    match error {
165        Error::UNSUPPORTED => Some("getrandom: this target is not supported"),
166        Error::ERRNO_NOT_POSITIVE => Some("errno: did not return a positive value"),
167        Error::IOS_SEC_RANDOM => Some("SecRandomCopyBytes: iOS Security framework failure"),
168        Error::WINDOWS_RTL_GEN_RANDOM => Some("RtlGenRandom: Windows system function failure"),
169        Error::FAILED_RDRAND => Some("RDRAND: failed multiple times: CPU issue likely"),
170        Error::NO_RDRAND => Some("RDRAND: instruction not supported"),
171        Error::WEB_CRYPTO => Some("Web Crypto API is unavailable"),
172        Error::WEB_GET_RANDOM_VALUES => Some("Calling Web API crypto.getRandomValues failed"),
173        Error::VXWORKS_RAND_SECURE => Some("randSecure: VxWorks RNG module is not initialized"),
174        Error::NODE_CRYPTO => Some("Node.js crypto CommonJS module is unavailable"),
175        Error::NODE_RANDOM_FILL_SYNC => Some("Calling Node.js API crypto.randomFillSync failed"),
176        Error::NODE_ES_MODULE => Some("Node.js ES modules are not directly supported, see https://docs.rs/getrandom#nodejs-es-module-support"),
177        _ => None,
178    }
179}
180
181#[cfg(test)]
182mod tests {
183    use super::Error;
184    use core::mem::size_of;
185
186    #[test]
187    fn test_size() {
188        assert_eq!(size_of::<Error>(), 4);
189        assert_eq!(size_of::<Result<(), Error>>(), 4);
190    }
191}
getrandom/error.rs

getrandom/
error.rs
