Improve Error handling

Cargo.toml

@@ -19,6 +19,7 @@ members = ["tests/wasm_bindgen"]
 
 [dependencies]
 log = { version = "0.4", optional = true }
+cfg-if = "0.1"
 
 [target.'cfg(any(unix, target_os = "redox", target_os = "wasi"))'.dependencies]
 libc = "0.2.54"

src/cloudabi.rs

@@ -7,24 +7,22 @@
 // except according to those terms.
 
 //! Implementation for CloudABI
-use crate::Error;
-use core::num::NonZeroU32;
+extern crate std;
+
+use std::io;
+
+pub type Error = io::Error;
 
 extern "C" {
     fn cloudabi_sys_random_get(buf: *mut u8, buf_len: usize) -> u16;
 }
 
 pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
     let errno = unsafe { cloudabi_sys_random_get(dest.as_mut_ptr(), dest.len()) };
-    if let Some(code) = NonZeroU32::new(errno as u32) {
-        error!("cloudabi_sys_random_get failed with code {}", code);
-        Err(Error::from(code))
+    if errno != 0 {
+        error!("cloudabi_sys_random_get failed with code {}", errno);
+        Err(Error::from_raw_os_error(errno as i32))
     } else {
         Ok(()) // Zero means success for CloudABI
     }
 }
-
-#[inline(always)]
-pub fn error_msg_inner(_: NonZeroU32) -> Option<&'static str> {
-    None
-}

src/dummy.rs

@@ -6,17 +6,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! A dummy implementation for unsupported targets which always returns
-//! `Err(Error::UNAVAILABLE)`
-use crate::Error;
-use core::num::NonZeroU32;
+//! A dummy implementation for unsupported targets which always fails.
+use crate::util::StaticError;
 
-pub fn getrandom_inner(_: &mut [u8]) -> Result<(), Error> {
-    error!("no support for this platform");
-    Err(Error::UNAVAILABLE)
-}
+pub type Error = StaticError;
 
-#[inline(always)]
-pub fn error_msg_inner(_: NonZeroU32) -> Option<&'static str> {
-    None
+pub fn getrandom_inner(_: &mut [u8]) -> Result<(), Error> {
+    Err(StaticError("getrandom: this target is not supported"))
 }

src/error_impls.rs

@@ -5,30 +5,12 @@
 // <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.
-extern crate std;
+use crate::Error;
 
-use crate::error::Error;
-use core::convert::From;
-use core::num::NonZeroU32;
-use std::{error, io};
-
-impl From<io::Error> for Error {
-    fn from(err: io::Error) -> Self {
-        err.raw_os_error()
-            .and_then(|code| NonZeroU32::new(code as u32))
-            .map(|code| Error(code))
-            // in practice this should never happen
-            .unwrap_or(Error::UNKNOWN)
-    }
-}
-
-impl From<Error> for io::Error {
+impl From<Error> for std::io::Error {
     fn from(err: Error) -> Self {
-        match err.msg() {
-            Some(msg) => io::Error::new(io::ErrorKind::Other, msg),
-            None => io::Error::from_raw_os_error(err.0.get() as i32),
-        }
+        err.0.into()
     }
 }
 
-impl error::Error for Error {}
+impl std::error::Error for Error {}

src/freebsd.rs

@@ -9,11 +9,11 @@
 //! Implementation for FreeBSD
 extern crate std;
 
-use crate::Error;
-use core::num::NonZeroU32;
 use core::ptr;
 use std::io;
 
+pub type Error = io::Error;
+
 fn kern_arnd(buf: &mut [u8]) -> Result<usize, Error> {
     static MIB: [libc::c_int; 2] = [libc::CTL_KERN, libc::KERN_ARND];
     let mut len = buf.len();
@@ -29,7 +29,7 @@ fn kern_arnd(buf: &mut [u8]) -> Result<usize, Error> {
     };
     if ret == -1 {
         error!("freebsd: kern.arandom syscall failed");
-        return Err(io::Error::last_os_error().into());
+        return Err(Error::last_os_error());
     }
     Ok(len)
 }
@@ -41,8 +41,3 @@ pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
     }
     Ok(())
 }
-
-#[inline(always)]
-pub fn error_msg_inner(_: NonZeroU32) -> Option<&'static str> {
-    None
-}

src/fuchsia.rs

@@ -7,8 +7,16 @@
 // except according to those terms.
 
 //! Implementation for Fuchsia Zircon
-use crate::Error;
-use core::num::NonZeroU32;
+use core::convert::Infallible;
+
+pub type Error = Infallible; // Zircon's RNG cannot fail
+
+#[cfg(feature = "std")]
+impl From<Error> for std::io::Error {
+    fn from(err: Error) -> Self {
+        match err {}
+    }
+}
 
 #[link(name = "zircon")]
 extern "C" {
@@ -19,8 +27,3 @@ pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
     unsafe { zx_cprng_draw(dest.as_mut_ptr(), dest.len()) }
     Ok(())
 }
-
-#[inline(always)]
-pub fn error_msg_inner(_: NonZeroU32) -> Option<&'static str> {
-    None
-}

src/ios.rs

@@ -7,11 +7,9 @@
 // except according to those terms.
 
 //! Implementation for iOS
-extern crate std;
+use crate::util::StaticError;
 
-use crate::Error;
-use core::num::NonZeroU32;
-use std::io;
+pub type Error = StaticError;
 
 // TODO: Make extern once extern_types feature is stabilized. See:
 //   https://github.com/rust-lang/rust/issues/43467
@@ -28,14 +26,8 @@ extern "C" {
 pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
     let ret = unsafe { SecRandomCopyBytes(kSecRandomDefault, dest.len(), dest.as_mut_ptr()) };
     if ret == -1 {
-        error!("SecRandomCopyBytes call failed");
-        Err(io::Error::last_os_error().into())
+        Err(StaticError("SecRandomCopyBytes: call failed"))
     } else {
         Ok(())
     }
 }
-
-#[inline(always)]
-pub fn error_msg_inner(_: NonZeroU32) -> Option<&'static str> {
-    None
-}