io: add error kinds from std.

embedded-io/src/adapters.rs

@@ -126,15 +126,51 @@ impl<T: crate::Seek + ?Sized> std::io::Seek for ToStd<T> {
     }
 }
 
-fn to_std_error<T: core::fmt::Debug>(err: T) -> std::io::Error {
-    let kind = std::io::ErrorKind::Other;
+fn to_std_error<T: crate::Error>(err: T) -> std::io::Error {
+    let kind = match err.kind() {
+        crate::ErrorKind::NotFound => std::io::ErrorKind::NotFound,
+        crate::ErrorKind::PermissionDenied => std::io::ErrorKind::PermissionDenied,
+        crate::ErrorKind::ConnectionRefused => std::io::ErrorKind::ConnectionRefused,
+        crate::ErrorKind::ConnectionReset => std::io::ErrorKind::ConnectionReset,
+        crate::ErrorKind::ConnectionAborted => std::io::ErrorKind::ConnectionAborted,
+        crate::ErrorKind::NotConnected => std::io::ErrorKind::NotConnected,
+        crate::ErrorKind::AddrInUse => std::io::ErrorKind::AddrInUse,
+        crate::ErrorKind::AddrNotAvailable => std::io::ErrorKind::AddrNotAvailable,
+        crate::ErrorKind::BrokenPipe => std::io::ErrorKind::BrokenPipe,
+        crate::ErrorKind::AlreadyExists => std::io::ErrorKind::AlreadyExists,
+        crate::ErrorKind::InvalidInput => std::io::ErrorKind::InvalidInput,
+        crate::ErrorKind::InvalidData => std::io::ErrorKind::InvalidData,
+        crate::ErrorKind::TimedOut => std::io::ErrorKind::TimedOut,
+        crate::ErrorKind::Interrupted => std::io::ErrorKind::Interrupted,
+        crate::ErrorKind::Unsupported => std::io::ErrorKind::Unsupported,
+        crate::ErrorKind::OutOfMemory => std::io::ErrorKind::OutOfMemory,
+        _ => std::io::ErrorKind::Other,
+    };
     std::io::Error::new(kind, format!("{:?}", err))
 }
 
 #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl crate::Error for std::io::Error {
     fn kind(&self) -> crate::ErrorKind {
-        crate::ErrorKind::Other
+        match self.kind() {
+            std::io::ErrorKind::NotFound => crate::ErrorKind::NotFound,
+            std::io::ErrorKind::PermissionDenied => crate::ErrorKind::PermissionDenied,
+            std::io::ErrorKind::ConnectionRefused => crate::ErrorKind::ConnectionRefused,
+            std::io::ErrorKind::ConnectionReset => crate::ErrorKind::ConnectionReset,
+            std::io::ErrorKind::ConnectionAborted => crate::ErrorKind::ConnectionAborted,
+            std::io::ErrorKind::NotConnected => crate::ErrorKind::NotConnected,
+            std::io::ErrorKind::AddrInUse => crate::ErrorKind::AddrInUse,
+            std::io::ErrorKind::AddrNotAvailable => crate::ErrorKind::AddrNotAvailable,
+            std::io::ErrorKind::BrokenPipe => crate::ErrorKind::BrokenPipe,
+            std::io::ErrorKind::AlreadyExists => crate::ErrorKind::AlreadyExists,
+            std::io::ErrorKind::InvalidInput => crate::ErrorKind::InvalidInput,
+            std::io::ErrorKind::InvalidData => crate::ErrorKind::InvalidData,
+            std::io::ErrorKind::TimedOut => crate::ErrorKind::TimedOut,
+            std::io::ErrorKind::Interrupted => crate::ErrorKind::Interrupted,
+            std::io::ErrorKind::Unsupported => crate::ErrorKind::Unsupported,
+            std::io::ErrorKind::OutOfMemory => crate::ErrorKind::OutOfMemory,
+            _ => crate::ErrorKind::Other,
+        }
     }
 }
 

embedded-io/src/lib.rs

@@ -29,9 +29,67 @@ pub enum SeekFrom {
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[non_exhaustive]
 /// Possible kinds of errors.
+///
+/// This list is intended to grow over time and it is not recommended to
+/// exhaustively match against it. In application code, use `match` for the `ErrorKind`
+/// values you are expecting; use `_` to match "all other errors".
+///
+/// This is the `embedded-io` equivalent of [`std::io::ErrorKind`], except with the following changes:
+///
+/// - `WouldBlock` is removed, since `embedded-io` traits are always blocking. See the [crate-level documentation](crate) for details.
+/// - `WriteZero` is removed, since it is a separate variant in [`WriteAllError`] and [`WriteFmtError`].
 pub enum ErrorKind {
     /// Unspecified error kind.
     Other,
+
+    /// An entity was not found, often a file.
+    NotFound,
+    /// The operation lacked the necessary privileges to complete.
+    PermissionDenied,
+    /// The connection was refused by the remote server.
+    ConnectionRefused,
+    /// The connection was reset by the remote server.
+    ConnectionReset,
+    /// The connection was aborted (terminated) by the remote server.
+    ConnectionAborted,
+    /// The network operation failed because it was not connected yet.
+    NotConnected,
+    /// A socket address could not be bound because the address is already in
+    /// use elsewhere.
+    AddrInUse,
+    /// A nonexistent interface was requested or the requested address was not
+    /// local.
+    AddrNotAvailable,
+    /// The operation failed because a pipe was closed.
+    BrokenPipe,
+    /// An entity already exists, often a file.
+    AlreadyExists,
+    /// A parameter was incorrect.
+    InvalidInput,
+    /// Data not valid for the operation were encountered.
+    ///
+    /// Unlike [`InvalidInput`], this typically means that the operation
+    /// parameters were valid, however the error was caused by malformed
+    /// input data.
+    ///
+    /// For example, a function that reads a file into a string will error with
+    /// `InvalidData` if the file's contents are not valid UTF-8.
+    ///
+    /// [`InvalidInput`]: ErrorKind::InvalidInput
+    InvalidData,
+    /// The I/O operation's timeout expired, causing it to be canceled.
+    TimedOut,
+    /// This operation was interrupted.
+    ///
+    /// Interrupted operations can typically be retried.
+    Interrupted,
+    /// This operation is unsupported on this platform.
+    ///
+    /// This means that the operation can never succeed.
+    Unsupported,
+    /// An operation could not be completed, because it failed
+    /// to allocate enough memory.
+    OutOfMemory,
 }
 
 /// Error trait.