io: add error kinds from std.

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.