ei: add support for libei

src/ei/ei_client/ei_error.rs

@@ -0,0 +1,45 @@
+use {
+    crate::{
+        ei::ei_object::{EiInterface, EiObjectId},
+        utils::buffd::{BufFdError, EiMsgParserError},
+    },
+    std::error::Error,
+    thiserror::Error,
+};
+
+#[derive(Debug, Error)]
+pub enum EiClientError {
+    #[error("An error occurred reading from/writing to the client")]
+    Io(#[from] BufFdError),
+    #[error("An error occurred while processing a request")]
+    RequestError(#[source] Box<EiClientError>),
+    #[error("Client tried to invoke a non-existent method")]
+    InvalidMethod,
+    #[error("The message size is < 16")]
+    MessageSizeTooSmall,
+    #[error("The message size is > 2^16")]
+    MessageSizeTooLarge,
+    #[error("The size of the message is not a multiple of 4")]
+    UnalignedMessage,
+    #[error("The object id is unknown")]
+    UnknownId,
+    #[error("Client tried to access non-existent object {0}")]
+    InvalidObject(EiObjectId),
+    #[error("The id is already in use")]
+    IdAlreadyInUse,
+    #[error("The client object id is out of bounds")]
+    ClientIdOutOfBounds,
+    #[error("Could not process a `{}.{}` request", .interface.name(), .method)]
+    MethodError {
+        interface: EiInterface,
+        method: &'static str,
+        #[source]
+        error: Box<dyn Error + 'static>,
+    },
+    #[error("Could not add object {0} to the client")]
+    AddObjectError(EiObjectId, #[source] Box<EiClientError>),
+}
+
+#[derive(Debug, Error)]
+#[error("Parsing failed")]
+pub struct EiParserError(#[source] pub EiMsgParserError);