mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-12-05 05:58:23 +00:00
37 lines
1.7 KiB
Markdown
37 lines
1.7 KiB
Markdown
|
# Exceptions in Core
|
||
|
|
||
|
From version 2.3.0 we try to follow few rules about how we use exceptions. All new
|
||
|
code MUST follow these.
|
||
|
|
||
|
## Usage
|
||
|
|
||
|
You MAY use any exceptions in Core's logic. Exceptions from `wire.errors` SHOULD be
|
||
|
the final exceptions that are thrown and SHOULD NOT be caught. Note that `wire.Error`
|
||
|
is a type of exception that is intended to be sent out over the wire. It should only
|
||
|
be used in contexts where that behavior is appropriate.
|
||
|
|
||
|
Custom exception type hierarchies SHOULD always be derived directly from Exception.
|
||
|
They SHOULD NOT be derived from other built-in exceptions (such as ValueError,
|
||
|
TypeError, etc.)
|
||
|
|
||
|
Deriving a custom exception type signals an intention to catch and handle it
|
||
|
somewhere in the code. For this reason, custom exception types SHOULD NOT be derived
|
||
|
from wire.Error and subclasses.
|
||
|
|
||
|
Exception strings, including in internal exceptions, SHOULD only be used in cases
|
||
|
where the text is intended to be shown on the host. Exception strings MUST NOT
|
||
|
contain any sensitive information. An explanation of an internal exception MAY be
|
||
|
placed as a comment on the raise statement, to aid debugging. If an exception is
|
||
|
thrown with no arguments, the exception class SHOULD be thrown instead of a new
|
||
|
object, i.e., `raise CustomError` instead of `raise CustomError()`.
|
||
|
|
||
|
## Tl;dr
|
||
|
|
||
|
- Do not use `wire.errors` for `try-catch` statements, use other exceptions.
|
||
|
- Use `wire.errors` solely as a way to communicate errors to the Host, do not include
|
||
|
them somewhere deep in the stack.
|
||
|
- Do not put sensitive information in exception's message. If you are not sure, do not
|
||
|
add any message and provide a comment next to the `raise` statement.
|
||
|
- Use `raise CustomError` instead of `raise CustomError()` if you are omitting the
|
||
|
exception message.
|