Please fail with KeyringError::NoBackendFound when there is no org.freedesktop.secrets available

[argv-minus-one]

When there is no Secret Service implementation available (i.e. connecting to D-Bus was successful, but there is no org.freedesktop.secrets service), the error is KeyringError::SecretServiceError(SsError::Dbus), where the name of the underlying dbus::Error is org.freedesktop.DBus.Error.ServiceUnknown.

In this situation, the keyring call should probably fail with KeyringError::NoBackendFound instead.

Failure to connect to D-Bus (because there is no session bus, and auto-starting it failed) should probably also result in KeyringError::NoBackendFound, but there doesn't appear to be a well-defined error name for that situation. Potential error names include org.freedesktop.DBus.Error.NoServer, org.freedesktop.DBus.Error.FileNotFound, or org.freedesktop.DBus.Error.NotSupported (not an exhaustive list).

[hwchen]

Thanks for looking into this! Having a KeyringError::NoBackendFound makes sense. Happy to take a PR, or I'll look into it when I have time.

[hwchen]

Finally realized that this probably belongs in keyring repo. At this moment it’s unlikely that I try to create more custom errors for dbus errors here.