if the past we had lots of crashes because of unexpected unwrap failures,
mostly related to string.
this commit avoids them eg. for string-conversions that may panic
eg. when encountering a null-byte or by logical programming errors
where an object is assumed to be set but is not under unexpected circumstances.
There is very little API guarantees about this, but clients seem to
expect *something* to work on a closed context. So split this up into
static info an more dynamic context-related info, but let's not
provide any guarantees about what keys are available when.
Fixes#599
A lot of work from @Hocuri and @Simon-Laux mostly.
This exposes the API of the deltachat-provider-overview crate on the
deltachat FFI API, allowing clients to use it to help users set up
their accounts.
This adopts the FFI API to use the new Context::new() and
Contest::drop() Rust-style APIs while preserving the semantics of the
existing FFI API. It introduces a wrapper around the context which
keeps an optional reference to the actual context, changing dc_open()
and dc_close() to create/destroy the actual reference.
This changes the events emitted on closing slightly: they only get
emitted when dc_close() was called while the context was open. While
dc_close() remains idempotent in that it can still be called safely
multiple times, the close events will only occur if the context is
actually closed.
A new context is now created by calling Context::new and therefore you
always have a valid context. This is much more in Rust style and will
allow a lot of furture simplifications on the context itself.
The FFI layer has not yet been adjusted in this commit and thus will
fail.
Adjust call sites as apporiate:
* src/dc_imex.rs(dc_continue_key_transfer): use if-let pattern
with dc_read_file_safe() and dc_msg_get_file()
* src/message.rs(dc_msg_get_setupcodebegin): ditto
* src/message.rs(dc_get_msg_info): simplify code to print information
about file inside a message.
* src/message.rs(dc_msg_get_file): simplify function using
dc_get_abs_path_safe()
* deltachat-ffi/src/lib.rs(dc_msg_get_file): convert PathBuf to `char *`
to preserve C API
