[BRLTTY] Low-level BrlAPI questions

[Aura Kelloniemi]

Hi list,

Thanks for the fixes Samuel!

On 2021-03-26 at 22:51 +0100, Samuel Thibault <samuel.thibault at ens-lyon.org> wrote:
 > Aura Kelloniemi, le ven. 26 mars 2021 22:45:43 +0200, a ecrit:
 > > - What is the best way to write to the display if the input text is always
 > >   UTF-8 encoded? (This is how Rust's strings work).

 > You can just emit UTF-8.

Byt what happens if the user's locale uses some other charset and I write with
brlapi__writeText?

How does the charset field in brlapi_writeArguments_t work? What kind of
charset names it understands?

 > > - What is the intended use of enterTtyModeWithPath?

 > It is meant for screen readers, that take control of a whole desktop.
 > For more rationale, see the “A pile of "paper sheets"” section of the
 > brlapi documentation.

Will the given tty path be prepended by tty numbers from other sources – e.g.
the WINDOWPATH environemnt variable?

 > > - It is not always clear who owns the data returned by BrlAPI functions.

 > For which function is this not clear?

- brlapi__openConnection: it manipulates the settings struct passd as
  parameter
- brlapi_strerror
- Possibly some others, but I haven't found them yet

I have digged information from the client source, but it would be good to
get it documented.

 > > To me it looks like brlapi_error_location allocates new memory for
 > > each thread, but it is never freed.

 > It uses pthread_once(&error_key_once, error_key_alloc); that calls
 > pthread_key_create(&error_key, error_key_free);

Yes, ok, great.

Additional questions:
- What is the displayNumber field in brlapi_writeArguments_t?

- What happens if I replace my display with another unit with a different size
  while BrlAPI clients are running? (Assuming that the same BRLTTY instance
  finds the new display and takes control of it. I cannot test this now.)

- Could the BRLAPI_ERROR_... constants form an enum type, or would it break
  something?
  
-- 
Aura