logging vty: rewrite 'logging level' vty cmd generation

Completely drop the implementations of log_vty_command_{str,description}().
These functions have been public API once, marked as deprecated since
c65c5b4ea075ef6cef11fff9442ae0b15c1d6af7 (March 2017). I considered to keep
them, or reduce them to useless stubs, but it is quite silly, really. These
functions are completely and utterly useless outside of libosmocore. Any
program linking these deserves to fail.

Re-implement vty logging level command gen, in logging_vty.c. logging.c is
simply the wrong place for that.

Introduce logging_internal.h to share logging definitions to logging_vty.c
without publishing as API.

Introduce static gen_logging_level_cmd_strs() to compose a list of category
arguments with their descriptions for VTY commands. Use osmo_talloc_asprintf()
instead of the previous error prone and chaotic strlen() counting method.

Do not dynamically generate log level arguments, just keep static strings. We
are super unlikely to ever change the log levels we have.

No changes in logging_vty_test.vty: proves that there is no functional change.

All of this, besides introducing basic sanity, is cosmetic preparation to be
able to re-use the generic command generation code for arbitrary commands with
category or level args (for deprecated and new keywords).

Rationale: I want to hide 'all' and 'everything' from the VTY command
documentation, by means of deprecating. I first tried to simply define a
deprecated 'logging level CAT everything' command:

  logging level (all|rsl|rr|...) (debug|info|notice|error|fatal)
  logging level CAT everything                   # <- deprecated and hidden

But unfortunately, command matching doesn't work as intended when the CAT
argument reflects a valid category; I want it to invoke the deprecated function
as soon as the 'everything' keyword follows, but it stays stuck to the "valid"
command when the category argument matches an explicit keyword in that list,
and will throw an error on the following 'everything' keyword. I.e.:

  logging level rsl everything
  % Unknown command  # <-- leads to config file parse error

  logging level unknown_string everything
  % Ignoring deprecated 'everything'  # <-- works only for invalid categories

So I need to define 'everything' separately, again with a list of each valid
category instead of a generic CAT arg.

Change-Id: I3b083f27e3d751ccec258880ae7676e9af959a63

0 files changed, 0 insertions, 0 deletions