No change in functionality, just code comprehension

This allows a server that's being terminated to stop the port-bind delay/retry
loops and terminate more quickly in cases of port binding failures.

Log the error string if it's non-blank, as a warning (e.g. unrecognized
text.ini text.dat string ID).

Reduce the number of logged messages when config load failure happens.

Commonize the load_cfg() error log messages.

uncrustify nl_split_if_one_liner setting

... using uncrustify mod_paren_on_return config

White-space changes only, exception being the rare insertion of NL before
closing brace (couldn't find the option to disable that behavior).

I excluded some header files (e.g. sbbs.h) since uncrustify seemed to be doing
more harm than good there. I might just end up applying different set of rules
to .h files.

This fixes issue #748

e.g. [can|is]_subject_something() is now named subject_[can|is]_something()

No functional change.

As an alternative to directory aliases configured in ftpalias.cfg and/or
web_alias.ini, a sysop can specify a shortcut (virtual directory name) per
directory in SCFG->File Areas. These shortcuts will appears as top/root level
directories in the FTP and Web servers for quick user access to important
directories.

The advantages (over ftpalias.cfg / web_alias.ini) are:
- one place to configure
- FILE_FTP_PATH and FILE_WEB_PATH @-codes will use the shortcut
  (usually a shorter, preferred virtual path to the directory)

* New JS file_area.dir[].vshortcut property

Can't used designated initializers in fmutex_init() because this file is still
built with C++Builder6.

For some reason, MSVC was initializing the time_t (second element of the
struct) to -1, not the int fd (the first element), which was initialized to
0. Weird.

The auto-remove param was only needed for fmutex(), which immediately closes
(and thus don't want auto-removal), so create an internal function that's
used by both fmutex() and fmutex_open().

This is needed for *nix where normal (i.e. not Samba-mount) file behavior
requires that we manually unlink() the file, but not until just before closing
it. So we have to keep track of the file name and the 'auto_remove' desire of
the caller. This is not necessary when the file is on a Linux-smbfs, but we
need to work as expected on normal/local *nix file systems too.

This solves atomic lock file removal for *nix, but does not gaurantee lock file
cleanup upon ungraceful process termination (e.g. crash). At least in this
particular case, Windows beats UNIX.

Add the errno value to help root-cause.

We really should be using safe_strerror() everywhere.

This appears to be the only way to 100% provide mutual exclusivity between
Windows and Linux client sharing a Samba file system.

Also, make fmutex_close() take a pointer to the file descriptor so that we can
better manage the resource (i.e. don't close a descriptor that's already been
closed and possibly valid in another thread).

Vertrauen's FTP server gets abused by QWKnet logins sometimes and handling
the race conditions around QWK packet creation attempts is silly - there's
no legit reason why a QWKnet account needs to be logged-in multiple times
concurrently to the hub's FTP server, so reject the subsequent logins even
when they're on different hosts (as is the case with Vertrauen).

As part of this change:
- fmutex() now takes an new time_t* argument to (optionally) store the
  time of the mutex file for helping logging (locked since when?).
- time_as_hhmm() created to format a string as either HH:MM or HH:MM[a|p]
  (depending on system configuration for 12 or 24 hour time formatting).
- renamed the old hhmmtostr ()to tm_as_hhmm() (since it takes a struct tm arg)
  and have it return a non-padded string (useful in more situations without
  requiring truncation) when the sysop prefers 24-hour time.

Trying to get to the bottom of user.tab corruption (issue #797).

There are still places where it could be logged in <> (if username is not yet
known).

receive_thread() needs to use the control session correctly for
TLS connections.

Ideally, a sysop would never need to disable FTPS support, but as a trouble
shooting measure, it can be helpful.

We don't log highwater valeus of 1, though those are published to MQTT.

Not dealing with 'services' server yet, cause that's kind of tricky with the
sysop likely wanting to know per-service stats (served counter, highwater
mark, etc.)

Fix observed crash when shutting down services server where the client_t
protocol was pointing to a freed service's protocol description string.

This was the last pointer in client_t and should resolve the last race
conditions (memory ownership issues) with its data members.

This also resolves a small memory leak in getnodeclient() where the last
client "gotten" would have its heap-duplicated protocol string leaked.

This allows each call to ftp_remote() to specify the log level for any remove
failure. All others file-removal failures will continue to log at ERROR level.

I get this particular (harmless) error a lot, so just reducing to warning:
ftp  ... !ERROR 13 (Permission denied) (line 860) removing file: path/to/*.qwk

The Git commit date/time is more useful information.

Commit 75c5c9e5 was initially to address server termination (sisue #236), but
expanded in scope to include server recycling (e.g. due to semaphore/config
file touch) and that turns out to not be what most sysops want.

If you want an immediate/ungraceful recycle, do a restart (shutdown/stop and
then start) instead.

Immediate/ungraceful server shutdown/termination is still in effect however.

No change to the "server pause" feature either, so combining pause with
recycle would be effective to prevent *new* client connections while waiting
for existing clients to disconnect and allow a recycle to happen.

value that's not an off_t as one.

These should've been static to begin with, like the other servers. Explains why FTP error message are with "term" as the server.

TLS 1.2.  For static services and JS sockets, add a new tls_minver
socket property which can be set to use a lower minver (down to the
wildly insecure TLS 1.0).

TLS 1.0 and 1.1 have been not reccomended since 2015, and deprecated
since 2021.

Use cryptDestroySession() instead.

Reported by Max (WESTLINE)...

Introduced in commit 75c5c9e5, since we are now calling the set_state()
callback periodically, and in sbbsctrl, it sets/resets the pause button
checked (depressed) state in response to this callback (should it?), this was
resetting the pause button checked/depressed state peridically (at the
configured sem file check interval, default 2 seconds).

The fix: if the new server state is the same as the previously set server
state, don't call the set_state() callback. I considered this as a potential
optimization when I first wrote that commit, but didn't see any obvious
downside to calling the set_state() callback redundantly. Now that I see a
downside, let's implement this saving/checking of the state to avoid
redundant "set" calls.

We have checks/loops/timeouts waiting for active clients to disconnect and
child thread threads to terminate whenever shutting down or recycling already,
so this should be safe. This pretty simple change fixes issue #236 (can't
terminate server under heavy load).

Also as part of this commit, introduced the ability to "pause" a server
(prevent it from accepting new connections) with the ctrl/pause semaphore
file or via the MQTT server/pause (and resume) topics. This feature is useful
when debugging server issues where you don't necessarily want to fully
shutdown/terminate the server, but don't want any new connections to be
accepted (the listen backlog will fill up with incoming connections though).
Unlike a server shutdown, a server pause can be "undone" via MQTT (by
publishing a message to the "resume" topic).

The "pause" semaphore file is just an "existence" semaphore file - its
date/time stamp doesn't matter. If the file exists, the server will enter
a paused state (and periodically log messages to that fact) until the semfile
is deleted.

This server pause feature is not the same as the pause button function in
sbbsctrl, which just pauses server log output.

Support was accidentally removed as part of commit 22e8d2e3, meaning
the ftpalias.cfg wasn't used at all in responses to the MLSx commands as
reported by Max (WESTLINE) using Total Commander, FileZilla and Directory
opus. The traditional "LIST" commands still worked fine with ftpalias.cfg
contents just fine.

The reason this code was accidentally removed was due to the errant
copy/pasted comparison with startup->html_index_file that did not belong here
and made the block appear related to HTML index file generation. It was not.
This was just a bug in the initial implementation of MLSx support in
commit d4deb4b3.

Also included in this commit:
- Return the date/size of the user's QWK packet file, if it exists, in MLSx
  response.
- send_mlsx_entry() won't report negative time_t values as file modify dates
 (flength returns -1 upon failure/file-not-found).
- get_owner_name() returns the string, making it easier to use in function
  calls.

There appears to still be some work to do to make the MLSx commands fully
compliant with RFC 3659 (e.g. "mlst filename" from ftpalias.cfg should work
but does not), but at least FileZilla displays ftpalias.cfg files and
directories correctly now.