The C++ std::getenv is guaranteed thread-safe by the C++11 specification,
whereas the POSIX/C getenv might not be thread-safe by the C11 specification.
We often ask people for their openttd.cfg, which now includes their
passwords, usernames, etc. It is easy for people to overlook this,
unwillingly sharing information they shouldn't.
By splitting this information over either private.cfg or secrets.cfg,
we make it more obvious they shouldn't be sharing those files, and
hint to what is inside them.
This is extreme useful for automated testing. Without this, OpenTTD
will always look in your personal-dir (like ~/.local/share/openttd
or %USER%\Documents\OpenTTD). For most users this is exactly what
we want, that there is a shared place for all their files.
However, for automated testing this is rather annoying, as your
local development files influence the automated test. As such,
'-X' counters this, and only gives the local folders. This is
especially useful in combination with '-x' and '-c'.
This means that if you start OpenTTD with "-c" to indicate another
location to store files, it can still read the content you already
downloaded from your PERSONAL_DIR. This folder is, however,
read-only.
This is useful for situations where you downloaded OpenGFX via
the content-service, but want to run the regression or want to
run with a clean configuration. With this change, you no longer
need to download OpenGFX again.
On Windows, relative folders don't work so well. So we need to
lookup the full path. This is best done in DetermineBasePaths()
and as a bonus that only sets SP_WORKING_DIR once.
Basically, with '-c' you now create a sandbox. It will still use
your personal-dir and global-dir to find files you installed there,
but all new files are stored with a base folder identical to the
folder the configuration is in.
This is a bit of an old bug, that we many have tried to solve in
various of different ways. The code has grown sufficiently complex
that it is hard to see what consequences of actions are. This is
in my opinion the most harmless solution, while increasing the
usefulness of the '-c' flag.
In essence, the problem was that empty folders were always created
in the directory where the configuration was, but as that directory
wasn't added to any searchpath, files weren't stored there, unless
by accident it was a folder already on the searchpath. For example,
if you do './openttd -c local.cfg', it did work as expected. But
in the more generic variant, it did not.
With this patch, you can run './openttd -c /new/folder/local.cfg',
and it will create and prepare that folder to receive new files.
'content_download' is also stored in the directory the
configuration is in; this was already the case. Important to
note that there is only one search-path for 'content_download'.
In other words, when using '-c', it will not look in '~/.openttd'
inside the 'content_download' folder.
This was just weird. With XDG _personal_dir was created already,
but later on it was checked if it was different from config_dir,
and the creation was skipped. All this checking and validation
makes my head spin .. let's make it a bit more simple.