Feature request: allow installed driver configs to live in /usr

[amluto]

In recent years, Linux distributions have moved in the direction of separating files: /usr contains files that actually belong to the distribution (although /usr/local/ is still there, etc), and /etc contains non-default configuration. The end goal would be for distributions to be able to leave /etc mostly blank or perhaps to have all-commented-out files in it.

There are certainly tricky exceptions: /etc/nsswitch.conf, /etc/hosts, /etc/resolve.conf, /etc/os-release, and quite a few others. These mostly get handled by symlinks, and the ones that don't are considered annoying and people are slowly working on them.

/etc/odbcinst.ini is a somewhat annoying special case. Drivers get installed, but they don't work until entries get added to /etc/odbcinst.ini, but making /etc/odbcinst.ini be a symlink to somewhere in /usr would make little sense.

So here's my feature request: make driver config locations more flexible. As a baseline improvement, right now driver configs come from the "system" path and the "user" path (in _SQLGetInstalledDrivers). Add a third path, e.g. /usr/lib/unixODBC/odbcinst.ini.

As an IMO better improvement, add an entire directory and get all the ini files in it, for example /usr/lib/unixODBC/odbcinst.d/*.ini. This would allow individual packages to install ODBC drivers without all touching the same file and thus requiring an installation and uninstallation script: the packages could just contain files, and the presence of the files would be sufficient for the driver to work.

(I don't actually represent any distribution, but I am doing some container work, and I currently have a special case for /etc/odbcinst.ini.)