Adjustable parameters for torrc-defaults file path and "Tor files" directory path
I propose that the firefox binary be augmented to support either command-line flags and/or to look for environment variables that specify where the
torrc-defaults file is located; and related, where the "Tor files" directory should be located/created. If it's not possible to augment the binary in this way, perhaps the paths can be configurable via firefox profile settings loaded immediately upon launch?
torrc-defaults file is always looked for in a hard-coded directory relative to the binary. On macOS that's
<app>/Contents/MacOS/../Resources/TorBrowser/Tor. And the "Tor files" directory is always located/created in a directory two levels up from the firefox profile-directory.
Those hard-wired settings make it nigh impossible, for example, to use TBB in conjunction with geckodriver, which always invokes the binary with a
--profile setting that has a parent path common to all invocations (barring OS reboots); thus, multiple running instances will collide over their "Tor files" directories. See: Command-line parameter for parent path of profile-directory?.