The fs.* files are already part of the libbitcoin_util library. With the
introduction of the fs_helpers.* it makes sense to move fs.* into the
util/ directory as well.
Add common InitConfig function to deduplicate bitcoind and bitcoin-qt code
reading config files and creating the datadir.
There are a few minor changes in behavior:
- In bitcoin-qt, when there is a problem reading the configuration file, the
GUI error text has changed from "Error: Cannot parse configuration file:" to
"Error reading configuration file:" to be consistent with bitcoind.
- In bitcoind, when there is a problem reading the settings.json file, the
error text has changed from "Failed loading settings file" to "Settings
file could not be read" to be consistent with bitcoin-qt.
- In bitcoind, when there is a problem writing the settings.json file, the
error text has changed from "Failed saving settings file" to "Settings file
could not be written" to be consistent with bitcoin-qt.
- In bitcoin-qt, if there datadir is not accessible (e.g. no permission to read),
there is an normal error dialog showing "Error: filesystem error: status:
Permission denied [.../settings.json]", instead of an uncaught exception
