With this change, we get more fine-grained error messages if something
goes wrong in the course of communicating with the SQLite database. To
pick some random examples, the error codes SQLITE_IOERR_NOMEM,
SQLITE_IOERR_CORRUPTFS or SQLITE_IOERR_FSYNC are way more specific than just a
plain SQLITE_IOERR, and the corresponding error messages generated by
sqlite3_errstr() will hence give a better hint to the user (or also to the
developers, if an error report is sent) what the cause for a failure is.
Since we want tests to run quickly, and since tests do a lot more db
operations than expected we expect to see in actual usage, we disable
sqlite's syncing behavior to make db operations run much faster. This
syncing behavior is necessary for normal operation as it helps guarantee
that data won't become lost or corrupted, but in tests, we don't care
about that.
No change in behavior. Just remove a little bit of code, reduce macro usage,
remove duplicative functions, and make BDB and SQLite implementations more
consistent with each other.
This commit does not change to any code and behavior. It it is easily reviewed
with the --color-moved=dimmed_zebra git diff option.
Motivation for this change is to:
- Consolidate redundant functions
IsBDBFile /ExistsBerkeleyDatabase / SplitWalletPath, and
IsSQLiteFile / ExistsSQLiteDatabase in the next commits
- Detect SQLite wallets consistently regardless whether bitcoin is built with
SQLite support in the next commits
- Avoid attempting to open SQLite databases with the BDB library when bitcoin
is built without SQLite support in the next commits
If there is no terminating zero within the 16 magic bytes, the buffer would be
over-read in the std::string constructor. Fixed by using the "from buffer"
variant of the ctor (that also takes a size) rather than the "from c-string"
variant.
Rewrite uses the VACUUM command which does exactly what we want. A
specific advertised use case is to compact a database and ensure that
any deleted data is actually deleted.
sqlite3 recommends that sqlite3_initialize be called when the
application starts, and sqlite3_shutdown when it stops. Since we don't
always use sqlite3, we initialize it when a SQLiteDatabse is constructed
(calling sqlite3_initialize after initialized is a no-op). We call
sqlite3_shutdown when we see that there are no databases opened. The
number of open databases is tracked by an atomic g_dbs_open.
