By loading extensions this way, it's not possible to later load
extensions using db.Exec, which improves security, and makes it much
easier to load extensions correctly. The zero value for the slice
(the empty slice) loads no extensions by default.
The extension example has been updated to use this much simpler system.
The ConnectHook field is still in SQLiteDriver in case it's needed for
other driver-wide initialization.
Updates #71 of mattn/go-sqlite3.
The ConnectHook field of an SQLiteDriver should return an error in
case something bad happened during the hook.
The extension example needs to load the extension in a ConnectHook,
otherwise the extension is only loaded in a single connection in the pool.
By putting the extension loading in the ConnectHook, its called for every
connection that is opened by the sql.DB.
This commit introduces a new type 'ErrNo', implementing the error
interface. Constants for all sqlite3 error codes are provided
in the new source file "error.go".
sqlite3 documentation states sqlite3_column_blob could modify the
the content and recommends the "safest and easiest" policy is to
invoke sqlite3_column_blob() followed by sqlite3_column_bytes()
from: http://www.sqlite.org/c3ref/column_blob.html
Sometimes it's best to not create files in the directories where code lives...
for example, that directory might be read-only, or folks might be using
source-control or build systems that disallow that behavior. To fix this, we
create a file in the temp directory and use it instead.
We don't use ioutil.TempFile(), since that actually creates the file, and we'd
like the tests to run as if the file had never existed. We use 16 bytes from
crypto/rand to avoid people doing bad things with symlinks in the temp
directory.
