How to install locally an extension in SQLite on a Mac? - php

Question

I've no real knowledge about installing an extension. I'm stuck because I cannot use SQRT in SQLite.
I'm using Laravel on a local machine and I'm working on my PHPunit Tests. In one Test I'm using a query with some heavy math functions.
I get the error:
Caused by
PDOException: SQLSTATE[HY000]: General error: 1 no such function: SQRT
I found out that SQLite has an extension called: extension-functions.c
I downloaded it, but I'm not sure if I did everything correctly (obviously not because it does not work):
I downloaded it and used this in my terminal
gcc -fno-common -dynamiclib extension-functions.c -o libsqlitefunctions.dylib
It compiled this data: libsqlitefunctions.dylib
With php --ini if found that my php.ini is located in /usr/local/etc/php/7.1/php.ini
Now I looked up for sqlite3 and found this commented ;sqlite3.extension_dir =
I changed it to
sqlite3.extension_dir =/usr/local/etc/php/7.1/extension/libsqlitefunctions.dylib
and created the extension folder and put the dylib file inside
I restarted my apache with sudo apachectl restart
And tried my Query and still, it fails. What did I do wrong?
For future readers
To use it in Laravel you call it like this:
$pdo = DB::connection()->getPdo();
$pdo->sqliteCreateFunction('SQRT', 'sqrt', 1);
$pdo->sqliteCreateFunction('ASIN', 'asin', 1);
$pdo->sqliteCreateFunction('SIN', 'sin', 1);
$pdo->sqliteCreateFunction('COS', 'cos', 1);
$pdo->sqliteCreateFunction('POWER', 'pow', 2);
$pdo->sqliteCreateFunction('pi', 'pi', 0);

Answer 1

It seems that you want to use this with PDO. The problem is that loading extensions only works with the SQLite3 api directly, using the SQLite3::loadExtension method.
The PDO driver does not allow the loading of extensions (see this wiki entry regarding LoadableExtensions under "Security Considerations").
So you could either swith to the SQLite3 api directly or you could use "user defined functions" with PDO. For example if you need the SQRT function:
$db = new PDO('sqlite:testdb.sqlite', null, null, [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
]);
$db->sqliteCreateFunction('SQRT', 'sqrt', 1);
$stmt = $db->query("SELECT sqrt(25)");
foreach ($stmt as $row) {
echo $row[0], PHP_EOL; // output: 5.0
}
Most of the math-functions your extension provides map 1:1 to the PHP function names (like sqrt), so it should be easy to create the functions you need.

Answer 2

It seems you are pointing the sqlite3.extension_dir property at a file instead of a directory. According to the manual for sqlite3, the extension_dir property is:
[The] Path to the directory where the loadable extensions for SQLite reside.
I think it may work if you change
sqlite3.extension_dir = /usr/local/etc/php/7.1/extension/libsqlitefunctions.dylib
to
sqlite3.extension_dir = /usr/local/etc/php/7.1/extension
However, I would create a separate directory for the SQLite3 extensions so they are not mixed with the PHP extensions; I say this since it seems like you are currently using the PHP extension directory for the sqlite3.extension_dir property. (If you aren't, then please disregard this note.) I assume that SQLite3 just scans the configured directory for loadable modules and loads them using something like dlopen. This might conflict if it tries to load a PHP extension. (Who knows, it may gracefully handle this.)