Swap system libsqlite3 for Doltlite and harden verification

The first attempt used LD_PRELOAD, but pdo_sqlite.so's DT_NEEDED on
libsqlite3.so.0 resolved to the system SQLite and the preload was
ignored — the tests passed against stock SQLite, not Doltlite.

Physically replace /usr/local/lib/libsqlite3.so.0 (and the multiarch
symlink) with libdoltlite.so, run ldconfig, and assert that
doltlite_engine() returns 'prolly' before running PHPUnit.

Author: JanJakes

.github/workflows/phpunit-tests-doltlite.yml

@@ -46,16 +46,41 @@ jobs:
           php-version: '${{ matrix.php }}'
           tools: phpunit-polyfills
 
-      - name: Verify Doltlite is wired up via LD_PRELOAD
-        env:
-          LD_PRELOAD: ${{ github.workspace }}/doltlite-src/build/libdoltlite.so
+      - name: Install Doltlite as the system libsqlite3
+        # Replace the system libsqlite3 the dynamic linker resolves for
+        # pdo_sqlite with the Doltlite build. This is more reliable than
+        # LD_PRELOAD, which loses to pdo_sqlite's DT_NEEDED on libsqlite3.so.0.
         run: |
+          SRC="${GITHUB_WORKSPACE}/doltlite-src/build/libdoltlite.so"
+          test -f "$SRC"
+
+          # Drop the build into /usr/local/lib and point libsqlite3 sonames at it,
+          # both in /usr/local/lib (takes precedence in ld.so.conf) and in the
+          # multiarch dir so anything hard-coded to that path still works.
+          sudo install -m 0755 "$SRC" /usr/local/lib/libdoltlite.so
+
+          sudo ln -sf /usr/local/lib/libdoltlite.so /usr/local/lib/libsqlite3.so
+          sudo ln -sf /usr/local/lib/libdoltlite.so /usr/local/lib/libsqlite3.so.0
+
+          MULTIARCH_DIR="$(dirname "$(readlink -f /lib/x86_64-linux-gnu/libsqlite3.so.0)")"
+          sudo rm -f "${MULTIARCH_DIR}/libsqlite3.so.0"
+          sudo ln -s /usr/local/lib/libdoltlite.so "${MULTIARCH_DIR}/libsqlite3.so.0"
+
+          sudo ldconfig
+
           echo "ldd pdo_sqlite:"
-          ldd "$(php -r 'echo ini_get("extension_dir");')/pdo_sqlite.so" || true
-          echo
-          php -r '$v = (new PDO("sqlite::memory:"))->query("SELECT SQLITE_VERSION()")->fetch()[0]; echo "SQLITE_VERSION() = $v\n";'
-          echo "If Doltlite is active, the engine() check below should print 'prolly':"
-          php -r '$r = (new PDO("sqlite::memory:"))->query("SELECT doltlite_engine()")->fetch(); var_dump($r);' || true
+          ldd "$(php -r 'echo ini_get("extension_dir");')/pdo_sqlite.so"
+
+      - name: Verify Doltlite is active in PHP
+        run: |
+          VERSION=$(php -r 'echo (new PDO("sqlite::memory:"))->query("SELECT SQLITE_VERSION()")->fetch()[0];')
+          ENGINE=$(php -r 'echo (new PDO("sqlite::memory:"))->query("SELECT doltlite_engine()")->fetch()[0];')
+          echo "SQLITE_VERSION()  = ${VERSION}"
+          echo "doltlite_engine() = ${ENGINE}"
+          if [ "${ENGINE}" != "prolly" ]; then
+            echo "::error::Doltlite is not active (expected doltlite_engine() = 'prolly', got '${ENGINE}')"
+            exit 1
+          fi
 
       - name: Install Composer dependencies (root)
         uses: ramsey/composer-install@v3
@@ -71,7 +96,5 @@ jobs:
           composer-options: "--optimize-autoloader"
 
       - name: Run PHPUnit tests against Doltlite
-        env:
-          LD_PRELOAD: ${{ github.workspace }}/doltlite-src/build/libdoltlite.so
         run: php ./vendor/bin/phpunit -c ./phpunit.xml.dist
         working-directory: packages/mysql-on-sqlite