db/sqlite3: add support for loading extensions

racket/collects/db/private/sqlite3/connection.rkt

@@ -1,5 +1,6 @@
 #lang racket/base
 (require racket/class
+         ffi/file
          ffi/unsafe
          ffi/unsafe/atomic
          ffi/unsafe/custodian
@@ -10,7 +11,10 @@
          "ffi.rkt"
          "dbsystem.rkt")
 (provide connection%
-         handle-status*)
+         handle-status*
+         (protect-out unsafe-load-extension))
+
+(define-local-member-name unsafe-load-extension)
 
 ;; == Connection
 
@@ -359,6 +363,18 @@
 
     ;; ----
 
+    (define/public (unsafe-load-extension who lib)
+      (define lib-path (cleanse-path (path->complete-path lib)))
+      (security-guard-check-file who lib-path '(read execute))
+      (call-with-lock who
+        (lambda ()
+          (HANDLE who (A (sqlite3_enable_load_extension -db 1)))
+          (HANDLE who (A (sqlite3_load_extension -db lib-path)))
+          (HANDLE who (A (sqlite3_enable_load_extension -db 0)))
+          (void))))
+
+    ;; ----
+
     (define-syntax HANDLE
       (syntax-rules ()
         [(HANDLE who expr)

racket/collects/db/private/sqlite3/ffi.rkt

@@ -222,3 +222,19 @@
 (define-sqlite sqlite3_last_insert_rowid
   (_fun _sqlite3_database
         -> _int64))
+
+;; ----------------------------------------
+
+(define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005) ;; int int*
+
+(define-sqlite sqlite3_db_config
+  (_fun _sqlite3_database _int _int (out : (_ptr o _int))
+        -> (r : _int) -> r)) ;; FIXME: return out?
+
+(define-sqlite sqlite3_enable_load_extension
+  (_fun _sqlite3_database _int -> _int))
+
+(define-sqlite sqlite3_load_extension
+  ;; FIXME: handle error string?
+  (_fun _sqlite3_database _path (_pointer = #f) (_pointer = #f)
+        -> _int))