From 464c03efdcf3db169847a2b95ce3f847c561add8 Mon Sep 17 00:00:00 2001
From: Pasquale De Rose <akira.zeta@gmail.com>
Date: Thu, 31 Dec 2020 20:04:07 +0100
Subject: [PATCH] Added support for load dynamic extensions

---
 samples/extension_load.cr  | 24 ++++++++++++++++++++++++
 src/sqlite3/connection.cr  | 15 +++++++++++++++
 src/sqlite3/lib_sqlite3.cr | 24 ++++++++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 samples/extension_load.cr

diff --git a/samples/extension_load.cr b/samples/extension_load.cr
new file mode 100644
index 0000000..ec16ed6
--- /dev/null
+++ b/samples/extension_load.cr
@@ -0,0 +1,24 @@
+require "db"
+require "../src/sqlite3"
+
+db = DB.open "sqlite3://%3Amemory%3A"
+
+db.setup_connection do |connection|
+  connection.enable_extension_load true
+  connection.load_extension "/usr/local/lib/mod_spatialite"
+  connection.enable_extension_load false
+end
+
+INSERT_POINT_QUERY = "insert into contacts values (?, SetSRID(MakePoint(?, ?),2261))"
+
+db.exec "create table contacts (name text, position)"
+db.exec INSERT_POINT_QUERY, "John Doe", 51.5074, 0.1278
+db.exec INSERT_POINT_QUERY, "Mario Rossi", 41.9028, 12.4964
+db.exec INSERT_POINT_QUERY, "Dewayne Abara", 9.7054, 43.6327
+db.exec INSERT_POINT_QUERY, "Toshiro Ito", 35.6762, 139.6503
+
+db.query "select a.name, b.name, st_distance(a.position, b.position) from contacts a, contacts b where a.name != b.name" do |rs|
+  rs.each do
+    puts "Distance between #{rs.read(String)} and #{rs.read(String)} is #{rs.read(Float)}"
+  end
+end
\ No newline at end of file
diff --git a/src/sqlite3/connection.cr b/src/sqlite3/connection.cr
index ca60043..dfe53ca 100644
--- a/src/sqlite3/connection.cr
+++ b/src/sqlite3/connection.cr
@@ -85,6 +85,21 @@ class SQLite3::Connection < DB::Connection
     @db
   end
 
+  # Enable or disable the loading of dynamic extensions in the current SQLite3 Connection
+  def enable_extension_load(onoff : Bool)
+    check LibSQLite3.db_config(@db, LibSQLite3::Option::SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, onoff ? 1 : 0, nil)
+  end
+
+  # Load a dynamic extension from file in the current SQLite3 Connection
+  def load_extension(filename : String)
+    pzErrMsg : UInt8** = Pointer( UInt8* ).new( ( Pointer( UInt8 ).malloc( 250 ) ).address )
+    code = LibSQLite3.load_extension(@db, filename, nil, pzErrMsg)
+    if code != LibSQLite3::Code::OKAY
+      puts String.new(pzErrMsg.value)
+      raise Exception.new(@db)
+    end
+  end
+
   private def check(code)
     raise Exception.new(self) unless code == 0
   end
diff --git a/src/sqlite3/lib_sqlite3.cr b/src/sqlite3/lib_sqlite3.cr
index 9455f8b..a32eb35 100644
--- a/src/sqlite3/lib_sqlite3.cr
+++ b/src/sqlite3/lib_sqlite3.cr
@@ -73,11 +73,35 @@ lib LibSQLite3
     DONE = 101
   end
 
+  enum Option
+    SQLITE_DBCONFIG_MAINDBNAME            = 1000 # UInt8*
+    SQLITE_DBCONFIG_LOOKASIDE             = 1001 # void* Int32 Int32
+    SQLITE_DBCONFIG_ENABLE_FKEY           = 1002 # Int32 Int32*
+    SQLITE_DBCONFIG_ENABLE_TRIGGER        = 1003 # Int32 Int32*
+    SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER = 1004 # Int32 Int32*
+    SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION = 1005 # Int32 Int32*
+    SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE      = 1006 # Int32 Int32*
+    SQLITE_DBCONFIG_ENABLE_QPSG           = 1007 # Int32 Int32*
+    SQLITE_DBCONFIG_TRIGGER_EQP           = 1008 # Int32 Int32*
+    SQLITE_DBCONFIG_RESET_DATABASE        = 1009 # Int32 Int32*
+    SQLITE_DBCONFIG_DEFENSIVE             = 1010 # Int32 Int32*
+    SQLITE_DBCONFIG_WRITABLE_SCHEMA       = 1011 # Int32 Int32*
+    SQLITE_DBCONFIG_LEGACY_ALTER_TABLE    = 1012 # Int32 Int32*
+    SQLITE_DBCONFIG_DQS_DML               = 1013 # Int32 Int32*
+    SQLITE_DBCONFIG_DQS_DDL               = 1014 # Int32 Int32*
+    SQLITE_DBCONFIG_ENABLE_VIEW           = 1015 # Int32 Int32*
+    SQLITE_DBCONFIG_LEGACY_FILE_FORMAT    = 1016 # Int32 Int32*
+    SQLITE_DBCONFIG_TRUSTED_SCHEMA        = 1017 # Int32 Int32*
+  end
+
   alias Callback = (Void*, Int32, UInt8**, UInt8**) -> Int32
   alias FuncCallback = (SQLite3Context, Int32, SQLite3Value*) -> Void
 
   fun open_v2 = sqlite3_open_v2(filename : UInt8*, db : SQLite3*, flags : ::SQLite3::Flag, zVfs : UInt8*) : Int32
 
+  fun db_config = sqlite3_db_config(db : SQLite3, op : Option, ...) : Int32
+  fun load_extension = sqlite3_load_extension(db : SQLite3, zFile : UInt8*, zProc : UInt8*, pzErrMsg : UInt8**) : Code
+
   fun errcode = sqlite3_errcode(SQLite3) : Int32
   fun errmsg = sqlite3_errmsg(SQLite3) : UInt8*