Add: PRAGMA secure_delete

ADD: Connection PRAGMA
ADD: Build tag for secure_delete mode: FAST

Author: gjrtimmer

README.md

@@ -87,6 +87,7 @@ Boolean values can be one of:
 | Mutex Locking | `_mutex` | <ul><li>no</li><li>full</li></ul> | Specify mutex mode. |
 | Query Only | `_query_only` | `boolean` | For more information see [PRAGMA query_only](https://www.sqlite.org/pragma.html#pragma_query_only) |
 | Recursive Triggers | `_recursive_triggers` \| `_rt` | `boolean` | For more information see [PRAGMA recursive_triggers](https://www.sqlite.org/pragma.html#pragma_recursive_triggers) |
+| Secure Delete | `_secure_delete` | `boolean` \| `FAST` | For more information see [PRAGMA secure_delete](https://www.sqlite.org/pragma.html#pragma_secure_delete) |
 | Shared-Cache Mode | `cache` | <ul><li>shared</li><li>private</li></ul> | Set cache mode for more information see [sqlite.org](https://www.sqlite.org/sharedcache.html) |
 | Time Zone Location | `_loc` | auto | Specify location of time format. |
 | Transaction Lock | `_txlock` | <ul><li>immediate</li><li>deferred</li><li>exclusive</li></ul> | Specify locking behavior for transactions. |
@@ -137,6 +138,7 @@ go build --tags "icu json1 fts5 secure_delete"
 | Introspect PRAGMAS | sqlite_introspect | This option adds some extra PRAGMA statements. <ul><li>PRAGMA function_list</li><li>PRAGMA module_list</li><li>PRAGMA pragma_list</li></ul> |
 | JSON SQL Functions | sqlite_json | When this option is defined in the amalgamation, the JSON SQL functions are added to the build automatically |
 | Secure Delete | sqlite_secure_delete | This compile-time option changes the default setting of the secure_delete pragma.<br><br>When this option is not used, secure_delete defaults to off. When this option is present, secure_delete defaults to on.<br><br>The secure_delete setting causes deleted content to be overwritten with zeros. There is a small performance penalty since additional I/O must occur.<br><br>On the other hand, secure_delete can prevent fragments of sensitive information from lingering in unused parts of the database file after it has been deleted. See the documentation on the secure_delete pragma for additional information |
+| Secure Delete (FAST) | sqlite_secure_delete_fast | For more information see [PRAGMA secure_delete](https://www.sqlite.org/pragma.html#pragma_secure_delete) |
 | Tracing / Debug | sqlite_trace | Activate trace functions |
 
 # Compilation

sqlite3.go

@@ -862,6 +862,10 @@ func errorString(err Error) string {
 //   _recursive_triggers=Boolean | _rt=Boolean
 //     Enable or disable recursive triggers.
 //
+//   _secure_delete=Boolean|FAST
+//     When secure_delete is on, SQLite overwrites deleted content with zeros.
+//     https://www.sqlite.org/pragma.html#pragma_secure_delete
+//
 //   _vacuum=X
 //     0 | none - Auto Vacuum disabled
 //     1 | full - Auto Vacuum FULL
@@ -889,6 +893,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	lockingMode := "NORMAL"
 	queryOnly := -1
 	recursiveTriggers := -1
+	secureDelete := "DEFAULT"
 
 	pos := strings.IndexRune(dsn, '?')
 	if pos >= 1 {
@@ -1109,6 +1114,23 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 			}
 		}
 
+		// Secure Delete (_secure_delete)
+		//
+		// https://www.sqlite.org/pragma.html#pragma_secure_delete
+		//
+		if val := params.Get("_secure_delete"); val != "" {
+			switch strings.ToLower(val) {
+			case "0", "no", "false", "off":
+				secureDelete = "OFF"
+			case "1", "yes", "true", "on":
+				secureDelete = "ON"
+			case "fast":
+				secureDelete = "FAST"
+			default:
+				return nil, fmt.Errorf("Invalid _recursive_triggers: %v, expecting boolean value of '0 1 false true no yes off on'", val)
+			}
+		}
+
 		if !strings.HasPrefix(dsn, "file:") {
 			dsn = dsn[:pos]
 		}
@@ -1214,6 +1236,18 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		}
 	}
 
+	// Secure Delete
+	//
+	// Because this package can set the compile time flag SQLITE_SECURE_DELETE with a build tag
+	// the default value for secureDelete var is 'DEFAULT' this way
+	// you can compile with secure_delete 'ON' and disable it for a specific database connection.
+	if secureDelete != "DEFAULT" {
+		if err := exec(fmt.Sprintf("PRAGMA secure_delete = %s;", secureDelete)); err != nil {
+			C.sqlite3_close_v2(db)
+			return nil, err
+		}
+	}
+
 	conn := &SQLiteConn{db: db, loc: loc, txlock: txlock}
 
 	if len(d.Extensions) > 0 {

sqlite3_opt_secure_delete.go

@@ -1,4 +1,5 @@
 // Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
+// Copyright (C) 2018 G.J.R. Timmer <gjr.timmer@gmail.com>.
 //
 // Use of this source code is governed by an MIT-style
 // license that can be found in the LICENSE file.
@@ -8,7 +9,7 @@
 package sqlite3
 
 /*
-#cgo CFLAGS: -DSQLITE_SECURE_DELETE
+#cgo CFLAGS: -DSQLITE_SECURE_DELETE=1
 #cgo LDFLAGS: -lm
 */
 import "C"

sqlite3_opt_secure_delete_fast.go

@@ -0,0 +1,15 @@
+// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
+// Copyright (C) 2018 G.J.R. Timmer <gjr.timmer@gmail.com>.
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+// +build sqlite_secure_delete_fast
+
+package sqlite3
+
+/*
+#cgo CFLAGS: -DSQLITE_SECURE_DELETE=FAST
+#cgo LDFLAGS: -lm
+*/
+import "C"