Backup database if a migration is needed (#415)

* Confirm before migrating database

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/mattn/go-sqlite3/sqlite3.go

@@ -1,4 +1,4 @@
-// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
+// Copyright (C) 2019 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
@@ -328,7 +328,7 @@ type SQLiteRows struct {
 	decltype []string
 	cls      bool
 	closed   bool
-	done     chan struct{}
+	ctx      context.Context // no better alternative to pass context into Next() method
 }
 
 type functionInfo struct {
@@ -683,7 +683,7 @@ func (c *SQLiteConn) RegisterAggregator(name string, impl interface{}, pure bool
 		ai.stepArgConverters = append(ai.stepArgConverters, conv)
 	}
 	if step.IsVariadic() {
-		conv, err := callbackArg(t.In(start + stepNArgs).Elem())
+		conv, err := callbackArg(step.In(start + stepNArgs).Elem())
 		if err != nil {
 			return err
 		}
@@ -740,6 +740,8 @@ func (c *SQLiteConn) RegisterAggregator(name string, impl interface{}, pure bool
 
 // AutoCommit return which currently auto commit or not.
 func (c *SQLiteConn) AutoCommit() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
 	return int(C.sqlite3_get_autocommit(c.db)) != 0
 }
 
@@ -998,7 +1000,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	deferForeignKeys := -1
 	foreignKeys := -1
 	ignoreCheckConstraints := -1
-	journalMode := "DELETE"
+	var journalMode string
 	lockingMode := "NORMAL"
 	queryOnly := -1
 	recursiveTriggers := -1
@@ -1230,7 +1232,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		if _, ok := params["_locking"]; ok {
 			pkey = "_locking"
 		}
-		if val := params.Get("_locking"); val != "" {
+		if val := params.Get(pkey); val != "" {
 			switch strings.ToUpper(val) {
 			case "NORMAL", "EXCLUSIVE":
 				lockingMode = strings.ToUpper(val)
@@ -1340,6 +1342,9 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		mutex|C.SQLITE_OPEN_READWRITE|C.SQLITE_OPEN_CREATE,
 		nil)
 	if rv != 0 {
+		if db != nil {
+			C.sqlite3_close_v2(db)
+		}
 		return nil, Error{Code: ErrNo(rv)}
 	}
 	if db == nil {
@@ -1376,7 +1381,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	//  - Activate User Authentication
 	//		Check if the user wants to activate User Authentication.
 	//		If so then first create a temporary AuthConn to the database
-	//		This is possible because we are already succesfully authenticated.
+	//		This is possible because we are already successfully authenticated.
 	//
 	//	- Check if `sqlite_user`` table exists
 	//		YES				=> Add the provided user from DSN as Admin User and
@@ -1387,7 +1392,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	// Create connection to SQLite
 	conn := &SQLiteConn{db: db, loc: loc, txlock: txlock}
 
-	// Password Cipher has to be registerd before authentication
+	// Password Cipher has to be registered before authentication
 	if len(authCrypt) > 0 {
 		switch strings.ToUpper(authCrypt) {
 		case "SHA1":
@@ -1517,10 +1522,10 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		// Before going any further, we need to check that the user
 		// has provided an username and password within the DSN.
 		// We are not allowed to continue.
-		if len(authUser) < 0 {
+		if len(authUser) == 0 {
 			return nil, fmt.Errorf("Missing '_auth_user' while user authentication was requested with '_auth'")
 		}
-		if len(authPass) < 0 {
+		if len(authPass) == 0 {
 			return nil, fmt.Errorf("Missing '_auth_pass' while user authentication was requested with '_auth'")
 		}
 
@@ -1566,10 +1571,11 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	}
 
 	// Journal Mode
-	// Because default Journal Mode is DELETE this PRAGMA can always be executed.
-	if err := exec(fmt.Sprintf("PRAGMA journal_mode = %s;", journalMode)); err != nil {
-		C.sqlite3_close_v2(db)
-		return nil, err
+	if journalMode != "" {
+		if err := exec(fmt.Sprintf("PRAGMA journal_mode = %s;", journalMode)); err != nil {
+			C.sqlite3_close_v2(db)
+			return nil, err
+		}
 	}
 
 	// Locking Mode
@@ -1674,7 +1680,7 @@ func (c *SQLiteConn) prepare(ctx context.Context, query string) (driver.Stmt, er
 	defer C.free(unsafe.Pointer(pquery))
 	var s *C.sqlite3_stmt
 	var tail *C.char
-	rv := C._sqlite3_prepare_v2_internal(c.db, pquery, -1, &s, &tail)
+	rv := C._sqlite3_prepare_v2_internal(c.db, pquery, C.int(-1), &s, &tail)
 	if rv != C.SQLITE_OK {
 		return nil, c.lastError()
 	}
@@ -1718,7 +1724,7 @@ func (c *SQLiteConn) GetFilename(schemaName string) string {
 // GetLimit returns the current value of a run-time limit.
 // See: sqlite3_limit, http://www.sqlite.org/c3ref/limit.html
 func (c *SQLiteConn) GetLimit(id int) int {
-	return int(C._sqlite3_limit(c.db, C.int(id), -1))
+	return int(C._sqlite3_limit(c.db, C.int(id), C.int(-1)))
 }
 
 // SetLimit changes the value of a run-time limits.
@@ -1841,28 +1847,13 @@ func (s *SQLiteStmt) query(ctx context.Context, args []namedValue) (driver.Rows,
 		decltype: nil,
 		cls:      s.cls,
 		closed:   false,
-		done:     make(chan struct{}),
-	}
-
-	if ctxdone := ctx.Done(); ctxdone != nil {
-		go func(db *C.sqlite3) {
-			select {
-			case <-ctxdone:
-				select {
-				case <-rows.done:
-				default:
-					C.sqlite3_interrupt(db)
-					rows.Close()
-				}
-			case <-rows.done:
-			}
-		}(s.c.db)
+		ctx:      ctx,
 	}
 
 	return rows, nil
 }
 
-// LastInsertId teturn last inserted ID.
+// LastInsertId return last inserted ID.
 func (r *SQLiteResult) LastInsertId() (int64, error) {
 	return r.id, nil
 }
@@ -1884,29 +1875,43 @@ func (s *SQLiteStmt) Exec(args []driver.Value) (driver.Result, error) {
 	return s.exec(context.Background(), list)
 }
 
+// exec executes a query that doesn't return rows. Attempts to honor context timeout.
 func (s *SQLiteStmt) exec(ctx context.Context, args []namedValue) (driver.Result, error) {
+	if ctx.Done() == nil {
+		return s.execSync(args)
+	}
+
+	type result struct {
+		r   driver.Result
+		err error
+	}
+	resultCh := make(chan result)
+	go func() {
+		r, err := s.execSync(args)
+		resultCh <- result{r, err}
+	}()
+	select {
+	case rv := <- resultCh:
+		return rv.r, rv.err
+	case <-ctx.Done():
+		select {
+		case <-resultCh: // no need to interrupt
+		default:
+			// this is still racy and can be no-op if executed between sqlite3_* calls in execSync.
+			C.sqlite3_interrupt(s.c.db)
+			<-resultCh // ensure goroutine completed
+		}
+		return nil, ctx.Err()
+	}
+}
+
+func (s *SQLiteStmt) execSync(args []namedValue) (driver.Result, error) {
 	if err := s.bind(args); err != nil {
 		C.sqlite3_reset(s.s)
 		C.sqlite3_clear_bindings(s.s)
 		return nil, err
 	}
 
-	if ctxdone := ctx.Done(); ctxdone != nil {
-		done := make(chan struct{})
-		defer close(done)
-		go func(db *C.sqlite3) {
-			select {
-			case <-done:
-			case <-ctxdone:
-				select {
-				case <-done:
-				default:
-					C.sqlite3_interrupt(db)
-				}
-			}
-		}(s.c.db)
-	}
-
 	var rowid, changes C.longlong
 	rv := C._sqlite3_step_row_internal(s.s, &rowid, &changes)
 	if rv != C.SQLITE_ROW && rv != C.SQLITE_OK && rv != C.SQLITE_DONE {
@@ -1927,9 +1932,6 @@ func (rc *SQLiteRows) Close() error {
 		return nil
 	}
 	rc.closed = true
-	if rc.done != nil {
-		close(rc.done)
-	}
 	if rc.cls {
 		rc.s.mu.Unlock()
 		return rc.s.Close()
@@ -1973,13 +1975,39 @@ func (rc *SQLiteRows) DeclTypes() []string {
 	return rc.declTypes()
 }
 
-// Next move cursor to next.
+// Next move cursor to next. Attempts to honor context timeout from QueryContext call.
 func (rc *SQLiteRows) Next(dest []driver.Value) error {
 	rc.s.mu.Lock()
 	defer rc.s.mu.Unlock()
+
 	if rc.s.closed {
 		return io.EOF
 	}
+
+	if rc.ctx.Done() == nil {
+		return rc.nextSyncLocked(dest)
+	}
+	resultCh := make(chan error)
+	go func() {
+		resultCh <- rc.nextSyncLocked(dest)
+	}()
+	select {
+	case err := <- resultCh:
+		return err
+	case <-rc.ctx.Done():
+		select {
+		case <-resultCh: // no need to interrupt
+		default:
+			// this is still racy and can be no-op if executed between sqlite3_* calls in nextSyncLocked.
+			C.sqlite3_interrupt(rc.s.c.db)
+			<-resultCh // ensure goroutine completed
+		}
+		return rc.ctx.Err()
+	}
+}
+
+// nextSyncLocked moves cursor to next; must be called with locked mutex.
+func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
 	rv := C._sqlite3_step_internal(rc.s.s)
 	if rv == C.SQLITE_DONE {
 		return io.EOF
@@ -2024,16 +2052,11 @@ func (rc *SQLiteRows) Next(dest []driver.Value) error {
 		case C.SQLITE_BLOB:
 			p := C.sqlite3_column_blob(rc.s.s, C.int(i))
 			if p == nil {
-				dest[i] = nil
+				dest[i] = []byte{}
 				continue
 			}
-			n := int(C.sqlite3_column_bytes(rc.s.s, C.int(i)))
-			switch dest[i].(type) {
-			default:
-				slice := make([]byte, n)
-				copy(slice[:], (*[1 << 30]byte)(p)[0:n])
-				dest[i] = slice
-			}
+			n := C.sqlite3_column_bytes(rc.s.s, C.int(i))
+			dest[i] = C.GoBytes(p, n)
 		case C.SQLITE_NULL:
 			dest[i] = nil
 		case C.SQLITE_TEXT:
@@ -2062,9 +2085,8 @@ func (rc *SQLiteRows) Next(dest []driver.Value) error {
 				}
 				dest[i] = t
 			default:
-				dest[i] = []byte(s)
+				dest[i] = s
 			}
-
 		}
 	}
 	return nil