Add backup. Close #104

_example/hook/hook.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"database/sql"
+	"github.com/mattn/go-sqlite3"
+	"log"
+	"os"
+)
+
+func main() {
+	sqlite3conn := []*sqlite3.SQLiteConn{}
+	sql.Register("sqlite3_with_hook_example",
+			&sqlite3.SQLiteDriver{
+					ConnectHook: func(conn *sqlite3.SQLiteConn) error {
+						sqlite3conn = append(sqlite3conn, conn)
+						return nil
+					},
+			})
+	os.Remove("./foo.db")
+	os.Remove("./bar.db")
+
+	destDb, err := sql.Open("sqlite3_with_hook_example", "./foo.db")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer destDb.Close()
+	destDb.Ping()
+
+	_, err = destDb.Exec("create table foo(id int, value text)")
+	if err != nil {
+		log.Fatal(err)
+	}
+	_, err = destDb.Exec("insert into foo values(1, 'foo')")
+	if err != nil {
+		log.Fatal(err)
+	}
+	_, err = destDb.Exec("insert into foo values(2, 'bar')")
+	if err != nil {
+		log.Fatal(err)
+	}
+	_, err = destDb.Query("select * from foo")
+	if err != nil {
+		log.Fatal(err)
+	}
+	srcDb, err := sql.Open("sqlite3_with_hook_example", "./bar.db")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer srcDb.Close()
+	srcDb.Ping()
+
+	bk, err := sqlite3conn[1].Backup("main", sqlite3conn[0], "main")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	bk.Step(-1)
+	if err != nil {
+		log.Fatal(err)
+	}
+	_, err = destDb.Query("select * from foo")
+	if err != nil {
+		log.Fatal(err)
+	}
+	_, err = destDb.Exec("insert into foo values(3, 'bar')")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	bk.Finish()
+}

backup.go

@@ -0,0 +1,42 @@
+package sqlite3
+
+/*
+#include <sqlite3.h>
+#include <stdlib.h>
+*/
+import "C"
+import (
+	"unsafe"
+)
+
+type Backup struct {
+	b *C.sqlite3_backup
+}
+
+func (c *SQLiteConn) Backup(dest string, conn *SQLiteConn, src string) (*Backup, error) {
+	destptr := C.CString(dest)
+	defer C.free(unsafe.Pointer(destptr))
+	srcptr := C.CString(src)
+	defer C.free(unsafe.Pointer(srcptr))
+
+	if b := C.sqlite3_backup_init(c.db, destptr, conn.db, srcptr); b != nil {
+		return &Backup{b: b}, nil
+	}
+	return nil, c.lastError()
+}
+
+func (b *Backup) Step(p int) error {
+	return Error{Code: ErrNo(C.sqlite3_backup_step(b.b, C.int(p)))}
+}
+
+func (b *Backup) Remaining() int {
+	return int(C.sqlite3_backup_remaining(b.b))
+}
+
+func (b *Backup) PageCount() int {
+	return int(C.sqlite3_backup_pagecount(b.b))
+}
+
+func (b *Backup) Finish() error {
+	return Error{Code: ErrNo(C.sqlite3_backup_finish(b.b))}
+}