400 lines
12 KiB
Go
400 lines
12 KiB
Go
package cli
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import (
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"context"
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"database/sql"
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"encoding/hex"
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"fmt"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"time"
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"git.pcux.cn/xuans/Scert/backend/internal/config"
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"git.pcux.cn/xuans/Scert/backend/internal/database"
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)
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// backupMySQL 将 MySQL 的表结构和数据导出为可在 MySQL 5.7/8.0 导入的 SQL 文件。
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func backupMySQL(ctx context.Context, cfg config.Config, output string) error {
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resolved, err := resolveMaintenanceDatabase(ctx, cfg.Database, cfg.Paths.Config)
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if err != nil {
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return err
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}
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return backupMySQLDatabase(ctx, resolved, output)
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}
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func backupMySQLDatabase(ctx context.Context, cfg config.DatabaseConfig, output string) error {
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db, err := database.Open(ctx, cfg)
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if err != nil {
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return fmt.Errorf("打开 MySQL 备份连接失败：%w", err)
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}
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defer db.Close()
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temporaryPath := output + ".tmp"
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file, err := os.OpenFile(temporaryPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o600)
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if err != nil {
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return fmt.Errorf("创建 MySQL 备份文件失败：%w", err)
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}
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removeTemporary := true
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defer func() {
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_ = file.Close()
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if removeTemporary {
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_ = os.Remove(temporaryPath)
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}
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}()
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// 所有表的数据必须来自同一个可重复读事务，不能按表从连接池独立读取。
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// 元数据变更不属于 MVCC 快照，运维期间仍需禁止外部并发 DDL。
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tx, err := db.DB.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelRepeatableRead, ReadOnly: true})
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if err != nil {
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return fmt.Errorf("创建 MySQL 一致性备份事务失败：%w", err)
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}
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defer tx.Rollback()
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// 客户端取消会关闭连接，但服务端等待元数据锁时未必立即感知断开。
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// 仅限制本次备份会话的单次锁等待；不限制总导出时间，也不修改全局配置。
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if _, err := tx.ExecContext(ctx, "SET SESSION lock_wait_timeout = 5"); err != nil {
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return fmt.Errorf("设置 MySQL 备份元数据锁等待上限失败：%w", err)
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}
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if _, err := fmt.Fprintf(file, "-- Scert MySQL 数据备份\n-- 生成时间：%s\n\nSET FOREIGN_KEY_CHECKS=0;\n\n", time.Now().UTC().Format(time.RFC3339)); err != nil {
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return fmt.Errorf("写入 MySQL 备份头失败：%w", err)
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}
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rows, err := tx.QueryContext(ctx, "SELECT TABLE_NAME, ENGINE, TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() ORDER BY TABLE_NAME")
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if err != nil {
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return fmt.Errorf("读取 MySQL 表列表失败：%w", err)
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}
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var tableNames []string
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for rows.Next() {
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var tableName, tableType string
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var engine sql.NullString
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if err := rows.Scan(&tableName, &engine, &tableType); err != nil {
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_ = rows.Close()
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return fmt.Errorf("读取 MySQL 表名失败：%w", err)
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}
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if tableType != "BASE TABLE" || !engine.Valid || !strings.EqualFold(engine.String, "InnoDB") {
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_ = rows.Close()
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return fmt.Errorf("MySQL 一致性备份当前仅支持 InnoDB 基础表，不能静默导出其他对象：%s", tableName)
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}
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tableNames = append(tableNames, tableName)
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}
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if err := rows.Err(); err != nil {
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_ = rows.Close()
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return fmt.Errorf("遍历 MySQL 表列表失败：%w", err)
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}
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if err := rows.Close(); err != nil {
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return fmt.Errorf("关闭 MySQL 表列表失败：%w", err)
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}
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for _, tableName := range tableNames {
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if err := dumpMySQLTable(ctx, tx, file, tableName); err != nil {
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return err
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}
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}
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if _, err := fmt.Fprint(file, "SET FOREIGN_KEY_CHECKS=1;\n"); err != nil {
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return fmt.Errorf("写入 MySQL 备份尾失败：%w", err)
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}
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if err := tx.Commit(); err != nil {
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return fmt.Errorf("结束 MySQL 一致性备份事务失败：%w", err)
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}
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if err := file.Sync(); err != nil {
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return fmt.Errorf("同步 MySQL 备份文件失败：%w", err)
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}
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if err := file.Close(); err != nil {
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return fmt.Errorf("关闭 MySQL 备份文件失败：%w", err)
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}
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if err := os.Chmod(temporaryPath, 0o600); err != nil {
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return fmt.Errorf("设置 MySQL 备份文件权限失败：%w", err)
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}
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if err := ctx.Err(); err != nil {
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return err
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}
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if err := os.Rename(temporaryPath, output); err != nil {
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return fmt.Errorf("保存 MySQL 备份文件失败：%w", err)
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}
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removeTemporary = false
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return nil
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}
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// createMySQLRestoreBackup 在恢复前保留目标数据库快照，供失败时回滚使用。
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// 快照目录不会在恢复成功后自动删除，便于管理员在需要时继续排查或手动恢复。
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func createMySQLRestoreBackup(ctx context.Context, cfg config.Config, connection config.DatabaseConfig) (string, error) {
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backupRoot := filepath.Clean(strings.TrimSpace(cfg.Paths.Backup))
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if backupRoot == "." || backupRoot == "" {
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return "", fmt.Errorf("MySQL 恢复前备份目录不能为空")
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}
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if err := os.MkdirAll(backupRoot, 0o700); err != nil {
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return "", fmt.Errorf("创建 MySQL 恢复前备份目录失败：%w", err)
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}
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info, err := os.Lstat(backupRoot)
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if err != nil {
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return "", fmt.Errorf("检查 MySQL 恢复前备份目录失败：%w", err)
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}
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if info.Mode()&os.ModeSymlink != 0 || !info.IsDir() {
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return "", fmt.Errorf("MySQL 恢复前备份目录必须是普通目录")
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}
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if err := os.Chmod(backupRoot, 0o700); err != nil {
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return "", fmt.Errorf("设置 MySQL 恢复前备份目录权限失败：%w", err)
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}
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rollbackDirectory, err := os.MkdirTemp(backupRoot, "scert-before-restore-")
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if err != nil {
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return "", fmt.Errorf("创建 MySQL 恢复快照目录失败：%w", err)
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}
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rollbackPath := filepath.Join(rollbackDirectory, "scert.sql")
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if err := backupMySQLDatabase(ctx, connection, rollbackPath); err != nil {
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return "", fmt.Errorf("创建 MySQL 恢复前快照失败：%w", err)
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}
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return rollbackPath, nil
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}
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func dumpMySQLTable(ctx context.Context, db *sql.Tx, output *os.File, tableName string) error {
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quotedTable := quoteMySQLIdentifier(tableName)
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var name, createSQL string
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if err := db.QueryRowContext(ctx, "SHOW CREATE TABLE "+quotedTable).Scan(&name, &createSQL); err != nil {
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return fmt.Errorf("读取 MySQL 表结构失败（%s）：%w", tableName, err)
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}
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if _, err := fmt.Fprintf(output, "DROP TABLE IF EXISTS %s;\n%s;\n\n", quotedTable, createSQL); err != nil {
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return fmt.Errorf("写入 MySQL 表结构失败（%s）：%w", tableName, err)
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}
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rows, err := db.QueryContext(ctx, "SELECT * FROM "+quotedTable)
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if err != nil {
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return fmt.Errorf("读取 MySQL 表数据失败（%s）：%w", tableName, err)
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}
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defer rows.Close()
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columns, err := rows.Columns()
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if err != nil {
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return fmt.Errorf("读取 MySQL 表字段失败（%s）：%w", tableName, err)
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}
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columnTypes, err := rows.ColumnTypes()
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if err != nil {
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return fmt.Errorf("读取 MySQL 表字段类型失败（%s）：%w", tableName, err)
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}
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for rows.Next() {
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values := make([]any, len(columns))
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pointers := make([]any, len(columns))
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for index := range values {
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pointers[index] = &values[index]
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}
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if err := rows.Scan(pointers...); err != nil {
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return fmt.Errorf("读取 MySQL 表行失败（%s）：%w", tableName, err)
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}
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literals := make([]string, len(values))
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for index, value := range values {
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literals[index] = mysqlColumnSQLLiteral(value, columnTypes[index].DatabaseTypeName())
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}
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if _, err := fmt.Fprintf(output, "INSERT INTO %s (%s) VALUES (%s);\n", quotedTable, quoteMySQLColumns(columns), strings.Join(literals, ", ")); err != nil {
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return fmt.Errorf("写入 MySQL 表数据失败（%s）：%w", tableName, err)
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}
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}
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if err := rows.Err(); err != nil {
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return fmt.Errorf("遍历 MySQL 表数据失败（%s）：%w", tableName, err)
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}
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_, err = fmt.Fprintln(output)
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return err
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}
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func quoteMySQLIdentifier(value string) string {
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return "`" + strings.ReplaceAll(value, "`", "``") + "`"
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}
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func quoteMySQLColumns(columns []string) string {
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quoted := make([]string, len(columns))
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for index, column := range columns {
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quoted[index] = quoteMySQLIdentifier(column)
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}
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return strings.Join(quoted, ", ")
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}
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func mysqlColumnSQLLiteral(value any, columnType string) string {
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// 驱动将 DECIMAL 返回为文本字节；十六进制字面量在数值列中会被当作整数。
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// 使用文本字面量保留任意精度，不经浮点转换；真正的二进制列仍按原样导出。
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if columnType == "DECIMAL" {
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switch typed := value.(type) {
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case sql.RawBytes:
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return mysqlStringLiteral(string(typed))
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case []byte:
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return mysqlStringLiteral(string(typed))
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}
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}
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return mysqlSQLLiteral(value)
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}
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func mysqlSQLLiteral(value any) string {
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switch typed := value.(type) {
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case nil:
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return "NULL"
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case sql.RawBytes:
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return "X'" + hex.EncodeToString(typed) + "'"
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case []byte:
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return "X'" + hex.EncodeToString(typed) + "'"
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case string:
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return mysqlStringLiteral(typed)
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case time.Time:
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return "'" + typed.UTC().Format("2006-01-02 15:04:05.999999") + "'"
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case bool:
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if typed {
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return "1"
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}
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return "0"
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case int64:
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return strconv.FormatInt(typed, 10)
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case uint64:
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return strconv.FormatUint(typed, 10)
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case float64:
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return strconv.FormatFloat(typed, 'g', -1, 64)
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case float32:
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return strconv.FormatFloat(float64(typed), 'g', -1, 32)
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default:
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return mysqlStringLiteral(fmt.Sprint(typed))
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}
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}
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func mysqlStringLiteral(value string) string {
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var builder strings.Builder
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builder.Grow(len(value) + 2)
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builder.WriteByte('\'')
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for index := 0; index < len(value); index++ {
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switch value[index] {
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case '\\':
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builder.WriteString(`\\`)
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case '\x00':
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builder.WriteString(`\0`)
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case '\n':
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builder.WriteString(`\n`)
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case '\r':
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builder.WriteString(`\r`)
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case '\x1a':
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builder.WriteString(`\Z`)
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case '\'':
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builder.WriteString(`''`)
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default:
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builder.WriteByte(value[index])
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}
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}
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builder.WriteByte('\'')
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return builder.String()
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}
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// restoreMySQL 执行 Scert 生成的 MySQL SQL 备份。
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func restoreMySQL(ctx context.Context, cfg config.DatabaseConfig, input string) error {
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script, err := os.ReadFile(input)
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if err != nil {
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return fmt.Errorf("读取 MySQL 备份文件失败：%w", err)
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}
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db, err := database.Open(ctx, cfg)
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if err != nil {
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return fmt.Errorf("打开 MySQL 恢复连接失败：%w", err)
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}
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defer db.Close()
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// 会话变量与外键开关必须留在同一条连接上；失败后返回，不切换连接重放。
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connection, err := db.DB.Conn(ctx)
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if err != nil {
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return fmt.Errorf("获取 MySQL 恢复会话失败：%w", err)
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}
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defer connection.Close()
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for _, statement := range splitMySQLStatements(string(script)) {
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if _, err := connection.ExecContext(ctx, statement); err != nil {
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return fmt.Errorf("执行 MySQL 恢复语句失败：%w", err)
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}
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}
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return nil
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}
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func splitMySQLStatements(script string) []string {
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var statements []string
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var statement strings.Builder
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var quote byte
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lineComment := false
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blockComment := false
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executableComment := false
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escaped := false
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flush := func() {
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value := strings.TrimSpace(statement.String())
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if value != "" {
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statements = append(statements, value)
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}
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statement.Reset()
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}
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for index := 0; index < len(script); index++ {
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current := script[index]
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if lineComment {
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if current == '\n' {
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lineComment = false
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statement.WriteByte('\n')
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}
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continue
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}
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if blockComment {
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if current == '*' && index+1 < len(script) && script[index+1] == '/' {
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blockComment = false
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index++
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statement.WriteByte(' ')
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}
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continue
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}
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if executableComment {
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statement.WriteByte(current)
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if current == '*' && index+1 < len(script) && script[index+1] == '/' {
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statement.WriteByte(script[index+1])
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index++
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executableComment = false
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}
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continue
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}
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if quote != 0 {
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statement.WriteByte(current)
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if escaped {
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escaped = false
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continue
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}
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if current == '\\' {
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escaped = true
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continue
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}
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if current == quote {
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if index+1 < len(script) && script[index+1] == quote {
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statement.WriteByte(script[index+1])
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index++
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continue
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}
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quote = 0
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}
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continue
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}
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if current == '\'' || current == '"' || current == '`' {
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quote = current
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statement.WriteByte(current)
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continue
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}
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if current == '#' {
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lineComment = true
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continue
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}
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if current == '-' && index+2 < len(script) && script[index+1] == '-' && (script[index+2] == ' ' || script[index+2] == '\t' || script[index+2] == '\n') {
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lineComment = true
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index++
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continue
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}
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if current == '/' && index+1 < len(script) && script[index+1] == '*' {
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if index+2 < len(script) && (script[index+2] == '!' || script[index+2] == '+') {
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statement.WriteByte(current)
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statement.WriteByte(script[index+1])
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index++
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executableComment = true
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continue
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}
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blockComment = true
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index++
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continue
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}
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if current == ';' {
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flush()
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continue
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}
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statement.WriteByte(current)
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}
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flush()
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return statements
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}
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