218 lines
6.6 KiB
Go
218 lines
6.6 KiB
Go
package cli
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import (
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"context"
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"database/sql"
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"fmt"
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"regexp"
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"strings"
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)
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var mysqlPrivilegeGrant = regexp.MustCompile("^(GRANT|REVOKE) (.+?) ON (" + "`(?:``|[^`])*`" + "|\\*)\\.(" + "`(?:``|[^`])*`" + "|\\*) (?:TO|FROM) ")
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// 元数据会按权限静默过滤；必须先证明每张可见基础表的 TRIGGER 权限，不能把空列表当成无触发器。
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func requireMySQLTriggerVisibility(ctx context.Context, tx *sql.Tx, tables []string) error {
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if len(tables) == 0 {
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return nil
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}
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var name, version string
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var lowerCaseNames int
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if err := tx.QueryRowContext(ctx, "SELECT DATABASE(), VERSION(), @@lower_case_table_names").Scan(&name, &version, &lowerCaseNames); err != nil {
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return err
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}
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normalize := func(value string) string {
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if lowerCaseNames != 0 {
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return strings.ToLower(value)
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}
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return value
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}
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name = normalize(name)
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grants, err := readMySQLEffectiveGrants(ctx, tx, version)
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if err != nil {
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return err
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}
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return requireMySQLTableTriggerGrants(ctx, tx, name, tables, grants, normalize)
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}
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func readMySQLEffectiveGrants(ctx context.Context, tx *sql.Tx, version string) ([]string, error) {
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query := "SHOW GRANTS FOR CURRENT_USER"
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if strings.HasPrefix(version, "8.0.") {
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rows, err := tx.QueryContext(ctx, "SELECT ROLE_NAME, ROLE_HOST FROM information_schema.ENABLED_ROLES ORDER BY ROLE_NAME, ROLE_HOST")
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if err != nil {
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return nil, fmt.Errorf("读取 MySQL 当前角色失败：%w", err)
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}
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var roles []string
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for rows.Next() {
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var role, host string
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if err := rows.Scan(&role, &host); err != nil {
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_ = rows.Close()
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return nil, err
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}
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roles = append(roles, quoteMySQLIdentifier(role)+"@"+quoteMySQLIdentifier(host))
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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 nil, err
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}
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if err := rows.Close(); err != nil {
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return nil, err
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}
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if len(roles) > 0 {
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query += " USING " + strings.Join(roles, ", ")
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}
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}
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rows, err := tx.QueryContext(ctx, query)
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if err != nil {
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return nil, fmt.Errorf("读取 MySQL 有效权限失败：%w", err)
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}
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var grants []string
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for rows.Next() {
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var grant string
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if err := rows.Scan(&grant); err != nil {
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_ = rows.Close()
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return nil, err
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}
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grants = append(grants, grant)
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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 nil, err
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}
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if err := rows.Close(); err != nil {
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return nil, err
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}
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return grants, nil
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}
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func requireMySQLTableTriggerGrants(ctx context.Context, tx *sql.Tx, name string, tables, grants []string, normalize func(string) string) error {
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return requireMySQLObjectGrants(ctx, tx, name, tables, grants, normalize, "TRIGGER", false)
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}
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func requireMySQLEventVisibility(ctx context.Context, tx *sql.Tx) error {
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var name, version string
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var lowerCaseNames int
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if err := tx.QueryRowContext(ctx, "SELECT DATABASE(), VERSION(), @@lower_case_table_names").Scan(&name, &version, &lowerCaseNames); err != nil {
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return err
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}
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grants, err := readMySQLEffectiveGrants(ctx, tx, version)
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if err != nil {
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return err
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}
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normalize := func(value string) string {
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if lowerCaseNames != 0 {
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return strings.ToLower(value)
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}
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return value
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}
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// EVENT 只有全局或库级授权，不能用某一张表的权限证明完整事件列表可见。
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return requireMySQLObjectGrants(ctx, tx, normalize(name), []string{name}, grants, normalize, "EVENT", true)
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}
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func requireMySQLObjectGrants(ctx context.Context, tx *sql.Tx, name string, objects, grants []string, normalize func(string) string, privilege string, schemaOnly bool) error {
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// 5.7 返回空列表；8.0 部分撤销模式下，数据库授权中的百分号和下划线为字面量。
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partialRevokes := false
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rows, err := tx.QueryContext(ctx, "SHOW GLOBAL VARIABLES LIKE 'partial_revokes'")
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if err != nil {
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return err
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}
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for rows.Next() {
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var variable, value string
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if err := rows.Scan(&variable, &value); err != nil {
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_ = rows.Close()
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return err
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}
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partialRevokes = strings.EqualFold(value, "ON")
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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 err
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}
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if err := rows.Close(); err != nil {
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return err
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}
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global, revoked := false, false
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exactSeen, exactAllowed := false, false
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wildcardSeen, wildcardAllowed := false, true
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covered := make(map[string]bool)
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for _, grant := range grants {
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match := mysqlPrivilegeGrant.FindStringSubmatch(grant)
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if len(match) == 0 {
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continue
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}
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hasPrivilege := mysqlHasPrivilege(match[2], privilege)
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if match[3] == "*" && match[4] == "*" {
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global = global || (match[1] == "GRANT" && hasPrivilege)
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continue
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}
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databaseName := normalize(unquoteMySQLGrantIdentifier(match[3]))
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matches := name == databaseName
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if match[4] == "*" && !partialRevokes && match[1] == "GRANT" {
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if err := tx.QueryRowContext(ctx, "SELECT BINARY ? LIKE BINARY ?", name, databaseName).Scan(&matches); err != nil {
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return err
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}
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}
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if !matches {
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continue
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}
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if match[1] == "REVOKE" {
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revoked = revoked || hasPrivilege
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} else if match[4] == "*" {
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if partialRevokes || !mysqlGrantHasWildcard(databaseName) {
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exactSeen = true
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exactAllowed = exactAllowed || hasPrivilege
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} else {
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wildcardSeen = true
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wildcardAllowed = wildcardAllowed && hasPrivilege
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}
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} else if hasPrivilege && !schemaOnly {
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covered[normalize(unquoteMySQLGrantIdentifier(match[4]))] = true
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}
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}
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// 精确库授权优先。多个匹配通配授权可能按内部顺序遮蔽，不能简单合并为更大权限。
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// 不能证明所有候选都包含 TRIGGER 时保守失败，管理员可提供明确的精确库或表级授权。
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schema := exactAllowed
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if !exactSeen {
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schema = wildcardSeen && wildcardAllowed
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}
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for _, object := range objects {
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if !((global && !revoked) || schema || covered[normalize(object)]) {
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return fmt.Errorf("MySQL 无法确认对象 %s 的 %s 可见权限，不能把隐藏的对象当成不存在", object, privilege)
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}
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}
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return nil
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}
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func mysqlGrantHasWildcard(value string) bool {
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escaped := false
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for _, char := range value {
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if escaped {
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escaped = false
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} else if char == rune(92) {
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escaped = true
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} else if char == '%' || char == '_' {
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return true
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}
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}
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return false
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}
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func mysqlHasTriggerPrivilege(privileges string) bool {
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return mysqlHasPrivilege(privileges, "TRIGGER")
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}
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func mysqlHasPrivilege(privileges, required string) bool {
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for _, privilege := range strings.Split(privileges, ",") {
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if value := strings.TrimSpace(privilege); value == required || value == "ALL PRIVILEGES" {
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return true
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}
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}
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return false
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}
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func unquoteMySQLGrantIdentifier(value string) string {
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if len(value) >= 2 && value[0] == '`' && value[len(value)-1] == '`' {
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return strings.ReplaceAll(value[1:len(value)-1], "``", "`")
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}
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return value
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}
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