mirror of https://github.com/docker/docs.git
76 lines
2.2 KiB
Go
76 lines
2.2 KiB
Go
// version implementes a versioned store for TUF metadata
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package version
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import (
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"database/sql"
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"fmt"
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)
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// VersionDB implements a versioned store using a relational database.
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// The database table must look like:
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// CREATE TABLE `tuf_files` (
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// `id` INT AUTO_INCREMENT,
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// `qdn` VARCHAR(255) NOT NULL
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// `role` VARCHAR(255) NOT NULL
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// `version` INT
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// `data` LONGBLOB
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// PRIMARY KEY (`id`)
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// UNIQUE INDEX (`qdn`, `role`, `version`)
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// ) DEFAULT CHARSET=utf8;
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type VersionDB struct {
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sql.DB
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}
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func NewVersionDB(db *sql.DB) *VersionDB {
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return &VersionDB{
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DB: *db,
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}
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}
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// Update multiple TUF records in a single transaction.
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// Always insert a new row. The unique constraint will ensure there is only ever
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func (vdb *VersionDB) UpdateCurrent(qdn, role string, version int, data []byte) error {
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checkStmt := "SELECT count(*) FROM `tuf_files` WHERE `qdn`=? AND `role`=? AND `version`=?;"
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insertStmt := "INSERT INTO `tuf_files` (`qdn`, `role`, `version`, `data`) VALUES (?,?,?,?) ;"
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// ensure immediately previous version exists
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row := vdb.QueryRow(checkStmt, qdn, role, version-1)
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var exists int
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err := row.Scan(&exists)
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if err != nil {
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return err
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}
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if exists == 0 && version > 0 {
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return fmt.Errorf("Attempting to increment version by more than 1 for QDN: %s, role: %s, version: %d", qdn, role, version)
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}
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// attempt to insert. Due to race conditions with the check this could fail.
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// That's OK, we're doing first write wins. The client will be messaged it
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// needs to rebase.
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_, err = vdb.Exec(insertStmt, qdn, role, version, data)
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if err != nil {
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return err
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}
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return nil
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}
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// Get a specific TUF record
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func (vdb *VersionDB) GetCurrent(qdn, tufRole string) (data []byte, err error) {
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stmt := "SELECT `data` FROM `tuf_files` WHERE `qdn`=? AND `role`=? ORDER BY `version` DESC LIMIT 1;"
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rows, err := vdb.Query(stmt, qdn, tufRole) // this should be a QueryRow()
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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// unique constraint on (qdn, role) will ensure only one row is returned (or none if no match is found)
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if !rows.Next() {
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return nil, nil
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}
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err = rows.Scan(&data)
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if err != nil {
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return nil, err
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}
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return data, nil
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}
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