first with full handle over rpm

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>
This commit is contained in:
GnomeZworc 2026-04-25 14:49:14 +02:00
commit 274ea454dd
Signed by: nicolas.boufideline
GPG key ID: 4406BBBF8845D632
50 changed files with 4309 additions and 0 deletions

View file

@ -0,0 +1,78 @@
package store
import (
"context"
"database/sql"
"fmt"
"strings"
"time"
)
type BlockedPackage struct {
ID int64
RepoID int64
Name string
Location string
CreatedAt time.Time
}
type BlockedPackageStore interface {
BlockPackages(ctx context.Context, repoID int64, pkgs []BlockedPackage) error
UnblockPackages(ctx context.Context, repoID int64, ids []int64) error
ListBlocked(ctx context.Context, repoID int64) ([]BlockedPackage, error)
}
type SQLiteBlockedPackageStore struct {
db *sql.DB
}
func NewBlockedPackageStore(db *sql.DB) *SQLiteBlockedPackageStore {
return &SQLiteBlockedPackageStore{db: db}
}
func (s *SQLiteBlockedPackageStore) BlockPackages(ctx context.Context, repoID int64, pkgs []BlockedPackage) error {
for _, p := range pkgs {
_, err := s.db.ExecContext(ctx,
`INSERT OR IGNORE INTO blocked_packages (repo_id, name, location) VALUES (?, ?, ?)`,
repoID, p.Name, p.Location)
if err != nil {
return err
}
}
return nil
}
func (s *SQLiteBlockedPackageStore) UnblockPackages(ctx context.Context, repoID int64, ids []int64) error {
if len(ids) == 0 {
return nil
}
placeholders := strings.Join(strings.Fields(strings.Repeat("? ", len(ids))), ", ")
query := fmt.Sprintf("DELETE FROM blocked_packages WHERE repo_id = ? AND id IN (%s)", placeholders)
args := make([]any, 0, len(ids)+1)
args = append(args, repoID)
for _, id := range ids {
args = append(args, id)
}
_, err := s.db.ExecContext(ctx, query, args...)
return err
}
func (s *SQLiteBlockedPackageStore) ListBlocked(ctx context.Context, repoID int64) ([]BlockedPackage, error) {
rows, err := s.db.QueryContext(ctx,
`SELECT id, repo_id, name, location, created_at FROM blocked_packages WHERE repo_id = ? ORDER BY id ASC`,
repoID)
if err != nil {
return nil, err
}
defer rows.Close()
var pkgs []BlockedPackage
for rows.Next() {
var p BlockedPackage
if err := rows.Scan(&p.ID, &p.RepoID, &p.Name, &p.Location, &p.CreatedAt); err != nil {
return nil, err
}
pkgs = append(pkgs, p)
}
return pkgs, rows.Err()
}

109
internal/store/clone_job.go Normal file
View file

@ -0,0 +1,109 @@
package store
import (
"context"
"database/sql"
"errors"
"time"
)
type CloneJobStatus string
const (
CloneJobPending CloneJobStatus = "pending"
CloneJobRunning CloneJobStatus = "running"
CloneJobCompleted CloneJobStatus = "completed"
CloneJobFailed CloneJobStatus = "failed"
)
type CloneJob struct {
ID int64
RepoID int64
Status CloneJobStatus
StartedAt *time.Time
FinishedAt *time.Time
Error *string
CreatedAt time.Time
}
type CloneJobStore interface {
CreateCloneJob(ctx context.Context, repoID int64) (int64, error)
GetCloneJob(ctx context.Context, id int64) (*CloneJob, error)
GetLatestCloneJob(ctx context.Context, repoID int64) (*CloneJob, error)
HasRunningCloneJob(ctx context.Context, repoID int64) (bool, error)
MarkCloneJobStarted(ctx context.Context, id int64) error
MarkCloneJobFinished(ctx context.Context, id int64, status CloneJobStatus, errMsg *string) error
}
type SQLiteCloneJobStore struct {
db *sql.DB
}
func NewCloneJobStore(db *sql.DB) *SQLiteCloneJobStore {
return &SQLiteCloneJobStore{db: db}
}
func (s *SQLiteCloneJobStore) CreateCloneJob(ctx context.Context, repoID int64) (int64, error) {
res, err := s.db.ExecContext(ctx, `INSERT INTO clone_jobs (repo_id) VALUES (?)`, repoID)
if err != nil {
return 0, err
}
return res.LastInsertId()
}
func (s *SQLiteCloneJobStore) GetCloneJob(ctx context.Context, id int64) (*CloneJob, error) {
row := s.db.QueryRowContext(ctx,
`SELECT id, repo_id, status, started_at, finished_at, error, created_at FROM clone_jobs WHERE id = ?`, id)
return scanCloneJob(row)
}
func (s *SQLiteCloneJobStore) GetLatestCloneJob(ctx context.Context, repoID int64) (*CloneJob, error) {
row := s.db.QueryRowContext(ctx,
`SELECT id, repo_id, status, started_at, finished_at, error, created_at FROM clone_jobs WHERE repo_id = ? ORDER BY created_at DESC LIMIT 1`, repoID)
return scanCloneJob(row)
}
func (s *SQLiteCloneJobStore) HasRunningCloneJob(ctx context.Context, repoID int64) (bool, error) {
var count int
err := s.db.QueryRowContext(ctx,
`SELECT COUNT(*) FROM clone_jobs WHERE repo_id = ? AND status IN ('pending','running')`, repoID,
).Scan(&count)
return count > 0, err
}
func (s *SQLiteCloneJobStore) MarkCloneJobStarted(ctx context.Context, id int64) error {
_, err := s.db.ExecContext(ctx,
`UPDATE clone_jobs SET status='running', started_at=CURRENT_TIMESTAMP WHERE id=?`, id)
return err
}
func (s *SQLiteCloneJobStore) MarkCloneJobFinished(ctx context.Context, id int64, status CloneJobStatus, errMsg *string) error {
_, err := s.db.ExecContext(ctx,
`UPDATE clone_jobs SET status=?, finished_at=CURRENT_TIMESTAMP, error=? WHERE id=?`,
status, errMsg, id)
return err
}
func scanCloneJob(row *sql.Row) (*CloneJob, error) {
var j CloneJob
var startedAt, finishedAt sql.NullTime
var errMsg sql.NullString
err := row.Scan(&j.ID, &j.RepoID, &j.Status, &startedAt, &finishedAt, &errMsg, &j.CreatedAt)
if errors.Is(err, sql.ErrNoRows) {
return nil, ErrNotFound
}
if err != nil {
return nil, err
}
if startedAt.Valid {
j.StartedAt = &startedAt.Time
}
if finishedAt.Valid {
j.FinishedAt = &finishedAt.Time
}
if errMsg.Valid {
j.Error = &errMsg.String
}
return &j, nil
}

88
internal/store/db.go Normal file
View file

@ -0,0 +1,88 @@
package store
import (
"database/sql"
_ "embed"
"fmt"
"github.com/syonad/clonepack/config"
_ "modernc.org/sqlite"
)
//go:embed migrations/000001_init.up.sql
var migration001 string
//go:embed migrations/000002_clone_jobs.up.sql
var migration002 string
//go:embed migrations/000003_sync.up.sql
var migration003 string
//go:embed migrations/000004_snapshot_packages.up.sql
var migration004 string
//go:embed migrations/000005_blocked_packages.up.sql
var migration005 string
//go:embed migrations/000006_blocked_packages_name.up.sql
var migration006 string
func Open(cfg config.DBConfig) (*sql.DB, error) {
db, err := sql.Open("sqlite", cfg.Path)
if err != nil {
return nil, fmt.Errorf("open db: %w", err)
}
if _, err := db.Exec("PRAGMA journal_mode=WAL"); err != nil {
return nil, fmt.Errorf("set WAL mode: %w", err)
}
if _, err := db.Exec("PRAGMA foreign_keys=ON"); err != nil {
return nil, fmt.Errorf("enable foreign keys: %w", err)
}
if err := runMigrations(db); err != nil {
return nil, fmt.Errorf("migrations: %w", err)
}
return db, nil
}
func runMigrations(db *sql.DB) error {
_, err := db.Exec(`CREATE TABLE IF NOT EXISTS schema_migrations (
version INTEGER PRIMARY KEY,
applied_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
)`)
if err != nil {
return err
}
migrations := []struct {
version int
sql string
}{
{1, migration001},
{2, migration002},
{3, migration003},
{4, migration004},
{5, migration005},
{6, migration006},
}
for _, m := range migrations {
var count int
row := db.QueryRow("SELECT COUNT(*) FROM schema_migrations WHERE version = ?", m.version)
if err := row.Scan(&count); err != nil {
return err
}
if count > 0 {
continue
}
if _, err := db.Exec(m.sql); err != nil {
return fmt.Errorf("migration %d: %w", m.version, err)
}
if _, err := db.Exec("INSERT INTO schema_migrations (version) VALUES (?)", m.version); err != nil {
return err
}
}
return nil
}

View file

@ -0,0 +1,3 @@
DROP TABLE IF EXISTS snapshots;
DROP TABLE IF EXISTS artifacts;
DROP TABLE IF EXISTS repos;

View file

@ -0,0 +1,25 @@
CREATE TABLE IF NOT EXISTS repos (
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL UNIQUE,
type TEXT NOT NULL CHECK(type IN ('apt','rpm','docker','binary')),
source_url TEXT NOT NULL,
frozen BOOLEAN NOT NULL DEFAULT FALSE,
created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE TABLE IF NOT EXISTS artifacts (
id INTEGER PRIMARY KEY AUTOINCREMENT,
repo_id INTEGER NOT NULL REFERENCES repos(id) ON DELETE CASCADE,
name TEXT NOT NULL,
version TEXT NOT NULL,
path TEXT NOT NULL,
checksum TEXT NOT NULL,
created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE TABLE IF NOT EXISTS snapshots (
id INTEGER PRIMARY KEY AUTOINCREMENT,
repo_id INTEGER NOT NULL REFERENCES repos(id) ON DELETE CASCADE,
label TEXT NOT NULL,
created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);

View file

@ -0,0 +1 @@
DROP TABLE IF EXISTS clone_jobs;

View file

@ -0,0 +1,11 @@
CREATE TABLE IF NOT EXISTS clone_jobs (
id INTEGER PRIMARY KEY AUTOINCREMENT,
repo_id INTEGER NOT NULL REFERENCES repos(id) ON DELETE CASCADE,
status TEXT NOT NULL CHECK(status IN ('pending','running','completed','failed')) DEFAULT 'pending',
started_at DATETIME,
finished_at DATETIME,
error TEXT,
created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE INDEX IF NOT EXISTS idx_clone_jobs_repo_id ON clone_jobs(repo_id);

View file

@ -0,0 +1 @@
DROP TABLE IF EXISTS pending_packages;

View file

@ -0,0 +1,18 @@
ALTER TABLE repos ADD COLUMN sync_mode TEXT NOT NULL DEFAULT 'auto'
CHECK(sync_mode IN ('auto', 'manual'));
CREATE TABLE IF NOT EXISTS pending_packages (
id INTEGER PRIMARY KEY AUTOINCREMENT,
repo_id INTEGER NOT NULL REFERENCES repos(id) ON DELETE CASCADE,
name TEXT NOT NULL,
version TEXT NOT NULL,
arch TEXT NOT NULL,
location TEXT NOT NULL,
checksum TEXT NOT NULL,
checksum_type TEXT NOT NULL,
size INTEGER NOT NULL DEFAULT 0,
created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
UNIQUE(repo_id, name, version, arch)
);
CREATE INDEX IF NOT EXISTS idx_pending_packages_repo_id ON pending_packages(repo_id);

View file

@ -0,0 +1,2 @@
DROP INDEX IF EXISTS idx_snapshot_packages_snapshot_id;
DROP TABLE IF EXISTS snapshot_packages;

View file

@ -0,0 +1,14 @@
CREATE TABLE IF NOT EXISTS snapshot_packages (
id INTEGER PRIMARY KEY AUTOINCREMENT,
snapshot_id INTEGER NOT NULL REFERENCES snapshots(id) ON DELETE CASCADE,
name TEXT NOT NULL,
version TEXT NOT NULL,
arch TEXT NOT NULL,
location TEXT NOT NULL,
checksum TEXT NOT NULL,
checksum_type TEXT NOT NULL,
size INTEGER NOT NULL DEFAULT 0
);
CREATE INDEX IF NOT EXISTS idx_snapshot_packages_snapshot_id
ON snapshot_packages(snapshot_id);

View file

@ -0,0 +1 @@
DROP TABLE IF EXISTS blocked_packages;

View file

@ -0,0 +1,7 @@
CREATE TABLE IF NOT EXISTS blocked_packages (
id INTEGER PRIMARY KEY AUTOINCREMENT,
repo_id INTEGER NOT NULL REFERENCES repos(id) ON DELETE CASCADE,
location TEXT NOT NULL,
created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
UNIQUE(repo_id, location)
);

View file

@ -0,0 +1,4 @@
-- SQLite ne supporte pas DROP COLUMN avant 3.35 ; recréation de la table sans la colonne name
CREATE TABLE blocked_packages_backup AS SELECT id, repo_id, location, created_at FROM blocked_packages;
DROP TABLE blocked_packages;
ALTER TABLE blocked_packages_backup RENAME TO blocked_packages;

View file

@ -0,0 +1 @@
ALTER TABLE blocked_packages ADD COLUMN name TEXT NOT NULL DEFAULT '';

View file

@ -0,0 +1,92 @@
package store
import (
"context"
"database/sql"
"fmt"
"strings"
"time"
)
type PendingPackage struct {
ID int64
RepoID int64
Name string
Version string
Arch string
Location string
Checksum string
ChecksumType string
Size int64
CreatedAt time.Time
}
type PendingPackageStore interface {
UpsertPending(ctx context.Context, pkgs []PendingPackage) error
ListPending(ctx context.Context, repoID int64) ([]PendingPackage, error)
DeletePending(ctx context.Context, ids []int64) error
DeleteAllPending(ctx context.Context, repoID int64) error
}
type SQLitePendingPackageStore struct {
db *sql.DB
}
func NewPendingPackageStore(db *sql.DB) *SQLitePendingPackageStore {
return &SQLitePendingPackageStore{db: db}
}
func (s *SQLitePendingPackageStore) UpsertPending(ctx context.Context, pkgs []PendingPackage) error {
for _, p := range pkgs {
_, err := s.db.ExecContext(ctx,
`INSERT OR IGNORE INTO pending_packages
(repo_id, name, version, arch, location, checksum, checksum_type, size)
VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
p.RepoID, p.Name, p.Version, p.Arch, p.Location, p.Checksum, p.ChecksumType, p.Size,
)
if err != nil {
return err
}
}
return nil
}
func (s *SQLitePendingPackageStore) ListPending(ctx context.Context, repoID int64) ([]PendingPackage, error) {
rows, err := s.db.QueryContext(ctx,
`SELECT id, repo_id, name, version, arch, location, checksum, checksum_type, size, created_at
FROM pending_packages WHERE repo_id = ? ORDER BY created_at ASC`, repoID)
if err != nil {
return nil, err
}
defer rows.Close()
var pkgs []PendingPackage
for rows.Next() {
var p PendingPackage
if err := rows.Scan(&p.ID, &p.RepoID, &p.Name, &p.Version, &p.Arch,
&p.Location, &p.Checksum, &p.ChecksumType, &p.Size, &p.CreatedAt); err != nil {
return nil, err
}
pkgs = append(pkgs, p)
}
return pkgs, rows.Err()
}
func (s *SQLitePendingPackageStore) DeletePending(ctx context.Context, ids []int64) error {
if len(ids) == 0 {
return nil
}
placeholders := strings.Join(strings.Fields(strings.Repeat("? ", len(ids))), ", ")
query := fmt.Sprintf("DELETE FROM pending_packages WHERE id IN (%s)", placeholders)
args := make([]any, len(ids))
for i, id := range ids {
args[i] = id
}
_, err := s.db.ExecContext(ctx, query, args...)
return err
}
func (s *SQLitePendingPackageStore) DeleteAllPending(ctx context.Context, repoID int64) error {
_, err := s.db.ExecContext(ctx, `DELETE FROM pending_packages WHERE repo_id = ?`, repoID)
return err
}

107
internal/store/repo.go Normal file
View file

@ -0,0 +1,107 @@
package store
import (
"context"
"database/sql"
"errors"
"time"
)
var ErrNotFound = errors.New("not found")
type Repo struct {
ID int64 `db:"id"`
Name string `db:"name"`
Type string `db:"type"`
SourceURL string `db:"source_url"`
Frozen bool `db:"frozen"`
SyncMode string `db:"sync_mode"`
CreatedAt time.Time `db:"created_at"`
}
type RepoStore interface {
CreateRepo(ctx context.Context, r *Repo) (int64, error)
ListRepos(ctx context.Context) ([]Repo, error)
GetRepo(ctx context.Context, id int64) (*Repo, error)
DeleteRepo(ctx context.Context, id int64) error
UpdateRepoSyncMode(ctx context.Context, id int64, mode string) error
}
type SQLiteRepoStore struct {
db *sql.DB
}
func NewRepoStore(db *sql.DB) *SQLiteRepoStore {
return &SQLiteRepoStore{db: db}
}
func (s *SQLiteRepoStore) CreateRepo(ctx context.Context, r *Repo) (int64, error) {
res, err := s.db.ExecContext(ctx,
`INSERT INTO repos (name, type, source_url, frozen, sync_mode) VALUES (?, ?, ?, ?, ?)`,
r.Name, r.Type, r.SourceURL, r.Frozen, r.SyncMode,
)
if err != nil {
return 0, err
}
return res.LastInsertId()
}
func (s *SQLiteRepoStore) ListRepos(ctx context.Context) ([]Repo, error) {
rows, err := s.db.QueryContext(ctx,
`SELECT id, name, type, source_url, frozen, sync_mode, created_at FROM repos ORDER BY created_at DESC`)
if err != nil {
return nil, err
}
defer rows.Close()
var repos []Repo
for rows.Next() {
var r Repo
if err := rows.Scan(&r.ID, &r.Name, &r.Type, &r.SourceURL, &r.Frozen, &r.SyncMode, &r.CreatedAt); err != nil {
return nil, err
}
repos = append(repos, r)
}
return repos, rows.Err()
}
func (s *SQLiteRepoStore) GetRepo(ctx context.Context, id int64) (*Repo, error) {
var r Repo
err := s.db.QueryRowContext(ctx,
`SELECT id, name, type, source_url, frozen, sync_mode, created_at FROM repos WHERE id = ?`, id,
).Scan(&r.ID, &r.Name, &r.Type, &r.SourceURL, &r.Frozen, &r.SyncMode, &r.CreatedAt)
if errors.Is(err, sql.ErrNoRows) {
return nil, ErrNotFound
}
if err != nil {
return nil, err
}
return &r, nil
}
func (s *SQLiteRepoStore) DeleteRepo(ctx context.Context, id int64) error {
res, err := s.db.ExecContext(ctx, `DELETE FROM repos WHERE id = ?`, id)
if err != nil {
return err
}
n, err := res.RowsAffected()
if err != nil {
return err
}
if n == 0 {
return ErrNotFound
}
return nil
}
func (s *SQLiteRepoStore) UpdateRepoSyncMode(ctx context.Context, id int64, mode string) error {
res, err := s.db.ExecContext(ctx, `UPDATE repos SET sync_mode = ? WHERE id = ?`, mode, id)
if err != nil {
return err
}
n, _ := res.RowsAffected()
if n == 0 {
return ErrNotFound
}
return nil
}

144
internal/store/snapshot.go Normal file
View file

@ -0,0 +1,144 @@
package store
import (
"context"
"database/sql"
"errors"
"time"
)
type Snapshot struct {
ID int64
RepoID int64
Label string
CreatedAt time.Time
}
type SnapshotPackage struct {
ID int64
SnapshotID int64
Name string
Version string
Arch string
Location string
Checksum string
ChecksumType string
Size int64
}
type SnapshotStore interface {
CreateSnapshot(ctx context.Context, repoID int64, label string) (int64, error)
AddSnapshotPackages(ctx context.Context, snapshotID int64, pkgs []SnapshotPackage) error
ListSnapshots(ctx context.Context, repoID int64) ([]Snapshot, error)
GetSnapshot(ctx context.Context, id int64) (*Snapshot, error)
GetSnapshotPackages(ctx context.Context, snapshotID int64) ([]SnapshotPackage, error)
DeleteSnapshot(ctx context.Context, id int64) error
}
type SQLiteSnapshotStore struct {
db *sql.DB
}
func NewSnapshotStore(db *sql.DB) *SQLiteSnapshotStore {
return &SQLiteSnapshotStore{db: db}
}
func (s *SQLiteSnapshotStore) CreateSnapshot(ctx context.Context, repoID int64, label string) (int64, error) {
res, err := s.db.ExecContext(ctx, `INSERT INTO snapshots (repo_id, label) VALUES (?, ?)`, repoID, label)
if err != nil {
return 0, err
}
return res.LastInsertId()
}
func (s *SQLiteSnapshotStore) AddSnapshotPackages(ctx context.Context, snapshotID int64, pkgs []SnapshotPackage) error {
tx, err := s.db.BeginTx(ctx, nil)
if err != nil {
return err
}
defer tx.Rollback()
stmt, err := tx.PrepareContext(ctx, `INSERT INTO snapshot_packages
(snapshot_id, name, version, arch, location, checksum, checksum_type, size)
VALUES (?, ?, ?, ?, ?, ?, ?, ?)`)
if err != nil {
return err
}
defer stmt.Close()
for _, p := range pkgs {
if _, err := stmt.ExecContext(ctx, snapshotID, p.Name, p.Version, p.Arch, p.Location, p.Checksum, p.ChecksumType, p.Size); err != nil {
return err
}
}
return tx.Commit()
}
func (s *SQLiteSnapshotStore) ListSnapshots(ctx context.Context, repoID int64) ([]Snapshot, error) {
rows, err := s.db.QueryContext(ctx,
`SELECT id, repo_id, label, created_at FROM snapshots WHERE repo_id = ? ORDER BY id DESC`, repoID)
if err != nil {
return nil, err
}
defer rows.Close()
var snaps []Snapshot
for rows.Next() {
var snap Snapshot
if err := rows.Scan(&snap.ID, &snap.RepoID, &snap.Label, &snap.CreatedAt); err != nil {
return nil, err
}
snaps = append(snaps, snap)
}
return snaps, rows.Err()
}
func (s *SQLiteSnapshotStore) GetSnapshot(ctx context.Context, id int64) (*Snapshot, error) {
var snap Snapshot
err := s.db.QueryRowContext(ctx,
`SELECT id, repo_id, label, created_at FROM snapshots WHERE id = ?`, id).
Scan(&snap.ID, &snap.RepoID, &snap.Label, &snap.CreatedAt)
if errors.Is(err, sql.ErrNoRows) {
return nil, ErrNotFound
}
if err != nil {
return nil, err
}
return &snap, nil
}
func (s *SQLiteSnapshotStore) GetSnapshotPackages(ctx context.Context, snapshotID int64) ([]SnapshotPackage, error) {
rows, err := s.db.QueryContext(ctx,
`SELECT id, snapshot_id, name, version, arch, location, checksum, checksum_type, size
FROM snapshot_packages WHERE snapshot_id = ?`, snapshotID)
if err != nil {
return nil, err
}
defer rows.Close()
var pkgs []SnapshotPackage
for rows.Next() {
var p SnapshotPackage
if err := rows.Scan(&p.ID, &p.SnapshotID, &p.Name, &p.Version, &p.Arch,
&p.Location, &p.Checksum, &p.ChecksumType, &p.Size); err != nil {
return nil, err
}
pkgs = append(pkgs, p)
}
return pkgs, rows.Err()
}
func (s *SQLiteSnapshotStore) DeleteSnapshot(ctx context.Context, id int64) error {
res, err := s.db.ExecContext(ctx, `DELETE FROM snapshots WHERE id = ?`, id)
if err != nil {
return err
}
n, err := res.RowsAffected()
if err != nil {
return err
}
if n == 0 {
return ErrNotFound
}
return nil
}