weichenandCursor
e3b72ad64b
Live apply now accepts only :5433/agent_system_dev plus a data/dev host root, maps stored work dirs fail-closed, and reports unique O_EXCL backups after a parent-directory fsync. Co-authored-by: Cursor <cursoragent@cursor.com>
103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
package fsutil
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import (
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"errors"
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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)
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// dirSync is the directory durability hook; tests replace it.
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var dirSync = syncDirImpl
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// WriteFileAtomic writes data via temp file + Sync + rename so readers never see a partial file.
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// After a successful rename the parent directory is opened and Sync'd.
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func WriteFileAtomic(path string, data []byte, perm os.FileMode) error {
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return writeFileAtomic(path, data, perm, false)
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}
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// WriteFileAtomicExclusive is WriteFileAtomic but creates the destination with O_EXCL.
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func WriteFileAtomicExclusive(path string, data []byte, perm os.FileMode) error {
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return writeFileAtomic(path, data, perm, true)
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}
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func writeFileAtomic(path string, data []byte, perm os.FileMode, exclusive bool) error {
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dir := filepath.Dir(path)
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if err := os.MkdirAll(dir, 0o755); err != nil {
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return err
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}
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if exclusive {
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f, err := os.OpenFile(path, os.O_CREATE|os.O_EXCL|os.O_WRONLY, perm)
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if err != nil {
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if os.IsExist(err) {
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return fmt.Errorf("fsutil: refuse overwrite of existing %s", path)
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}
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return err
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}
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if cerr := f.Close(); cerr != nil {
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return cerr
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}
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}
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tmp, err := os.CreateTemp(dir, "."+filepath.Base(path)+".*.tmp")
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if err != nil {
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return err
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}
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tmpName := tmp.Name()
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cleanup := true
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defer func() {
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if cleanup {
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_ = os.Remove(tmpName)
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}
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}()
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if _, err := tmp.Write(data); err != nil {
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_ = tmp.Close()
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return fmt.Errorf("atomic write: %w", err)
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}
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if err := tmp.Sync(); err != nil {
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_ = tmp.Close()
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return fmt.Errorf("atomic sync: %w", err)
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}
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if err := tmp.Close(); err != nil {
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return err
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}
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if err := os.Chmod(tmpName, perm); err != nil {
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return err
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}
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if err := os.Rename(tmpName, path); err != nil {
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return err
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}
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cleanup = false
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if err := dirSync(dir); err != nil {
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if ignorableDirSync(err) {
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return nil
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}
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return err
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}
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return nil
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}
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// SyncDir fsyncs a directory so create/rename/unlink entries become durable.
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func SyncDir(dir string) error {
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return dirSync(dir)
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}
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func syncDirImpl(dir string) error {
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d, err := os.Open(dir)
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if err != nil {
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return fmt.Errorf("fsutil: open dir %s: %w", dir, err)
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}
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defer d.Close()
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if err := d.Sync(); err != nil {
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if ignorableDirSync(err) {
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return nil
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}
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return fmt.Errorf("fsutil: sync dir %s: %w", dir, err)
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}
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return nil
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}
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func ignorableDirSync(err error) bool {
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return errors.Is(err, syscall.EINVAL) || errors.Is(err, syscall.ENOTSUP) || errors.Is(err, syscall.ENOSYS)
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}
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