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// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
// SPDX-License-Identifier: Apache-2.0
package errext
import "fmt"
// WithCleanup combines two errors into a single error:
// - (optionally) a main error from an IO operation (e.g. a directory listing or a database read)
// - an auxiliary error from closing or otherwise cleaning up the respective IO handle
//
// It is intended to simplify situations where a Close() or Commit()/Rollback() call is required at the end of the operation,
// but its error should not be swallowed if there is one.
// For example:
//
// db, err := sql.Open("postgres", dbURL)
// if err != nil {
// return nil, err
// }
// err = applySchema(db)
// if err != nil {
// err2 := db.Close()
// if err2 == nil {
// return nil, err
// } else {
// return nil, fmt.Errorf("%w (additional error during db.Close(): %s)", err, err2.Error())
// }
// }
// return db, nil
//
// can be shortened to:
//
// db, err := sql.Open("postgres", dbURL)
// if err != nil {
// return nil, err
// }
// err = applySchema(db)
// if err != nil {
// return errext.WithCleanup(err, "db.Close", db.Close())
// }
// return db, nil
//
// If cleanupErr is nil, err is returned unchanged.
//
// If err is nil, but cleanupErr is not nil, cleanupErr will be wrapped to indicate the name of the cleanup operation that failed.
func WithCleanup(err error, cleanupOperation string, cleanupErr error) error {
if cleanupErr == nil {
return err
}
return cleanupError{err, cleanupErr, cleanupOperation}
}
type cleanupError struct {
MainError error
CleanupError error
CleanupOperation string
}
// Error implements the builtin/error interface.
func (e cleanupError) Error() string {
if e.MainError == nil {
return fmt.Sprintf("during %s(): %s", e.CleanupOperation, e.CleanupError.Error())
} else {
return fmt.Sprintf("%s (additional error during %s(): %s)", e.MainError.Error(), e.CleanupOperation, e.CleanupError.Error())
}
}
// Unwrap implements the interface implied by the documentation of package errors.
func (e cleanupError) Unwrap() []error {
if e.MainError == nil {
return []error{e.CleanupError}
} else {
return []error{e.MainError, e.CleanupError}
}
}
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