safeio

Documentation

Overview

Package safeio provides small helpers to safely drain and close readers and to propagate close errors without losing earlier errors.

Index

• func CloseWithErr(dstErr *error, c io.Closer)
• func DrainAndClose(rc io.ReadCloser) error

Examples

• CloseWithErr
• CloseWithErr (PreserveFirstError)
• DrainAndClose

Functions

func CloseWithErr

func CloseWithErr(dstErr *error, c io.Closer)

CloseWithErr closes c and, if dstErr is non-nil and not already set, stores the close error into *dstErr. This helps preserve the first error while ensuring resources are closed.

Example

var err = errPrimaryOp

// We still want to close resources even if the primary operation failed
closer := &mockCloser{}
CloseWithErr(&err, closer)

// The original error is preserved
fmt.Printf("Final error: %v\n", err)

Output:
Final error: primary operation failed

Example (PreserveFirstError)

var err error

// Successful primary operation (err is nil)
// But closer fails
closer := &mockCloser{closeErr: errCloseExample}
CloseWithErr(&err, closer)

// The close error is now stored in err
fmt.Printf("Final error: %v\n", err)

Output:
Final error: close failed

func DrainAndClose

func DrainAndClose(rc io.ReadCloser) error

DrainAndClose drains all data from rc to io.Discard and then closes rc. It returns a wrapped error if the drain or close operation fails.

Example

Example usage tests to demonstrate the API.

// Simulate a reader with some data
reader := strings.NewReader("some data to drain")
rc := &mockReadCloser{reader: reader}

err := DrainAndClose(rc)
if err != nil {
	fmt.Printf("Error: %v\n", err)

	return
}

fmt.Println("Successfully drained and closed")

Output:
Successfully drained and closed