package linux

import (
	"errors"
	"os"
)

// ExtractErrno extracts an [Errno] from an error, best effort.
//
// If the system-specific or Go-specific error cannot be mapped to anything, it
// will be logged and EIO will be returned.
func ExtractErrno(err error) Errno {
	for _, pair := range []struct {
		error
		Errno
	}{
		{os.ErrNotExist, ENOENT},
		{os.ErrExist, EEXIST},
		{os.ErrPermission, EACCES},
		{os.ErrInvalid, EINVAL},
	} {
		if errors.Is(err, pair.error) {
			return pair.Errno
		}
	}

	var errno Errno
	if errors.As(err, &errno) {
		return errno
	}

	if e := sysErrno(err); e != 0 {
		return e
	}

	// Default case.
	return EIO
}