110 lines
2.5 KiB
Go
110 lines
2.5 KiB
Go
// Package agherr contains AdGuard Home's error handling helpers.
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package agherr
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import (
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"fmt"
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"strings"
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)
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// Error is the constant error type.
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type Error string
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// Error implements the error interface for Error.
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func (err Error) Error() (msg string) {
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return string(err)
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}
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// manyError is an error containing several wrapped errors. It is created to be
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// a simpler version of the API provided by github.com/joomcode/errorx.
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type manyError struct {
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message string
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underlying []error
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}
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// Many wraps several errors and returns a single error.
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//
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// TODO(a.garipov): Add formatting to message.
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func Many(message string, underlying ...error) (err error) {
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err = &manyError{
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message: message,
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underlying: underlying,
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}
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return err
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}
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// Error implements the error interface for *manyError.
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func (e *manyError) Error() (msg string) {
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switch len(e.underlying) {
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case 0:
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return e.message
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case 1:
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return fmt.Sprintf("%s: %s", e.message, e.underlying[0])
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default:
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b := &strings.Builder{}
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// Ignore errors, since strings.(*Buffer).Write never returns
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// errors.
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_, _ = fmt.Fprintf(b, "%s: %s (hidden: %s", e.message, e.underlying[0], e.underlying[1])
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for _, u := range e.underlying[2:] {
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// See comment above.
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_, _ = fmt.Fprintf(b, ", %s", u)
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}
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// See comment above.
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_, _ = b.WriteString(")")
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return b.String()
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}
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}
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// Unwrap implements the hidden errors.wrapper interface for *manyError.
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func (e *manyError) Unwrap() (err error) {
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if len(e.underlying) == 0 {
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return nil
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}
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return e.underlying[0]
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}
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// wrapper is a copy of the hidden errors.wrapper interface for tests, linting,
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// etc.
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type wrapper interface {
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Unwrap() error
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}
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// Annotate annotates the error with the message, unless the error is nil. This
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// is a helper function to simplify code like this:
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//
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// func (f *foo) doStuff(s string) (err error) {
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// defer func() {
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// if err != nil {
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// err = fmt.Errorf("bad foo string %q: %w", s, err)
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// }
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// }()
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//
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// // …
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// }
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//
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// Instead, write:
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//
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// func (f *foo) doStuff(s string) (err error) {
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// defer agherr.Annotate("bad foo string %q: %w", &err, s)
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//
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// // …
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// }
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//
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// msg must contain the final ": %w" verb.
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func Annotate(msg string, errPtr *error, args ...interface{}) {
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if errPtr == nil {
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return
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}
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err := *errPtr
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if err != nil {
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args = append(args, err)
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*errPtr = fmt.Errorf(msg, args...)
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}
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}
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