go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/common/errors/wrap.go (about)

     1  // Copyright 2016 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package errors
    16  
    17  // Wrapped indicates an error that wraps another error.
    18  type Wrapped interface {
    19  	// Unwrap returns the wrapped error.
    20  	Unwrap() error
    21  }
    22  
    23  // Unwrap unwraps a wrapped error recursively, returning its inner error.
    24  //
    25  // If the supplied error is not nil, Unwrap will never return nil. If a
    26  // wrapped error reports that its Unwrap is nil, that error will be
    27  // returned.
    28  func Unwrap(err error) error {
    29  	for {
    30  		wrap, ok := err.(Wrapped)
    31  		if !ok {
    32  			return err
    33  		}
    34  
    35  		inner := wrap.Unwrap()
    36  		if inner == nil {
    37  			break
    38  		}
    39  		err = inner
    40  	}
    41  	return err
    42  }