github.com/zntrio/harp/v2@v2.0.9/pkg/sdk/value/hash/multi.go (about)

     1  // Licensed to Elasticsearch B.V. under one or more contributor
     2  // license agreements. See the NOTICE file distributed with
     3  // this work for additional information regarding copyright
     4  // ownership. Elasticsearch B.V. licenses this file to you under
     5  // the Apache License, Version 2.0 (the "License"); you may
     6  // not use this file except in compliance with the License.
     7  // You may obtain a copy of the License at
     8  //
     9  //     http://www.apache.org/licenses/LICENSE-2.0
    10  //
    11  // Unless required by applicable law or agreed to in writing,
    12  // software distributed under the License is distributed on an
    13  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    14  // KIND, either express or implied.  See the License for the
    15  // specific language governing permissions and limitations
    16  // under the License.
    17  
    18  package hash
    19  
    20  import (
    21  	"encoding/hex"
    22  	"fmt"
    23  	"hash"
    24  	"io"
    25  )
    26  
    27  func NewMultiHash(r io.Reader, algorithms ...string) (map[string]string, error) {
    28  	hashers := map[string]hash.Hash{}
    29  
    30  	// Instantiate hashers
    31  	for _, algo := range algorithms {
    32  		// Create an hasher instance.
    33  		h, err := NewHasher(algo)
    34  		if err != nil {
    35  			return nil, fmt.Errorf("unable to initialize %q algorithm: %w", algo, err)
    36  		}
    37  
    38  		// Assign to hashers.
    39  		hashers[algo] = h
    40  	}
    41  
    42  	// Copy to all hashers
    43  	_, err := io.Copy(io.MultiWriter(hashToMultiWriter(hashers)), r)
    44  	if err != nil {
    45  		return nil, err
    46  	}
    47  
    48  	// Finalize
    49  	res := make(map[string]string)
    50  	for algo, v := range hashers {
    51  		res[algo] = hex.EncodeToString(v.Sum(nil))
    52  	}
    53  
    54  	// No error
    55  	return res, nil
    56  }
    57  
    58  // -----------------------------------------------------------------------------
    59  
    60  func hashToMultiWriter(hashers map[string]hash.Hash) io.Writer {
    61  	w := make([]io.Writer, 0, len(hashers))
    62  	for _, v := range hashers {
    63  		w = append(w, v)
    64  	}
    65  	return io.MultiWriter(w...)
    66  }