github.com/rkt/rkt@v1.30.1-0.20200224141603-171c416fac02/pkg/pod/uuid.go (about)

     1  // Copyright 2015 The rkt 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 pod
    16  
    17  import (
    18  	"bytes"
    19  	"errors"
    20  	"fmt"
    21  	"io/ioutil"
    22  	"strings"
    23  
    24  	"github.com/appc/spec/schema/types"
    25  	"github.com/hashicorp/errwrap"
    26  )
    27  
    28  // matchUUID attempts to match the uuid specified as uuid against all pods present.
    29  // An array of matches is returned, which may be empty when nothing matches.
    30  func matchUUID(dataDir, uuid string) ([]string, error) {
    31  	if uuid == "" {
    32  		return nil, types.ErrNoEmptyUUID
    33  	}
    34  
    35  	ls, err := listPods(dataDir, IncludeMostDirs)
    36  	if err != nil {
    37  		return nil, err
    38  	}
    39  
    40  	var matches []string
    41  	for _, p := range ls {
    42  		if strings.HasPrefix(p, uuid) {
    43  			matches = append(matches, p)
    44  		}
    45  	}
    46  
    47  	return matches, nil
    48  }
    49  
    50  // resolveUUID attempts to resolve the uuid specified as uuid against all pods present.
    51  // An unambiguously matched uuid or nil is returned.
    52  func resolveUUID(dataDir, uuid string) (*types.UUID, error) {
    53  	uuid = strings.ToLower(uuid)
    54  	m, err := matchUUID(dataDir, uuid)
    55  	if err != nil {
    56  		return nil, err
    57  	}
    58  
    59  	if len(m) == 0 {
    60  		return nil, fmt.Errorf("no matches found for %q", uuid)
    61  	}
    62  
    63  	if len(m) > 1 {
    64  		return nil, fmt.Errorf("ambiguous uuid, %d matches", len(m))
    65  	}
    66  
    67  	u, err := types.NewUUID(m[0])
    68  	if err != nil {
    69  		return nil, errwrap.Wrap(errors.New("invalid UUID"), err)
    70  	}
    71  
    72  	return u, nil
    73  }
    74  
    75  // ReadUUIDFromFile reads the uuid string from the given path.
    76  func ReadUUIDFromFile(path string) (string, error) {
    77  	uuid, err := ioutil.ReadFile(path)
    78  	if err != nil {
    79  		return "", err
    80  	}
    81  	return string(bytes.TrimSpace(uuid)), nil
    82  }
    83  
    84  // WriteUUIDToFile writes the uuid string to the given path.
    85  func WriteUUIDToFile(uuid *types.UUID, path string) error {
    86  	return ioutil.WriteFile(path, []byte(uuid.String()), 0644)
    87  }