github.com/googleapis/api-linter@v1.65.2/rules/aip0121/no_mutable_cycles.go (about)

     1  // Copyright 2023 Google LLC
     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  //     https://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 aip0121
    16  
    17  import (
    18  	"strings"
    19  
    20  	"bitbucket.org/creachadair/stringset"
    21  	"github.com/googleapis/api-linter/lint"
    22  	"github.com/googleapis/api-linter/locations"
    23  	"github.com/googleapis/api-linter/rules/internal/utils"
    24  	"github.com/jhump/protoreflect/desc"
    25  )
    26  
    27  var noMutableCycles = &lint.MessageRule{
    28  	Name:   lint.NewRuleName(121, "no-mutable-cycles"),
    29  	OnlyIf: utils.IsResource,
    30  	LintMessage: func(m *desc.MessageDescriptor) []lint.Problem {
    31  		res := utils.GetResource(m)
    32  
    33  		return findCycles(res.GetType(), m, stringset.New(), nil)
    34  	},
    35  }
    36  
    37  func findCycles(start string, node *desc.MessageDescriptor, seen stringset.Set, chain []string) []lint.Problem {
    38  	var problems []lint.Problem
    39  	nodeRes := utils.GetResource(node)
    40  
    41  	chain = append(chain, nodeRes.GetType())
    42  	seen.Add(nodeRes.GetType())
    43  
    44  	for _, f := range node.GetFields() {
    45  		if !isMutableReference(f) {
    46  			continue
    47  		}
    48  		ref := utils.GetResourceReference(f)
    49  		// Skip indirect references for now.
    50  		if ref.GetChildType() != "" {
    51  			continue
    52  		}
    53  		if ref.GetType() == start {
    54  			cycle := strings.Join(append(chain, start), " > ")
    55  			problems = append(problems, lint.Problem{
    56  				Message:    "mutable resource reference introduces a reference cycle:\n" + cycle,
    57  				Descriptor: f,
    58  				Location:   locations.FieldResourceReference(f),
    59  			})
    60  		} else if !seen.Contains(ref.GetType()) {
    61  			next := utils.FindResourceMessage(ref.GetType(), node.GetFile())
    62  			// Skip unresolvable references.
    63  			if next == nil {
    64  				continue
    65  			}
    66  			if probs := findCycles(start, next, seen.Clone(), chain); len(probs) == 1 {
    67  				// A recursive call will only have one finding as it returns
    68  				// immediately.
    69  				p := probs[0]
    70  				p.Descriptor = f
    71  				p.Location = locations.FieldResourceReference(f)
    72  
    73  				problems = append(problems, p)
    74  			}
    75  		}
    76  		// Recursive calls should return immediately upon finding a cycle.
    77  		// The initial scan of the starting resource message should scan
    78  		// all of its own fields and not return immediately.
    79  		if len(problems) > 0 && len(chain) > 1 {
    80  			return problems
    81  		}
    82  	}
    83  
    84  	return problems
    85  }
    86  
    87  func isMutableReference(f *desc.FieldDescriptor) bool {
    88  	behaviors := utils.GetFieldBehavior(f)
    89  	return utils.HasResourceReference(f) && !behaviors.Contains("OUTPUT_ONLY")
    90  }