GetObjectAcl of S3 always returns an empty grantee type

[shogo82148]

Confirm by changing [ ] to [x] below to ensure that it's a bug:

• I've gone though the API reference
• I've checked AWS Forums and StackOverflow for answers
• I've searched for previous similar issues and didn't find any solution

Describe the bug

GetObjectAcl of S3 always returns an empty grantee type.

Version of AWS SDK for Go?

module main

go 1.15

require (
	github.com/aws/aws-sdk-go v1.36.20
	github.com/aws/aws-sdk-go-v2 v0.31.0
	github.com/aws/aws-sdk-go-v2/config v0.4.0
	github.com/aws/aws-sdk-go-v2/service/s3 v0.31.0
	github.com/kr/pretty v0.2.1
)

Version of Go (go version)?

go version go1.15.6 darwin/amd64

To Reproduce

package main

import (
	"context"
	"log"
	"strings"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/s3"

	awsv2 "github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	s3v2 "github.com/aws/aws-sdk-go-v2/service/s3"

	"github.com/kr/pretty"
)

func main() {
	const bucket = "shogo82148-test"
	const key = "debug.txt"
	const region = "ap-northeast-1" // the region of shogo82148-test bucket

	sess := session.Must(session.NewSession(&aws.Config{
		Region: aws.String(region),
	}))

	ctx := context.Background()
	v1 := s3.New(sess)
	_, err := v1.PutObjectWithContext(ctx, &s3.PutObjectInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
		Body:   strings.NewReader("foobar"),
	})
	if err != nil {
		log.Fatal(err)
	}

	// AWS SDK v1
	respv1, err := v1.GetObjectAclWithContext(ctx, &s3.GetObjectAclInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
	})
	if err != nil {
		log.Fatal(err)
	}
	pretty.Log(respv1.Grants)

	// AWS SDK v2
	cfg, err := config.LoadDefaultConfig(ctx, config.WithRegion(region))
	if err != nil {
		log.Fatal(err)
	}
	v2 := s3v2.NewFromConfig(cfg)
	respv2, err := v2.GetObjectAcl(ctx, &s3v2.GetObjectAclInput{
		Bucket: awsv2.String(bucket),
		Key:    awsv2.String(key),
	})
	if err != nil {
		log.Fatal(err)
	}
	pretty.Log(respv2.Grants)
}

result:

% go run main.go
2021/01/05 16:53:42 []*s3.Grant{
    &s3.Grant{
        _:       struct {}{},
        Grantee: &s3.Grantee{
            _:            struct {}{},
            DisplayName:  &"shogo82148",
            EmailAddress: (*string)(nil),
            ID:           &"51915c5bd71c959533019b53a63318b74bf3f85d6cbe9708d564187d200649c7",
            Type:         &"CanonicalUser",
            URI:          (*string)(nil),
        },
        Permission: &"FULL_CONTROL",
    },
}
2021/01/05 16:53:42 []types.Grant{
    {
        Grantee: &types.Grantee{
            Type:         "",
            DisplayName:  &"shogo82148",
            EmailAddress: (*string)(nil),
            ID:           &"51915c5bd71c959533019b53a63318b74bf3f85d6cbe9708d564187d200649c7",
            URI:          (*string)(nil),
        },
        Permission: "FULL_CONTROL",
    },
}

Expected behavior

I want to get "CanonicalUser" grantee type.

2021/01/05 16:53:42 []types.Grant{
    {
        Grantee: &types.Grantee{
            Type:         "CanonicalUser", // I got ""
            DisplayName:  &"shogo82148",
            EmailAddress: (*string)(nil),
            ID:           &"51915c5bd71c959533019b53a63318b74bf3f85d6cbe9708d564187d200649c7",
            URI:          (*string)(nil),
        },
        Permission: "FULL_CONTROL",
    },
}

AWS SDK v1 returns my expected result, but v2 doesn't.

Additional context

Is types.TypeCanonicaluser intended name? it should be types.TypeCanonicalUser ?

https://pkg.go.dev/github.com/aws/aws-sdk-go-v2/service/s3/types#Type

[jasdel]

Thanks for reporting this issue @shogo82148. The SDK's behavior of not being able to deserialize the Grantee type is definitely a bug in the SDK. This most likely is related to the SDK's handling of XML attributes with namespaces. There was a similar bug in the v1 SDK few years ago, aws/aws-sdk-go#975 and aws/aws-sdk-go#916.

Also thanks for pointing out the unexpected enum name casing. I've corrected the enum casing in #1020.

[JordonPhillips]

This does seem to be related to namespaces. For example, the actual XML returned looks something like this:

<Grantee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="CanonicalUser">
    <ID>foo</ID>
    <DisplayName>bar</DisplayName>
</Grantee>

We try to decode this right around here. The parsed values of the attrs look something like this:

[]xml.Attr{
    {
        Name:  xml.Name{Space:"xmlns", Local:"xsi"},
        Value: "http://www.w3.org/2001/XMLSchema-instance",
    },
    {
        Name:  xml.Name{Space:"http://www.w3.org/2001/XMLSchema-instance", Local:"type"},
        Value: "CanonicalUser",
    },
}

We're checking Name.Local for xsi:type on each of these, but it would never equal that both because the namespace is separate and because it appears fully resolved.

[JordonPhillips]

And this does appear to be exactly the same issue referenced above

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