问在Golang中使用UploadPartCopy to MultiPartUpload时遇到AccessDenied

EN

mpuOut, err := s3CreateMultipartUpload(&S3.CreateMultipartUploadInput{
    Bucket: aws.String(bucket),
    Key:    aws.String(concatenatedFile),
})
if err != nil {
    return err
}

var ps []*S3.CompletedPart
for i, part := range parts { // parts is a list of paths to things in s3
    partNumber := int64(i) + 1
    upOut, err := s3UploadPartCopy(&S3.UploadPartCopyInput{
        Bucket:     aws.String(bucket),
        CopySource: aws.String(part),
        Key:        aws.String(concatenatedFile),
        UploadId:   aws.String(*mpuOut.UploadId),
        PartNumber: aws.Int64(partNumber),
    })
    if err != nil {
        return err // <- fails here
    }
    ps = append(ps, &S3.CompletedPart{
        ETag:       s3Out.CopyPartResult.ETag,
        PartNumber: aws.Int64(int64(i)),
    })
}

_, err = s3CompleteMultipartUpload(&S3.CompleteMultipartUploadInput{
    Bucket:          aws.String(bucket),
    Key:             aws.String(concatenatedFile),
    MultipartUpload: &S3.CompletedMultipartUpload{Parts: ps},
    UploadId:        aws.String(*mpuOut.UploadId),
})
if err != nil {
    return err
}

_, err = s3CompleteMultipartUpload(&S3.CompleteMultipartUploadInput{
    Bucket:          aws.String(bucket),
    Key:             aws.String(concatenatedFile),
    MultipartUpload: &S3.CompletedMultipartUpload{Parts: ps},
    UploadId:        aws.String(*mpuOut.UploadId),
})
if err != nil {
    return err
}