func unmarshalError(r *request.Request) {
	defer r.HTTPResponse.Body.Close()

	if r.HTTPResponse.StatusCode == http.StatusMovedPermanently {
		r.Error = awserr.New("BucketRegionError",
			fmt.Sprintf("incorrect region, the bucket is not in '%s' region", aws.StringValue(r.Service.Config.Region)), nil)
		return
	}

	if r.HTTPResponse.ContentLength == int64(0) {
		// No body, use status code to generate an awserr.Error
		r.Error = awserr.NewRequestFailure(
			awserr.New(strings.Replace(r.HTTPResponse.Status, " ", "", -1), r.HTTPResponse.Status, nil),
			r.HTTPResponse.StatusCode,
			"",
		)
		return
	}

	resp := &xmlErrorResponse{}
	err := xml.NewDecoder(r.HTTPResponse.Body).Decode(resp)
	if err != nil && err != io.EOF {
		r.Error = awserr.New("SerializationError", "failed to decode S3 XML error response", nil)
	} else {
		r.Error = awserr.NewRequestFailure(
			awserr.New(resp.Code, resp.Message, nil),
			r.HTTPResponse.StatusCode,
			"",
		)
	}
}

// loadProfiles loads from the file pointed to by shared credentials filename for profile.
// The credentials retrieved from the profile will be returned or error. Error will be
// returned if it fails to read from the file, or the data is invalid.
func loadProfile(filename, profile string) (Value, error) {
	config, err := ini.LoadFile(filename)
	if err != nil {
		return Value{}, awserr.New("SharedCredsLoad", "failed to load shared credentials file", err)
	}
	iniProfile := config.Section(profile)

	id, ok := iniProfile["aws_access_key_id"]
	if !ok {
		return Value{}, awserr.New("SharedCredsAccessKey",
			fmt.Sprintf("shared credentials %s in %s did not contain aws_access_key_id", profile, filename),
			nil)
	}

	secret, ok := iniProfile["aws_secret_access_key"]
	if !ok {
		return Value{}, awserr.New("SharedCredsSecret",
			fmt.Sprintf("shared credentials %s in %s did not contain aws_secret_access_key", profile, filename),
			nil)
	}

	token := iniProfile["aws_session_token"]

	return Value{
		AccessKeyID:     id,
		SecretAccessKey: secret,
		SessionToken:    token,
	}, nil
}

// UnmarshalError unmarshals an error response for an AWS Query service.
func UnmarshalError(r *request.Request) {
	defer r.HTTPResponse.Body.Close()

	resp := &xmlErrorResponse{}
	err := xml.NewDecoder(r.HTTPResponse.Body).Decode(resp)
	if err != nil && err != io.EOF {
		r.Error = awserr.New("SerializationError", "failed to decode query XML error response", err)
	} else {
		r.Error = awserr.NewRequestFailure(
			awserr.New(resp.Code, resp.Message, nil),
			r.HTTPResponse.StatusCode,
			resp.RequestID,
		)
	}
}

func buildQueryString(query url.Values, v reflect.Value, name string) error {
	switch value := v.Interface().(type) {
	case []*string:
		for _, item := range value {
			query.Add(name, *item)
		}
	case map[string]*string:
		for key, item := range value {
			query.Add(key, *item)
		}
	case map[string][]*string:
		for key, items := range value {
			for _, item := range items {
				query.Add(key, *item)
			}
		}
	default:
		str, err := convertType(v)
		if err == errValueNotSet {
			return nil
		} else if err != nil {
			return awserr.New("SerializationError", "failed to encode REST request", err)
		}
		query.Set(name, str)
	}

	return nil
}

// Retrieve retrieves credentials from the EC2 service.
// Error will be returned if the request fails, or unable to extract
// the desired credentials.
func (m *EC2RoleProvider) Retrieve() (credentials.Value, error) {
	if m.Client == nil {
		m.Client = ec2metadata.New(nil)
	}

	credsList, err := requestCredList(m.Client)
	if err != nil {
		return credentials.Value{}, err
	}

	if len(credsList) == 0 {
		return credentials.Value{}, awserr.New("EmptyEC2RoleList", "empty EC2 Role list", nil)
	}
	credsName := credsList[0]

	roleCreds, err := requestCred(m.Client, credsName)
	if err != nil {
		return credentials.Value{}, err
	}

	m.SetExpiration(roleCreds.Expiration, m.ExpiryWindow)

	return credentials.Value{
		AccessKeyID:     roleCreds.AccessKeyID,
		SecretAccessKey: roleCreds.SecretAccessKey,
		SessionToken:    roleCreds.Token,
	}, nil
}

func unmarshalError(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	_, err := ioutil.ReadAll(r.HTTPResponse.Body)
	if err != nil {
		r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata error respose", err)
	}

	// TODO extract the error...
}

// requestCredList requests a list of credentials from the EC2 service.
// If there are no credentials, or there is an error making or receiving the request
func requestCredList(client *ec2metadata.Client) ([]string, error) {
	resp, err := client.GetMetadata(iamSecurityCredsPath)
	if err != nil {
		return nil, awserr.New("EC2RoleRequestError", "failed to list EC2 Roles", err)
	}

	credsList := []string{}
	s := bufio.NewScanner(strings.NewReader(resp))
	for s.Scan() {
		credsList = append(credsList, s.Text())
	}

	if err := s.Err(); err != nil {
		return nil, awserr.New("SerializationError", "failed to read list of EC2 Roles", err)
	}

	return credsList, nil
}

func unmarshalHandler(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	b, err := ioutil.ReadAll(r.HTTPResponse.Body)
	if err != nil {
		r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata respose", err)
	}

	data := r.Data.(*metadataOutput)
	data.Content = string(b)
}

// Unmarshal unmarshals a response for an AWS Query service.
func Unmarshal(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	if r.DataFilled() {
		decoder := xml.NewDecoder(r.HTTPResponse.Body)
		err := xmlutil.UnmarshalXML(r.Data, decoder, r.Operation.Name+"Result")
		if err != nil {
			r.Error = awserr.New("SerializationError", "failed decoding Query response", err)
			return
		}
	}
}

func buildHeader(header *http.Header, v reflect.Value, name string) error {
	str, err := convertType(v)
	if err == errValueNotSet {
		return nil
	} else if err != nil {
		return awserr.New("SerializationError", "failed to encode REST request", err)
	}

	header.Add(name, str)

	return nil
}

func unmarshalBody(r *request.Request, v reflect.Value) {
	if field, ok := v.Type().FieldByName("SDKShapeTraits"); ok {
		if payloadName := field.Tag.Get("payload"); payloadName != "" {
			pfield, _ := v.Type().FieldByName(payloadName)
			if ptag := pfield.Tag.Get("type"); ptag != "" && ptag != "structure" {
				payload := v.FieldByName(payloadName)
				if payload.IsValid() {
					switch payload.Interface().(type) {
					case []byte:
						b, err := ioutil.ReadAll(r.HTTPResponse.Body)
						if err != nil {
							r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
						} else {
							payload.Set(reflect.ValueOf(b))
						}
					case *string:
						b, err := ioutil.ReadAll(r.HTTPResponse.Body)
						if err != nil {
							r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
						} else {
							str := string(b)
							payload.Set(reflect.ValueOf(&str))
						}
					default:
						switch payload.Type().String() {
						case "io.ReadSeeker":
							payload.Set(reflect.ValueOf(aws.ReadSeekCloser(r.HTTPResponse.Body)))
						case "aws.ReadSeekCloser", "io.ReadCloser":
							payload.Set(reflect.ValueOf(r.HTTPResponse.Body))
						default:
							r.Error = awserr.New("SerializationError",
								"failed to decode REST response",
								fmt.Errorf("unknown payload type %s", payload.Type()))
						}
					}
				}
			}
		}
	}
}

// Unmarshal unmarshals a payload response for the REST XML protocol.
func Unmarshal(r *request.Request) {
	if t := rest.PayloadType(r.Data); t == "structure" || t == "" {
		defer r.HTTPResponse.Body.Close()
		decoder := xml.NewDecoder(r.HTTPResponse.Body)
		err := xmlutil.UnmarshalXML(r.Data, decoder, "")
		if err != nil {
			r.Error = awserr.New("SerializationError", "failed to decode REST XML response", err)
			return
		}
	} else {
		rest.Unmarshal(r)
	}
}

// Build builds a request payload for the REST XML protocol.
func Build(r *request.Request) {
	rest.Build(r)

	if t := rest.PayloadType(r.Params); t == "structure" || t == "" {
		var buf bytes.Buffer
		err := xmlutil.BuildXML(r.Params, xml.NewEncoder(&buf))
		if err != nil {
			r.Error = awserr.New("SerializationError", "failed to encode rest XML request", err)
			return
		}
		r.SetBufferBody(buf.Bytes())
	}
}

// contentMD5 computes and sets the HTTP Content-MD5 header for requests that
// require it.
func contentMD5(r *request.Request) {
	h := md5.New()

	// hash the body.  seek back to the first position after reading to reset
	// the body for transmission.  copy errors may be assumed to be from the
	// body.
	_, err := io.Copy(h, r.Body)
	if err != nil {
		r.Error = awserr.New("ContentMD5", "failed to read body", err)
		return
	}
	_, err = r.Body.Seek(0, 0)
	if err != nil {
		r.Error = awserr.New("ContentMD5", "failed to seek body", err)
		return
	}

	// encode the md5 checksum in base64 and set the request header.
	sum := h.Sum(nil)
	sum64 := make([]byte, base64.StdEncoding.EncodedLen(len(sum)))
	base64.StdEncoding.Encode(sum64, sum)
	r.HTTPRequest.Header.Set("Content-MD5", string(sum64))
}

func buildHeaderMap(header *http.Header, v reflect.Value, prefix string) error {
	for _, key := range v.MapKeys() {
		str, err := convertType(v.MapIndex(key))
		if err == errValueNotSet {
			continue
		} else if err != nil {
			return awserr.New("SerializationError", "failed to encode REST request", err)

		}

		header.Add(prefix+key.String(), str)
	}
	return nil
}

// requestCred requests the credentials for a specific credentials from the EC2 service.
//
// If the credentials cannot be found, or there is an error reading the response
// and error will be returned.
func requestCred(client *ec2metadata.Client, credsName string) (ec2RoleCredRespBody, error) {
	resp, err := client.GetMetadata(path.Join(iamSecurityCredsPath, credsName))
	if err != nil {
		return ec2RoleCredRespBody{},
			awserr.New("EC2RoleRequestError",
				fmt.Sprintf("failed to get %s EC2 Role credentials", credsName),
				err)
	}

	respCreds := ec2RoleCredRespBody{}
	if err := json.NewDecoder(strings.NewReader(resp)).Decode(&respCreds); err != nil {
		return ec2RoleCredRespBody{},
			awserr.New("SerializationError",
				fmt.Sprintf("failed to decode %s EC2 Role credentials", credsName),
				err)
	}

	if respCreds.Code != "Success" {
		// If an error code was returned something failed requesting the role.
		return ec2RoleCredRespBody{}, awserr.New(respCreds.Code, respCreds.Message, nil)
	}

	return respCreds, nil
}

func buildURI(u *url.URL, v reflect.Value, name string) error {
	value, err := convertType(v)
	if err == errValueNotSet {
		return nil
	} else if err != nil {
		return awserr.New("SerializationError", "failed to encode REST request", err)
	}

	uri := u.Path
	uri = strings.Replace(uri, "{"+name+"}", EscapePath(value, true), -1)
	uri = strings.Replace(uri, "{"+name+"+}", EscapePath(value, false), -1)
	u.Path = uri

	return nil
}

func unmarshalLocationElements(r *request.Request, v reflect.Value) {
	for i := 0; i < v.NumField(); i++ {
		m, field := v.Field(i), v.Type().Field(i)
		if n := field.Name; n[0:1] == strings.ToLower(n[0:1]) {
			continue
		}

		if m.IsValid() {
			name := field.Tag.Get("locationName")
			if name == "" {
				name = field.Name
			}

			switch field.Tag.Get("location") {
			case "statusCode":
				unmarshalStatusCode(m, r.HTTPResponse.StatusCode)
			case "header":
				err := unmarshalHeader(m, r.HTTPResponse.Header.Get(name))
				if err != nil {
					r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
					break
				}
			case "headers":
				prefix := field.Tag.Get("locationName")
				err := unmarshalHeaderMap(m, r.HTTPResponse.Header, prefix)
				if err != nil {
					r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
					break
				}
			}
		}
		if r.Error != nil {
			return
		}
	}
}

func buildGetBucketLocation(r *request.Request) {
	if r.DataFilled() {
		out := r.Data.(*GetBucketLocationOutput)
		b, err := ioutil.ReadAll(r.HTTPResponse.Body)
		if err != nil {
			r.Error = awserr.New("SerializationError", "failed reading response body", err)
			return
		}

		match := reBucketLocation.FindSubmatch(b)
		if len(match) > 1 {
			loc := string(match[1])
			out.LocationConstraint = &loc
		}
	}
}

// Build builds a request for an AWS Query service.
func Build(r *request.Request) {
	body := url.Values{
		"Action":  {r.Operation.Name},
		"Version": {r.Service.APIVersion},
	}
	if err := queryutil.Parse(body, r.Params, false); err != nil {
		r.Error = awserr.New("SerializationError", "failed encoding Query request", err)
		return
	}

	if r.ExpireTime == 0 {
		r.HTTPRequest.Method = "POST"
		r.HTTPRequest.Header.Set("Content-Type", "application/x-www-form-urlencoded; charset=utf-8")
		r.SetBufferBody([]byte(body.Encode()))
	} else { // This is a pre-signed request
		r.HTTPRequest.Method = "GET"
		r.HTTPRequest.URL.RawQuery = body.Encode()
	}
}