vendor: update buildkit to master@31c870e82a48

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/aws/smithy-go/encoding/json/decoder_util.go

@@ -0,0 +1,139 @@
+package json
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+// DiscardUnknownField discards unknown fields from a decoder body.
+// This function is useful while deserializing a JSON body with additional
+// unknown information that should be discarded.
+func DiscardUnknownField(decoder *json.Decoder) error {
+	// This deliberately does not share logic with CollectUnknownField, even
+	// though it could, because if we were to delegate to that then we'd incur
+	// extra allocations and general memory usage.
+	v, err := decoder.Token()
+	if err == io.EOF {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+
+	if _, ok := v.(json.Delim); ok {
+		for decoder.More() {
+			err = DiscardUnknownField(decoder)
+		}
+		endToken, err := decoder.Token()
+		if err != nil {
+			return err
+		}
+		if _, ok := endToken.(json.Delim); !ok {
+			return fmt.Errorf("invalid JSON : expected json delimiter, found %T %v",
+				endToken, endToken)
+		}
+	}
+
+	return nil
+}
+
+// CollectUnknownField grabs the contents of unknown fields from the decoder body
+// and returns them as a byte slice. This is useful for skipping unknown fields without
+// completely discarding them.
+func CollectUnknownField(decoder *json.Decoder) ([]byte, error) {
+	result, err := collectUnknownField(decoder)
+	if err != nil {
+		return nil, err
+	}
+
+	buff := bytes.NewBuffer(nil)
+	encoder := json.NewEncoder(buff)
+
+	if err := encoder.Encode(result); err != nil {
+		return nil, err
+	}
+
+	return buff.Bytes(), nil
+}
+
+func collectUnknownField(decoder *json.Decoder) (interface{}, error) {
+	// Grab the initial value. This could either be a concrete value like a string or a a
+	// delimiter.
+	token, err := decoder.Token()
+	if err == io.EOF {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// If it's an array or object, we'll need to recurse.
+	delim, ok := token.(json.Delim)
+	if ok {
+		var result interface{}
+		if delim == '{' {
+			result, err = collectUnknownObject(decoder)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			result, err = collectUnknownArray(decoder)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		// Discard the closing token. decoder.Token handles checking for matching delimiters
+		if _, err := decoder.Token(); err != nil {
+			return nil, err
+		}
+		return result, nil
+	}
+
+	return token, nil
+}
+
+func collectUnknownArray(decoder *json.Decoder) ([]interface{}, error) {
+	// We need to create an empty array here instead of a nil array, since by getting
+	// into this function at all we necessarily have seen a non-nil list.
+	array := []interface{}{}
+
+	for decoder.More() {
+		value, err := collectUnknownField(decoder)
+		if err != nil {
+			return nil, err
+		}
+		array = append(array, value)
+	}
+
+	return array, nil
+}
+
+func collectUnknownObject(decoder *json.Decoder) (map[string]interface{}, error) {
+	object := make(map[string]interface{})
+
+	for decoder.More() {
+		key, err := collectUnknownField(decoder)
+		if err != nil {
+			return nil, err
+		}
+
+		// Keys have to be strings, which is particularly important as the encoder
+		// won't except a map with interface{} keys
+		stringKey, ok := key.(string)
+		if !ok {
+			return nil, fmt.Errorf("expected string key, found %T", key)
+		}
+
+		value, err := collectUnknownField(decoder)
+		if err != nil {
+			return nil, err
+		}
+
+		object[stringKey] = value
+	}
+
+	return object, nil
+}