Add support for decoding base64 strings without padding (#1604)

pkg/yqlib/decoder_base64.go

@@ -4,10 +4,33 @@ import (
  "bytes"
  "encoding/base64"
  "io"
+ "strings"
 
  yaml "gopkg.in/yaml.v3"
 )
 
+type base64Padder struct {
+ count uint64
+ io.Reader
+}
+
+func (c *base64Padder) pad(buf []byte) (int, error) {
+ pad := strings.Repeat("=", int(4-c.count%4))
+ n, err := strings.NewReader(pad).Read(buf)
+ c.count += uint64(n)
+ return n, err
+}
+
+func (c *base64Padder) Read(buf []byte) (int, error) {
+ n, err := c.Reader.Read(buf)
+ c.count += uint64(n)
+
+ if err == io.EOF && c.count%4 != 0 {
+ return c.pad(buf)
+ }
+ return n, err
+}
+
 type base64Decoder struct {
  reader io.Reader
  finished bool
@@ -20,7 +43,7 @@ func NewBase64Decoder() Decoder {
 }
 
 func (dec *base64Decoder) Init(reader io.Reader) error {
- dec.reader = reader
+ dec.reader = &base64Padder{Reader: reader}
  dec.readAnything = false
  dec.finished = false
  return nil

pkg/yqlib/operator_encoder_decoder_test.go

@@ -310,6 +310,14 @@ var encoderDecoderOperatorScenarios = []expressionScenario{
  "D0, P[], (!!str)::\n",
  },
  },
+ {
+ description: "base64 missing padding test",
+ skipDoc: true,
+ expression: `"Y2F0cw" | @base64d`,
+ expected: []string{
+ "D0, P[], (!!str)::cats\n",
+ },
+ },
  {
  requiresFormat: "xml",
  description: "empty xml decode",