encoding/base32: use correct length for unpadded buffer in Read

If unpadded content was passed, in some occassions content was omitted,
because the division result was floored. Ceiling it makes sure all
content is always read.

Fixes #65166

Change-Id: I1d8ee7ef436080483ed8f0e615b70a1013455f92
Reviewed-on: https://go-review.googlesource.com/c/go/+/581415
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/encoding/base32/base32.go b/src/encoding/base32/base32.go
index 4a61199a59d0d88dba1feed138675be5da03d031..9e988ef39b4f4dfcff2b3690c7044a5dbfdd0828 100644 (file)
--- a/src/encoding/base32/base32.go
+++ b/src/encoding/base32/base32.go
@@ -467,7 +467,7 @@ func (d *decoder) Read(p []byte) (n int, err error) {
        }
 
        // Read a chunk.
-       nn := len(p) / 5 * 8
+       nn := (len(p) + 4) / 5 * 8
        if nn < 8 {
                nn = 8
        }

diff --git a/src/encoding/base32/base32_test.go b/src/encoding/base32/base32_test.go
index 33638adeac691313c0a12ab8e1edca32820ac215..f5d3c49e38fbef48781ca87913c35d54672caaa5 100644 (file)
--- a/src/encoding/base32/base32_test.go
+++ b/src/encoding/base32/base32_test.go
@@ -92,6 +92,43 @@ func TestEncoderBuffering(t *testing.T) {
        }
 }
 
+func TestDecoderBufferingWithPadding(t *testing.T) {
+       for bs := 0; bs <= 12; bs++ {
+               for _, s := range pairs {
+                       decoder := NewDecoder(StdEncoding, strings.NewReader(s.encoded))
+                       buf := make([]byte, len(s.decoded)+bs)
+
+                       var n int
+                       var err error
+                       n, err = decoder.Read(buf)
+
+                       if err != nil && err != io.EOF {
+                               t.Errorf("Read from %q at pos %d = %d, unexpected error %v", s.encoded, len(s.decoded), n, err)
+                       }
+                       testEqual(t, "Decoding/%d of %q = %q, want %q\n", bs, s.encoded, string(buf[:n]), s.decoded)
+               }
+       }
+}
+
+func TestDecoderBufferingWithoutPadding(t *testing.T) {
+       for bs := 0; bs <= 12; bs++ {
+               for _, s := range pairs {
+                       encoded := strings.TrimRight(s.encoded, "=")
+                       decoder := NewDecoder(StdEncoding.WithPadding(NoPadding), strings.NewReader(encoded))
+                       buf := make([]byte, len(s.decoded)+bs)
+
+                       var n int
+                       var err error
+                       n, err = decoder.Read(buf)
+
+                       if err != nil && err != io.EOF {
+                               t.Errorf("Read from %q at pos %d = %d, unexpected error %v", encoded, len(s.decoded), n, err)
+                       }
+                       testEqual(t, "Decoding/%d of %q = %q, want %q\n", bs, encoded, string(buf[:n]), s.decoded)
+               }
+       }
+}
+
 func TestDecode(t *testing.T) {
        for _, p := range pairs {
                dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)))