fix: fr32: Make UnpadReader be a correct Reader

storage/sealer/fr32/readers.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"math/bits"
 
+	pool "github.com/libp2p/go-buffer-pool"
 	"golang.org/x/xerrors"
 
 	"github.com/filecoin-project/go-state-types/abi"
@@ -14,6 +15,8 @@ type unpadReader struct {
 
 	left uint64
 	work []byte
+
+	stash []byte
 }
 
 func BufSize(sz abi.PaddedPieceSize) int {
@@ -31,6 +34,10 @@ func NewUnpadReaderBuf(src io.Reader, sz abi.PaddedPieceSize, buf []byte) (io.Re
 		return nil, xerrors.Errorf("bad piece size: %w", err)
 	}
 
+	if abi.PaddedPieceSize(len(buf)).Validate() != nil {
+		return nil, xerrors.Errorf("bad buffer size")
+	}
+
 	return &unpadReader{
 		src: src,
 
@@ -40,6 +47,39 @@ func NewUnpadReaderBuf(src io.Reader, sz abi.PaddedPieceSize, buf []byte) (io.Re
 }
 
 func (r *unpadReader) Read(out []byte) (int, error) {
+	idealReadSize := abi.PaddedPieceSize(len(r.work)).Unpadded()
+
+	var err error
+	var rn int
+	if len(r.stash) == 0 && len(out) < int(idealReadSize) {
+		r.stash = pool.Get(int(idealReadSize))
+
+		rn, err = r.readInner(r.stash)
+		r.stash = r.stash[:rn]
+	}
+
+	if len(r.stash) > 0 {
+		n := copy(out, r.stash)
+		r.stash = r.stash[n:]
+
+		if len(r.stash) == 0 {
+			pool.Put(r.stash)
+			r.stash = nil
+		}
+
+		if err == io.EOF && rn > n {
+			err = nil
+		}
+
+		return n, err
+	}
+
+	return r.readInner(out)
+}
+
+// readInner reads from the underlying reader into the provided buffer.
+// It requires that out[] is padded(power-of-two).unpadded()-sized, ideally quite large.
+func (r *unpadReader) readInner(out []byte) (int, error) {
 	if r.left == 0 {
 		return 0, io.EOF
 	}

storage/sealer/fr32/readers_test.go

@@ -3,6 +3,8 @@
 import (
 	"bufio"
 	"bytes"
+	"crypto/rand"
+	"fmt"
 	"io"
 	"testing"
 
@@ -34,3 +36,134 @@
 
 	require.Equal(t, raw, readered)
 }
+
+func TestPadWriterUnpadReader(t *testing.T) {
+	testCases := []struct {
+		name      string
+		unpadSize abi.UnpaddedPieceSize
+		readSizes []int
+	}{
+		{
+			name:      "2K with aligned reads",
+			unpadSize: 2 * 127 * 8, // 2K unpadded
+			readSizes: []int{127, 127 * 4},
+		},
+		{
+			name:      "Small piece, various read sizes",
+			unpadSize: 2 * 127 * 8, // 1016 bytes unpadded
+			readSizes: []int{1, 63, 127, 128, 255, 1016},
+		},
+		{
+			name:      "Medium piece, various read sizes",
+			unpadSize: 127 * 1024, // 128KB unpadded
+			readSizes: []int{1, 127, 128, 255, 1024, 4096, 65536},
+		},
+		{
+			name:      "Large piece, various read sizes",
+			unpadSize: 127 * 1024 * 1024, // 128MB unpadded
+			readSizes: []int{1, 127, 128, 255, 1024, 4096, 65536, 10 << 20, 11 << 20, 11<<20 + 134},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Generate random unpadded data
+			unpadded := make([]byte, tc.unpadSize)
+			rand.Read(unpadded)
+
+			// Create a buffer to store padded data
+			paddedBuf := new(bytes.Buffer)
+
+			// Create and use PadWriter
+			padWriter := fr32.NewPadWriter(paddedBuf)
+			written, err := padWriter.Write(unpadded)
+			require.NoError(t, err)
+			require.Equal(t, int(tc.unpadSize), written)
+			require.NoError(t, padWriter.Close())
+
+			// Create UnpadReader
+			paddedSize := tc.unpadSize.Padded()
+			unpadReader, err := fr32.NewUnpadReader(bytes.NewReader(paddedBuf.Bytes()), paddedSize)
+			require.NoError(t, err)
+
+			offset := int64(0)
+			for _, readSize := range tc.readSizes {
+				t.Run(fmt.Sprintf("ReadSize_%d_Offset_%d", readSize, offset), func(t *testing.T) {
+					// Seek to offset
+					require.NoError(t, err)
+
+					// Read data
+					readBuf := make([]byte, readSize)
+					n, err := io.ReadFull(unpadReader, readBuf)
+					require.NoError(t, err)
+					require.Equal(t, readSize, n)
+
+					// Compare with original unpadded data
+					expected := unpadded[offset : offset+int64(len(readBuf))]
+					require.Equal(t, expected, readBuf)
+					offset += int64(n)
+				})
+			}
+		})
+	}
+}
+
+func TestUnpadReaderSmallReads(t *testing.T) {
+	unpadSize := abi.UnpaddedPieceSize(127 * 1024) // 128KB unpadded
+	unpadded := make([]byte, unpadSize)
+	rand.Read(unpadded)
+
+	paddedBuf := new(bytes.Buffer)
+	padWriter := fr32.NewPadWriter(paddedBuf)
+	_, err := padWriter.Write(unpadded)
+	require.NoError(t, err)
+	require.NoError(t, padWriter.Close())
+
+	paddedSize := unpadSize.Padded()
+	unpadReader, err := fr32.NewUnpadReader(bytes.NewReader(paddedBuf.Bytes()), paddedSize)
+	require.NoError(t, err)
+
+	result := make([]byte, 0, unpadSize)
+	smallBuf := make([]byte, 1) // Read one byte at a time
+
+	for {
+		n, err := unpadReader.Read(smallBuf)
+		if err == io.EOF {
+			break
+		}
+		require.NoError(t, err)
+		result = append(result, smallBuf[:n]...)
+	}
+
+	require.Equal(t, unpadded, result)
+}
+
+func TestUnpadReaderLargeReads(t *testing.T) {
+	unpadSize := abi.UnpaddedPieceSize(127 * 1024 * 1024) // 128MB unpadded
+	unpadded := make([]byte, unpadSize)
+	rand.Read(unpadded)
+
+	paddedBuf := new(bytes.Buffer)
+	padWriter := fr32.NewPadWriter(paddedBuf)
+	_, err := padWriter.Write(unpadded)
+	require.NoError(t, err)
+	require.NoError(t, padWriter.Close())
+
+	paddedSize := unpadSize.Padded()
+	unpadReader, err := fr32.NewUnpadReader(bytes.NewReader(paddedBuf.Bytes()), paddedSize)
+	require.NoError(t, err)
+
+	largeBuf := make([]byte, 10*1024*1024) // 10MB buffer
+	result := make([]byte, 0, unpadSize)
+
+	for {
+		n, err := unpadReader.Read(largeBuf)
+		if err == io.EOF {
+			break
+		}
+		require.NoError(t, err)
+		result = append(result, largeBuf[:n]...)
+	}
+
+	require.Equal(t, unpadded, result)
+}