From 236771bffa11cf83cbd3b94755dd61de97a9d622 Mon Sep 17 00:00:00 2001
From: Kirill Reshke <reshke@double.cloud>
Date: Tue, 18 Aug 2026 00:09:35 +0500
Subject: [PATCH] fuzz reads

---
 cmd/yfuzzer/main.go | 119 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/cmd/yfuzzer/main.go b/cmd/yfuzzer/main.go
index 20ea2d80..4dda65d4 100644
--- a/cmd/yfuzzer/main.go
+++ b/cmd/yfuzzer/main.go
@@ -1,7 +1,11 @@
 package main
 
 import (
+	"errors"
+	"fmt"
+	"io"
 	"math/rand"
+	"syscall"
 
 	"github.com/spf13/cobra"
 
@@ -10,9 +14,11 @@ import (
 	"github.com/yezzey-gp/yproxy/pkg/client"
 	"github.com/yezzey-gp/yproxy/pkg/core"
 	"github.com/yezzey-gp/yproxy/pkg/crypt"
+	pio "github.com/yezzey-gp/yproxy/pkg/io"
 	"github.com/yezzey-gp/yproxy/pkg/message"
 	"github.com/yezzey-gp/yproxy/pkg/object"
 	"github.com/yezzey-gp/yproxy/pkg/proc"
+	"github.com/yezzey-gp/yproxy/pkg/proc/yio"
 	"github.com/yezzey-gp/yproxy/pkg/settings"
 	"github.com/yezzey-gp/yproxy/pkg/storage"
 	"github.com/yezzey-gp/yproxy/pkg/ylogger"
@@ -88,10 +94,122 @@ func (f *FuzzerProtoMgr) ProcessListExtended(
 	return nil
 }
 
+// ProcessCatExtended proxies the real object read from storage, but writes
+// the contents back to the client in randomly-sized chunks, mimicking the
+// fragmented writes used for listing batches.
+func (f *FuzzerProtoMgr) ProcessCatExtended(
+	s storage.StorageInteractor,
+	_ *pio.ProtoReader,
+	name string,
+	decrypt bool,
+	kek bool,
+	startOffset uint64,
+	settings []settings.StorageSettings,
+	cr crypt.Crypter,
+	ycl client.YproxyClient,
+) error {
+	ycl.SetExternalFilePath(name)
+
+	yr := yio.NewYRetryReader(yio.NewRestartReader(s, name, settings), ycl)
+
+	var contentReader io.Reader = yr
+	defer func() { _ = yr.Close() }()
+
+	if decrypt {
+		if cr == nil {
+			err := fmt.Errorf("failed to decrypt object, decrypter not configured")
+			ylogger.Zero.Error().Err(err).Msg("yfuzzer: cat failed")
+			return err
+		}
+		ylogger.Zero.Debug().Str("object-path", name).Msg("yfuzzer: decrypt object")
+		var err error
+		contentReader, err = cr.Decrypt(yr)
+		if err != nil {
+			ylogger.Zero.Error().Err(err).Msg("yfuzzer: failed to decrypt object")
+			return err
+		}
+	}
+
+	if kek {
+		err := fmt.Errorf("KEK is currently unsupported")
+		ylogger.Zero.Error().Err(err).Msg("yfuzzer: cat failed")
+	}
+
+	if startOffset != 0 {
+		if _, err := io.CopyN(io.Discard, contentReader, int64(startOffset)); err != nil {
+			return err
+		}
+	}
+
+	rw := ycl.GetRW()
+	chunk := make([]byte, maxCatChunk)
+	var total int64
+	for {
+		n, rerr := contentReader.Read(chunk)
+		if n > 0 {
+			/* Write the freshly read slice in small random-sized pieces,
+			 * exercising partial-write handling on the client side. */
+			pending := chunk[:n]
+			for len(pending) > 0 {
+				var writeChunk []byte
+				if len(pending) < 2 {
+					writeChunk = pending
+					pending = nil
+				} else {
+					currLen := rand.Intn(len(pending)) + 1
+					writeChunk = pending[:currLen]
+					pending = pending[currLen:]
+				}
+
+				if _, werr := rw.Write(writeChunk); werr != nil {
+					if errors.Is(werr, syscall.EPIPE) || errors.Is(werr, io.ErrClosedPipe) {
+						ylogger.Zero.Warn().Err(werr).Uint("client id", ycl.ID()).Int64("copied bytes", total).Msg("yfuzzer: client disconnected during cat")
+					} else {
+						ylogger.Zero.Error().Err(werr).Uint("client id", ycl.ID()).Int64("copied bytes", total).Msg("yfuzzer: failed to cat object")
+					}
+					_ = ycl.ReplyError(werr, "yfuzzer: failed to write cat chunk")
+					return werr
+				}
+			}
+			total += int64(n)
+		}
+		if rerr != nil {
+			if !errors.Is(rerr, io.EOF) {
+				if errors.Is(rerr, syscall.EPIPE) || errors.Is(rerr, io.ErrClosedPipe) {
+					ylogger.Zero.Warn().Err(rerr).Uint("client id", ycl.ID()).Int64("copied bytes", total).Msg("yfuzzer: client disconnected during cat")
+				} else {
+					ylogger.Zero.Error().Err(rerr).Uint("client id", ycl.ID()).Int64("copied bytes", total).Msg("yfuzzer: failed to read object")
+				}
+				return rerr
+			}
+			break
+		}
+	}
+
+	ylogger.Zero.Debug().Int64("copied bytes", total).Msg("yfuzzer: cat object")
+
+	if _, err := rw.Write(message.NewReadyForQueryMessage().Encode()); err != nil {
+		_ = ycl.ReplyError(err, "yfuzzer: failed to write ready for query")
+		return err
+	}
+
+	return nil
+}
+
 var cfgPath string
 
 var logLevel string
 
+<<<<<<< HEAD
+=======
+var (
+	maxIterations = 100
+	maxBatchSize  = 500
+	maxPathLen    = 256
+	maxCatChunk   = 8192
+)
+
+>>>>>>> f60a47a (fuzz reads)
 var rootCmd = &cobra.Command{
 	Use: "yfuzzer",
 	RunE: func(cmd *cobra.Command, args []string) error {
@@ -125,6 +243,7 @@ func init() {
 	/* For regular storage config, use this until we (if ever) proxy r-w calls.  */
 	rootCmd.PersistentFlags().StringVarP(&cfgPath, "config", "c", "/etc/yproxy/yproxy.yaml", "path to yproxy config file")
 	rootCmd.PersistentFlags().StringVarP(&logLevel, "log-level", "l", "", "log level")
+	rootCmd.PersistentFlags().IntVar(&maxCatChunk, "max-cat-chunk", maxCatChunk, "upper bound (exclusive) for cat read buffer size in bytes")
 }
 
 func main() {