From 8e744de5e6c40ef612295fe084fe887fe759aa0a Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 25 Aug 2026 12:18:22 +0100
Subject: [PATCH] pikpak: fix truncated single part uploads reported as ok when
 source ends early

If the source supplied fewer bytes than its declared size, the single
part upload path accepted the short body and stored a truncated file
recorded with the declared size, reporting a successful upload. The
multipart path already checks for this.

Count the bytes actually read and fail the upload if they do not match
the declared size, which cancels the partially created file.

This was found by the FsPutShortEOF integration test.
---
 backend/pikpak/pikpak.go | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/backend/pikpak/pikpak.go b/backend/pikpak/pikpak.go
index 59d10d294..df5c3f499 100644
--- a/backend/pikpak/pikpak.go
+++ b/backend/pikpak/pikpak.go
@@ -58,6 +58,7 @@ import (
 	"github.com/rclone/rclone/lib/oauthutil"
 	"github.com/rclone/rclone/lib/pacer"
 	"github.com/rclone/rclone/lib/random"
+	"github.com/rclone/rclone/lib/readers"
 	"github.com/rclone/rclone/lib/rest"
 	"golang.org/x/oauth2"
 )
@@ -1446,10 +1447,11 @@ func (f *Fs) uploadByResumable(ctx context.Context, in io.Reader, name string, s
 	if err != nil {
 		return fmt.Errorf("failed to create upload client: %w", err)
 	}
+	counter := readers.NewCountingReader(in)
 	req := &s3.PutObjectInput{
 		Bucket: &p.Bucket,
 		Key:    &p.Key,
-		Body:   io.NopCloser(in),
+		Body:   io.NopCloser(counter),
 	}
 	// Apply upload options
 	for _, option := range options {
@@ -1477,7 +1479,14 @@ func (f *Fs) uploadByResumable(ctx context.Context, in io.Reader, name string, s
 		_, err = client.PutObject(ctx, req, s3opts...)
 		return f.shouldRetry(ctx, nil, err)
 	})
-	return
+	if err != nil {
+		return err
+	}
+	// Check for truncation of input
+	if size >= 0 && int64(counter.BytesRead()) != size {
+		return fmt.Errorf("expected %d bytes in input, but got %d: %w", size, counter.BytesRead(), io.ErrUnexpectedEOF)
+	}
+	return nil
 }
 
 func (f *Fs) upload(ctx context.Context, in io.Reader, leaf, dirID, gcid string, size int64, options ...fs.OpenOption) (info *api.File, err error) {