From dff2a85c6145f3f7240cf6f8e05ae3b3f76d878f Mon Sep 17 00:00:00 2001
From: Nils Braun <nilslennartbraun@gmail.com>
Date: Tue, 5 Nov 2024 10:16:50 +0100
Subject: [PATCH 1/2] Fix a bug in the _upload_file_part_concurrent method for
 certain file sizes

---
 s3fs/core.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/s3fs/core.py b/s3fs/core.py
index f3dc411d..3b9ed995 100644
--- a/s3fs/core.py
+++ b/s3fs/core.py
@@ -1285,7 +1285,7 @@ async def _upload_chunk(chunk, part_number):
                     )
                 )
             else:
-                out.append(await _upload_chunk(chunk, len(out) + 1))
+                out.append(await _upload_chunk(chunks[0], len(out) + 1))
         return out
 
     async def _get_file(

From bedae4a2960878b2b33a0d40c44ea9da00620079 Mon Sep 17 00:00:00 2001
From: Nils Braun <nilslennartbraun@gmail.com>
Date: Wed, 6 Nov 2024 16:41:31 +0100
Subject: [PATCH 2/2] Added test against file truncation and only use a single
 code

---
 s3fs/core.py            | 17 +++++++----------
 s3fs/tests/test_s3fs.py | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/s3fs/core.py b/s3fs/core.py
index 3b9ed995..9b9a3f57 100644
--- a/s3fs/core.py
+++ b/s3fs/core.py
@@ -1275,17 +1275,14 @@ async def _upload_chunk(chunk, part_number):
                     chunks.append(chunk)
             if not chunks:
                 break
-            if len(chunks) > 1:
-                out.extend(
-                    await asyncio.gather(
-                        *[
-                            _upload_chunk(chunk, len(out) + i)
-                            for i, chunk in enumerate(chunks, 1)
-                        ]
-                    )
+            out.extend(
+                await asyncio.gather(
+                    *[
+                        _upload_chunk(chunk, len(out) + i)
+                        for i, chunk in enumerate(chunks, 1)
+                    ]
                 )
-            else:
-                out.append(await _upload_chunk(chunks[0], len(out) + 1))
+            )
         return out
 
     async def _get_file(
diff --git a/s3fs/tests/test_s3fs.py b/s3fs/tests/test_s3fs.py
index 3379da52..b64907d1 100644
--- a/s3fs/tests/test_s3fs.py
+++ b/s3fs/tests/test_s3fs.py
@@ -1017,6 +1017,24 @@ def test_put_file_with_callback(s3, tmpdir, size):
     assert cb.size == os.stat(test_file).st_size
     assert cb.value == cb.size
 
+    assert s3.size(test_bucket_name + "/temp") == 11 * size
+
+
+@pytest.mark.parametrize("factor", [1, 5, 6])
+def test_put_file_does_not_truncate(s3, tmpdir, factor):
+    test_file = str(tmpdir.join("test.json"))
+
+    chunksize = 5 * 2**20
+    block = b"x" * chunksize
+
+    with open(test_file, "wb") as f:
+        f.write(block * factor)
+
+    s3.put_file(
+        test_file, test_bucket_name + "/temp", max_concurrency=5, chunksize=chunksize
+    )
+    assert s3.size(test_bucket_name + "/temp") == factor * chunksize
+
 
 @pytest.mark.parametrize("size", [2**10, 2**20, 10 * 2**20])
 def test_pipe_cat_big(s3, size):