From f09c6fedf135543a95ff2111da24b4ec02d2eebd Mon Sep 17 00:00:00 2001
From: Muhammad Haris Awan <an25mbbs026.student@fui.edu.pk>
Date: Wed, 28 Oct 2026 01:44:59 +0500
Subject: [PATCH 1/3] gh-41668: Add partial data recovery support for truncated
 gzip streams

---
 Lib/compression/_common/_streams.py                   |  9 +++++++--
 Lib/gzip.py                                           | 11 +++++++++--
 Lib/test/test_gzip.py                                 | 11 +++++++++++
 ...026-10-28-01-44-00.gh-issue-41668.gzip-partial.rst |  1 +
 4 files changed, 28 insertions(+), 4 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-10-28-01-44-00.gh-issue-41668.gzip-partial.rst

diff --git a/Lib/compression/_common/_streams.py b/Lib/compression/_common/_streams.py
index 9f367d4e30440f..3450d39e741b07 100644
--- a/Lib/compression/_common/_streams.py
+++ b/Lib/compression/_common/_streams.py
@@ -115,8 +115,13 @@ def readall(self):
         # sys.maxsize means the max length of output buffer is unlimited,
         # so that the whole input buffer can be decompressed within one
         # .decompress() call.
-        while data := self.read(sys.maxsize):
-            chunks.append(data)
+        try:
+            while data := self.read(sys.maxsize):
+                chunks.append(data)
+        except EOFError as exc:
+            if chunks:
+                exc.partial_data = b"".join(chunks)
+            raise
 
         return b"".join(chunks)
 
diff --git a/Lib/gzip.py b/Lib/gzip.py
index 5b6ebcfef45c3a..b917bc05bed67b 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -677,9 +677,10 @@ def compress(data, compresslevel=_COMPRESS_LEVEL_TRADEOFF, *, mtime=0):
     return header + gzip_data[10:]
 
 
-def decompress(data):
+def decompress(data, *, partial=False):
     """Decompress a gzip compressed string in one shot.
     Return the decompressed string.
+    If partial is True, returns data decompressed prior to an unexpected EOF.
     """
     decompressed_members = []
     while True:
@@ -691,8 +692,14 @@ def decompress(data):
         # Read all the data except the header
         decompressed = do.decompress(data[fp.tell():])
         if not do.eof or len(do.unused_data) < 8:
-            raise EOFError("Compressed file ended before the end-of-stream "
+            if partial and decompressed:
+                decompressed_members.append(decompressed)
+                return b"".join(decompressed_members)
+            exc = EOFError("Compressed file ended before the end-of-stream "
                            "marker was reached")
+            if decompressed:
+                exc.partial_data = decompressed
+            raise exc
         crc, length = struct.unpack("<II", do.unused_data[:8])
         if crc != zlib.crc32(decompressed):
             raise BadGzipFile("CRC check failed")
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index 8bc8e507683cb5..eb24faa795087a 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -827,6 +827,17 @@ def test_decompress_missing_trailer(self):
         compressed_data = gzip.compress(data1)
         self.assertRaises(EOFError, gzip.decompress, compressed_data[:-8])
 
+    def test_decompress_truncated_partial(self):
+        compressed_data = gzip.compress(data1)
+        truncated = compressed_data[:-8]
+        self.assertEqual(gzip.decompress(truncated, partial=True), data1)
+        try:
+            gzip.decompress(truncated)
+        except EOFError as exc:
+            self.assertEqual(getattr(exc, "partial_data", None), data1)
+        else:
+            self.fail("EOFError was not raised")
+
     def test_truncated_header(self):
         truncated_headers = [
             b"\x1f\x8b\x08\x00\x00\x00\x00\x00\x00",             # Missing OS byte
diff --git a/Misc/NEWS.d/next/Library/2026-10-28-01-44-00.gh-issue-41668.gzip-partial.rst b/Misc/NEWS.d/next/Library/2026-10-28-01-44-00.gh-issue-41668.gzip-partial.rst
new file mode 100644
index 00000000000000..8523db5cea18c2
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-10-28-01-44-00.gh-issue-41668.gzip-partial.rst
@@ -0,0 +1 @@
+Add partial data recovery support in :func:`gzip.decompress` via ``partial=True`` and attach ``partial_data`` attribute to :exc:`EOFError` on truncated gzip streams.

From 205388491e80bfa9478b3ca3df9117cd1debbb36 Mon Sep 17 00:00:00 2001
From: Muhammad Haris Awan <an25mbbs026.student@fui.edu.pk>
Date: Wed, 28 Oct 2026 23:44:43 +0500
Subject: [PATCH 2/3] gh-41668: Retrigger CI for macOS runner


From dc08ea5ade3772cc93690b25d1e87eb91f15b68f Mon Sep 17 00:00:00 2001
From: Muhammad Haris Awan <an25mbbs026.student@fui.edu.pk>
Date: Thu, 29 Oct 2026 04:17:47 +0500
Subject: [PATCH 3/3] gh-41668: Retrigger CI