From 3773d9a0e34c9213a7989a0d08a88470a16ba3c4 Mon Sep 17 00:00:00 2001
From: Zo Bot <github-automation@zo.computer>
Date: Fri, 19 Jun 2026 01:28:01 +0000
Subject: [PATCH] narrow bare except around _try_inline_read to Exception in
 five readers
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The bare 'except:' in read_until_regex, read_until, read_bytes, read_into,
and read_until_close was wrapping self._try_inline_read() so the caller
could install a done_callback that pulls .exception() off the future and
silence the 'Future exception was never retrieved' warning before
re-raising. That bare except also caught BaseException, so a
KeyboardInterrupt, SystemExit, asyncio.CancelledError, MemoryError, or
RecursionError raised inside _try_inline_read() (or any of the per-call
setup just above the try block, like re.compile()) was intercepted,
queued the done_callback, then re-raised — meaning Ctrl-C during a
network read briefly invoked a useless future.add_done_callback on its
way out instead of cancelling the awaitable immediately.

Narrowing to 'except Exception:' preserves the documented intent
(silence the unexamined-future warning for ordinary failures like
UnsatisfiableReadError, StreamClosedError, OSError, ValueError from
re.compile, and LookupError from a bad regex) while letting real
shutdown signals propagate straight through to the awaiting coroutine.
---
 tornado/iostream.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tornado/iostream.py b/tornado/iostream.py
index 53e81fff3..89814c0b6 100644
--- a/tornado/iostream.py
+++ b/tornado/iostream.py
@@ -346,7 +346,7 @@ def read_until_regex(
             gen_log.info("Unsatisfiable read, closing connection: %s" % e)
             self.close(exc_info=e)
             return future
-        except:
+        except Exception:
             # Ensure that the future doesn't log an error because its
             # failure was never examined.
             future.add_done_callback(lambda f: f.exception())
@@ -383,7 +383,7 @@ def read_until(
             gen_log.info("Unsatisfiable read, closing connection: %s" % e)
             self.close(exc_info=e)
             return future
-        except:
+        except Exception:
             future.add_done_callback(lambda f: f.exception())
             raise
         return future
@@ -411,7 +411,7 @@ def read_bytes(self, num_bytes: int, partial: bool = False) -> Awaitable[bytes]:
         self._read_partial = partial
         try:
             self._try_inline_read()
-        except:
+        except Exception:
             future.add_done_callback(lambda f: f.exception())
             raise
         return future
@@ -456,7 +456,7 @@ def read_into(self, buf: bytearray, partial: bool = False) -> Awaitable[int]:
 
         try:
             self._try_inline_read()
-        except:
+        except Exception:
             future.add_done_callback(lambda f: f.exception())
             raise
         return future
@@ -486,7 +486,7 @@ def read_until_close(self) -> Awaitable[bytes]:
         self._read_until_close = True
         try:
             self._try_inline_read()
-        except:
+        except Exception:
             future.add_done_callback(lambda f: f.exception())
             raise
         return future