From: Cody Maloney <cmaloney@users.noreply.github.com>
Date: Thu, 30 Jan 2025 22:24:52 +0000 (-0800)
Subject: gh-129205: Update multiprocessing.forkserver to use os.readinto() (#129425)
X-Git-Tag: v3.14.0a5~164
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=10ee2d9d3bcde27c75f179214ad41c00e4852a7a;p=thirdparty%2FPython%2Fcpython.git

gh-129205: Update multiprocessing.forkserver to use os.readinto() (#129425)
---

diff --git a/Lib/multiprocessing/forkserver.py b/Lib/multiprocessing/forkserver.py
index df9b9be9d189..681af2610e9b 100644
--- a/Lib/multiprocessing/forkserver.py
+++ b/Lib/multiprocessing/forkserver.py
@@ -382,13 +382,14 @@ def _serve_one(child_r, fds, unused_fds, handlers):
 #
 
 def read_signed(fd):
-    data = b''
-    length = SIGNED_STRUCT.size
-    while len(data) < length:
-        s = os.read(fd, length - len(data))
-        if not s:
+    data = bytearray(SIGNED_STRUCT.size)
+    unread = memoryview(data)
+    while unread:
+        count = os.readinto(fd, unread)
+        if count == 0:
             raise EOFError('unexpected EOF')
-        data += s
+        unread = unread[count:]
+
     return SIGNED_STRUCT.unpack(data)[0]
 
 def write_signed(fd, n):