Issue #11459: A `bufsize` value of 0 in subprocess.Popen() really creates
unbuffered pipes, such that select() works properly on them.
diff --git a/Lib/os.py b/Lib/os.py
index aa1a40f..b46c02f 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -629,11 +629,13 @@
return bs
# Supply os.popen()
-def popen(cmd, mode="r", buffering=None):
+def popen(cmd, mode="r", buffering=-1):
if not isinstance(cmd, str):
raise TypeError("invalid cmd type (%s, expected string)" % type(cmd))
if mode not in ("r", "w"):
raise ValueError("invalid mode %r" % mode)
+ if buffering == 0 or buffering == None:
+ raise ValueError("popen() does not support unbuffered streams")
import subprocess, io
if mode == "r":
proc = subprocess.Popen(cmd,