From: Michael Prokop <mika@grml.org>
Date: Tue, 15 Oct 2019 10:07:07 +0000 (+0200)
Subject: Avoid subprocess.Popen with stdout/stderr=PIPE and wait() usage
X-Git-Tag: v0.16.7~3^2
X-Git-Url: http://git.grml.org/?p=grml2usb.git;a=commitdiff_plain;h=29d54d4a9505cf92bae9fc4ba24b6253bdadedc9

Avoid subprocess.Popen with stdout/stderr=PIPE and wait() usage

Quoting from https://docs.python.org/2/library/subprocess.html#popen-objects:

| Popen.wait()
|   Wait for child process to terminate. Set and return returncode attribute.
|
|   Warning
|   This will deadlock when using stdout=PIPE and/or stderr=PIPE and the child
|   process generates enough output to a pipe such that it blocks waiting for the
|   OS pipe buffer to accept more data. Use communicate() to avoid that.

While modprobe isn't expected to ever output enough output to be
relevant, let's better be safe than sorry.

While at it fix typo (it's -> its)

Closes grml/grml2usb#21
---

diff --git a/grml2usb b/grml2usb
index 9c6c8c5..c139f72 100755
--- a/grml2usb
+++ b/grml2usb
@@ -1855,14 +1855,14 @@ def check_programs():
 
 
 def load_loop():
-    """Runs modprobe loop and throws away it's output"""
+    """Runs modprobe loop and throws away its output"""
     if not which("modprobe"):
         logging.critical("Fatal: modprobe not available, can not continue - sorry.")
         logging.critical("Hint: is /sbin missing in PATH?")
         sys.exit(1)
 
     proc = subprocess.Popen(["modprobe", "loop"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-    proc.wait()
+    proc.communicate()
 
 
 def main():