tests: capture stdin to get the vsftpd version number

vsftpd 3.0 at least writes its version number to stdin (!) instead of
stderr. This works due for backwards compatibility reasons in UNIX, so
we must check stdin for anything written there to reliably parse the
version string.

Closes #15278

diff --git a/tests/http/testenv/env.py b/tests/http/testenv/env.py
index d382acf5ef2d5882a9f533f680f892d05a653dd7..3998be980f7584dc63887ef026aff15220b203f1 100644 (file)
--- a/tests/http/testenv/env.py
+++ b/tests/http/testenv/env.py
@@ -30,6 +30,7 @@ import re
 import shutil
 import socket
 import subprocess
+import tempfile
 from configparser import ConfigParser, ExtendedInterpolation
 from typing import Optional
 
@@ -186,12 +187,22 @@ class EnvConfig:
         self._vsftpd_version = None
         if self.vsftpd is not None:
             try:
-                p = subprocess.run(args=[self.vsftpd, '-v'],
-                                   capture_output=True, text=True)
-                if p.returncode != 0:
-                    # not a working vsftpd
-                    self.vsftpd = None
-                m = re.match(r'vsftpd: version (\d+\.\d+\.\d+)', p.stderr)
+                with tempfile.TemporaryFile('w+') as tmp:
+                    p = subprocess.run(args=[self.vsftpd, '-v'],
+                                       capture_output=True, text=True, stdin=tmp)
+                    if p.returncode != 0:
+                        # not a working vsftpd
+                        self.vsftpd = None
+                    if p.stderr:
+                        ver_text = p.stderr
+                    else:
+                        # Oddly, some versions of vsftpd write to stdin (!)
+                        # instead of stderr, which is odd but works. If there
+                        # is nothing on stderr, read the file on stdin and use
+                        # any data there instead.
+                        tmp.seek(0)
+                        ver_text = tmp.read()
+                m = re.match(r'vsftpd: version (\d+\.\d+\.\d+)', ver_text)
                 if m:
                     self._vsftpd_version = m.group(1)
                 elif len(p.stderr) == 0: