From 69c8d37de30abe82c1013282f31ebf3620cc3501 Mon Sep 17 00:00:00 2001
From: Bhaskar Brahma <bhbrahma@microsoft.com>
Date: Wed, 20 May 2020 17:25:26 +0000
Subject: [PATCH] Added compatibility for python 2.6 subprocess.check_output
 (#1112)

* Added a definition for subprocess.check_outout for centos 6.9 (Python 2.6)

* Also use /etc/system-release to detect distro

* more fixes for centos 6.9
---
 Utils/constants.py      |  1 +
 Utils/distroutils.py    | 16 +++++++++++-----
 Utils/extensionutils.py | 31 +++++++++++++++++++++++++++++++
 VMAccess/manifest.xml   |  2 +-
 VMAccess/vmaccess.py    | 19 ++++++++++++-------
 5 files changed, 56 insertions(+), 13 deletions(-)

diff --git a/Utils/constants.py b/Utils/constants.py
index 7ef4f15bf..8de073679 100644
--- a/Utils/constants.py
+++ b/Utils/constants.py
@@ -2,6 +2,7 @@
 
 Openssl = "openssl"
 os_release = "/etc/os-release"
+system_release = "/etc/system-release"
 
 
 class WALAEventOperation:
diff --git a/Utils/distroutils.py b/Utils/distroutils.py
index 6aa69a5d2..6e211e991 100644
--- a/Utils/distroutils.py
+++ b/Utils/distroutils.py
@@ -13,18 +13,24 @@
 def get_my_distro(config):
     if 'FreeBSD' in platform.system():
         return FreeBSDDistro(config)
-    os_name = ext_utils.get_line_starting_with("NAME", constants.os_release)
+
+    if os.path.isfile(constants.os_release):
+        os_name = ext_utils.get_line_starting_with("NAME", constants.os_release)
+    elif os.path.isfile(constants.system_release):
+        os_name = ext_utils.get_file_contents(constants.system_release)
+    else:
+        return GenericDistro(config)
     if os_name is not None:
-        if re.match("fedora", os_name, re.IGNORECASE):
+        if re.search("fedora", os_name, re.IGNORECASE):
             # Fedora
             return FedoraDistro(config)
-        if re.match("red\s?hat", os_name, re.IGNORECASE):
+        if re.search("red\s?hat", os_name, re.IGNORECASE):
             # Red Hat
             return RedhatDistro(config)
-        if re.match("coreos", os_name, re.IGNORECASE):
+        if re.search("coreos", os_name, re.IGNORECASE):
             # CoreOs
             return CoreOSDistro(config)
-        if re.match("freebsd", os_name, re.IGNORECASE):
+        if re.search("freebsd", os_name, re.IGNORECASE):
             # FreeBSD
             return FreeBSDDistro(config)
     return GenericDistro(config)
diff --git a/Utils/extensionutils.py b/Utils/extensionutils.py
index 1aaefe915..c1ac9f4b1 100644
--- a/Utils/extensionutils.py
+++ b/Utils/extensionutils.py
@@ -10,6 +10,37 @@
 import Utils.logger as logger
 
 
+if not hasattr(subprocess, 'check_output'):
+    def check_output(*popenargs, **kwargs):
+        r"""Backport from subprocess module from python 2.7"""
+        if 'stdout' in kwargs:
+            raise ValueError('stdout argument not allowed, it will be overridden.')
+        process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
+        output, unused_err = process.communicate()
+        retcode = process.poll()
+        if retcode:
+            cmd = kwargs.get("args")
+            if cmd is None:
+                cmd = popenargs[0]
+            raise subprocess.CalledProcessError(retcode, cmd, output=output)
+        return output
+
+
+    # Exception classes used by this module.
+    class CalledProcessError(Exception):
+        def __init__(self, returncode, cmd, output=None):
+            self.returncode = returncode
+            self.cmd = cmd
+            self.output = output
+
+        def __str__(self):
+            return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+
+
+    subprocess.check_output = check_output
+    subprocess.CalledProcessError = CalledProcessError
+    
+
 def change_owner(file_path, user):
     """
     Lookup user.  Attempt chown 'filepath' to 'user'.
diff --git a/VMAccess/manifest.xml b/VMAccess/manifest.xml
index 5228a500e..54eaa5270 100644
--- a/VMAccess/manifest.xml
+++ b/VMAccess/manifest.xml
@@ -2,7 +2,7 @@
 <ExtensionImage xmlns="http://schemas.microsoft.com/windowsazure">
   <ProviderNameSpace>Microsoft.OSTCExtensions</ProviderNameSpace>
   <Type>VMAccessForLinux</Type>
-  <Version>1.5.5</Version>
+  <Version>1.5.6</Version>
   <Label>Microsoft Azure VM Access Extension for Linux Virtual Machines</Label>
   <HostingResources>VmRole</HostingResources>
   <MediaLink></MediaLink>
diff --git a/VMAccess/vmaccess.py b/VMAccess/vmaccess.py
index 357f86ece..bae339e31 100644
--- a/VMAccess/vmaccess.py
+++ b/VMAccess/vmaccess.py
@@ -367,21 +367,26 @@ def _set_sshd_config(config, name, val):
 
 
 def _get_default_ssh_config_filename():
-    os_name = ext_utils.get_line_starting_with("NAME", constants.os_release)
+    if os.path.isfile(constants.os_release):
+        os_name = ext_utils.get_line_starting_with("NAME", constants.os_release)
+    elif os.path.isfile(constants.system_release):
+        os_name = ext_utils.get_file_contents(constants.system_release)
+    else:
+        return "default"
     if os_name is not None:
         # the default ssh config files are present in
         # /var/lib/waagent/Microsoft.OSTCExtensions.VMAccessForLinux-<version>/resources/
-        if re.match("centos", os_name, re.IGNORECASE):
+        if re.search("centos", os_name, re.IGNORECASE):
             return "centos_default"
-        if re.match("debian", os_name, re.IGNORECASE):
+        if re.search("debian", os_name, re.IGNORECASE):
             return "debian_default"
-        if re.match("fedora", os_name, re.IGNORECASE):
+        if re.search("fedora", os_name, re.IGNORECASE):
             return "fedora_default"
-        if re.match("red\s?hat", os_name, re.IGNORECASE):
+        if re.search("red\s?hat", os_name, re.IGNORECASE):
             return "redhat_default"
-        if re.match("suse", os_name, re.IGNORECASE):
+        if re.search("suse", os_name, re.IGNORECASE):
             return "SuSE_default"
-        if re.match("ubuntu", os_name, re.IGNORECASE):
+        if re.search("ubuntu", os_name, re.IGNORECASE):
             return "ubuntu_default"
         return "default"