buildserver: move code into main() method to always stop thread

By running the whole program in a main() function, it can be wrapped in
try/finally in order to stop the background display thread.  This is also
done in ./fdroid, its standard practice for Python CLI utilities.

makebuildserver

@@ -20,7 +20,7 @@ if not os.path.exists('makebuildserver') and not os.path.exists('buildserver'):
 
 
 boxfile = os.path.join(os.getcwd(), 'buildserver.box')
-serverdir = 'buildserver'
+tail = None
 
 parser = OptionParser()
 parser.add_option("-v", "--verbose", action="store_true", default=False,
@@ -293,7 +293,10 @@ def sha256_for_file(path):
         return s.hexdigest()
 
 
-for srcurl, shasum in cachefiles:
+def main():
+    global cachedir, cachefiles, config, tail
+
+    for srcurl, shasum in cachefiles:
         filename = os.path.basename(srcurl)
         local_filename = os.path.join(cachedir, filename)
 
@@ -345,44 +348,45 @@ for srcurl, shasum in cachefiles:
             os.remove(local_filename)
             sys.exit(1)
 
-local_qt_filename = os.path.join(cachedir, 'qt-opensource-linux-x64-android-5.7.0.run')
-print("Setting executable bit for " + local_qt_filename)
-os.chmod(local_qt_filename, 0o755)
+    local_qt_filename = os.path.join(cachedir, 'qt-opensource-linux-x64-android-5.7.0.run')
+    print("Setting executable bit for " + local_qt_filename)
+    os.chmod(local_qt_filename, 0o755)
 
-# use VirtualBox software virtualization if hardware is not available,
-# like if this is being run in kvm or some other VM platform, like
-# http://jenkins.debian.net, the values are 'on' or 'off'
-if sys.platform.startswith('darwin'):
+    # use VirtualBox software virtualization if hardware is not available,
+    # like if this is being run in kvm or some other VM platform, like
+    # http://jenkins.debian.net, the values are 'on' or 'off'
+    if sys.platform.startswith('darwin'):
         # all < 10 year old Macs work, and OSX servers as VM host are very
         # rare, but this could also be auto-detected if someone codes it
         config['hwvirtex'] = 'on'
-elif os.path.exists('/proc/cpuinfo'):
+    elif os.path.exists('/proc/cpuinfo'):
         with open('/proc/cpuinfo') as f:
             contents = f.read()
         if 'vmx' in contents or 'svm' in contents:
             config['hwvirtex'] = 'on'
 
-logfilename = os.path.join(serverdir, 'up.log')
-if not os.path.exists(logfilename):
+    serverdir = os.path.join(os.getcwd(), 'buildserver')
+    logfilename = os.path.join(serverdir, 'up.log')
+    if not os.path.exists(logfilename):
         open(logfilename, 'a').close()  # create blank file
-log_cm = vagrant.make_file_cm(logfilename)
-v = vagrant.Vagrant(root=serverdir, out_cm=log_cm, err_cm=log_cm)
+    log_cm = vagrant.make_file_cm(logfilename)
+    v = vagrant.Vagrant(root=serverdir, out_cm=log_cm, err_cm=log_cm)
 
-if options.verbose:
+    if options.verbose:
         tail = fdroidserver.tail.Tail(logfilename)
         tail.start()
 
-if options.clean:
+    if options.clean:
         v.destroy()
         if config['vm_provider'] == 'libvirt':
             subprocess.call(['virsh', 'undefine', 'buildserver_default'])
             subprocess.call(['virsh', 'vol-delete', '/var/lib/libvirt/images/buildserver_default.img'])
 
-# Check against the existing Vagrantfile.yaml, and if they differ, we
-# need to create a new box:
-vf = os.path.join(serverdir, 'Vagrantfile.yaml')
-writevf = True
-if os.path.exists(vf):
+    # Check against the existing Vagrantfile.yaml, and if they differ, we
+    # need to create a new box:
+    vf = os.path.join(serverdir, 'Vagrantfile.yaml')
+    writevf = True
+    if os.path.exists(vf):
         print('Halting', serverdir)
         v.halt()
         with open(vf, 'r', encoding='utf-8') as f:
@@ -393,13 +397,13 @@ if os.path.exists(vf):
         else:
             print("Re-provisioning existing server")
             writevf = False
-else:
+    else:
         print("No existing server - building from scratch")
-if writevf:
+    if writevf:
         with open(vf, 'w', encoding='utf-8') as f:
             yaml.dump(config, f)
 
-if config['vm_provider'] == 'libvirt':
+    if config['vm_provider'] == 'libvirt':
         found_basebox = False
         needs_mutate = False
         for box in v.box_list():
@@ -422,29 +426,34 @@ if config['vm_provider'] == 'libvirt':
             print('Removing virtualbox format copy of', config['basebox'])
             v.box_remove(config['basebox'], 'virtualbox')
 
-print("Configuring build server VM")
-v.up(provision=True)
+    print("Configuring build server VM")
+    v.up(provision=True)
 
-print("Writing buildserver ID")
-p = subprocess.Popen(['git', 'rev-parse', 'HEAD'], stdout=subprocess.PIPE,
+    print("Writing buildserver ID")
+    p = subprocess.Popen(['git', 'rev-parse', 'HEAD'], stdout=subprocess.PIPE,
                          universal_newlines=True)
-buildserverid = p.communicate()[0].strip()
-print("...ID is " + buildserverid)
-subprocess.call(
+    buildserverid = p.communicate()[0].strip()
+    print("...ID is " + buildserverid)
+    subprocess.call(
         ['vagrant', 'ssh', '-c', 'sh -c "echo {0} >/home/vagrant/buildserverid"'
             .format(buildserverid)],
         cwd=serverdir)
 
-print("Stopping build server VM")
-v.halt()
+    print("Stopping build server VM")
+    v.halt()
 
-print("Packaging")
-v.package(output=boxfile)
+    print("Packaging")
+    v.package(output=boxfile)
 
-print("Adding box")
-v.box_add('buildserver', boxfile, force=True)
+    print("Adding box")
+    v.box_add('buildserver', boxfile, force=True)
 
-os.remove(boxfile)
+    os.remove(boxfile)
 
-if tail is not None:
+
+if __name__ == '__main__':
+    try:
+        main()
+    finally:
+        if tail is not None:
             tail.stop()