added a main function

diff --git a/lxcsu b/lxcsu
index 97600cf..20381ad 100644 (file)
--- a/lxcsu
+++ b/lxcsu
@@ -25,129 +25,133 @@ def umount(fs_dir):
     output = os.popen('/bin/umount %s 2>&1'%fs_dir).read()
     return ('device is busy' not in fs_dir)
 
-parser = OptionParser()
-parser.add_option("-n", "--nonet",
-                  action="store_true", dest="netns", default=False,
-                  help="Don't enter network namespace")
-parser.add_option("-m", "--nomnt",
-                  action="store_true", dest="mntns", default=False,
-                  help="Don't enter mount namespace")
-parser.add_option("-p", "--nopid",
-                  action="store_true", dest="pidns", default=False,
-                  help="Don't enter pid namespace")
-parser.add_option("-r", "--root",
-                  action="store_true", dest="root", default=False,
-                  help="Enter as root: be careful")
-
-(options, args) = parser.parse_args()
-
-try:
-    slice_name = args[0]
-except IndexError:
-    print "You must specify a vm name"
-    exit(1)
-
-try:
-    cmd = 'grep %s /proc/*/cgroup | grep freezer'%slice_name
-    output = os.popen(cmd).readlines()
-except:
-    print "Error finding slice %s"%slice_name
-    exit(1)
-
-slice_spec = None
-
-# xxx fixme xxx - provide a default as this is not always properly computed
-arch = 'x86_64'
-
-for e in output:
+def main ():
+    parser = OptionParser()
+    parser.add_option("-n", "--nonet",
+                      action="store_true", dest="netns", default=False,
+                      help="Don't enter network namespace")
+    parser.add_option("-m", "--nomnt",
+                      action="store_true", dest="mntns", default=False,
+                      help="Don't enter mount namespace")
+    parser.add_option("-p", "--nopid",
+                      action="store_true", dest="pidns", default=False,
+                      help="Don't enter pid namespace")
+    parser.add_option("-r", "--root",
+                      action="store_true", dest="root", default=False,
+                      help="Enter as root: be careful")
+
+    (options, args) = parser.parse_args()
+
+    try:
+        slice_name = args[0]
+    except IndexError:
+        print "You must specify a vm name"
+        exit(1)
+
+    try:
+        cmd = 'grep %s /proc/*/cgroup | grep freezer'%slice_name
+        output = os.popen(cmd).readlines()
+    except:
+        print "Error finding slice %s"%slice_name
+        exit(1)
+
+    slice_spec = None
+
+    # xxx fixme xxx - provide a default as this is not always properly computed
+    arch = 'x86_64'
+
+    for e in output:
+        try:
+            l = e.rstrip()
+            path = l.split(':')[0]  
+            comp = l.rsplit(':')[-1]
+            slice_name_check = comp.rsplit('/')[-1]
+            
+            if (slice_name_check == slice_name):
+                slice_path = path
+                pid = slice_path.split('/')[2]
+                cmdline = open('/proc/%s/cmdline'%pid).read().rstrip('\n\x00')
+                if (cmdline == '/sbin/init'):
+                    slice_spec = slice_path
+                    arch = getarch('/proc/%s/exe'%pid)
+                    break
+        except:
+            break
+
+    if (not slice_spec or not pid):
+        print "Not started: %s"%slice_name
+        exit(1)
+
+    # Enter cgroups
     try:
-        l = e.rstrip()
-        path = l.split(':')[0]  
-        comp = l.rsplit(':')[-1]
-        slice_name_check = comp.rsplit('/')[-1]
-
-        if (slice_name_check == slice_name):
-            slice_path = path
-            pid = slice_path.split('/')[2]
-            cmdline = open('/proc/%s/cmdline'%pid).read().rstrip('\n\x00')
-            if (cmdline == '/sbin/init'):
-                slice_spec = slice_path
-                arch = getarch('/proc/%s/exe'%pid)
-                break
+        for subsystem in ['cpuset','memory','blkio']:
+            open('/sys/fs/cgroup/%s/libvirt/lxc/%s/tasks'%(subsystem,slice_name),'w').write(str(os.getpid()))
+
     except:
-        break
-
-if (not slice_spec or not pid):
-    print "Not started: %s"%slice_name
-    exit(1)
-
-# Enter cgroups
-try:
-    for subsystem in ['cpuset','memory','blkio']:
-        open('/sys/fs/cgroup/%s/libvirt/lxc/%s/tasks'%(subsystem,slice_name),'w').write(str(os.getpid()))
-
-except:
-    print "Error assigning resources: %s"%slice_name
-    exit(1)
-
-try:
-    open('/sys/fs/cgroup/cpuacct/system/libvirtd.service/libvirt/lxc/%s/tasks'%slice_name,'w').write(str(os.getpid()))
-except:
-    print "Error assigning cpuacct: %s" % slice_name
-    exit(1)
-
-# If the slice is frozen, then we'll get an EBUSY when trying to write to the task
-# list for the freezer cgroup. Since the user couldn't do anything anyway, it's best
-# in this case to error out the shell. (an alternative would be to un-freeze it,
-# add the task, and re-freeze it)
-try:
-    f=open('/sys/fs/cgroup/freezer/libvirt/lxc/%s/tasks'%(slice_name),'w')
-    f.write(str(os.getpid()))
-    # note: we need to call f.close() explicitly, or we'll get an exception in
-    # the object destructor, which will not be caught
-    f.close()
-except:
-    print "Error adding task to freezer cgroup. Slice is probably frozen: %s" % slice_name
-    exit(1)
-
-setns.chcontext('/proc/%s/ns/uts'%pid)
-setns.chcontext('/proc/%s/ns/ipc'%pid)
-
-if (not options.netns):
-  setns.chcontext('/proc/%s/ns/net'%pid)
-
-if (not options.mntns):
-  open('/proc/lxcsu','w').write(pid)
-
-if (not options.pidns):
-  open('/proc/pidsu','w').write(pid)
-
-# cgroups is not yet LXC-safe, so we need to use the course grained access control
-# strategy of unmounting the filesystem
-
-umount_result = True
-for subsystem in ['cpuset','cpu,cpuacct','memory','devices','freezer','net_cls','blkio','perf_event']:
-    fs_path = '/sys/fs/cgroup/%s'%subsystem
-    if (not umount(fs_path)):
+        print "Error assigning resources: %s"%slice_name
+        exit(1)
+
+    try:
+        open('/sys/fs/cgroup/cpuacct/system/libvirtd.service/libvirt/lxc/%s/tasks'%slice_name,'w').write(str(os.getpid()))
+    except:
+        print "Error assigning cpuacct: %s" % slice_name
+        exit(1)
+
+    # If the slice is frozen, then we'll get an EBUSY when trying to write to the task
+    # list for the freezer cgroup. Since the user couldn't do anything anyway, it's best
+    # in this case to error out the shell. (an alternative would be to un-freeze it,
+    # add the task, and re-freeze it)
+    try:
+        f=open('/sys/fs/cgroup/freezer/libvirt/lxc/%s/tasks'%(slice_name),'w')
+        f.write(str(os.getpid()))
+        # note: we need to call f.close() explicitly, or we'll get an exception in
+        # the object destructor, which will not be caught
+        f.close()
+    except:
+        print "Error adding task to freezer cgroup. Slice is probably frozen: %s" % slice_name
+        exit(1)
+
+    setns.chcontext('/proc/%s/ns/uts'%pid)
+    setns.chcontext('/proc/%s/ns/ipc'%pid)
+
+    if (not options.netns):
+        setns.chcontext('/proc/%s/ns/net'%pid)
+
+    if (not options.mntns):
+        open('/proc/lxcsu','w').write(pid)
+
+    if (not options.pidns):
+        open('/proc/pidsu','w').write(pid)
+
+    # cgroups is not yet LXC-safe, so we need to use the course grained access control
+    # strategy of unmounting the filesystem
+
+    umount_result = True
+    for subsystem in ['cpuset','cpu,cpuacct','memory','devices','freezer','net_cls','blkio','perf_event']:
+        fs_path = '/sys/fs/cgroup/%s'%subsystem
+        if (not umount(fs_path)):
+            print "Error disabling cgroup access"
+            exit(1)
+
+    if (not umount('/sys/fs/cgroup')):
         print "Error disabling cgroup access"
         exit(1)
 
-if (not umount('/sys/fs/cgroup')):
-    print "Error disabling cgroup access"
-    exit(1)
+    pid = os.fork()
 
-pid = os.fork()
+    if (pid == 0):
+        cap_arg = '--drop='+drop_capabilities
 
-if (pid == 0):
-    cap_arg = '--drop='+drop_capabilities
+        if (not options.root):
+            exec_args = [arch,'/usr/sbin/capsh',cap_arg,'--','--login']+args[1:]
+        else:
+            exec_args = [arch,'/usr/sbin/capsh','--','--login']+args[1:]
 
-    if (not options.root):
-      exec_args = [arch,'/usr/sbin/capsh',cap_arg,'--','--login']+args[1:]
+        os.environ['SHELL'] = '/bin/sh'
+        os.execv('/usr/bin/setarch',exec_args)
     else:
-      exec_args = [arch,'/usr/sbin/capsh','--','--login']+args[1:]
+        _,status = os.waitpid(pid,0)
+        exit(os.WEXITSTATUS(status))
 
-    os.environ['SHELL'] = '/bin/sh'
-    os.execv('/usr/bin/setarch',exec_args)
-else:
-    _,status = os.waitpid(pid,0)
-    exit(os.WEXITSTATUS(status))
+if __name__ == '__main__':
+    main()