# Copyright 2005 Princeton University

import errno
import fcntl
import os
import re
import sys
import time
import traceback

import mountimpl
import passfdimpl
import utmp
import vserverimpl, vduimpl
import cpulimit, bwlimit



#
# these are the flags taken from the kernel linux/vserver/legacy.h
#
FLAGS_LOCK = 1
FLAGS_SCHED = 2  # XXX - defined in util-vserver/src/chcontext.c
FLAGS_NPROC = 4
FLAGS_PRIVATE = 8
FLAGS_INIT = 16
FLAGS_HIDEINFO = 32
FLAGS_ULIMIT = 64
FLAGS_NAMESPACE = 128


              
class VServer:

    INITSCRIPTS = [('/etc/rc.vinit', 'start'),
                   ('/etc/rc.d/rc', '%(runlevel)d')]

    def __init__(self, name, vm_id, vm_running = False, resources = {}):

        self.name = name
        self.config_file = "/etc/vservers/%s.conf" % name
        self.dir = "%s/%s" % (vserverimpl.VSERVER_BASEDIR, name)
        if not (os.path.isdir(self.dir) and
                os.access(self.dir, os.R_OK | os.W_OK | os.X_OK)):
            raise Exception, "no such vserver: " + name
        self.config = {}
        for config_file in ["/etc/vservers.conf", self.config_file]:
            try:
                self.config.update(self.__read_config_file(config_file))
            except IOError, ex:
                if ex.errno != errno.ENOENT:
                    raise
        self.remove_caps = ~vserverimpl.CAP_SAFE;
        self.ctx = vm_id
        self.vm_running = vm_running
        self.resources = resources

    config_var_re = re.compile(r"^ *([A-Z_]+)=(.*)\n?$", re.MULTILINE)

    def __read_config_file(self, filename):

        f = open(filename, "r")
        data = f.read()
        f.close()
        config = {}
        for m in self.config_var_re.finditer(data):
            (key, val) = m.groups()
            config[key] = val.strip('"')
        return config

    def __update_config_file(self, filename, newvars):

        # read old file, apply changes
        f = open(filename, "r")
        data = f.read()
        f.close()
        todo = newvars.copy()
        changed = False
        for m in self.config_var_re.finditer(data):
            (key, val) = m.groups()
            newval = todo.pop(key, None)
            if newval != None:
                data = data[:m.start(2)] + str(newval) + data[m.end(2):]
                changed = True
        for (newkey, newval) in todo.items():
            data += "%s=%s\n" % (newkey, newval)
            changed = True

        if not changed:
            return

        # write new file
        newfile = filename + ".new"
        f = open(newfile, "w")
        f.write(data)
        f.close()

        # 'copy' original file, rename new to original
        backup = filename + ".old"
        try:
            os.unlink(backup)
        except OSError, ex:
            if ex.errno != errno.ENOENT:
                raise
        os.link(filename, backup)
        os.rename(newfile, filename)

    def __do_chroot(self):

        os.chroot(self.dir)
        os.chdir("/")

    def set_disklimit(self, block_limit):

        # block_limit is in kB
        if block_limit == 0:
            vserverimpl.unsetdlimit(self.dir, self.ctx)
            return

        if self.vm_running:
            block_usage = vserverimpl.DLIMIT_KEEP
            inode_usage = vserverimpl.DLIMIT_KEEP
        else:
            # init_disk_info() must have been called to get usage values
            block_usage = self.disk_blocks
            inode_usage = self.disk_inodes

        vserverimpl.setdlimit(self.dir,
                              self.ctx,
                              block_usage,
                              block_limit,
                              inode_usage,
                              vserverimpl.DLIMIT_INF,  # inode limit
                              2)   # %age reserved for root

    def get_disklimit(self):

        try:
            blocksused, blocktotal, inodesused, inodestotal, reserved = \
                        vserverimpl.getdlimit(self.dir, self.ctx)
        except OSError, ex:
            if ex.errno != errno.ESRCH:
                raise
            # get here if no vserver disk limit has been set for xid
            blocktotal = -1

        return blocktotal

    def set_sched(self, cpu_share):

        if cpu_share == int(self.config.get("CPULIMIT", -1)):
            return

        self.__update_config_file(self.config_file, { "CPULIMIT": cpu_share })
        if self.vm_running:
            vserverimpl.setsched(self.ctx, self.resources)

    def get_sched(self):
        # have no way of querying scheduler right now on a per vserver basis
        return (-1, False)

    def set_memlimit(self, limit):
        ret = vserverimpl.setrlimit(self.ctx,5,limit)
        return ret

    def get_memlimit(self):
        ret = vserverimpl.getrlimit(self.ctx,5)
        return ret
    
    def set_tasklimit(self, limit):
        ret = vserverimpl.setrlimit(self.ctx,6,limit)
        return ret

    def get_tasklimit(self):
        ret = vserverimpl.getrlimit(self.ctx,6)
        return ret

    def set_bwlimit(self, share, minrate = 1, maxrate = None, dev = "eth0"):

        if share:
            bwlimit.on(self.ctx, dev, share, minrate, maxrate)
        else:
            bwlimit.off(self.ctx, dev)

    def get_bwlimit(self, eth):
        # not implemented yet
        bwlimit = -1
        cap = "unknown"
        minrate = "unknown"
        maxrate = "unknown"
        return (bwlimit, cap, minrate, maxrate)
        
    def open(self, filename, mode = "r", bufsize = -1):

        (sendsock, recvsock) = passfdimpl.socketpair()
        child_pid = os.fork()
        if child_pid == 0:
            try:
                # child process
                self.__do_chroot()
                f = open(filename, mode)
                passfdimpl.sendmsg(f.fileno(), sendsock)
                os._exit(0)
            except EnvironmentError, ex:
                (result, errmsg) = (ex.errno, ex.strerror)
            except Exception, ex:
                (result, errmsg) = (255, str(ex))
            os.write(sendsock, errmsg)
            os._exit(result)

        # parent process

        # XXX - need this since a lambda can't raise an exception
        def __throw(ex):
            raise ex

        os.close(sendsock)
        throw = lambda : __throw(Exception(errmsg))
        while True:
            try:
                (pid, status) = os.waitpid(child_pid, 0)
                if os.WIFEXITED(status):
                    result = os.WEXITSTATUS(status)
                    if result != 255:
                        errmsg = os.strerror(result)
                        throw = lambda : __throw(IOError(result, errmsg))
                    else:
                        errmsg = "unexpected exception in child"
                else:
                    result = -1
                    errmsg = "child killed"
                break
            except OSError, ex:
                if ex.errno != errno.EINTR:
                    os.close(recvsock)
                    raise ex
        fcntl.fcntl(recvsock, fcntl.F_SETFL, os.O_NONBLOCK)
        try:
            (fd, errmsg) = passfdimpl.recvmsg(recvsock)
        except OSError, ex:
            if ex.errno != errno.EAGAIN:
                throw = lambda : __throw(ex)
            fd = 0
        os.close(recvsock)
        if not fd:
            throw()

        return os.fdopen(fd, mode, bufsize)

    def __do_chcontext(self, state_file):

        vserverimpl.chcontext(self.ctx, self.resources)

        if not state_file:
            return
        print >>state_file, "S_CONTEXT=%d" % self.ctx
        print >>state_file, "S_PROFILE=%s" % self.config.get("S_PROFILE", "")
        state_file.close()

    def __prep(self, runlevel, log):

        """ Perform all the crap that the vserver script does before
        actually executing the startup scripts. """

        # remove /var/run and /var/lock/subsys files
        # but don't remove utmp from the top-level /var/run
        RUNDIR = "/var/run"
        LOCKDIR = "/var/lock/subsys"
        filter_fn = lambda fs: filter(lambda f: f != 'utmp', fs)
        garbage = reduce((lambda (out, ff), (dir, subdirs, files):
                          (out + map((dir + "/").__add__, ff(files)),
                           lambda fs: fs)),
                         list(os.walk(RUNDIR)),
                         ([], filter_fn))[0]
        garbage += filter(os.path.isfile, map((LOCKDIR + "/").__add__,
                                              os.listdir(LOCKDIR)))
        for f in garbage:
            os.unlink(f)

        # set the initial runlevel
        f = open(RUNDIR + "/utmp", "w")
        utmp.set_runlevel(f, runlevel)
        f.close()

        # mount /proc and /dev/pts
        self.__do_mount("none", "/proc", "proc")
        # XXX - magic mount options
        self.__do_mount("none", "/dev/pts", "devpts", 0, "gid=5,mode=0620")

    def __do_mount(self, *mount_args):

        try:
            mountimpl.mount(*mount_args)
        except OSError, ex:
            if ex.errno == errno.EBUSY:
                # assume already mounted
                return
            raise ex

    def enter(self):

        state_file = open("/var/run/vservers/%s.ctx" % self.name, "w")
        self.__do_chroot()
        self.__do_chcontext(state_file)

    def start(self, wait, runlevel = 3):

        self.vm_running = True

        child_pid = os.fork()
        if child_pid == 0:
            # child process
            try:
                # get a new session
                os.setsid()

                # open state file to record vserver info
                state_file = open("/var/run/vservers/%s.ctx" % self.name, "w")

                # use /dev/null for stdin, /var/log/boot.log for stdout/err
                os.close(0)
                os.close(1)
                os.open("/dev/null", os.O_RDONLY)
                self.__do_chroot()
                log = open("/var/log/boot.log", "w", 0)
                os.dup2(1, 2)
                # XXX - close all other fds

                print >>log, ("%s: starting the virtual server %s" %
                              (time.asctime(time.gmtime()), self.name))

                # perform pre-init cleanup
                self.__prep(runlevel, log)

                # execute each init script in turn
                # XXX - we don't support all scripts that vserver script does
                cmd_pid = 0
                first_child = True
                for cmd in self.INITSCRIPTS + [None]:
                    # wait for previous command to terminate, unless it
                    # is the last one and the caller has specified to wait
                    if cmd_pid and (cmd != None or wait):
                        try:
                            os.waitpid(cmd_pid, 0)
                        except:
                            print >>log, "error waiting for %s:" % cmd_pid
                            traceback.print_exc()

                    # end of list
                    if cmd == None:
                        os._exit(0)

                    # fork and exec next command
                    cmd_pid = os.fork()
                    if cmd_pid == 0:
                        try:
                            # enter vserver context
                            self.__do_chcontext(state_file)
                            arg_subst = { 'runlevel': runlevel }
                            cmd_args = [cmd[0]] + map(lambda x: x % arg_subst,
                                                      cmd[1:])
                            print >>log, "executing '%s'" % " ".join(cmd_args)
                            os.execl(cmd[0], *cmd_args)
                        except:
                            traceback.print_exc()
                            os._exit(1)
                    else:
                        # don't want to write state_file multiple times
                        state_file = None

            # we get here due to an exception in the top-level child process
            except Exception, ex:
                traceback.print_exc()
            os._exit(0)

        # parent process
        return child_pid

    def update_resources(self, resources):

        self.config.update(resources)

        # write new values to configuration file
        self.__update_config_file(self.config_file, resources)

    def init_disk_info(self):

        (self.disk_inodes, self.disk_blocks, size) = vduimpl.vdu(self.dir)

        return size