root / pykota / trunk / bin / cupspykota @ 1200

#! /usr/bin/env python
# -*- coding: ISO-8859-15 -*-

# CUPSPyKota accounting backend
#
# PyKota - Print Quotas for CUPS and LPRng
#
# (c) 2003 Jerome Alet <alet@librelogiciel.com>
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
#
# $Id$
#
# $Log$
# Revision 1.12  2003/11/21 14:28:43  jalet
# More complete job history.
#
# Revision 1.11  2003/11/19 23:19:35  jalet
# Code refactoring work.
# Explicit redirection to /dev/null has to be set in external policy now, just
# like in external mailto.
#
# Revision 1.10  2003/11/18 17:54:24  jalet
# SIGTERMs are now transmitted to original backends.
#
# Revision 1.9  2003/11/18 14:11:07  jalet
# Small fix for bizarre urls
#
# Revision 1.8  2003/11/15 14:26:44  jalet
# General improvements to the documentation.
# Email address changed in sample configuration file, because
# I receive low quota messages almost every day...
#
# Revision 1.7  2003/11/14 22:05:12  jalet
# New CUPS backend fully functionnal.
# Old CUPS configuration method is now officially deprecated.
#
# Revision 1.6  2003/11/14 20:13:11  jalet
# We exit the loop too soon.
#
# Revision 1.5  2003/11/14 18:31:27  jalet
# Not perfect, but seems to work with the poll() loop.
#
# Revision 1.4  2003/11/14 17:04:15  jalet
# More (untested) work on the CUPS backend.
#
# Revision 1.3  2003/11/12 23:27:44  jalet
# More work on new backend. This commit may be unstable.
#
# Revision 1.2  2003/11/12 09:33:34  jalet
# New CUPS backend supports device enumeration
#
# Revision 1.1  2003/11/08 16:05:31  jalet
# CUPS backend added for people to experiment.
#
#
#

import sys
import os
import popen2
import time
import cStringIO
import shlex
import select
import signal

from pykota.tool import PyKotaFilterOrBackend, PyKotaToolError
from pykota.config import PyKotaConfigError
from pykota.storage import PyKotaStorageError
from pykota.accounter import PyKotaAccounterError
from pykota.requester import PyKotaRequesterError

class PyKotaPopen3(popen2.Popen3) :
    """Our own class to execute real backends.
    
       Their first argument is different from their path so using
       native popen2.Popen3 would not be feasible.
    """
    def __init__(self, cmd, capturestderr=False, bufsize=-1, arg0=None) :
        self.arg0 = arg0
        popen2.Popen3.__init__(self, cmd, capturestderr, bufsize)
        
    def _run_child(self, cmd):
        for i in range(3, 256): # TODO : MAXFD in original popen2 module
            try:
                os.close(i)
            except OSError:
                pass
        try:
            os.execvpe(cmd[0], [self.arg0 or cmd[0]] + cmd[1:], os.environ)
        finally:
            os._exit(1)
    
gotSigTerm = 0
def sigterm_handler(signum, frame) :
    """Sets a global variable whenever SIGTERM is received."""
    # SIGTERM will be ignore most of the time, but during
    # the call to the real backend, we have to pass it through.
    global gotSigTerm
    gotSigTerm = 1
    
def main(thebackend) :    
    """Do it, and do it right !"""
    # first deal with signals
    # CUPS backends ignore SIGPIPE and exit(1) on SIGTERM
    # Fortunately SIGPIPE is already ignored by Python
    # It's there just in case this changes in the future.
    # Here we have to handle SIGTERM correctly, and pass
    # it to the original backend if needed.
    global gotSigTerm
    gotSigTerm = 0
    signal.signal(signal.SIGPIPE, signal.SIG_IGN)
    signal.signal(signal.SIGTERM, sigterm_handler)
    
    #
    # retrieve some informations on the current printer and user
    # from the Quota Storage.
    printer = thebackend.storage.getPrinter(thebackend.printername)
    if not printer.Exists :
        # The printer is unknown from the Quota Storage perspective
        # we let the job pass through, but log a warning message
        thebackend.logger.log_message(_("Printer %s not registered in the PyKota system") % thebackend.printername, "warn")
        action = "ALLOW"
    else :    
        for dummy in range(2) :
            user = thebackend.storage.getUser(thebackend.username)
            if user.Exists :
                break
            else :    
                # The user is unknown from the Quota Storage perspective
                # Depending on the default policy for this printer, we
                # either let the job pass through or reject it, but we
                # log a message in any case.
                (policy, args) = thebackend.config.getPrinterPolicy(thebackend.printername)
                if policy == "ALLOW" :
                    action = "POLICY_ALLOW"
                elif policy == "EXTERNAL" :    
                    commandline = thebackend.formatCommandLine(args, user, printer)
                    thebackend.logger.log_message(_("User %s not registered in the PyKota system, applying external policy (%s) for printer %s") % (thebackend.username, commandline, thebackend.printername), "info")
                    if os.system(commandline) :
                        # if an error occured, we die without error,
                        # so that the job doesn't stop the print queue.
                        thebackend.logger.log_message(_("External policy %s for printer %s produced an error. Job rejected. Please check PyKota's configuration files.") % (commandline, thebackend.printername), "error")
                        return 0
                    else :    
                        # here we try a second time, because the goal
                        # of the external action was to add the user
                        # in the database.
                        continue 
                else :    
                    action = "POLICY_DENY"
                thebackend.logger.log_message(_("User %s not registered in the PyKota system, applying default policy (%s) for printer %s") % (thebackend.username, action, thebackend.printername), "warn")
                if action == "POLICY_DENY" :
                    # if not allowed to print then die, else proceed.
                    # we die without error, so that the job doesn't 
                    # stop the print queue.
                    return 0
                # when we get there, the printer policy allows the job to pass 
                break    
                    
        if user.Exists :
            # Is the current user allowed to print at all ?
            action = thebackend.warnUserPQuota(thebackend.storage.getUserPQuota(user, printer))
        elif policy == "EXTERNAL" :                
            # if the extenal policy produced no error, but the 
            # user still doesn't exist, we die without error,
            # so that the job doesn't stop the print queue.
            thebackend.logger.log_message(_("External policy %s for printer %s couldn't add user %s. Job rejected.") % (commandline, thebackend.printername, thebackend.username), "error")
            return 0
        
    if action not in ["ALLOW", "WARN"] :    
        # if not allowed to print then die, else proceed.
        # we die without error, so that the job doesn't 
        # stop the print queue.
        retcode = 0
    else :
        # pass the job untouched to the underlying layer
        # and starts accounting at the same time
        thebackend.accounter.beginJob(printer, user)
        
        # Now it becomes tricky...
        
        # First ensure that we have a file object as input
        mustclose = 0    
        if thebackend.inputfile is not None :    
            if hasattr(thebackend.inputfile, "read") :
                infile = thebackend.inputfile
            else :    
                infile = open(thebackend.inputfile, "rb")
            mustclose = 1
        else :    
            infile = sys.stdin
            
        # Find the real backend pathname    
        realbackend = os.path.join(os.path.split(sys.argv[0])[0], thebackend.originalbackend)
        
        # And launch it
        subprocess = PyKotaPopen3([realbackend] + sys.argv[1:], capturestderr=1, bufsize=0, arg0=os.environ["DEVICE_URI"])
        
        # Save file descriptors, we will need them later.
        infno = infile.fileno()
        stdoutfno = sys.stdout.fileno()
        stderrfno = sys.stderr.fileno()
        fromcfno = subprocess.fromchild.fileno()
        tocfno = subprocess.tochild.fileno()
        cerrfno = subprocess.childerr.fileno()
        
        # We will have to be careful when dealing with I/O 
        # So we use a poll object to know when to read or write
        pollster = select.poll()
        pollster.register(infno, select.POLLIN | select.POLLPRI)
        pollster.register(fromcfno, select.POLLIN | select.POLLPRI)
        pollster.register(cerrfno, select.POLLIN | select.POLLPRI)
        pollster.register(stdoutfno, select.POLLOUT)
        pollster.register(stderrfno, select.POLLOUT)
        pollster.register(tocfno, select.POLLOUT)
        
        # Initialize our buffers
        indata = ""
        outdata = ""
        errdata = ""
        endinput = 0
        status = -1
        while status == -1 :
            # First check if original backend is still alive
            status = subprocess.poll()
            
            # Now if we got SIGTERM, we have 
            # to kill -TERM the original backend
            if gotSigTerm :
                try :
                    os.kill(subprocess.pid, signal.SIGTERM)
                except : # ignore if process was already killed.
                    pass
            
            # In any case, deal with any remaining I/O
            availablefds = pollster.poll()
            for (fd, mask) in availablefds :
                if mask & select.POLLOUT :
                    # We can write
                    if fd == tocfno :
                        if indata :
                            os.write(fd, indata)    
                            indata = ""
                    elif fd == stdoutfno :
                        if outdata :
                            os.write(fd, outdata)
                            outdata = ""
                    elif fd == stderrfno :
                        if errdata :
                            os.write(fd, errdata)
                            errdata = ""
                if (mask & select.POLLIN) or (mask & select.POLLPRI) :     
                    # We have something to read
                    data = os.read(fd, 256 * 1024)
                    if fd == infno :
                        indata += data
                        if not data :    # If yes, then no more input data
                            endinput = 1 # this happens with real files.
                    elif fd == fromcfno :
                        outdata += data
                    elif fd == cerrfno :    
                        errdata += data
                if (mask & select.POLLHUP) or (mask & select.POLLERR) :
                    # I've never seen POLLERR myself, but this probably
                    # can't hurt to treat an error condition just like 
                    # an EOF.
                    # 
                    # Some standard I/O stream has no more datas
                    if fd == infno :
                        # Here we are in the case where the input file is stdin.
                        # which has no more data to be read.
                        endinput = 1
                    elif fd == fromcfno :    
                        # This should never happen, since
                        # CUPS backends don't send anything on their
                        # standard output
                        if outdata :                
                            try :
                                os.write(stdoutfno, outdata)
                                outdata = ""
                            except :    
                                pass
                        try :        
                            pollster.unregister(fromcfno)        
                        except KeyError :    
                            pass
                        else :    
                            os.close(fromcfno)
                    elif fd == cerrfno :    
                        # Original CUPS backend has finished 
                        # to write informations on its standard error
                        if errdata :                
                            # Try to write remaining info (normally "Ready to print.")
                            try :
                                os.write(stderrfno, errdata)
                                errdata = ""
                            except :    
                                pass
                        # We are no more interested in this file descriptor        
                        try :        
                            pollster.unregister(cerrfno)        
                        except KeyError :    
                            pass
                        else :    
                            os.close(cerrfno)
                        
            if endinput :            
                # We deal with remaining input datas here
                # because EOF can happen in two different
                # situations and I don't want to duplicate
                # code, nor making functions.
                if indata :                
                    try :
                        os.write(tocfno, indata)
                        indata = ""
                    except :    
                        pass
                # Again, we're not interested in this file descriptor        
                # anymore.
                try :        
                    pollster.unregister(tocfno)        
                except KeyError :    
                    pass
                else :    
                    os.close(tocfno)
                
        # Input file was a real file, we have to close it.    
        if mustclose :
            infile.close()
            
        # Check exit code of original CUPS backend.    
        if os.WIFEXITED(status) :
            retcode = os.WEXITSTATUS(status)
        else :    
            thebackend.logger.log_message(_("CUPS backend %s died abnormally.") % realbackend, "error")
            retcode = -1
    
    # stops accounting. 
    thebackend.accounter.endJob(printer, user)
        
    # retrieve the job size    
    jobsize = thebackend.accounter.getJobSize()
    
    # update the quota for the current user on this printer 
    if printer.Exists :
        if jobsize :
            userquota = thebackend.storage.getUserPQuota(user, printer)
            if userquota.Exists :
                userquota.increasePagesUsage(jobsize)
        
        # adds the current job to history    
        printer.addJobToHistory(thebackend.jobid, user, thebackend.accounter.getLastPageCounter(), action, jobsize, thebackend.preserveinputfile, thebackend.title, thebackend.copies, thebackend.options)
    
    return retcode # return (retcode or gotSigTerm) shouldn't be needed

if __name__ == "__main__" :    
    # This is a CUPS backend, we should act and die like a CUPS backend
    if len(sys.argv) == 1 :
        # we will execute each existing backend in device enumeration mode
        # and generate their PyKota accounting counterpart
        (directory, myname) = os.path.split(sys.argv[0])
        for backend in [os.path.join(directory, b) for b in os.listdir(directory) if os.path.isfile(os.path.join(directory, b)) and (b != myname)] :
            answer = os.popen(backend, "r")
            try :
                devices = [line.strip() for line in answer.readlines()]
            except :    
                devices = []
            status = answer.close()
            if status is None :
                for d in devices :
                    # each line is of the form : 'xxxx xxxx "xxxx xxx" "xxxx xxx"'
                    # so we have to decompose it carefully
                    fdevice = cStringIO.StringIO("%s" % d)
                    tokenizer = shlex.shlex(fdevice)
                    tokenizer.wordchars = tokenizer.wordchars + r".:,?!~/\_$*-+={}[]()#"
                    arguments = []
                    while 1 :
                        token = tokenizer.get_token()
                        if token :
                            arguments.append(token)
                        else :
                            break
                    fdevice.close()
                    try :
                        (devicetype, device, name, fullname) = arguments
                    except ValueError :    
                        pass    # ignore this 'bizarre' device
                    else :    
                        if name.startswith('"') and name.endswith('"') :
                            name = name[1:-1]
                        if fullname.startswith('"') and fullname.endswith('"') :
                            fullname = fullname[1:-1]
                        print '%s cupspykota:%s "PyKota+%s" "PyKota managed %s"' % (devicetype, device, name, fullname)
        retcode = 0
    elif len(sys.argv) not in (6, 7) :    
        sys.stderr.write("ERROR: %s job-id user title copies options [file]\n" % sys.argv[0])
        retcode = 1
    else :    
        try :
            # Initializes the backend
            kotabackend = PyKotaFilterOrBackend()    
            retcode = main(kotabackend)
        except (PyKotaToolError, PyKotaConfigError, PyKotaStorageError, PyKotaAccounterError, PyKotaRequesterError, AttributeError, KeyError, IndexError, ValueError, TypeError, IOError), msg :
            sys.stderr.write("ERROR : cupspykota backend failed (%s)\n" % msg)
            sys.stderr.flush()
            retcode = 1
        
        try :
            kotabackend.storage.close()
        except (TypeError, NameError, AttributeError) :    
            pass
        
    sys.exit(retcode)