Mini Shell

# -*- Mode: Python -*-

import supervisor.medusa.asynchat_25 as asynchat
import socket
import time         # these three are for the rotating logger
import os           # |
import stat         # v

#
# two types of log:
# 1) file
#    with optional flushing.  Also, one that rotates the log.
# 2) socket
#    dump output directly to a socket connection. [how do we
#    keep it open?]

#
# The 'standard' interface to a logging object is simply
# log_object.log (message)
#

# a file-like object that captures output, and
# makes sure to flush it always...  this could
# be connected to:
#  o    stdio file
#  o    low-level file
#  o    socket channel
#  o    syslog output...

class file_logger:

    # pass this either a path or a file object.
    def __init__ (self, file, flush=1, mode='a'):
        if isinstance(file, str):
            if file == '-':
                import sys
                self.file = sys.stdout
            else:
                self.file = open (file, mode)
        else:
            self.file = file
        self.do_flush = flush

    def __repr__ (self):
        return '<file logger: %s>' % self.file

    def write (self, data):
        self.file.write (data)
        self.maybe_flush()

    def writeline (self, line):
        self.file.writeline (line)
        self.maybe_flush()

    def writelines (self, lines):
        self.file.writelines (lines)
        self.maybe_flush()

    def maybe_flush (self):
        if self.do_flush:
            self.file.flush()

    def flush (self):
        self.file.flush()

    def softspace (self, *args):
        pass

    def log (self, message):
        if message[-1] not in ('\r', '\n'):
            self.write (message + '\n')
        else:
            self.write (message)

# like a file_logger, but it must be attached to a filename.
# When the log gets too full, or a certain time has passed,
# it backs up the log and starts a new one.  Note that backing
# up the log is done via "mv" because anything else (cp, gzip)
# would take time, during which medusa would do nothing else.

class rotating_file_logger (file_logger):

    # If freq is non-None we back up "daily", "weekly", or "monthly".
    # Else if maxsize is non-None we back up whenever the log gets
    # to big.  If both are None we never back up.
    def __init__ (self, file, freq=None, maxsize=None, flush=1, mode='a'):
        file_logger.__init__ (self, file, flush, mode)
        self.filename = file
        self.mode = mode
        self.freq = freq
        self.maxsize = maxsize
        self.rotate_when = self.next_backup(self.freq)

    def __repr__ (self):
        return '<rotating-file logger: %s>' % self.file

    # We back up at midnight every 1) day, 2) monday, or 3) 1st of month
    def next_backup (self, freq):
        (yr, mo, day, hr, min, sec, wd, jday, dst) = time.localtime(time.time())
        if freq == 'daily':
            return time.mktime((yr,mo,day+1, 0,0,0, 0,0,-1))
        elif freq == 'weekly':
            return time.mktime((yr,mo,day-wd+7, 0,0,0, 0,0,-1)) # wd(monday)==0
        elif freq == 'monthly':
            return time.mktime((yr,mo+1,1, 0,0,0, 0,0,-1))
        else:
            return None                  # not a date-based backup

    def maybe_flush (self):              # rotate first if necessary
        self.maybe_rotate()
        if self.do_flush:                # from file_logger()
            self.file.flush()

    def maybe_rotate (self):
        if self.freq and time.time() > self.rotate_when:
            self.rotate()
            self.rotate_when = self.next_backup(self.freq)
        elif self.maxsize:               # rotate when we get too big
            try:
                if os.stat(self.filename)[stat.ST_SIZE] > self.maxsize:
                    self.rotate()
            except os.error:             # file not found, probably
                self.rotate()            # will create a new file

    def rotate (self):
        (yr, mo, day, hr, min, sec, wd, jday, dst) = time.localtime(time.time())
        try:
            self.file.close()
            newname = '%s.ends%04d%02d%02d' % (self.filename, yr, mo, day)
            try:
                open(newname, "r").close()      # check if file exists
                newname += "-%02d%02d%02d" % (hr, min, sec)
            except:                             # YEAR_MONTH_DAY is unique
                pass
            os.rename(self.filename, newname)
            self.file = open(self.filename, self.mode)
        except:
            pass

# log to a stream socket, asynchronously

class socket_logger (asynchat.async_chat):

    def __init__ (self, address):
        asynchat.async_chat.__init__(self)
        if isinstance(address, str):
            self.create_socket (socket.AF_UNIX, socket.SOCK_STREAM)
        else:
            self.create_socket (socket.AF_INET, socket.SOCK_STREAM)

        self.connect (address)
        self.address = address

    def __repr__ (self):
        return '<socket logger: address=%s>' % self.address

    def log (self, message):
        if message[-2:] != '\r\n':
            self.socket.push (message + '\r\n')
        else:
            self.socket.push (message)

# log to multiple places
class multi_logger:
    def __init__ (self, loggers):
        self.loggers = loggers

    def __repr__ (self):
        return '<multi logger: %s>' % (repr(self.loggers))

    def log (self, message):
        for logger in self.loggers:
            logger.log (message)

class resolving_logger:
    """Feed (ip, message) combinations into this logger to get a
    resolved hostname in front of the message.  The message will not
    be logged until the PTR request finishes (or fails)."""

    def __init__ (self, resolver, logger):
        self.resolver = resolver
        self.logger = logger

    class logger_thunk:
        def __init__ (self, message, logger):
            self.message = message
            self.logger = logger

        def __call__ (self, host, ttl, answer):
            if not answer:
                answer = host
            self.logger.log ('%s:%s' % (answer, self.message))

    def log (self, ip, message):
        self.resolver.resolve_ptr (
                ip,
                self.logger_thunk (
                        message,
                        self.logger
                        )
                )

class unresolving_logger:
    """Just in case you don't want to resolve"""
    def __init__ (self, logger):
        self.logger = logger

    def log (self, ip, message):
        self.logger.log ('%s:%s' % (ip, message))


def strip_eol (line):
    while line and line[-1] in '\r\n':
        line = line[:-1]
    return line

class tail_logger:
    """Keep track of the last <size> log messages"""
    def __init__ (self, logger, size=500):
        self.size = size
        self.logger = logger
        self.messages = []

    def log (self, message):
        self.messages.append (strip_eol (message))
        if len (self.messages) > self.size:
            del self.messages[0]
        self.logger.log (message)