PC World Komputer 2010 April/PCWorld0410.iso/hity wydania/Ubuntu 9.10 PL/karmelkowy-koliberek-desktop-9.10-i386-PL.iso/casper/filesystem.squashfs/usr/lib/python2.6/cgi.pyc

Python Compiled Bytecode | 2009-11-11 | 33KB | 1,132 lines

# Source Generated with Decompyle++
# File: in.pyc (Python 2.6)

'''Support module for CGI (Common Gateway Interface) scripts.

This module defines a number of utilities for use by CGI scripts
written in Python.
'''
__version__ = '2.6'
from operator import attrgetter
import sys
import os
import urllib
import UserDict
import urlparse
from warnings import filterwarnings, catch_warnings, warn
catch_warnings().__enter__()

try:
    import mimetools
    if sys.py3kwarning:
        filterwarnings('ignore', '.*rfc822 has been removed', DeprecationWarning)

    import rfc822
finally:
    pass


try:
    from cStringIO import StringIO
except ImportError:
    catch_warnings().__exit__
    catch_warnings().__exit__
    catch_warnings()
    from StringIO import StringIO
except:
    catch_warnings().__exit__

__all__ = [
    'MiniFieldStorage',
    'FieldStorage',
    'FormContentDict',
    'SvFormContentDict',
    'InterpFormContentDict',
    'FormContent',
    'parse',
    'parse_qs',
    'parse_qsl',
    'parse_multipart',
    'parse_header',
    'print_exception',
    'print_environ',
    'print_form',
    'print_directory',
    'print_arguments',
    'print_environ_usage',
    'escape']
logfile = ''
logfp = None

def initlog(*allargs):
    '''Write a log message, if there is a log file.

    Even though this function is called initlog(), you should always
    use log(); log is a variable that is set either to initlog
    (initially), to dolog (once the log file has been opened), or to
    nolog (when logging is disabled).

    The first argument is a format string; the remaining arguments (if
    any) are arguments to the % operator, so e.g.
        log("%s: %s", "a", "b")
    will write "a: b" to the log file, followed by a newline.

    If the global logfp is not None, it should be a file object to
    which log data is written.

    If the global logfp is None, the global logfile may be a string
    giving a filename to open, in append mode.  This file should be
    world writable!!!  If the file can\'t be opened, logging is
    silently disabled (since there is no safe place where we could
    send an error message).

    '''
    global logfp, log
    if logfile and not logfp:

        try:
            logfp = open(logfile, 'a')
        except IOError:
            pass
        except:
            None<EXCEPTION MATCH>IOError


    None<EXCEPTION MATCH>IOError
    if not logfp:
        log = nolog
    else:
        log = dolog
    log(*allargs)


def dolog(fmt, *args):
    '''Write a log message to the log file.  See initlog() for docs.'''
    logfp.write(fmt % args + '\n')


def nolog(*allargs):
    '''Dummy function, assigned to log when logging is disabled.'''
    pass

log = initlog
maxlen = 0

def parse(fp = None, environ = os.environ, keep_blank_values = 0, strict_parsing = 0):
    '''Parse a query in the environment or from a file (default stdin)

        Arguments, all optional:

        fp              : file pointer; default: sys.stdin

        environ         : environment dictionary; default: os.environ

        keep_blank_values: flag indicating whether blank values in
            URL encoded forms should be treated as blank strings.
            A true value indicates that blanks should be retained as
            blank strings.  The default false value indicates that
            blank values are to be ignored and treated as if they were
            not included.

        strict_parsing: flag indicating what to do with parsing errors.
            If false (the default), errors are silently ignored.
            If true, errors raise a ValueError exception.
    '''
    if fp is None:
        fp = sys.stdin

    if 'REQUEST_METHOD' not in environ:
        environ['REQUEST_METHOD'] = 'GET'

    if environ['REQUEST_METHOD'] == 'POST':
        (ctype, pdict) = parse_header(environ['CONTENT_TYPE'])
        if ctype == 'multipart/form-data':
            return parse_multipart(fp, pdict)
        if ctype == 'application/x-www-form-urlencoded':
            clength = int(environ['CONTENT_LENGTH'])
            if maxlen and clength > maxlen:
                raise ValueError, 'Maximum content length exceeded'
            clength > maxlen
            qs = fp.read(clength)
        else:
            qs = ''
        if 'QUERY_STRING' in environ:
            if qs:
                qs = qs + '&'

            qs = qs + environ['QUERY_STRING']
        elif sys.argv[1:]:
            if qs:
                qs = qs + '&'

            qs = qs + sys.argv[1]

        environ['QUERY_STRING'] = qs
    elif 'QUERY_STRING' in environ:
        qs = environ['QUERY_STRING']
    elif sys.argv[1:]:
        qs = sys.argv[1]
    else:
        qs = ''
    environ['QUERY_STRING'] = qs
    return parse_qs(qs, keep_blank_values, strict_parsing)


def parse_qs(qs, keep_blank_values = 0, strict_parsing = 0):
    '''Parse a query given as a string argument.'''
    warn('cgi.parse_qs is deprecated, use urlparse.parse_qs             instead', PendingDeprecationWarning, 2)
    return urlparse.parse_qs(qs, keep_blank_values, strict_parsing)


def parse_qsl(qs, keep_blank_values = 0, strict_parsing = 0):
    '''Parse a query given as a string argument.'''
    warn('cgi.parse_qsl is deprecated, use urlparse.parse_qsl instead', PendingDeprecationWarning, 2)
    return urlparse.parse_qsl(qs, keep_blank_values, strict_parsing)


def parse_multipart(fp, pdict):
    '''Parse multipart input.

    Arguments:
    fp   : input file
    pdict: dictionary containing other parameters of content-type header

    Returns a dictionary just like parse_qs(): keys are the field names, each
    value is a list of values for that field.  This is easy to use but not
    much good if you are expecting megabytes to be uploaded -- in that case,
    use the FieldStorage class instead which is much more flexible.  Note
    that content-type is the raw, unparsed contents of the content-type
    header.

    XXX This does not parse nested multipart parts -- use FieldStorage for
    that.

    XXX This should really be subsumed by FieldStorage altogether -- no
    point in having two implementations of the same parsing algorithm.
    Also, FieldStorage protects itself better against certain DoS attacks
    by limiting the size of the data read in one chunk.  The API here
    does not support that kind of protection.  This also affects parse()
    since it can call parse_multipart().

    '''
    boundary = ''
    if 'boundary' in pdict:
        boundary = pdict['boundary']

    if not valid_boundary(boundary):
        raise ValueError, 'Invalid boundary in multipart form: %r' % (boundary,)
    valid_boundary(boundary)
    nextpart = '--' + boundary
    lastpart = '--' + boundary + '--'
    partdict = { }
    terminator = ''
    while terminator != lastpart:
        bytes = -1
        data = None
        if terminator:
            headers = mimetools.Message(fp)
            clength = headers.getheader('content-length')
            if clength:

                try:
                    bytes = int(clength)
                except ValueError:
                    pass
                except:
                    None<EXCEPTION MATCH>ValueError


            None<EXCEPTION MATCH>ValueError
            if bytes > 0:
                if maxlen and bytes > maxlen:
                    raise ValueError, 'Maximum content length exceeded'
                bytes > maxlen
                data = fp.read(bytes)
            else:
                data = ''

        lines = []
        while None:
            line = fp.readline()
            if not line:
                terminator = lastpart
                break

            if line[:2] == '--':
                terminator = line.strip()
                if terminator in (nextpart, lastpart):
                    break


            continue
            if data is None:
                continue

        if bytes < 0:
            if lines:
                line = lines[-1]
                if line[-2:] == '\r\n':
                    line = line[:-2]
                elif line[-1:] == '\n':
                    line = line[:-1]

                lines[-1] = line
                data = ''.join(lines)


        line = headers['content-disposition']
        if not line:
            continue

        (key, params) = parse_header(line)
        if key != 'form-data':
            continue

        if 'name' in params:
            name = params['name']

        if name in partdict:
            partdict[name].append(data)
            continue
        'name' in params
        partdict[name] = [
            data]
    return partdict


def _parseparam(s):
    while s[:1] == ';':
        s = s[1:]
        end = s.find(';')
        while end > 0 and s.count('"', 0, end) % 2:
            end = s.find(';', end + 1)
        if end < 0:
            end = len(s)

        f = s[:end]
        yield f.strip()
        s = s[end:]


def parse_header(line):
    '''Parse a Content-type like header.

    Return the main content-type and a dictionary of options.

    '''
    parts = _parseparam(';' + line)
    key = parts.next()
    pdict = { }
    for p in parts:
        i = p.find('=')
        if i >= 0:
            name = p[:i].strip().lower()
            value = p[i + 1:].strip()
            if len(value) >= 2:
                if value[-1] == value[-1]:
                    pass
                elif value[-1] == '"':
                    value = value[1:-1]
                    value = value.replace('\\\\', '\\').replace('\\"', '"')

            pdict[name] = value
            continue
        value[0]

    return (key, pdict)


class MiniFieldStorage:
    '''Like FieldStorage, for use when no file uploads are possible.'''
    filename = None
    list = None
    type = None
    file = None
    type_options = { }
    disposition = None
    disposition_options = { }
    headers = { }

    def __init__(self, name, value):
        '''Constructor from field name and value.'''
        self.name = name
        self.value = value


    def __repr__(self):
        '''Return printable representation.'''
        return 'MiniFieldStorage(%r, %r)' % (self.name, self.value)



class FieldStorage:
    """Store a sequence of fields, reading multipart/form-data.

    This class provides naming, typing, files stored on disk, and
    more.  At the top level, it is accessible like a dictionary, whose
    keys are the field names.  (Note: None can occur as a field name.)
    The items are either a Python list (if there's multiple values) or
    another FieldStorage or MiniFieldStorage object.  If it's a single
    object, it has the following attributes:

    name: the field name, if specified; otherwise None

    filename: the filename, if specified; otherwise None; this is the
        client side filename, *not* the file name on which it is
        stored (that's a temporary file you don't deal with)

    value: the value as a *string*; for file uploads, this
        transparently reads the file every time you request the value

    file: the file(-like) object from which you can read the data;
        None if the data is stored a simple string

    type: the content-type, or None if not specified

    type_options: dictionary of options specified on the content-type
        line

    disposition: content-disposition, or None if not specified

    disposition_options: dictionary of corresponding options

    headers: a dictionary(-like) object (sometimes rfc822.Message or a
        subclass thereof) containing *all* headers

    The class is subclassable, mostly for the purpose of overriding
    the make_file() method, which is called internally to come up with
    a file open for reading and writing.  This makes it possible to
    override the default choice of storing all files in a temporary
    directory and unlinking them as soon as they have been opened.

    """

    def __init__(self, fp = None, headers = None, outerboundary = '', environ = os.environ, keep_blank_values = 0, strict_parsing = 0):
        '''Constructor.  Read multipart/* until last part.

        Arguments, all optional:

        fp              : file pointer; default: sys.stdin
            (not used when the request method is GET)

        headers         : header dictionary-like object; default:
            taken from environ as per CGI spec

        outerboundary   : terminating multipart boundary
            (for internal use only)

        environ         : environment dictionary; default: os.environ

        keep_blank_values: flag indicating whether blank values in
            URL encoded forms should be treated as blank strings.
            A true value indicates that blanks should be retained as
            blank strings.  The default false value indicates that
            blank values are to be ignored and treated as if they were
            not included.

        strict_parsing: flag indicating what to do with parsing errors.
            If false (the default), errors are silently ignored.
            If true, errors raise a ValueError exception.

        '''
        method = 'GET'
        self.keep_blank_values = keep_blank_values
        self.strict_parsing = strict_parsing
        if 'REQUEST_METHOD' in environ:
            method = environ['REQUEST_METHOD'].upper()

        self.qs_on_post = None
        if method == 'GET' or method == 'HEAD':
            if 'QUERY_STRING' in environ:
                qs = environ['QUERY_STRING']
            elif sys.argv[1:]:
                qs = sys.argv[1]
            else:
                qs = ''
            fp = StringIO(qs)
            if headers is None:
                headers = {
                    'content-type': 'application/x-www-form-urlencoded' }


        if headers is None:
            headers = { }
            if method == 'POST':
                headers['content-type'] = 'application/x-www-form-urlencoded'

            if 'CONTENT_TYPE' in environ:
                headers['content-type'] = environ['CONTENT_TYPE']

            if 'QUERY_STRING' in environ:
                self.qs_on_post = environ['QUERY_STRING']

            if 'CONTENT_LENGTH' in environ:
                headers['content-length'] = environ['CONTENT_LENGTH']


        if not fp:
            pass
        self.fp = sys.stdin
        self.headers = headers
        self.outerboundary = outerboundary
        cdisp = ''
        pdict = { }
        if 'content-disposition' in self.headers:
            (cdisp, pdict) = parse_header(self.headers['content-disposition'])

        self.disposition = cdisp
        self.disposition_options = pdict
        self.name = None
        if 'name' in pdict:
            self.name = pdict['name']

        self.filename = None
        if 'filename' in pdict:
            self.filename = pdict['filename']

        if 'content-type' in self.headers:
            (ctype, pdict) = parse_header(self.headers['content-type'])
        elif self.outerboundary or method != 'POST':
            ctype = 'text/plain'
            pdict = { }
        else:
            ctype = 'application/x-www-form-urlencoded'
            pdict = { }
        self.type = ctype
        self.type_options = pdict
        self.innerboundary = ''
        if 'boundary' in pdict:
            self.innerboundary = pdict['boundary']

        clen = -1
        if 'content-length' in self.headers:

            try:
                clen = int(self.headers['content-length'])
            except ValueError:
                pass

            if maxlen and clen > maxlen:
                raise ValueError, 'Maximum content length exceeded'
            clen > maxlen

        self.length = clen
        self.list = None
        self.file = None
        self.done = 0
        if ctype == 'application/x-www-form-urlencoded':
            self.read_urlencoded()
        elif ctype[:10] == 'multipart/':
            self.read_multi(environ, keep_blank_values, strict_parsing)
        else:
            self.read_single()


    def __repr__(self):
        '''Return a printable representation.'''
        return 'FieldStorage(%r, %r, %r)' % (self.name, self.filename, self.value)


    def __iter__(self):
        return iter(self.keys())


    def __getattr__(self, name):
        if name != 'value':
            raise AttributeError, name
        name != 'value'
        if self.file:
            self.file.seek(0)
            value = self.file.read()
            self.file.seek(0)
        elif self.list is not None:
            value = self.list
        else:
            value = None
        return value


    def __getitem__(self, key):
        '''Dictionary style indexing.'''
        if self.list is None:
            raise TypeError, 'not indexable'
        self.list is None
        found = []
        for item in self.list:
            if item.name == key:
                found.append(item)
                continue

        if not found:
            raise KeyError, key
        found
        if len(found) == 1:
            return found[0]
        return found


    def getvalue(self, key, default = None):
        """Dictionary style get() method, including 'value' lookup."""
        if key in self:
            value = self[key]
            if type(value) is type([]):
                return map(attrgetter('value'), value)
            return value.value
        key in self
        return default


    def getfirst(self, key, default = None):
        ''' Return the first value received.'''
        if key in self:
            value = self[key]
            if type(value) is type([]):
                return value[0].value
            return value.value
        key in self
        return default


    def getlist(self, key):
        ''' Return list of received values.'''
        if key in self:
            value = self[key]
            if type(value) is type([]):
                return map(attrgetter('value'), value)
            return [
                value.value]
        key in self
        return []


    def keys(self):
        '''Dictionary style keys() method.'''
        if self.list is None:
            raise TypeError, 'not indexable'
        self.list is None
        return list(set((lambda .0: for item in .0:
item.name)(self.list)))


    def has_key(self, key):
        '''Dictionary style has_key() method.'''
        if self.list is None:
            raise TypeError, 'not indexable'
        self.list is None
        return (any,)((lambda .0: for item in .0:
item.name == key)(self.list))


    def __contains__(self, key):
        '''Dictionary style __contains__ method.'''
        if self.list is None:
            raise TypeError, 'not indexable'
        self.list is None
        return (any,)((lambda .0: for item in .0:
item.name == key)(self.list))


    def __len__(self):
        '''Dictionary style len(x) support.'''
        return len(self.keys())


    def __nonzero__(self):
        return bool(self.list)


    def read_urlencoded(self):
        '''Internal: read data in query string format.'''
        qs = self.fp.read(self.length)
        if self.qs_on_post:
            qs += '&' + self.qs_on_post

        self.list = list = []
        for key, value in urlparse.parse_qsl(qs, self.keep_blank_values, self.strict_parsing):
            list.append(MiniFieldStorage(key, value))

        self.skip_lines()

    FieldStorageClass = None

    def read_multi(self, environ, keep_blank_values, strict_parsing):
        '''Internal: read a part that is itself multipart.'''
        ib = self.innerboundary
        if not valid_boundary(ib):
            raise ValueError, 'Invalid boundary in multipart form: %r' % (ib,)
        valid_boundary(ib)
        self.list = []
        if self.qs_on_post:
            for key, value in urlparse.parse_qsl(self.qs_on_post, self.keep_blank_values, self.strict_parsing):
                self.list.append(MiniFieldStorage(key, value))

            FieldStorageClass = None

        if not self.FieldStorageClass:
            pass
        klass = self.__class__
        part = klass(self.fp, { }, ib, environ, keep_blank_values, strict_parsing)
        while not part.done:
            headers = rfc822.Message(self.fp)
            part = klass(self.fp, headers, ib, environ, keep_blank_values, strict_parsing)
            self.list.append(part)
        self.skip_lines()


    def read_single(self):
        '''Internal: read an atomic part.'''
        if self.length >= 0:
            self.read_binary()
            self.skip_lines()
        else:
            self.read_lines()
        self.file.seek(0)

    bufsize = 8192

    def read_binary(self):
        '''Internal: read binary data.'''
        self.file = self.make_file('b')
        todo = self.length
        if todo >= 0:
            while todo > 0:
                data = self.fp.read(min(todo, self.bufsize))
                if not data:
                    self.done = -1
                    break

                self.file.write(data)
                todo = todo - len(data)



    def read_lines(self):
        '''Internal: read lines until EOF or outerboundary.'''
        self.file = self._FieldStorage__file = StringIO()
        if self.outerboundary:
            self.read_lines_to_outerboundary()
        else:
            self.read_lines_to_eof()


    def __write(self, line):
        if self._FieldStorage__file is not None:
            if self._FieldStorage__file.tell() + len(line) > 1000:
                self.file = self.make_file('')
                self.file.write(self._FieldStorage__file.getvalue())
                self._FieldStorage__file = None


        self.file.write(line)


    def read_lines_to_eof(self):
        '''Internal: read lines until EOF.'''
        while None:
            line = self.fp.readline(65536)
            if not line:
                self.done = -1
                break

            continue
            return None


    def read_lines_to_outerboundary(self):
        '''Internal: read lines until outerboundary.'''
        next = '--' + self.outerboundary
        last = next + '--'
        delim = ''
        last_line_lfend = True
        while None:
            line = self.fp.readline(65536)
            if not line:
                self.done = -1
                break

            if line[:2] == '--' and last_line_lfend:
                strippedline = line.strip()
                if strippedline == next:
                    break

                if strippedline == last:
                    self.done = 1
                    break


            odelim = delim
            if line[-2:] == '\r\n':
                delim = '\r\n'
                line = line[:-2]
                last_line_lfend = True
            elif line[-1] == '\n':
                delim = '\n'
                line = line[:-1]
                last_line_lfend = True
            else:
                delim = ''
                last_line_lfend = False
            continue
            return None


    def skip_lines(self):
        '''Internal: skip lines until outer boundary if defined.'''
        if not (self.outerboundary) or self.done:
            return None
        next = '--' + self.outerboundary
        last = next + '--'
        last_line_lfend = True
        while None:
            line = self.fp.readline(65536)
            if not line:
                self.done = -1
                break

            if line[:2] == '--' and last_line_lfend:
                strippedline = line.strip()
                if strippedline == next:
                    break

                if strippedline == last:
                    self.done = 1
                    break


            last_line_lfend = line.endswith('\n')
            continue
            return None


    def make_file(self, binary = None):
        """Overridable: return a readable & writable file.

        The file will be used as follows:
        - data is written to it
        - seek(0)
        - data is read from it

        The 'binary' argument is unused -- the file is always opened
        in binary mode.

        This version opens a temporary file for reading and writing,
        and immediately deletes (unlinks) it.  The trick (on Unix!) is
        that the file can still be used, but it can't be opened by
        another process, and it will automatically be deleted when it
        is closed or when the current process terminates.

        If you want a more permanent file, you derive a class which
        overrides this method.  If you want a visible temporary file
        that is nevertheless automatically deleted when the script
        terminates, try defining a __del__ method in a derived class
        which unlinks the temporary files you have created.

        """
        import tempfile as tempfile
        return tempfile.TemporaryFile('w+b')



class FormContentDict(UserDict.UserDict):
    '''Form content as dictionary with a list of values per field.

    form = FormContentDict()

    form[key] -> [value, value, ...]
    key in form -> Boolean
    form.keys() -> [key, key, ...]
    form.values() -> [[val, val, ...], [val, val, ...], ...]
    form.items() ->  [(key, [val, val, ...]), (key, [val, val, ...]), ...]
    form.dict == {key: [val, val, ...], ...}

    '''

    def __init__(self, environ = os.environ, keep_blank_values = 0, strict_parsing = 0):
        self.dict = self.data = parse(environ = environ, keep_blank_values = keep_blank_values, strict_parsing = strict_parsing)
        self.query_string = environ['QUERY_STRING']



class SvFormContentDict(FormContentDict):
    '''Form content as dictionary expecting a single value per field.

    If you only expect a single value for each field, then form[key]
    will return that single value.  It will raise an IndexError if
    that expectation is not true.  If you expect a field to have
    possible multiple values, than you can use form.getlist(key) to
    get all of the values.  values() and items() are a compromise:
    they return single strings where there is a single value, and
    lists of strings otherwise.

    '''

    def __getitem__(self, key):
        if len(self.dict[key]) > 1:
            raise IndexError, 'expecting a single value'
        len(self.dict[key]) > 1
        return self.dict[key][0]


    def getlist(self, key):
        return self.dict[key]


    def values(self):
        result = []
        for value in self.dict.values():
            if len(value) == 1:
                result.append(value[0])
                continue
            result.append(value)

        return result


    def items(self):
        result = []
        for key, value in self.dict.items():
            if len(value) == 1:
                result.append((key, value[0]))
                continue
            result.append((key, value))

        return result



class InterpFormContentDict(SvFormContentDict):
    '''This class is present for backwards compatibility only.'''

    def __getitem__(self, key):
        v = SvFormContentDict.__getitem__(self, key)
        if v[0] in '0123456789+-.':

            try:
                return int(v)
            except ValueError:

                try:
                    return float(v)
                except ValueError:
                    pass
                except:
                    None<EXCEPTION MATCH>ValueError


                None<EXCEPTION MATCH>ValueError


        None<EXCEPTION MATCH>ValueError
        return v.strip()


    def values(self):
        result = []
        for key in self.keys():

            try:
                result.append(self[key])
            continue
            except IndexError:
                result.append(self.dict[key])
                continue



        return result


    def items(self):
        result = []
        for key in self.keys():

            try:
                result.append((key, self[key]))
            continue
            except IndexError:
                result.append((key, self.dict[key]))
                continue



        return result



class FormContent(FormContentDict):
    '''This class is present for backwards compatibility only.'''

    def values(self, key):
        if key in self.dict:
            return self.dict[key]
        return None


    def indexed_value(self, key, location):
        if key in self.dict:
            if len(self.dict[key]) > location:
                return self.dict[key][location]
            return None
        key in self.dict
        return None


    def value(self, key):
        if key in self.dict:
            return self.dict[key][0]
        return None


    def length(self, key):
        return len(self.dict[key])


    def stripped(self, key):
        if key in self.dict:
            return self.dict[key][0].strip()
        return None


    def pars(self):
        return self.dict



def test(environ = os.environ):
    '''Robust test CGI script, usable as main program.

    Write minimal HTTP headers and dump all information provided to
    the script in HTML form.

    '''
    global maxlen
    print 'Content-type: text/html'
    print
    sys.stderr = sys.stdout

    try:
        form = FieldStorage()
        print_directory()
        print_arguments()
        print_form(form)
        print_environ(environ)
        print_environ_usage()

        def f():
            exec 'testing print_exception() -- <I>italics?</I>'


        def g(f = f):
            f()

        print '<H3>What follows is a test, not an actual exception:</H3>'
        g()
    except:
        print_exception()

    print '<H1>Second try with a small maxlen...</H1>'
    maxlen = 50

    try:
        form = FieldStorage()
        print_directory()
        print_arguments()
        print_form(form)
        print_environ(environ)
    except:
        print_exception()



def print_exception(type = None, value = None, tb = None, limit = None):
    if type is None:
        (type, value, tb) = sys.exc_info()

    import traceback as traceback
    print
    print '<H3>Traceback (most recent call last):</H3>'
    list = traceback.format_tb(tb, limit) + traceback.format_exception_only(type, value)
    print '<PRE>%s<B>%s</B></PRE>' % (escape(''.join(list[:-1])), escape(list[-1]))
    del tb


def print_environ(environ = os.environ):
    '''Dump the shell environment as HTML.'''
    keys = environ.keys()
    keys.sort()
    print
    print '<H3>Shell Environment:</H3>'
    print '<DL>'
    for key in keys:
        print '<DT>', escape(key), '<DD>', escape(environ[key])

    print '</DL>'
    print


def print_form(form):
    '''Dump the contents of a form as HTML.'''
    keys = form.keys()
    keys.sort()
    print
    print '<H3>Form Contents:</H3>'
    if not keys:
        print '<P>No form fields.'

    print '<DL>'
    for key in keys:
        print '<DT>' + escape(key) + ':',
        value = form[key]
        print '<i>' + escape(repr(type(value))) + '</i>'
        print '<DD>' + escape(repr(value))

    print '</DL>'
    print


def print_directory():
    '''Dump the current directory as HTML.'''
    print
    print '<H3>Current Working Directory:</H3>'

    try:
        pwd = os.getcwd()
    except os.error:
        msg = None
        print 'os.error:', escape(str(msg))

    print escape(pwd)
    print


def print_arguments():
    print
    print '<H3>Command Line Arguments:</H3>'
    print
    print sys.argv
    print


def print_environ_usage():
    '''Dump a list of environment variables used by CGI as HTML.'''
    print '\n<H3>These environment variables could have been set:</H3>\n<UL>\n<LI>AUTH_TYPE\n<LI>CONTENT_LENGTH\n<LI>CONTENT_TYPE\n<LI>DATE_GMT\n<LI>DATE_LOCAL\n<LI>DOCUMENT_NAME\n<LI>DOCUMENT_ROOT\n<LI>DOCUMENT_URI\n<LI>GATEWAY_INTERFACE\n<LI>LAST_MODIFIED\n<LI>PATH\n<LI>PATH_INFO\n<LI>PATH_TRANSLATED\n<LI>QUERY_STRING\n<LI>REMOTE_ADDR\n<LI>REMOTE_HOST\n<LI>REMOTE_IDENT\n<LI>REMOTE_USER\n<LI>REQUEST_METHOD\n<LI>SCRIPT_NAME\n<LI>SERVER_NAME\n<LI>SERVER_PORT\n<LI>SERVER_PROTOCOL\n<LI>SERVER_ROOT\n<LI>SERVER_SOFTWARE\n</UL>\nIn addition, HTTP headers sent by the server may be passed in the\nenvironment as well.  Here are some common variable names:\n<UL>\n<LI>HTTP_ACCEPT\n<LI>HTTP_CONNECTION\n<LI>HTTP_HOST\n<LI>HTTP_PRAGMA\n<LI>HTTP_REFERER\n<LI>HTTP_USER_AGENT\n</UL>\n'


def escape(s, quote = None):
    '''Replace special characters "&", "<" and ">" to HTML-safe sequences.
    If the optional flag quote is true, the quotation mark character (")
    is also translated.'''
    s = s.replace('&', '&')
    s = s.replace('<', '<')
    s = s.replace('>', '>')
    if quote:
        s = s.replace('"', '"')

    return s


def valid_boundary(s, _vb_pattern = '^[ -~]{0,200}[!-~]$'):
    import re as re
    return re.match(_vb_pattern, s)