# (c) 2005 Ian Bicking and contributors; written for Paste (http://pythonpaste.org)
# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
"""
Exception-catching middleware that allows interactive debugging.
This middleware catches all unexpected exceptions. A normal
traceback, like produced by
``paste.exceptions.errormiddleware.ErrorMiddleware`` is given, plus
controls to see local variables and evaluate expressions in a local
context.
This can only be used in single-process environments, because
subsequent requests must go back to the same process that the
exception originally occurred in. Threaded or non-concurrent
environments both work.
This shouldn't be used in production in any way. That would just be
silly.
If calling from an XMLHttpRequest call, if the GET variable ``_`` is
given then it will make the response more compact (and less
Javascripty), since if you use innerHTML it'll kill your browser. You
can look for the header X-Debug-URL in your 500 responses if you want
to see the full debuggable traceback. Also, this URL is printed to
``wsgi.errors``, so you can open it up in another browser window.
"""
from __future__ import print_function
import sys
import os
import cgi
import traceback
import six
from six.moves import cStringIO as StringIO
import pprint
import itertools
import time
import re
from paste.exceptions import errormiddleware, formatter, collector
from paste import wsgilib
from paste import urlparser
from paste import httpexceptions
from paste import registry
from paste import request
from paste import response
from paste.evalexception import evalcontext
limit = 200
def html_quote(v):
"""
Escape HTML characters, plus translate None to ''
"""
if v is None:
return ''
return cgi.escape(str(v), 1)
def preserve_whitespace(v, quote=True):
"""
Quote a value for HTML, preserving whitespace (translating
newlines to ``<br>`` and multiple spaces to use `` ``).
If ``quote`` is true, then the value will be HTML quoted first.
"""
if quote:
v = html_quote(v)
v = v.replace('\n', '<br>\n')
v = re.sub(r'()( +)', _repl_nbsp, v)
v = re.sub(r'(\n)( +)', _repl_nbsp, v)
v = re.sub(r'^()( +)', _repl_nbsp, v)
return '<code>%s</code>' % v
def _repl_nbsp(match):
if len(match.group(2)) == 1:
return ' '
return match.group(1) + ' ' * (len(match.group(2))-1) + ' '
def simplecatcher(application):
"""
A simple middleware that catches errors and turns them into simple
tracebacks.
"""
def simplecatcher_app(environ, start_response):
try:
return application(environ, start_response)
except:
out = StringIO()
traceback.print_exc(file=out)
start_response('500 Server Error',
[('content-type', 'text/html')],
sys.exc_info())
res = out.getvalue()
return ['<h3>Error</h3><pre>%s</pre>'
% html_quote(res)]
return simplecatcher_app
def wsgiapp():
"""
Turns a function or method into a WSGI application.
"""
def decorator(func):
def wsgiapp_wrapper(*args):
# we get 3 args when this is a method, two when it is
# a function :(
if len(args) == 3:
environ = args[1]
start_response = args[2]
args = [args[0]]
else:
environ, start_response = args
args = []
def application(environ, start_response):
form = wsgilib.parse_formvars(environ,
include_get_vars=True)
headers = response.HeaderDict(
{'content-type': 'text/html',
'status': '200 OK'})
form['environ'] = environ
form['headers'] = headers
res = func(*args, **form.mixed())
status = headers.pop('status')
start_response(status, headers.headeritems())
return [res]
app = httpexceptions.make_middleware(application)
app = simplecatcher(app)
return app(environ, start_response)
wsgiapp_wrapper.exposed = True
return wsgiapp_wrapper
return decorator
def get_debug_info(func):
"""
A decorator (meant to be used under ``wsgiapp()``) that resolves
the ``debugcount`` variable to a ``DebugInfo`` object (or gives an
error if it can't be found).
"""
def debug_info_replacement(self, **form):
try:
if 'debugcount' not in form:
raise ValueError('You must provide a debugcount parameter')
debugcount = form.pop('debugcount')
try:
debugcount = int(debugcount)
except ValueError:
raise ValueError('Bad value for debugcount')
if debugcount not in self.debug_infos:
raise ValueError(
'Debug %s no longer found (maybe it has expired?)'
% debugcount)
debug_info = self.debug_infos[debugcount]
return func(self, debug_info=debug_info, **form)
except ValueError as e:
form['headers']['status'] = '500 Server Error'
return '<html>There was an error: %s</html>' % html_quote(e)
return debug_info_replacement
debug_counter = itertools.count(int(time.time()))
def get_debug_count(environ):
"""
Return the unique debug count for the current request
"""
if 'paste.evalexception.debug_count' in environ:
return environ['paste.evalexception.debug_count']
else:
environ['paste.evalexception.debug_count'] = next = six.next(debug_counter)
return next
class EvalException(object):
def __init__(self, application, global_conf=None,
xmlhttp_key=None):
self.application = application
self.debug_infos = {}
if xmlhttp_key is None:
if global_conf is None:
xmlhttp_key = '_'
else:
xmlhttp_key = global_conf.get('xmlhttp_key', '_')
self.xmlhttp_key = xmlhttp_key
def __call__(self, environ, start_response):
assert not environ['wsgi.multiprocess'], (
"The EvalException middleware is not usable in a "
"multi-process environment")
environ['paste.evalexception'] = self
if environ.get('PATH_INFO', '').startswith('/_debug/'):
return self.debug(environ, start_response)
else:
return self.respond(environ, start_response)
def debug(self, environ, start_response):
assert request.path_info_pop(environ) == '_debug'
next_part = request.path_info_pop(environ)
method = getattr(self, next_part, None)
if not method:
exc = httpexceptions.HTTPNotFound(
'%r not found when parsing %r'
% (next_part, wsgilib.construct_url(environ)))
return exc.wsgi_application(environ, start_response)
if not getattr(method, 'exposed', False):
exc = httpexceptions.HTTPForbidden(
'%r not allowed' % next_part)
return exc.wsgi_application(environ, start_response)
return method(environ, start_response)
def media(self, environ, start_response):
"""
Static path where images and other files live
"""
app = urlparser.StaticURLParser(
os.path.join(os.path.dirname(__file__), 'media'))
return app(environ, start_response)
media.exposed = True
def mochikit(self, environ, start_response):
"""
Static path where MochiKit lives
"""
app = urlparser.StaticURLParser(
os.path.join(os.path.dirname(__file__), 'mochikit'))
return app(environ, start_response)
mochikit.exposed = True
def summary(self, environ, start_response):
"""
Returns a JSON-format summary of all the cached
exception reports
"""
start_response('200 OK', [('Content-type', 'text/x-json')])
data = [];
items = self.debug_infos.values()
items.sort(lambda a, b: cmp(a.created, b.created))
data = [item.json() for item in items]
return [repr(data)]
summary.exposed = True
def view(self, environ, start_response):
"""
View old exception reports
"""
id = int(request.path_info_pop(environ))
if id not in self.debug_infos:
start_response(
'500 Server Error',
[('Content-type', 'text/html')])
return [
"Traceback by id %s does not exist (maybe "
"the server has been restarted?)"
% id]
debug_info = self.debug_infos[id]
return debug_info.wsgi_application(environ, start_response)
view.exposed = True
def make_view_url(self, environ, base_path, count):
return base_path + '/_debug/view/%s' % count
#@wsgiapp()
#@get_debug_info
def show_frame(self, tbid, debug_info, **kw):
frame = debug_info.frame(int(tbid))
vars = frame.tb_frame.f_locals
if vars:
registry.restorer.restoration_begin(debug_info.counter)
local_vars = make_table(vars)
registry.restorer.restoration_end()
else:
local_vars = 'No local vars'
return input_form(tbid, debug_info) + local_vars
show_frame = wsgiapp()(get_debug_info(show_frame))
#@wsgiapp()
#@get_debug_info
def exec_input(self, tbid, debug_info, input, **kw):
if not input.strip():
return ''
input = input.rstrip() + '\n'
frame = debug_info.frame(int(tbid))
vars = frame.tb_frame.f_locals
glob_vars = frame.tb_frame.f_globals
context = evalcontext.EvalContext(vars, glob_vars)
registry.restorer.restoration_begin(debug_info.counter)
output = context.exec_expr(input)
registry.restorer.restoration_end()
input_html = formatter.str2html(input)
return ('<code style="color: #060">>>></code> '
'<code>%s</code><br>\n%s'
% (preserve_whitespace(input_html, quote=False),
preserve_whitespace(output)))
exec_input = wsgiapp()(get_debug_info(exec_input))
def respond(self, environ, start_response):
if environ.get('paste.throw_errors'):
return self.application(environ, start_response)
base_path = request.construct_url(environ, with_path_info=False,
with_query_string=False)
environ['paste.throw_errors'] = True
started = []
def detect_start_response(status, headers, exc_info=None):
try:
return start_response(status, headers, exc_info)
except:
raise
else:
started.append(True)
try:
__traceback_supplement__ = errormiddleware.Supplement, self, environ
app_iter = self.application(environ, detect_start_response)
try:
return_iter = list(app_iter)
return return_iter
finally:
if hasattr(app_iter, 'close'):
app_iter.close()
except:
exc_info = sys.exc_info()
for expected in environ.get('paste.expected_exceptions', []):
if isinstance(exc_info[1], expected):
raise
# Tell the Registry to save its StackedObjectProxies current state
# for later restoration
registry.restorer.save_registry_state(environ)
count = get_debug_count(environ)
view_uri = self.make_view_url(environ, base_path, count)
if not started:
headers = [('content-type', 'text/html')]
headers.append(('X-Debug-URL', view_uri))
start_response('500 Internal Server Error',
headers,
exc_info)
msg = 'Debug at: %s\n' % view_uri
if six.PY3:
msg = msg.encode('utf8')
environ['wsgi.errors'].write(msg)
exc_data = collector.collect_exception(*exc_info)
debug_info = DebugInfo(count, exc_info, exc_data, base_path,
environ, view_uri)
assert count not in self.debug_infos
self.debug_infos[count] = debug_info
if self.xmlhttp_key:
get_vars = request.parse_querystring(environ)
if dict(get_vars).get(self.xmlhttp_key):
exc_data = collector.collect_exception(*exc_info)
html = formatter.format_html(
exc_data, include_hidden_frames=False,
include_reusable=False, show_extra_data=False)
return [html]
# @@: it would be nice to deal with bad content types here
return debug_info.content()
def exception_handler(self, exc_info, environ):
simple_html_error = False
if self.xmlhttp_key:
get_vars = request.parse_querystring(environ)
if dict(get_vars).get(self.xmlhttp_key):
simple_html_error = True
return errormiddleware.handle_exception(
exc_info, environ['wsgi.errors'],
html=True,
debug_mode=True,
simple_html_error=simple_html_error)
class DebugInfo(object):
def __init__(self, counter, exc_info, exc_data, base_path,
environ, view_uri):
self.counter = counter
self.exc_data = exc_data
self.base_path = base_path
self.environ = environ
self.view_uri = view_uri
self.created = time.time()
self.exc_type, self.exc_value, self.tb = exc_info
__exception_formatter__ = 1
self.frames = []
n = 0
tb = self.tb
while tb is not None and (limit is None or n < limit):
if tb.tb_frame.f_locals.get('__exception_formatter__'):
# Stop recursion. @@: should make a fake ExceptionFrame
break
self.frames.append(tb)
tb = tb.tb_next
n += 1
def json(self):
"""Return the JSON-able representation of this object"""
return {
'uri': self.view_uri,
'created': time.strftime('%c', time.gmtime(self.created)),
'created_timestamp': self.created,
'exception_type': str(self.exc_type),
'exception': str(self.exc_value),
}
def frame(self, tbid):
for frame in self.frames:
if id(frame) == tbid:
return frame
else:
raise ValueError("No frame by id %s found from %r" % (tbid, self.frames))
def wsgi_application(self, environ, start_response):
start_response('200 OK', [('content-type', 'text/html')])
return self.content()
def content(self):
html = format_eval_html(self.exc_data, self.base_path, self.counter)
head_html = (formatter.error_css + formatter.hide_display_js)
head_html += self.eval_javascript()
repost_button = make_repost_button(self.environ)
page = error_template % {
'repost_button': repost_button or '',
'head_html': head_html,
'body': html}
if six.PY3:
page = page.encode('utf8')
return [page]
def eval_javascript(self):
base_path = self.base_path + '/_debug'
return (
'<script type="text/javascript" src="%s/media/MochiKit.packed.js">'
'</script>\n'
'<script type="text/javascript" src="%s/media/debug.js">'
'</script>\n'
'<script type="text/javascript">\n'
'debug_base = %r;\n'
'debug_count = %r;\n'
'</script>\n'
% (base_path, base_path, base_path, self.counter))
class EvalHTMLFormatter(formatter.HTMLFormatter):
def __init__(self, base_path, counter, **kw):
super(EvalHTMLFormatter, self).__init__(**kw)
self.base_path = base_path
self.counter = counter
def format_source_line(self, filename, frame):
line = formatter.HTMLFormatter.format_source_line(
self, filename, frame)
return (line +
' <a href="#" class="switch_source" '
'tbid="%s" onClick="return showFrame(this)"> '
'<img src="%s/_debug/media/plus.jpg" border=0 width=9 '
'height=9> </a>'
% (frame.tbid, self.base_path))
def make_table(items):
if isinstance(items, dict):
items = items.items()
items.sort()
rows = []
i = 0
for name, value in items:
i += 1
out = StringIO()
try:
pprint.pprint(value, out)
except Exception as e:
print('Error: %s' % e, file=out)
value = html_quote(out.getvalue())
if len(value) > 100:
# @@: This can actually break the HTML :(
# should I truncate before quoting?
orig_value = value
value = value[:100]
value += '<a class="switch_source" style="background-color: #999" href="#" onclick="return expandLong(this)">...</a>'
value += '<span style="display: none">%s</span>' % orig_value[100:]
value = formatter.make_wrappable(value)
if i % 2:
attr = ' class="even"'
else:
attr = ' class="odd"'
rows.append('<tr%s style="vertical-align: top;"><td>'
'<b>%s</b></td><td style="overflow: auto">%s<td></tr>'
% (attr, html_quote(name),
preserve_whitespace(value, quote=False)))
return '<table>%s</table>' % (
'\n'.join(rows))
def format_eval_html(exc_data, base_path, counter):
short_formatter = EvalHTMLFormatter(
base_path=base_path,
counter=counter,
include_reusable=False)
short_er = short_formatter.format_collected_data(exc_data)
long_formatter = EvalHTMLFormatter(
base_path=base_path,
counter=counter,
show_hidden_frames=True,
show_extra_data=False,
include_reusable=False)
long_er = long_formatter.format_collected_data(exc_data)
text_er = formatter.format_text(exc_data, show_hidden_frames=True)
if short_formatter.filter_frames(exc_data.frames) != \
long_formatter.filter_frames(exc_data.frames):
# Only display the full traceback when it differs from the
# short version
full_traceback_html = """
<br>
<script type="text/javascript">
show_button('full_traceback', 'full traceback')
</script>
<div id="full_traceback" class="hidden-data">
%s
</div>
""" % long_er
else:
full_traceback_html = ''
return """
%s
%s
<br>
<script type="text/javascript">
show_button('text_version', 'text version')
</script>
<div id="text_version" class="hidden-data">
<textarea style="width: 100%%" rows=10 cols=60>%s</textarea>
</div>
""" % (short_er, full_traceback_html, cgi.escape(text_er))
def make_repost_button(environ):
url = request.construct_url(environ)
if environ['REQUEST_METHOD'] == 'GET':
return ('<button onclick="window.location.href=%r">'
'Re-GET Page</button><br>' % url)
else:
# @@: I'd like to reconstruct this, but I can't because
# the POST body is probably lost at this point, and
# I can't get it back :(
return None
# @@: Use or lose the following code block
"""
fields = []
for name, value in wsgilib.parse_formvars(
environ, include_get_vars=False).items():
if hasattr(value, 'filename'):
# @@: Arg, we'll just submit the body, and leave out
# the filename :(
value = value.value
fields.append(
'<input type="hidden" name="%s" value="%s">'
% (html_quote(name), html_quote(value)))
return '''
<form action="%s" method="POST">
%s
<input type="submit" value="Re-POST Page">
</form>''' % (url, '\n'.join(fields))
"""
def input_form(tbid, debug_info):
return '''
<form action="#" method="POST"
onsubmit="return submitInput($(\'submit_%(tbid)s\'), %(tbid)s)">
<div id="exec-output-%(tbid)s" style="width: 95%%;
padding: 5px; margin: 5px; border: 2px solid #000;
display: none"></div>
<input type="text" name="input" id="debug_input_%(tbid)s"
style="width: 100%%"
autocomplete="off" onkeypress="upArrow(this, event)"><br>
<input type="submit" value="Execute" name="submitbutton"
onclick="return submitInput(this, %(tbid)s)"
id="submit_%(tbid)s"
input-from="debug_input_%(tbid)s"
output-to="exec-output-%(tbid)s">
<input type="submit" value="Expand"
onclick="return expandInput(this)">
</form>
''' % {'tbid': tbid}
error_template = '''
<html>
<head>
<title>Server Error</title>
%(head_html)s
</head>
<body>
<div id="error-area" style="display: none; background-color: #600; color: #fff; border: 2px solid black">
<div id="error-container"></div>
<button onclick="return clearError()">clear this</button>
</div>
%(repost_button)s
%(body)s
</body>
</html>
'''
def make_eval_exception(app, global_conf, xmlhttp_key=None):
"""
Wraps the application in an interactive debugger.
This debugger is a major security hole, and should only be
used during development.
xmlhttp_key is a string that, if present in QUERY_STRING,
indicates that the request is an XMLHttp request, and the
Javascript/interactive debugger should not be returned. (If you
try to put the debugger somewhere with innerHTML, you will often
crash the browser)
"""
if xmlhttp_key is None:
xmlhttp_key = global_conf.get('xmlhttp_key', '_')
return EvalException(app, xmlhttp_key=xmlhttp_key)