cpython/Lib/cgitb.py at fa78d0fbe45a7f16d5d30c3d4e3ad30dc4933e8f · python/cpython · GitHub

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"""Handle exceptions in CGI scripts by formatting tracebacks into nice HTML.

To enable this module, do:

import cgitb; cgitb.enable()

at the top of your CGI script. The optional arguments to enable() are:

display - if true, tracebacks are displayed in the web browser

logdir - if set, tracebacks are written to files in this directory

context - number of lines of source code to show for each stack frame

By default, tracebacks are displayed but not saved, and context is 5.

Alternatively, if you have caught an exception and want cgitb to display it

for you, call cgitb.handle(). The optional argument to handle() is a 3-item

tuple (etype, evalue, etb) just like the value of sys.exc_info()."""

__author__ = 'Ka-Ping Yee'

__version__ = '$Revision$'

import sys

def reset():

"""Return a string that resets the CGI and browser to a known state."""

return '''<!--: spam

Content-Type: text/html

</font> </font> </font> </script> </object> </blockquote> </pre>

</table> </table> </table> </table> </table> </font> </font> </font>'''

__UNDEF__ = [] # a special sentinel object

def small(text): return '<small>' + text + '</small>'

def strong(text): return '<strong>' + text + '</strong>'

def grey(text): return '<font color="#909090">' + text + '</font>'

def lookup(name, frame, locals):

"""Find the value for a given name in the given environment."""

if name in locals:

return 'local', locals[name]

if name in frame.f_globals:

return 'global', frame.f_globals[name]

return None, __UNDEF__

def scanvars(reader, frame, locals):

"""Scan one logical line of Python and look up values of variables used."""

import tokenize, keyword

vars, lasttoken, parent, prefix = [], None, None, ''

for ttype, token, start, end, line in tokenize.generate_tokens(reader):

if ttype == tokenize.NEWLINE: break

if ttype == tokenize.NAME and token not in keyword.kwlist:

if lasttoken == '.':

if parent is not __UNDEF__:

value = getattr(parent, token, __UNDEF__)

vars.append((prefix + token, prefix, value))

else:

where, value = lookup(token, frame, locals)

vars.append((token, where, value))

elif token == '.':

prefix += lasttoken + '.'

parent = value

else:

parent, prefix = None, ''

lasttoken = token

return vars

def html((etype, evalue, etb), context=5):

"""Return a nice HTML document describing a given traceback."""

import os, types, time, traceback, linecache, inspect, pydoc

if type(etype) is types.ClassType:

etype = etype.__name__

pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable

date = time.ctime(time.time())

head = '<body bgcolor="#f0f0f8">' + pydoc.html.heading(

'<big><big><strong>%s</strong></big></big>' % str(etype),

'#ffffff', '#6622aa', pyver + '<br>' + date) + '''

<p>A problem occurred in a Python script. Here is the sequence of

function calls leading up to the error, in the order they occurred.'''

indent = '<tt>' + small(' ' * 5) + ' </tt>'

frames = []

records = inspect.getinnerframes(etb, context)

for frame, file, lnum, func, lines, index in records:

file = file and os.path.abspath(file) or '?'

link = '<a href="file://%s">%s</a>' % (file, pydoc.html.escape(file))

args, varargs, varkw, locals = inspect.getargvalues(frame)

call = ''

if func != '?':

call = 'in ' + strong(func) + \

inspect.formatargvalues(args, varargs, varkw, locals,

formatvalue=lambda value: '=' + pydoc.html.repr(value))

highlight = {}

def reader(lnum=[lnum]):

highlight[lnum[0]] = 1

try: return linecache.getline(file, lnum[0])

finally: lnum[0] += 1

vars = scanvars(reader, frame, locals)

rows = ['<tr><td bgcolor="#d8bbff">%s%s %s</td></tr>' %

('<big> </big>', link, call)]

if index is not None:

i = lnum - index

for line in lines:

num = small(' ' * (5-len(str(i))) + str(i)) + ' '

line = '<tt>%s%s</tt>' % (num, pydoc.html.preformat(line))

if i in highlight:

rows.append('<tr><td bgcolor="#ffccee">%s</td></tr>' % line)

else:

rows.append('<tr><td>%s</td></tr>' % grey(line))

i += 1

done, dump = {}, []

for name, where, value in vars:

if name in done: continue

done[name] = 1

if value is not __UNDEF__:

if where == 'global': name = '<em>global</em> ' + strong(name)

elif where == 'local': name = strong(name)

else: name = where + strong(name.split('.')[-1])

dump.append('%s = %s' % (name, pydoc.html.repr(value)))

else:

dump.append(name + ' <em>undefined</em>')

rows.append('<tr><td>%s</td></tr>' % small(grey(', '.join(dump))))

frames.append('''<p>

%s</table>''' % '\n'.join(rows))

exception = ['<p>%s: %s' % (strong(str(etype)), str(evalue))]

if type(evalue) is types.InstanceType:

for name in dir(evalue):

value = pydoc.html.repr(getattr(evalue, name))

exception.append('\n<br>%s%s =\n%s' % (indent, name, value))

import traceback

return head + ''.join(frames) + ''.join(exception) + '''

<!-- The above is a description of an error in a Python program, formatted

for a Web browser because the 'cgitb' module was enabled. In case you

are not reading this in a Web browser, here is the original traceback:

-->

''' % ''.join(traceback.format_exception(etype, evalue, etb))

class Hook:

"""A hook to replace sys.excepthook that shows tracebacks in HTML."""

def __init__(self, display=1, logdir=None, context=5, file=None):

self.display = display # send tracebacks to browser if true

self.logdir = logdir # log tracebacks to files if not None

self.context = context # number of source code lines per frame

self.file = file or sys.stdout # place to send the output

def __call__(self, etype, evalue, etb):

self.handle((etype, evalue, etb))

def handle(self, info=None):

info = info or sys.exc_info()

self.file.write(reset())

try:

text, doc = 0, html(info, self.context)

except: # just in case something goes wrong

import traceback

text, doc = 1, ''.join(traceback.format_exception(*info))

if self.display:

if text:

doc = doc.replace('&', '&').replace('<', '<')

self.file.write('<pre>' + doc + '</pre>\n')

else:

self.file.write(doc + '\n')

else:

self.file.write('<p>A problem occurred in a Python script.\n')

if self.logdir is not None:

import os, tempfile

name = tempfile.mktemp(['.html', '.txt'][text])

path = os.path.join(self.logdir, os.path.basename(name))

try:

file = open(path, 'w')

file.write(doc)

file.close()

msg = '<p> %s contains the description of this error.' % path

except:

msg = '<p> Tried to save traceback to %s, but failed.' % path

self.file.write(msg + '\n')

try:

self.file.flush()

except: pass

handler = Hook().handle

def enable(display=1, logdir=None, context=5):

"""Install an exception handler that formats tracebacks as HTML.

The optional argument 'display' can be set to 0 to suppress sending the

traceback to the browser, and 'logdir' can be set to a directory to cause

tracebacks to be written to files there."""

sys.excepthook = Hook(display, logdir, context)

cpython/Lib/cgitb.py at fa78d0fbe45a7f16d5d30c3d4e3ad30dc4933e8f · python/cpython · GitHub

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