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205 lines
8.1 KiB
Python
205 lines
8.1 KiB
Python
"""Handle exceptions in CGI scripts by formatting tracebacks into nice HTML.
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To enable this module, do:
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import cgitb; cgitb.enable()
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at the top of your CGI script. The optional arguments to enable() are:
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display - if true, tracebacks are displayed in the web browser
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logdir - if set, tracebacks are written to files in this directory
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context - number of lines of source code to show for each stack frame
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By default, tracebacks are displayed but not saved, and context is 5.
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Alternatively, if you have caught an exception and want cgitb to display it
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for you, call cgitb.handler(). The optional argument to handler() is a 3-item
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tuple (etype, evalue, etb) just like the value of sys.exc_info()."""
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__author__ = 'Ka-Ping Yee'
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__version__ = '$Revision$'
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import sys
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def reset():
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"""Return a string that resets the CGI and browser to a known state."""
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return '''<!--: spam
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Content-Type: text/html
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<body bgcolor="#f0f0f8"><font color="#f0f0f8" size="-5"> -->
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<body bgcolor="#f0f0f8"><font color="#f0f0f8" size="-5"> --> -->
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</font> </font> </font> </script> </object> </blockquote> </pre>
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</table> </table> </table> </table> </table> </font> </font> </font>'''
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__UNDEF__ = [] # a special sentinel object
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def small(text): return '<small>' + text + '</small>'
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def strong(text): return '<strong>' + text + '</strong>'
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def grey(text): return '<font color="#909090">' + text + '</font>'
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def lookup(name, frame, locals):
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"""Find the value for a given name in the given environment."""
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if name in locals:
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return 'local', locals[name]
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if name in frame.f_globals:
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return 'global', frame.f_globals[name]
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return None, __UNDEF__
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def scanvars(reader, frame, locals):
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"""Scan one logical line of Python and look up values of variables used."""
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import tokenize, keyword
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vars, lasttoken, parent, prefix = [], None, None, ''
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for ttype, token, start, end, line in tokenize.generate_tokens(reader):
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if ttype == tokenize.NEWLINE: break
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if ttype == tokenize.NAME and token not in keyword.kwlist:
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if lasttoken == '.':
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if parent is not __UNDEF__:
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value = getattr(parent, token, __UNDEF__)
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vars.append((prefix + token, prefix, value))
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else:
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where, value = lookup(token, frame, locals)
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vars.append((token, where, value))
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elif token == '.':
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prefix += lasttoken + '.'
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parent = value
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else:
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parent, prefix = None, ''
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lasttoken = token
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return vars
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def html((etype, evalue, etb), context=5):
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"""Return a nice HTML document describing a given traceback."""
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import os, types, time, traceback, linecache, inspect, pydoc
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if type(etype) is types.ClassType:
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etype = etype.__name__
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pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
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date = time.ctime(time.time())
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head = '<body bgcolor="#f0f0f8">' + pydoc.html.heading(
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'<big><big><strong>%s</strong></big></big>' % str(etype),
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'#ffffff', '#6622aa', pyver + '<br>' + date) + '''
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<p>A problem occurred in a Python script. Here is the sequence of
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function calls leading up to the error, in the order they occurred.'''
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indent = '<tt>' + small(' ' * 5) + ' </tt>'
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frames = []
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records = inspect.getinnerframes(etb, context)
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for frame, file, lnum, func, lines, index in records:
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file = file and os.path.abspath(file) or '?'
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link = '<a href="file://%s">%s</a>' % (file, pydoc.html.escape(file))
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args, varargs, varkw, locals = inspect.getargvalues(frame)
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call = ''
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if func != '?':
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call = 'in ' + strong(func) + \
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inspect.formatargvalues(args, varargs, varkw, locals,
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formatvalue=lambda value: '=' + pydoc.html.repr(value))
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highlight = {}
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def reader(lnum=[lnum]):
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highlight[lnum[0]] = 1
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try: return linecache.getline(file, lnum[0])
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finally: lnum[0] += 1
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vars = scanvars(reader, frame, locals)
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rows = ['<tr><td bgcolor="#d8bbff">%s%s %s</td></tr>' %
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('<big> </big>', link, call)]
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if index is not None:
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i = lnum - index
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for line in lines:
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num = small(' ' * (5-len(str(i))) + str(i)) + ' '
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line = '<tt>%s%s</tt>' % (num, pydoc.html.preformat(line))
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if i in highlight:
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rows.append('<tr><td bgcolor="#ffccee">%s</td></tr>' % line)
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else:
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rows.append('<tr><td>%s</td></tr>' % grey(line))
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i += 1
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done, dump = {}, []
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for name, where, value in vars:
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if name in done: continue
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done[name] = 1
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if value is not __UNDEF__:
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if where == 'global': name = '<em>global</em> ' + strong(name)
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elif where == 'local': name = strong(name)
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else: name = where + strong(name.split('.')[-1])
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dump.append('%s = %s' % (name, pydoc.html.repr(value)))
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else:
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dump.append(name + ' <em>undefined</em>')
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rows.append('<tr><td>%s</td></tr>' % small(grey(', '.join(dump))))
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frames.append('''<p>
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<table width="100%%" cellspacing=0 cellpadding=0 border=0>
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%s</table>''' % '\n'.join(rows))
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exception = ['<p>%s: %s' % (strong(str(etype)), str(evalue))]
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if type(evalue) is types.InstanceType:
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for name in dir(evalue):
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value = pydoc.html.repr(getattr(evalue, name))
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exception.append('\n<br>%s%s =\n%s' % (indent, name, value))
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import traceback
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return head + ''.join(frames) + ''.join(exception) + '''
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<!-- The above is a description of an error in a Python program, formatted
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for a Web browser because the 'cgitb' module was enabled. In case you
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are not reading this in a Web browser, here is the original traceback:
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%s
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-->
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''' % ''.join(traceback.format_exception(etype, evalue, etb))
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class Hook:
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"""A hook to replace sys.excepthook that shows tracebacks in HTML."""
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def __init__(self, display=1, logdir=None, context=5, file=None):
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self.display = display # send tracebacks to browser if true
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self.logdir = logdir # log tracebacks to files if not None
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self.context = context # number of source code lines per frame
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self.file = file or sys.stdout # place to send the output
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def __call__(self, etype, evalue, etb):
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self.handle((etype, evalue, etb))
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def handle(self, info=None):
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info = info or sys.exc_info()
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self.file.write(reset())
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try:
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text, doc = 0, html(info, self.context)
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except: # just in case something goes wrong
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import traceback
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text, doc = 1, ''.join(traceback.format_exception(*info))
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if self.display:
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if text:
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doc = doc.replace('&', '&').replace('<', '<')
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self.file.write('<pre>' + doc + '</pre>\n')
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else:
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self.file.write(doc + '\n')
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else:
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self.file.write('<p>A problem occurred in a Python script.\n')
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if self.logdir is not None:
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import os, tempfile
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name = tempfile.mktemp(['.html', '.txt'][text])
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path = os.path.join(self.logdir, os.path.basename(name))
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try:
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file = open(path, 'w')
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file.write(doc)
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file.close()
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msg = '<p> %s contains the description of this error.' % path
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except:
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msg = '<p> Tried to save traceback to %s, but failed.' % path
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self.file.write(msg + '\n')
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try:
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self.file.flush()
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except: pass
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handler = Hook().handle
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def enable(display=1, logdir=None, context=5):
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"""Install an exception handler that formats tracebacks as HTML.
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The optional argument 'display' can be set to 0 to suppress sending the
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traceback to the browser, and 'logdir' can be set to a directory to cause
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tracebacks to be written to files there."""
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sys.excepthook = Hook(display, logdir, context)
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