Source code for cgitb


"""More comprehensive traceback formatting for Python scripts.

To enable this module, do:

    import cgitb; cgitb.enable()

at the top of your 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
    format      - 'text' or 'html' controls the output format

By default, tracebacks are displayed but not saved, the context is 5 lines
and the output format is 'html' (for backwards compatibility with the
original use of this module)

Alternatively, if you have caught an exception and want cgitb to display it
for you, call cgitb.handler().  The optional argument to handler() is a
3-item tuple (etype, evalue, etb) just like the value of sys.exc_info().
The default handler displays output as HTML.

"""
import inspect
import keyword
import linecache
import os
import pydoc
import sys
import tempfile
import time
import tokenize
import traceback

def reset():
    """Return a string that resets the CGI and browser to a known state."""
    return '''
 --> -->
      

__UNDEF__ = [] # a special sentinel object def small(text): if text: return '' + text + else: return def strong(text): if text: return ''' + text + else: return def grey(text): if text: return + text + else: return 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] if '__builtins__' in frame.f_globals: builtins = frame.f_globals['__builtins__'] if type(builtins) is type({}): if name in builtins: return 'builtin', builtins[name] else: if hasattr(builtins, name): return 'builtin', getattr(builtins, name) return None, __UNDEF__ def scanvars(reader, frame, locals): """Scan one logical line of Python and look up values of variables used.""" vars, lasttoken, parent, prefix, value = [], None, None, , __UNDEF__ 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(einfo, context=5): """Return a nice HTML document describing a given traceback.""" etype, evalue, etb = einfo if isinstance(etype, type): etype = etype.__name__ pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable date = time.ctime(time.time()) head = + pydoc.html.heading( '%s' % strong(pydoc.html.escape(str(etype))), '#ffffff', '#6622aa', pyver + '
'
+ date) + 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 = + small(' ' * 5) + ' ' frames = [] records = inspect.getinnerframes(etb, context) for frame, file, lnum, func, lines, index in records: if file: file = os.path.abspath(file) link = '[file://%3C/span%3E%3Cspan%20class= %s]">%s' % (file, pydoc.html.escape(file)) else: file = link = '?' args, varargs, varkw, locals = inspect.getargvalues(frame) call = if func != '?': call = 'in ' + strong(pydoc.html.escape(func)) if func != "": call += 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 = [' %s%s %s

' % (' ', link, call)] if index is not None: i = lnum - index for line in lines: num = small(' ' * (5-len(str(i))) + str(i)) + ' ' if i in highlight: line = '=>%s%s' % (num, pydoc.html.preformat(line)) rows.append('

%s

' % line) else: line = '  %s%s' % (num, pydoc.html.preformat(line)) rows.append('

%s

' % 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 in ('global', 'builtin'): name = (%s ' % where) + 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 + ' undefined') rows.append('

%s

' % small(grey(', '.join(dump)))) frames.append(

%%" cellspacing=0 cellpadding=0 border=0> %s

% '\n'.join(rows)) exception = ['

%s: %s' % (strong(pydoc.html.escape(str(etype))), pydoc.html.escape(str(evalue)))] for name in dir(evalue): if name[:1] == '_': continue value = pydoc.html.repr(getattr(evalue, name)) exception.append('\n
%s%s =\n%s' % (indent, name, value)) return head + .join(frames) + .join(exception) + % pydoc.html.escape( .join(traceback.format_exception(etype, evalue, etb))) def text(einfo, context=5): """Return a plain text document describing a given traceback.""" etype, evalue, etb = einfo if isinstance(etype, type): etype = etype.__name__ pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable date = time.ctime(time.time()) head = "%s\n%s\n%s\n" % (str(etype), pyver, date) + A problem occurred in a Python script. Here is the sequence of function calls leading up to the error, in the order they occurred. frames = [] records = inspect.getinnerframes(etb, context) for frame, file, lnum, func, lines, index in records: file = file and os.path.abspath(file) or '?' args, varargs, varkw, locals = inspect.getargvalues(frame) call = if func != '?': call = 'in ' + func if func != "": call += inspect.formatargvalues(args, varargs, varkw, locals, formatvalue=lambda value: '=' + pydoc.text.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 = [' %s %s' % (file, call)] if index is not None: i = lnum - index for line in lines: num = '%5d ' % i rows.append(num+line.rstrip()) 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 = 'global ' + name elif where != 'local': name = where + name.split('.')[-1] dump.append('%s = %s' % (name, pydoc.text.repr(value))) else: dump.append(name + ' undefined') rows.append('\n'.join(dump)) frames.append('\n%s\n' % '\n'.join(rows)) exception = ['%s: %s' % (str(etype), str(evalue))] for name in dir(evalue): value = pydoc.text.repr(getattr(evalue, name)) exception.append('\n%s%s = %s' % (" "*4, name, value)) return head + .join(frames) + .join(exception) + The above is a description of an error in a Python program. Here is the original traceback: %s ' % .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, format="html"): 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 self.format = format def __call__(self, etype, evalue, etb): self.handle((etype, evalue, etb)) def handle(self, info=None): info = info or sys.exc_info() if self.format == "html": self.file.write(reset()) formatter = (self.format=="html") and html or text plain = False try: doc = formatter(info, self.context) except: # just in case something goes wrong doc = .join(traceback.format_exception(*info)) plain = True if self.display: if plain: doc = pydoc.html.escape(doc) self.file.write('

'

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

A problem occurred in a Python script.

\n') if self.logdir is not None: suffix = ['.txt', '.html'][self.format=="html"] (fd, path) = tempfile.mkstemp(suffix=suffix, dir=self.logdir) try: with os.fdopen(fd, 'w') as file: file.write(doc) msg = '%s contains the description of this error.' % path except: msg = 'Tried to save traceback to %s, but failed.' % path if self.format == 'html': self.file.write('

%s\n' % msg) else: self.file.write(msg + '\n') try: self.file.flush() except: pass handler = Hook().handle

[docs]def enable(display=1, logdir=None, context=5, format="html"): """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=display, logdir=logdir, context=context, format=format)