summaryrefslogtreecommitdiffstats
path: root/Lib/cgitb.py
blob: 8ce0e833a989aa6a9f7f886763c26bd4dfe482f2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
"""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
import warnings
from html import escape as html_escape

warnings._deprecated(__name__, remove=(3, 13))


def reset():
    """Return a string that resets the CGI and browser to a known state."""
    return '''<!--: spam
Content-Type: text/html

<body bgcolor="#f0f0f8"><font color="#f0f0f8" size="-5"> -->
<body bgcolor="#f0f0f8"><font color="#f0f0f8" size="-5"> --> -->
</font> </font> </font> </script> </object> </blockquote> </pre>
</table> </table> </table> </table> </table> </font> </font> </font>'''

__UNDEF__ = []                          # a special sentinel object
def small(text):
    if text:
        return '<small>' + text + '</small>'
    else:
        return ''

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

def grey(text):
    if text:
        return '<font color="#909090">' + text + '</font>'
    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 = f'''
<body bgcolor="#f0f0f8">
<table width="100%" cellspacing=0 cellpadding=2 border=0 summary="heading">
<tr bgcolor="#6622aa">
<td valign=bottom>&nbsp;<br>
<font color="#ffffff" face="helvetica, arial">&nbsp;<br>
<big><big><strong>{html_escape(str(etype))}</strong></big></big></font></td>
<td align=right valign=bottom>
<font color="#ffffff" face="helvetica, arial">{pyver}<br>{date}</font></td>
</tr></table>
<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.</p>'''

    indent = '<tt>' + small('&nbsp;' * 5) + '&nbsp;</tt>'
    frames = []
    records = inspect.getinnerframes(etb, context)
    for frame, file, lnum, func, lines, index in records:
        if file:
            file = os.path.abspath(file)
            link = '<a href="file://%s">%s</a>' % (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 != "<module>":
                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 = ['<tr><td bgcolor="#d8bbff">%s%s %s</td></tr>' %
                ('<big>&nbsp;</big>', link, call)]
        if index is not None:
            i = lnum - index
            for line in lines:
                num = small('&nbsp;' * (5-len(str(i))) + str(i)) + '&nbsp;'
                if i in highlight:
                    line = '<tt>=&gt;%s%s</tt>' % (num, pydoc.html.preformat(line))
                    rows.append('<tr><td bgcolor="#ffccee">%s</td></tr>' % line)
                else:
                    line = '<tt>&nbsp;&nbsp;%s%s</tt>' % (num, pydoc.html.preformat(line))
                    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 in ('global', 'builtin'):
                    name = ('<em>%s</em> ' % where) + strong(name)
                elif where == 'local':
                    name = strong(name)
                else:
                    name = where + strong(name.split('.')[-1])
                dump.append('%s&nbsp;= %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('''
<table width="100%%" cellspacing=0 cellpadding=0 border=0>
%s</table>''' % '\n'.join(rows))

    exception = ['<p>%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<br>%s%s&nbsp;=\n%s' % (indent, name, value))

    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:

%s
-->
''' % 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 != "<module>":
                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('<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:
            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('<p>%s</p>\n' % msg)
            else:
                self.file.write(msg + '\n')
        try:
            self.file.flush()
        except: pass

handler = Hook().handle
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)