view contrib/showstack.py @ 42919:6ccf539aec71

hgweb: fix websub regex flag syntax on Python 3

The `websub` config section for hgweb is broken under Python 3
when using regex flags syntax (ie the optional `i` in the example
from `hg help config.websub`:

    patternname = s/SEARCH_REGEX/REPLACE_EXPRESSION/[i]

Flags are pulled out of the specified byte-string using a regular
expression, and uppercased. The flags are then iterated over and
passed to the `re` module using `re.__dict__[item]`, to get the
object attribute of the same name from the `re` module. So on Python
2 if the `il` flags are passed, this transition looks like:

    `'il'` -> `'IL'` -> `'I'` -> `re.__dict__['I']` -> `re.I`

However on Python 3, these are bytes objects. When we iterate over
a bytes object in Python 3, instead of getting the individual characters
in the string as string objects of length one, we get the integer \
value corresponding to that byte. So the same transition looks like:

    `b'il'` -> `b'IL'` -> `73` -> `re.__dict__[73]` -> `KeyError`

This commit fixes the type mismatch by converting the bytes to a
system string before iterating over each element to pass to `re`.
The transition will now look like:

    `b'il'` -> `u'IL'` -> `u'I'` -> `re.__dict__[u'I']` -> `re.I`

In addition we expand `test-websub.t` to cover the regex flag case
(for both the `websub` section and `interhg`).

Differential Revision: https://phab.mercurial-scm.org/D6788

# showstack.py - extension to dump a Python stack trace on signal
#
# binds to both SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)
r"""dump stack trace when receiving SIGQUIT (Ctrl-\) or SIGINFO (Ctrl-T on BSDs)
"""

from __future__ import absolute_import, print_function
import signal
import sys
import traceback

def sigshow(*args):
    sys.stderr.write("\n")
    traceback.print_stack(args[1], limit=10, file=sys.stderr)
    sys.stderr.write("----\n")

def sigexit(*args):
    sigshow(*args)
    print('alarm!')
    sys.exit(1)

def extsetup(ui):
    signal.signal(signal.SIGQUIT, sigshow)
    signal.signal(signal.SIGALRM, sigexit)
    try:
        signal.signal(signal.SIGINFO, sigshow)
    except AttributeError:
        pass