tests/svn-safe-append.py

narrow_widen_acl: enforce narrowacl in narrow_widen (SEC)

Reviewer note: this was sent by the author as a simple bugfix, but can be
considered a security patch, since it allows users to access things outside
of the ACL, hence the (SEC) prefix.

However, this affects the `narrow` extention which is still marked as
experimental and has relatively few users aside from large companies with
their own security layers on top from what we can gather.
We feel (Alphare: or at least, I feel) like pinging the packaging list is
enough in this case.

#!/usr/bin/env python3

from __future__ import absolute_import

__doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b.
Without this svn will not detect workspace changes."""

import os
import stat
import sys

if sys.version_info[0] >= 3:
    text = os.fsencode(sys.argv[1])
    fname = os.fsencode(sys.argv[2])
else:
    text = sys.argv[1]
    fname = sys.argv[2]

f = open(fname, "ab")
try:
    before = os.fstat(f.fileno())[stat.ST_MTIME]
    f.write(text)
    f.write(b"\n")
finally:
    f.close()
inc = 1
now = os.stat(fname)[stat.ST_MTIME]
while now == before:
    t = now + inc
    inc += 1
    os.utime(fname, (t, t))
    now = os.stat(fname)[stat.ST_MTIME]