tests/printenv.py

wix: tell ComponentSearch that it is finding a directory (not a file)

This is to fix an issue we've noticed where fresh installations start at
`C:\Program Files\Mercurial`, and then upgrades "walk up" the tree and end up in
`C:\Program Files` and finally `C:\` (where they stay).

ComponentSearch defaults to finding files, which I think means "it produces a
string like `C:\Program Files\Mercurial`", whereas with the type being
explicitly a directory, it would return `C:\Program Files\Mercurial\` (note the
final trailing backslash). Presumably, a latter step then tries to turn that
file name into a proper directory, by removing everything after the last `\`.

This could likely also be fixed by actually searching for the component for
hg.exe itself. That seemed a lot more complicated, as the GUID for hg.exe isn't
known in this file (it's one of the "auto-derived" ones). We could also consider
adding a Condition that I think could check the Property and ensure it's either
empty or ends in a trailing slash, but that would be an installer runtime check
and I'm not convinced it'd actually be useful.

This will *not* cause existing installations that are in one of the bad
directories to fix themselves. Doing that would require a fair amount more
understanding of wix and windows installer than I have, and it *probably*
wouldn't be possible to be 100% correct about it either (there's nothing
preventing a user from intentionally installing it in C:\, though I don't know
why they would do so).

If someone wants to tackle fixing existing installations, I think that the first
installation is actually the only one that shows up in "Add or Remove Programs",
and that its registry keys still exist. You might be able to find something
under HKEY_USERS that lists both the "good" and the "bad" InstallDirs. Mine was
under `HKEY_USERS\S-1-5-18\Software\Mercurial\InstallDir` (C:\), and
`HKEY_USERS\S-1-5-21-..numbers..\Software\Mercurial\InstallDir` (C:\Program
Files\Mercurial). If you find exactly two, with one being the default path, and
the other being a prefix of it, the user almost certainly hit this bug :D

We had originally thought that this bug might be due to unattended
installations/upgrades, but I no longer think that's the case. We were able to
reproduce the issue by uninstalling all copies of Mercurial I could find,
installing one version (it chose the correct location), and then starting the
installer for a different version (higher or lower didn't matter). I did not
need to deal with an unattended or headless installation/upgrade to trigger the
issue, but it's possible that my system was "primed" for this bug to happen
because of a previous unattended installation/upgrade.

Differential Revision: https://phab.mercurial-scm.org/D9891

#!/usr/bin/env python3
#
# simple script to be used in hooks
#
# put something like this in the repo .hg/hgrc:
#
#     [hooks]
#     changegroup = python "$TESTDIR/printenv.py" <hookname> [exit] [output]
#
#   - <hookname> is a mandatory argument (e.g. "changegroup")
#   - [exit] is the exit code of the hook (default: 0)
#   - [output] is the name of the output file (default: use sys.stdout)
#              the file will be opened in append mode.
#
from __future__ import absolute_import
import argparse
import os
import sys

try:
    import msvcrt

    msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

parser = argparse.ArgumentParser()
parser.add_argument("name", help="the hook name, used for display")
parser.add_argument(
    "exitcode",
    nargs="?",
    default=0,
    type=int,
    help="the exit code for the hook",
)
parser.add_argument(
    "out", nargs="?", default=None, help="where to write the output"
)
parser.add_argument(
    "--line",
    action="store_true",
    help="print environment variables one per line instead of on a single line",
)
args = parser.parse_args()

if args.out is None:
    out = sys.stdout
    out = getattr(out, "buffer", out)
else:
    out = open(args.out, "ab")

# variables with empty values may not exist on all platforms, filter
# them now for portability sake.
env = [(k, v) for k, v in os.environ.items() if k.startswith("HG_") and v]
env.sort()

out.write(b"%s hook: " % args.name.encode('ascii'))
if os.name == 'nt':
    filter = lambda x: x.replace('\\', '/')
else:
    filter = lambda x: x

vars = [
    b"%s=%s" % (k.encode('ascii'), filter(v).encode('ascii')) for k, v in env
]

# Print variables on out
if not args.line:
    out.write(b" ".join(vars))
else:
    for var in vars:
        out.write(var)
        out.write(b"\n")

out.write(b"\n")
out.close()

sys.exit(args.exitcode)