+++ /dev/null
-I've started reviewing this, and the main thing I don't like is the
-post-commit wrapper wrapper that ikiwiki-makerepo is patched to set up.
-That just seems unnecessarily complicated. Why can't ikiwiki itself detect
-the "cvs add <directory>" call and avoid doing anything in that case?
---[[Joey]]
-
-> The wrapper wrapper does three things:
->
-> 7. It ignores `cvs add <directory>`, since this is a weird CVS
-> behavior that ikiwiki gets confused by and doesn't need to act on.
-> 7. It prevents `cvs` locking against itself: `cvs commit` takes a
-> write lock and runs the post-commit hook, which runs `cvs update`,
-> which wants a read lock and sleeps forever -- unless the post-commit
-> hook runs in the background so the commit can "finish".
-> 7. It fails silently if the ikiwiki post-commit hook is missing.
-> CVS doesn't have any magic post-commit filenames, so hooks have to
-> be configured explicitly. I don't think a commit will actually fail
-> if a configured post-commit hook is missing (though I can't test
-> this at the moment).
->
-> Thing 1 can probably be handled within ikiwiki, if that seems less
-> gross to you.
-
->> It seems like it might be. You can use a `getopt` hook to check
->> `@ARGV` to see how it was called. --[[Joey]]
-
->>> This does the trick iff the post-commit wrapper passes its args
->>> along. Committed on my branch. This seems potentially dangerous,
->>> since the args passed to ikiwiki are influenced by web commits.
->>> I don't see an exploit, but for paranoia's sake, maybe the wrapper
->>> should only be built with execv() if the cvs plugin is loaded?
->>> --[[schmonz]]
-
->>>> Hadn't considered that. While in wrapper mode the normal getopt is not
->>>> done, plugin getopt still runs, and so any unsafe options that
->>>> other plugins support could be a problem if another user runs
->>>> the setuid wrapper and passes those options through. --[[Joey]]
-
->>>>> I've tried compiling the argument check into the wrapper as
->>>>> the first thing main() does, and was surprised to find that
->>>>> this doesn't prevent the `cvs add <dir>` deadlock in a web
->>>>> commit. I was convinced this'd be a reasonable solution,
->>>>> especially if conditionalized on the cvs plugin being loaded,
->>>>> but it doesn't work. And I stuck debug printfs at the beginning
->>>>> of all the rcs_foo() subs, and whatever `cvs add <dir>` is
->>>>> doing to ikiwiki isn't visible to my plugin, because none of
->>>>> those subs are getting called. Nuts. Can you think of anything
->>>>> else that might solve the problem, or should I go back to
->>>>> generating a minimal wrapper wrapper that checks for just
->>>>> this one thing? --[[schmonz]]
-
->>>>>> I don't see how there could possibly be a difference between
->>>>>> ikiwiki's C wrapper and your shell wrapper wrapper here. --[[Joey]]
-
->>>>>>> I was comparing strings overly precisely. Fixed on my branch.
->>>>>>> I've also knocked off the two most pressing to-do items. I
->>>>>>> think the plugin's ready for prime time. --[[schmonz]]
-
-> Thing 2 I'm less sure of. (I'd like to see the web UI return
-> immediately on save anyway, to a temporary "rebuilding, please wait
-> if you feel like knowing when it's done" page, but this problem
-> with CVS happens with any kind of commit, and could conceivably
-> happen with some other VCS.)
-
->> None of the other VCSes let a write lock block a read lock, apparently.
->>
->> Anyway, re the backgrounding, when committing via the web, the
->> post-commit hook doesn't run anyway; the rendering is done via the
->> ikiwiki CGI. It would certianly be nice if it popped up a quick "working"
->> page and replaced it with the updated page when done, but that's
->> unrelated; the post-commit
->> hook only does rendering when committing using the VCS directly. The
->> backgrounding you do actually seems safe enough -- but tacking
->> on a " &" to the ikiwiki wrapper call doesn't need a wrapper script,
->> does it? --[[Joey]]
-
->>> Nope, it works fine to append it to the `CVSROOT/loginfo` line.
->>> Fixed on my branch. --[[schmonz]]
-
-> Thing 3 I think I did in order to squelch the error messages that
-> were bollixing up the CGI. It was easy to do this in the wrapper
-> wrapper, but if that's going away, it can be done just as easily
-> with output redirection in `CVSROOT/loginfo`.
->
-> --[[schmonz]]
-
->> If the error messages screw up the CGI they must go to stdout.
->> I thought we had stderr even in the the CVS dark ages. ;-) --[[Joey]]
-
->>> Some messages go to stderr, but definitely not all. That's why
->>> I wound up reaching for IPC::Cmd, to execute the command line
->>> safely while shutting CVS up. Anyway, I've tested what happens
->>> if a configured post-commit hook is missing, and it seems fine,
->>> probably also thanks to IPC::Cmd.
->>> --[[schmonz]]
-
-----
-
-
-Further review.. --[[Joey]]
-
-I don't understand what `cvs_shquote_commit` is
-trying to do with the test message, but it seems
-highly likely to be insecure; I never trust anything
-that relies on safely quoting user input passed to the shell.
-
-(As an aside, `shell_quote` can die on certian inputs.)
-
-Seems to me that, if `IPC::Cmd` exposes input to the shell
-(which I have not verified but its docs don't specify; a bad sign)
-you chose the wrong tool and ended up doing down the wrong
-route, dragging in shell quoting problems and fixes. Since you
-chose to use `IPC::Cmd` just because you wanted to shut
-up CVS stderr, my suggestion would be to use plain `system`
-to run the command, with stderr temporarily sent to /dev/null:
-
- open(my $savederr, ">&STDERR");
- open(STDERR, ">", "/dev/null");
- my $ret=system("cvs", "-Q", @_);
- open(STDERR, ">$savederr");
-
-`cvs_runcvs` should not take an array reference. It's
-usual for this type of function to take a list of parameters
-to pass to the command.
-
-> Thanks for reading carefully. I've tested your suggestions and
-> applied them on my branch. --[[schmonz]]
-
-----
-
-I've abstracted out CVS's involvement in the wrapper, adding a new
-"wrapperargcheck" hook to examine `argc/argv` and return success or
-failure (failure causes the wrapper to terminate) and implementing
-this hook in the plugin. In the non-CVS case, the check immediately
-returns success, so the added overhead is just a function call.
-
-Given how rarely anything should need to reach in and modify the
-wrapper -- I'd go so far as to say we shouldn't make it too easy
--- I don't think it's worth the effort to try and design a more
-general-purpose way to do so. If and when some other problem thinks
-it wants to be solved by a new wrapper hook, it's easy enough to add
-one. Until then, I'd say it's more important to keep the wrapper as
-short and clear as possible. --[[schmonz]]
-
-> I've committed a slightly different hook, which should be general enough
-> that `IkiWiki::Receive` can also use it, so please adapt your code to
-> that. --[[Joey]]
-
->> Done. --[[schmonz]].