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 " call and avoid doing anything in that case? --[[Joey]] > The wrapper wrapper does three things: > > 7. It ignores `cvs add `, 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 ` 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 ` 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]]. ---- I'm attempting to bring some polish to this plugin, starting with fuller test coverage. In preparation, I've refactored the tests a bunch (and shuffled the code a bit) in my branch. I'm worried, however, that my misunderstanding of `git rebase` may have made my branch harder for you to pull. Before I go writing a whole swack of test cases, could you merge my latest? Through at least ad0e56cdcaaf76bc68d1b5c56e6845307b51c44a there should be no functional change. --[[schmonz]]