X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/e3f5fdcf3789ca4f0e9704a390bf357d11160904..e5d9d3cc52598c68fc91903a5ca5fd43c7d1cf21:/doc/plugins/contrib/cvs/discussion.mdwn diff --git a/doc/plugins/contrib/cvs/discussion.mdwn b/doc/plugins/contrib/cvs/discussion.mdwn deleted file mode 100644 index 645b2388b..000000000 --- a/doc/plugins/contrib/cvs/discussion.mdwn +++ /dev/null @@ -1,149 +0,0 @@ -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]].