Merge branch 'ready/trail-sort'

[ikiwiki] / doc / todo / Auto-setup_and_maintain_Mercurial_wrapper_hooks.mdwn

Attempt to fix a `TODO` in `Automator.pm` in combination with the Mercurial backend.

1. To define hooks, Mercurial uses paths given in the config file `.hg/hgrc`. To enable Mercurial to call `ikiwiki-wrapper` automatically after blog/wiki setup, ikiwiki thus needs to create `hgrc`.
2. To reflect changes in `$config{srcdir}` and/or `$config{mercurial_wrapper}`, relevant lines in `hgrc` need to be updated on wrapper creation.

ikiwiki can keep track of lines in `hgrc` for which it is responsible by adding a `.ikiwiki` suffix to its hooks. This is correct and recommended markup, Mercurial-wise.

Two ways follow below. I prefer the long one. --[[Daniel Andersson]]

> I comment myself: this can probably be solved without adding ad-hoc hooks and stuff (maybe not as "correct" as changing the config file only directly after wrappers have been generated, but good enough). I have a large rewrite of `mercurial.pm` ready, currently under local testing before I upload it for comments, trying to make it equal in function to `git.pm`. Comments below are of course welcome, but I will look into other ways of solving it later. Maybe `rcs_checkconfig` or `rcs_genwrapper` should host the `hgrc`-changing code. --[[Daniel Andersson]]

>> Having a hook that runs after a wrapper is generated may well be a good
>> thing anyway. In ikiwiki-hosting, there are some genwrapper hooks
>> that don't add any code to the wrapper, but are there only to run at,
>> essentially, that time.
>> 
>> With that said, here it seems like unnecessary complexity.
>> Why is `mercurial_wrapper` configurable at all? Why not just always
>> write it to a specific place relative to the srcdir, and always make
>> the hgrc look there?
>> 
>> (Other rcs plugins have good reasons to make their wrappers
>> configurable, because one might want the wrapper to run as a git
>> post-update or post-commit hook.) --[[Joey]]

Compact way (addresses only point 1)
------------------------------------
[This patch at pastebin](http://pastebin.com/by9f4dwX) ([raw version](http://pastebin.com/raw.php?i=by9f4dwX)).

Set default `ikiwiki-wrapper` path.

        diff -r 8faf136ca94f Setup/Automator.pm
        --- a/Setup/Automator.pm        Tue Jul 19 21:04:13 2011 +0200
        +++ b/Setup/Automator.pm        Wed Jul 20 15:33:21 2011 +0200
        @@ -75,8 +75,7 @@
                                print STDERR "warning: do not know how to set up the bzr_wrapper hook!\n";
                        }
                        elsif ($config{rcs} eq 'mercurial') {
        -                       # TODO
        -                       print STDERR "warning: do not know how to set up the mercurial_wrapper hook!\n";
        +                       $config{mercurial_wrapper}=$config{srcdir}."/.hg/ikiwiki-wrapper";
                        }
                        elsif ($config{rcs} eq 'tla') {
                                # TODO

Create `$config{srcdir}/.hg/hgrc` with hook info during auto-installation script. Use relative paths to not require manual `hgrc` intervention if `$config{srcdir}` is changed. If `$config{mercurial_wrapper}` is changed, manual edit of `hgrc` is needed to catch the new wrapper path.

(Is there a security risk with relative paths?)

> The code seems to assume that hg will be run from within the srcdir,
> specifically the top of the srcdir. If it's run from somewhere else,
> even a subdirectory, this will fail to find the wrapper, or could
> run some other program. Unless mercurial always interprets these paths
> as relative to the top of the repository? --[[Joey]]

        @@ -187,6 +186,22 @@
                        die "ikiwiki --wrappers --setup $config{dumpsetup} failed";
                }
         
        +       # Setup initial config file for Mercurial to hook up the wrapper.
        +       if ($config{rcs} eq 'mercurial' && exists $config{mercurial_wrapper}
        +               && length $config{mercurial_wrapper}) {
        +               # Use a relative path to avoid having to manually change the
        +               # autogenerated hgrc if the user changes $config{srcdir}.
        +               use File::Spec;
        +               my $mercurial_wrapper_relpath=File::Spec->abs2rel($config{mercurial_wrapper}, $config{srcdir});
        +               open (HGRC, '>', $config{srcdir}.'/.hg/hgrc');
        +               print HGRC <<EOF;
        +[hooks]
        +post-commit.ikiwiki = $mercurial_wrapper_relpath
        +incoming.ikiwiki = $mercurial_wrapper_relpath
        +EOF
        +               close (HGRC);
        +       }
        +
                # Add it to the wikilist.
                mkpath("$ENV{HOME}/.ikiwiki");
                open (WIKILIST, ">>$ENV{HOME}/.ikiwiki/wikilist") || die "$ENV{HOME}/.ikiwiki/wikilist: $!";


Less compact but more robust way (addresses point 1 and 2)
----------------------------------------------------------
[This complete patch at pastebin](http://pastebin.com/AcDHjbK6) ([raw version](http://pastebin.com/raw.php?i=AcDHjbK6)).

This way leaks onto additional files and adds general functionality that may or may not be wanted. The main part of the extra code is contained within `mercurial.pm`, though.

Set default `ikiwiki-wrapper` path.

        diff -r b08179653c00 IkiWiki/Setup/Automator.pm
        --- a/IkiWiki/Setup/Automator.pm        Wed Jul 20 16:56:09 2011 +0200
        +++ b/IkiWiki/Setup/Automator.pm        Wed Jul 20 19:28:21 2011 +0200
        @@ -75,8 +75,7 @@
                                print STDERR "warning: do not know how to set up the bzr_wrapper hook!\n";
                        }
                        elsif ($config{rcs} eq 'mercurial') {
        -                       # TODO
        -                       print STDERR "warning: do not know how to set up the mercurial_wrapper hook!\n";
        +                       $config{mercurial_wrapper}=$config{srcdir}."/.hg/ikiwiki-wrapper";
                        }
                        elsif ($config{rcs} eq 'tla') {
                                # TODO

Create `$config{srcdir}/.hg/hgrc` during auto-installation with hook info.

        @@ -182,6 +181,19 @@
                        }
                }
                
        +       # Setup initial config file for Mercurial to hook up the wrapper. The
        +       # path to the wrapper will be automatically added when it is generated.
        +       if ($config{rcs} eq 'mercurial' && exists $config{mercurial_wrapper}
        +               && length $config{mercurial_wrapper}) {
        +               open (HGRC, '>', $config{srcdir}.'/.hg/hgrc');
        +               print HGRC <<EOF;
        +[hooks]
        +post-commit.ikiwiki = 
        +incoming.ikiwiki = 
        +EOF
        +               close (HGRC);
        +       }
        +
                # Add wrappers, make live.
                if (system("ikiwiki", "--wrappers", "--setup", $config{dumpsetup}) != 0) {
                        die "ikiwiki --wrappers --setup $config{dumpsetup} failed";

`hgrc` is setup initially. Below follows code to keep `hgrc` updated.

Add backend specific function `rcs_wrapper_postcall()` for later call in `Wrappers.pm`.

        diff -r b08179653c00 IkiWiki/Plugin/mercurial.pm
        --- a/IkiWiki/Plugin/mercurial.pm       Wed Jul 20 16:56:09 2011 +0200
        +++ b/IkiWiki/Plugin/mercurial.pm       Wed Jul 20 19:28:21 2011 +0200
        @@ -21,6 +21,7 @@
                hook(type => "rcs", id => "rcs_diff", call => \&rcs_diff);
                hook(type => "rcs", id => "rcs_getctime", call => \&rcs_getctime);
                hook(type => "rcs", id => "rcs_getmtime", call => \&rcs_getmtime);
        +       hook(type => "rcs", id => "rcs_wrapper_postcall", call => \&rcs_wrapper_postcall);
         }
         
         sub checkconfig () {

Pass variable to `gen_wrapper()` to decide if `rcs_wrapper_postcall()` should run. Default is `1` to update `hgrc`, since it is done non-intrusive (won't create `hgrc` if it doesn't exist, won't overwrite anything unless it is set by ikiwiki itself).

        @@ -28,6 +29,7 @@
                        push @{$config{wrappers}}, {
                                wrapper => $config{mercurial_wrapper},
                                wrappermode => (defined $config{mercurial_wrappermode} ? $config{mercurial_wrappermode} : "06755"),
        +                       wrapper_postcall => (defined $config{mercurial_wrapper_hgrc_update} ? $config{mercurial_wrapper_hgrc_update} : "1"),
                        };
                }
         }

Include default configuration value and comment.

        @@ -53,6 +55,13 @@
                                safe => 0,
                                rebuild => 0,
                        },
        +               mercurial_wrapper_hgrc_update => {
        +                       type => "string",
        +                       example => "1",
        +                       description => "updates existing hgrc to reflect path changes for mercurial_wrapper",
        +                       safe => 0,
        +                       rebuild => 0,
        +               },
                        historyurl => {
                                type => "string",
                                example => "http://example.com:8000/log/tip/\[[file]]",

`hgrc` should be updated to point to the new wrapper path. The regexp transforms lines as e.g.

        post-commit.ikiwiki = /home/daniel/blog/.hg/ikiwiki-wrapper-oldpath
        incoming.ikiwiki = /home/daniel/blog/.hg/ikiwiki-wrapper-oldpath

to

        post-commit.ikiwiki = $config{mercurial_wrapper}
        incoming.ikiwiki = $config{mercurial_wrapper}

with absolute paths.

        @@ -402,4 +411,23 @@
                return findtimes($file, 0);
         }
         
        +sub rcs_wrapper_postcall($) {
        +       # Update hgrc if it exists. Change post-commit/incoming hooks with the
        +       # .ikiwiki suffix to point to the wrapper path given in the setup file.
        +       # Work with a tempfile to not delete hgrc if the loop is interrupted
        +       # midway.
        +       my $hgrc=$config{srcdir}.'/.hg/hgrc';
        +       my $backup_suffix='.ikiwiki.bak';
        +       if (-e $hgrc) {
        +               use File::Spec;
        +               my $mercurial_wrapper_abspath=File::Spec->rel2abs($config{mercurial_wrapper}, $config{srcdir});
        +               local ($^I, @ARGV)=($backup_suffix, $hgrc);
        +               while (<>) {
        +                       s/^(post-commit|incoming)(\.ikiwiki[ \t]*=[ \t]*).*$/$1$2$mercurial_wrapper_abspath/;
        +                       print;
        +               }
        +               unlink($hgrc.$backup_suffix);
        +       }
        +}
        +
         1

`rcs_wrapper_postcall` is made available.

        diff -r b08179653c00 IkiWiki.pm
        --- a/IkiWiki.pm        Wed Jul 20 16:56:09 2011 +0200
        +++ b/IkiWiki.pm        Wed Jul 20 19:28:21 2011 +0200
        @@ -2059,6 +2059,10 @@
                $hooks{rcs}{rcs_getmtime}{call}->(@_);
         }
         
        +sub rcs_wrapper_postcall (@) {
        +       $hooks{rcs}{rcs_wrapper_postcall}{call}->(@_);
        +}
        +
         sub rcs_receive () {
                $hooks{rcs}{rcs_receive}{call}->();
         }


`rcs_wrapper_postcall` is called if $config{wrapper_postcall} is true, which it should only be for Mercurial at the moment.

        diff -r b08179653c00 IkiWiki/Wrapper.pm
        --- a/IkiWiki/Wrapper.pm        Wed Jul 20 16:56:09 2011 +0200
        +++ b/IkiWiki/Wrapper.pm        Wed Jul 20 19:28:21 2011 +0200
        @@ -238,6 +238,10 @@
                }
                #translators: The parameter is a filename.
                debug(sprintf(gettext("successfully generated %s"), $wrapper));
        +
        +       if (defined $config{wrapper_postcall} && $config{wrapper_postcall} ) {
        +               IkiWiki::rcs_wrapper_postcall();
        +       }
         }
         
         1