path: root/IkiWiki.pm

#!/usr/bin/perl

package IkiWiki;

use warnings;
use strict;
use Encode;
use HTML::Entities;
use URI::Escape q{uri_escape_utf8};
use POSIX;
use Storable;
use open qw{:utf8 :std};

use vars qw{%config %links %oldlinks %pagemtime %pagectime %pagecase
        %pagestate %wikistate %renderedfiles %oldrenderedfiles
        %pagesources %destsources %depends %depends_simple %hooks
        %forcerebuild %loaded_plugins};

use Exporter q{import};
our @EXPORT = qw(hook debug error template htmlpage deptype
                 add_depends pagespec_match pagespec_match_list bestlink
         htmllink readfile writefile pagetype srcfile pagename
         displaytime will_render gettext ngettext urlto targetpage
         add_underlay pagetitle titlepage linkpage newpagefile
         inject add_link
                 %config %links %pagestate %wikistate %renderedfiles
                 %pagesources %destsources);
our $VERSION = 3.00; # plugin interface version, next is ikiwiki version
our $version='unknown'; # VERSION_AUTOREPLACE done by Makefile, DNE
our $installdir='/usr'; # INSTALLDIR_AUTOREPLACE done by Makefile, DNE

# Page dependency types.
our $DEPEND_CONTENT=1;
our $DEPEND_PRESENCE=2;
our $DEPEND_LINKS=4;

# Optimisation.
use Memoize;
memoize("abs2rel");
memoize("pagespec_translate");
memoize("template_file");

sub getsetup () {
    wikiname => {
        type => "string",
        default => "wiki",
        description => "name of the wiki",
        safe => 1,
        rebuild => 1,
    },
    adminemail => {
        type => "string",
        default => undef,
        example => 'me@example.com',
        description => "contact email for wiki",
        safe => 1,
        rebuild => 0,
    },
    adminuser => {
        type => "string",
        default => [],
        description => "users who are wiki admins",
        safe => 1,
        rebuild => 0,
    },
    banned_users => {
        type => "string",
        default => [],
        description => "users who are banned from the wiki",
        safe => 1,
        rebuild => 0,
    },
    srcdir => {
        type => "string",
        default => undef,
        example => "$ENV{HOME}/wiki",
        description => "where the source of the wiki is located",
        safe => 0, # path
        rebuild => 1,
    },
    destdir => {
        type => "string",
        default => undef,
        example => "/var/www/wiki",
        description => "where to build the wiki",
        safe => 0, # path
        rebuild => 1,
    },
    url => {
        type => "string",
        default => '',
        example => "http://example.com/wiki",
        description => "base url to the wiki",
        safe => 1,
        rebuild => 1,
    },
    cgiurl => {
        type => "string",
        default => '',
        example => "http://example.com/wiki/ikiwiki.cgi",
        description => "url to the ikiwiki.cgi",
        safe => 1,
        rebuild => 1,
    },
    cgi_wrapper => {
        type => "string",
        default => '',
        example => "/var/www/wiki/ikiwiki.cgi",
        description => "filename of cgi wrapper to generate",
        safe => 0, # file
        rebuild => 0,
    },
    cgi_wrappermode => {
        type => "string",
        default => '06755',
        description => "mode for cgi_wrapper (can safely be made suid)",
        safe => 0,
        rebuild => 0,
    },
    rcs => {
        type => "string",
        default => '',
        description => "rcs backend to use",
        safe => 0, # don't allow overriding
        rebuild => 0,
    },
    default_plugins => {
        type => "internal",
        default => [qw{mdwn link inline meta htmlscrubber passwordauth
                openid signinedit lockedit conditional
                recentchanges parentlinks editpage}],
        description => "plugins to enable by default",
        safe => 0,
        rebuild => 1,
    },
    add_plugins => {
        type => "string",
        default => [],
        description => "plugins to add to the default configuration",
        safe => 1,
        rebuild => 1,
    },
    disable_plugins => {
        type => "string",
        default => [],
        description => "plugins to disable",
        safe => 1,
        rebuild => 1,
    },
    templatedir => {
        type => "string",
        default => "$installdir/share/ikiwiki/templates",
        description => "location of template files",
        advanced => 1,
        safe => 0, # path
        rebuild => 1,
    },
    templatedirs => {
        type => "internal",
        default => [],
        description => "additional directories containing template files",
        safe => 0,
        rebuild => 0,
    },
    underlaydir => {
        type => "string",
        default => "$installdir/share/ikiwiki/basewiki",
        description => "base wiki source location",
        advanced => 1,
        safe => 0, # path
        rebuild => 0,
    },
    underlaydirbase => {
        type => "internal",
        default => "$installdir/share/ikiwiki",
        description => "parent directory containing additional underlays",
        safe => 0,
        rebuild => 0,
    },
    wrappers => {
        type => "internal",
        default => [],
        description => "wrappers to generate",
        safe => 0,
        rebuild => 0,
    },
    underlaydirs => {
        type => "internal",
        default => [],
        description => "additional underlays to use",
        safe => 0,
        rebuild => 0,
    },
    verbose => {
        type => "boolean",
        example => 1,
        description => "display verbose messages?",
        safe => 1,
        rebuild => 0,
    },
    syslog => {
        type => "boolean",
        example => 1,
        description => "log to syslog?",
        safe => 1,
        rebuild => 0,
    },
    usedirs => {
        type => "boolean",
        default => 1,
        description => "create output files named page/index.html?",
        safe => 0, # changing requires manual transition
        rebuild => 1,
    },
    prefix_directives => {
        type => "boolean",
        default => 1,
        description => "use '!'-prefixed preprocessor directives?",
        safe => 0, # changing requires manual transition
        rebuild => 1,
    },
    indexpages => {
        type => "boolean",
        default => 0,
        description => "use page/index.mdwn source files",
        safe => 1,
        rebuild => 1,
    },
    discussion => {
        type => "boolean",
        default => 1,
        description => "enable Discussion pages?",
        safe => 1,
        rebuild => 1,
    },
    discussionpage => {
        type => "string",
        default => gettext("Discussion"),
        description => "name of Discussion pages",
        safe => 1,
        rebuild => 1,
    },
    sslcookie => {
        type => "boolean",
        default => 0,
        description => "only send cookies over SSL connections?",
        advanced => 1,
        safe => 1,
        rebuild => 0,
    },
    default_pageext => {
        type => "string",
        default => "mdwn",
        description => "extension to use for new pages",
        safe => 0, # not sanitized
        rebuild => 0,
    },
    htmlext => {
        type => "string",
        default => "html",
        description => "extension to use for html files",
        safe => 0, # not sanitized
        rebuild => 1,
    },
    timeformat => {
        type => "string",
        default => '%c',
        description => "strftime format string to display date",
        advanced => 1,
        safe => 1,
        rebuild => 1,
    },
    locale => {
        type => "string",
        default => undef,
        example => "en_US.UTF-8",
        description => "UTF-8 locale to use",
        advanced => 1,
        safe => 0,
        rebuild => 1,
    },
    userdir => {
        type => "string",
        default => "",
        example => "users",
        description => "put user pages below specified page",
        safe => 1,
        rebuild => 1,
    },
    numbacklinks => {
        type => "integer",
        default => 10,
        description => "how many backlinks to show before hiding excess (0 to show all)",
        safe => 1,
        rebuild => 1,
    },
    hardlink => {
        type => "boolean",
        default => 0,
        description => "attempt to hardlink source files? (optimisation for large files)",
        advanced => 1,
        safe => 0, # paranoia
        rebuild => 0,
    },
    umask => {
        type => "integer",
        example => "022",
        description => "force ikiwiki to use a particular umask",
        advanced => 1,
        safe => 0, # paranoia
        rebuild => 0,
    },
    wrappergroup => {
        type => "string",
        example => "ikiwiki",
        description => "group for wrappers to run in",
        advanced => 1,
        safe => 0, # paranoia
        rebuild => 0,
    },
    libdir => {
        type => "string",
        default => "",
        example => "$ENV{HOME}/.ikiwiki/",
        description => "extra library and plugin directory",
        advanced => 1,
        safe => 0, # directory
        rebuild => 0,
    },
    ENV => {
        type => "string", 
        default => {},
        description => "environment variables",
        safe => 0, # paranoia
        rebuild => 0,
    },
    include => {
        type => "string",
        default => undef,
        example => '^\.htaccess$',
        description => "regexp of normally ignored source files to include",
        advanced => 1,
        safe => 0, # regexp
        rebuild => 1,
    },
    exclude => {
        type => "string",
        default => undef,
        example => '\.wav$',
        description => "regexp of source files to ignore",
        advanced => 1,
        safe => 0, # regexp
        rebuild => 1,
    },
    wiki_file_prune_regexps => {
        type => "internal",
        default => [qr/(^|\/)\.\.(\/|$)/, qr/^\./, qr/\/\./,
            qr/\.x?html?$/, qr/\.ikiwiki-new$/,
            qr/(^|\/).svn\//, qr/.arch-ids\//, qr/{arch}\//,
            qr/(^|\/)_MTN\//, qr/(^|\/)_darcs\//,
            qr/(^|\/)CVS\//, qr/\.dpkg-tmp$/],
        description => "regexps of source files to ignore",
        safe => 0,
        rebuild => 1,
    },
    wiki_file_chars => {
        type => "string",
        description => "specifies the characters that are allowed in source filenames",
        default => "-[:alnum:]+/.:_",
        safe => 0,
        rebuild => 1,
    },
    wiki_file_regexp => {
        type => "internal",
        description => "regexp of legal source files",
        safe => 0,
        rebuild => 1,
    },
    web_commit_regexp => {
        type => "internal",
        default => qr/^web commit (by (.*?(?=: |$))|from ([0-9a-fA-F:.]+[0-9a-fA-F])):?(.*)/,
        description => "regexp to parse web commits from logs",
        safe => 0,
        rebuild => 0,
    },
    cgi => {
        type => "internal",
        default => 0,
        description => "run as a cgi",
        safe => 0,
        rebuild => 0,
    },
    cgi_disable_uploads => {
        type => "internal",
        default => 1,
        description => "whether CGI should accept file uploads",
        safe => 0,
        rebuild => 0,
    },
    post_commit => {
        type => "internal",
        default => 0,
        description => "run as a post-commit hook",
        safe => 0,
        rebuild => 0,
    },
    rebuild => {
        type => "internal",
        default => 0,
        description => "running in rebuild mode",
        safe => 0,
        rebuild => 0,
    },
    setup => {
        type => "internal",
        default => undef,
        description => "running in setup mode",
        safe => 0,
        rebuild => 0,
    },
    clean => {
        type => "internal",
        default => 0,
        description => "running in clean mode",
        safe => 0,
        rebuild => 0,
    },
    refresh => {
        type => "internal",
        default => 0,
        description => "running in refresh mode",
        safe => 0,
        rebuild => 0,
    },
    test_receive => {
        type => "internal",
        default => 0,
        description => "running in receive test mode",
        safe => 0,
        rebuild => 0,
    },
    getctime => {
        type => "internal",
        default => 0,
        description => "running in getctime mode",
        safe => 0,
        rebuild => 0,
    },
    w3mmode => {
        type => "internal",
        default => 0,
        description => "running in w3mmode",
        safe => 0,
        rebuild => 0,
    },
    wikistatedir => {
        type => "internal",
        default => undef,
        description => "path to the .ikiwiki directory holding ikiwiki state",
        safe => 0,
        rebuild => 0,
    },
    setupfile => {
        type => "internal",
        default => undef,
        description => "path to setup file",
        safe => 0,
        rebuild => 0,
    },
    allow_symlinks_before_srcdir => {
        type => "boolean",
        default => 0,
        description => "allow symlinks in the path leading to the srcdir (potentially insecure)",
        safe => 0,
        rebuild => 0,
    },
}

sub defaultconfig () {
    my %s=getsetup();
    my @ret;
    foreach my $key (keys %s) {
        push @ret, $key, $s{$key}->{default};
    }
    use Data::Dumper;
    return @ret;
}

sub checkconfig () {
    # locale stuff; avoid LC_ALL since it overrides everything
    if (defined $ENV{LC_ALL}) {
        $ENV{LANG} = $ENV{LC_ALL};
        delete $ENV{LC_ALL};
    }
    if (defined $config{locale}) {
        if (POSIX::setlocale(&POSIX::LC_ALL, $config{locale})) {
            $ENV{LANG}=$config{locale};
            define_gettext();
        }
    }
        
    if (! defined $config{wiki_file_regexp}) {
        $config{wiki_file_regexp}=qr/(^[$config{wiki_file_chars}]+$)/;
    }

    if (ref $config{ENV} eq 'HASH') {
        foreach my $val (keys %{$config{ENV}}) {
            $ENV{$val}=$config{ENV}{$val};
        }
    }

    if ($config{w3mmode}) {
        eval q{use Cwd q{abs_path}};
        error($@) if $@;
        $config{srcdir}=possibly_foolish_untaint(abs_path($config{srcdir}));
        $config{destdir}=possibly_foolish_untaint(abs_path($config{destdir}));
        $config{cgiurl}="file:///\$LIB/ikiwiki-w3m.cgi/".$config{cgiurl}
            unless $config{cgiurl} =~ m!file:///!;
        $config{url}="file://".$config{destdir};
    }

    if ($config{cgi} && ! length $config{url}) {
        error(gettext("Must specify url to wiki with --url when using --cgi"));
    }
    
    $config{wikistatedir}="$config{srcdir}/.ikiwiki"
        unless exists $config{wikistatedir} && defined $config{wikistatedir};

    if (defined $config{umask}) {
        umask(possibly_foolish_untaint($config{umask}));
    }

    run_hooks(checkconfig => sub { shift->() });

    return 1;
}

sub listplugins () {
    my %ret;

    foreach my $dir (@INC, $config{libdir}) {
        next unless defined $dir && length $dir;
        foreach my $file (glob("$dir/IkiWiki/Plugin/*.pm")) {
            my ($plugin)=$file=~/.*\/(.*)\.pm$/;
            $ret{$plugin}=1;
        }
    }
    foreach my $dir ($config{libdir}, "$installdir/lib/ikiwiki") {
        next unless defined $dir && length $dir;
        foreach my $file (glob("$dir/plugins/*")) {
            $ret{basename($file)}=1 if -x $file;
        }
    }

    return keys %ret;
}

sub loadplugins () {
    if (defined $config{libdir} && length $config{libdir}) {
        unshift @INC, possibly_foolish_untaint($config{libdir});
    }

    foreach my $plugin (@{$config{default_plugins}}, @{$config{add_plugins}}) {
        loadplugin($plugin);
    }
    
    if ($config{rcs}) {
        if (exists $hooks{rcs}) {
            error(gettext("cannot use multiple rcs plugins"));
        }
        loadplugin($config{rcs});
    }
    if (! exists $hooks{rcs}) {
        loadplugin("norcs");
    }

    run_hooks(getopt => sub { shift->() });
    if (grep /^-/, @ARGV) {
        print STDERR "Unknown option (or missing parameter): $_\n"
            foreach grep /^-/, @ARGV;
        usage();
    }

    return 1;
}

sub loadplugin ($) {
    my $plugin=shift;

    return if grep { $_ eq $plugin} @{$config{disable_plugins}};

    foreach my $dir (defined $config{libdir} ? possibly_foolish_untaint($config{libdir}) : undef,
                     "$installdir/lib/ikiwiki") {
        if (defined $dir && -x "$dir/plugins/$plugin") {
            eval { require IkiWiki::Plugin::external };
            if ($@) {
                my $reason=$@;
                error(sprintf(gettext("failed to load external plugin needed for %s plugin: %s"), $plugin, $reason));
            }
            import IkiWiki::Plugin::external "$dir/plugins/$plugin";
            $loaded_plugins{$plugin}=1;
            return 1;
        }
    }

    my $mod="IkiWiki::Plugin::".possibly_foolish_untaint($plugin);
    eval qq{use $mod};
    if ($@) {
        error("Failed to load plugin $mod: $@");
    }
    $loaded_plugins{$plugin}=1;
    return 1;
}

sub error ($;$) {
    my $message=shift;
    my $cleaner=shift;
    log_message('err' => $message) if $config{syslog};
    if (defined $cleaner) {
        $cleaner->();
    }
    die $message."\n";
}

sub debug ($) {
    return unless $config{verbose};
    return log_message(debug => @_);
}

my $log_open=0;
sub log_message ($$) {
    my $type=shift;

    if ($config{syslog}) {
        require Sys::Syslog;
        if (! $log_open) {
            Sys::Syslog::setlogsock('unix');
            Sys::Syslog::openlog('ikiwiki', '', 'user');
            $log_open=1;
        }
        return eval {
            Sys::Syslog::syslog($type, "[$config{wikiname}] %s", join(" ", @_));
        };
    }
    elsif (! $config{cgi}) {
        return print "@_\n";
    }
    else {
        return print STDERR "@_\n";
    }
}

sub possibly_foolish_untaint ($) {
    my $tainted=shift;
    my ($untainted)=$tainted=~/(.*)/s;
    return $untainted;
}

sub basename ($) {
    my $file=shift;

    $file=~s!.*/+!!;
    return $file;
}

sub dirname ($) {
    my $file=shift;

    $file=~s!/*[^/]+$!!;
    return $file;
}

sub isinternal ($) {
    my $page=shift;
    return exists $pagesources{$page} &&
        $pagesources{$page} =~ /\._([^.]+)$/;
}

sub pagetype ($) {
    my $file=shift;
    
    if ($file =~ /\.([^.]+)$/) {
        return $1 if exists $hooks{htmlize}{$1};
    }
    my $base=basename($file);
    if (exists $hooks{htmlize}{$base} &&
        $hooks{htmlize}{$base}{noextension}) {
        return $base;
    }
    return;
}

my %pagename_cache;

sub pagename ($) {
    my $file=shift;

    if (exists $pagename_cache{$file}) {
        return $pagename_cache{$file};
    }

    my $type=pagetype($file);
    my $page=$file;
    $page=~s/\Q.$type\E*$//
        if defined $type && !$hooks{htmlize}{$type}{keepextension}
            && !$hooks{htmlize}{$type}{noextension};
    if ($config{indexpages} && $page=~/(.*)\/index$/) {
        $page=$1;
    }

    $pagename_cache{$file} = $page;
    return $page;
}

sub newpagefile ($$) {
    my $page=shift;
    my $type=shift;

    if (! $config{indexpages} || $page eq 'index') {
        return $page.".".$type;
    }
    else {
        return $page."/index.".$type;
    }
}

sub targetpage ($$;$) {
    my $page=shift;
    my $ext=shift;
    my $filename=shift;
    
    if (defined $filename) {
        return $page."/".$filename.".".$ext;
    }
    elsif (! $config{usedirs} || $page eq 'index') {
        return $page.".".$ext;
    }
    else {
        return $page."/index.".$ext;
    }
}

sub htmlpage ($) {
    my $page=shift;
    
    return targetpage($page, $config{htmlext});
}

sub srcfile_stat {
    my $file=shift;
    my $nothrow=shift;

    return "$config{srcdir}/$file", stat(_) if -e "$config{srcdir}/$file";
    foreach my $dir (@{$config{underlaydirs}}, $config{underlaydir}) {
        return "$dir/$file", stat(_) if -e "$dir/$file";
    }
    error("internal error: $file cannot be found in $config{srcdir} or underlay") unless $nothrow;
    return;
}

sub srcfile ($;$) {
    return (srcfile_stat(@_))[0];
}

sub add_underlay ($) {
    my $dir=shift;

    if ($dir !~ /^\//) {
        $dir="$config{underlaydirbase}/$dir";
    }

    if (! grep { $_ eq $dir } @{$config{underlaydirs}}) {
        unshift @{$config{underlaydirs}}, $dir;
    }

    return 1;
}

sub readfile ($;$$) {
    my $file=shift;
    my $binary=shift;
    my $wantfd=shift;

    if (-l $file) {
        error("cannot read a symlink ($file)");
    }
    
    local $/=undef;
    open (my $in, "<", $file) || error("failed to read $file: $!");
    binmode($in) if ($binary);
    return \*$in if $wantfd;
    my $ret=<$in>;
    # check for invalid utf-8, and toss it back to avoid crashes
    if (! utf8::valid($ret)) {
        $ret=encode_utf8($ret);
    }
    close $in || error("failed to read $file: $!");
    return $ret;
}

sub prep_writefile ($$) {
    my $file=shift;
    my $destdir=shift;
    
    my $test=$file;
    while (length $test) {
        if (-l "$destdir/$test") {
            error("cannot write to a symlink ($test)");
        }
        $test=dirname($test);
    }

    my $dir=dirname("$destdir/$file");
    if (! -d $dir) {
        my $d="";
        foreach my $s (split(m!/+!, $dir)) {
            $d.="$s/";
            if (! -d $d) {
                mkdir($d) || error("failed to create directory $d: $!");
            }
        }
    }

    return 1;
}

sub writefile ($$$;$$) {
    my $file=shift; # can include subdirs
    my $destdir=shift; # directory to put file in
    my $content=shift;
    my $binary=shift;
    my $writer=shift;
    
    prep_writefile($file, $destdir);
    
    my $newfile="$destdir/$file.ikiwiki-new";
    if (-l $newfile) {
        error("cannot write to a symlink ($newfile)");
    }
    
    my $cleanup = sub { unlink($newfile) };
    open (my $out, '>', $newfile) || error("failed to write $newfile: $!", $cleanup);
    binmode($out) if ($binary);
    if ($writer) {
        $writer->(\*$out, $cleanup);
    }
    else {
        print $out $content or error("failed writing to $newfile: $!", $cleanup);
    }
    close $out || error("failed saving $newfile: $!", $cleanup);
    rename($newfile, "$destdir/$file") || 
        error("failed renaming $newfile to $destdir/$file: $!", $cleanup);

    return 1;
}

my %cleared;
sub will_render ($$;$) {
    my $page=shift;
    my $dest=shift;
    my $clear=shift;

    # Important security check.
    if (-e "$config{destdir}/$dest" && ! $config{rebuild} &&
        ! grep { $_ eq $dest } (@{$renderedfiles{$page}}, @{$oldrenderedfiles{$page}}, @{$wikistate{editpage}{previews}})) {
        error("$config{destdir}/$dest independently created, not overwriting with version from $page");
    }

    if (! $clear || $cleared{$page}) {
        $renderedfiles{$page}=[$dest, grep { $_ ne $dest } @{$renderedfiles{$page}}];
    }
    else {
        foreach my $old (@{$renderedfiles{$page}}) {
            delete $destsources{$old};
        }
        $renderedfiles{$page}=[$dest];
        $cleared{$page}=1;
    }
    $destsources{$dest}=$page;

    return 1;
}

sub bestlink ($$) {
    my $page=shift;
    my $link=shift;
    
    my $cwd=$page;
    if ($link=~s/^\/+//) {
        # absolute links
        $cwd="";
    }
    $link=~s/\/$//;

    do {
        my $l=$cwd;
        $l.="/" if length $l;
        $l.=$link;

        if (exists $pagesources{$l}) {
            return $l;
        }
        elsif (exists $pagecase{lc $l}) {
            return $pagecase{lc $l};
        }
    } while $cwd=~s{/?[^/]+$}{};

    if (length $config{userdir}) {
        my $l = "$config{userdir}/".lc($link);
        if (exists $pagesources{$l}) {
            return $l;
        }
        elsif (exists $pagecase{lc $l}) {
            return $pagecase{lc $l};
        }
    }

    #print STDERR "warning: page $page, broken link: $link\n";
    return "";
}

sub isinlinableimage ($) {
    my $file=shift;
    
    return $file =~ /\.(png|gif|jpg|jpeg)$/i;
}

sub pagetitle ($;$) {
    my $page=shift;
    my $unescaped=shift;

    if ($unescaped) {
        $page=~s/(__(\d+)__|_)/$1 eq '_' ? ' ' : chr($2)/eg;
    }
    else {
        $page=~s/(__(\d+)__|_)/$1 eq '_' ? ' ' : "&#$2;"/eg;
    }

    return $page;
}

sub titlepage ($) {
    my $title=shift;
    # support use w/o %config set
    my $chars = defined $config{wiki_file_chars} ? $config{wiki_file_chars} : "-[:alnum:]+/.:_";
    $title=~s/([^$chars]|_)/$1 eq ' ' ? '_' : "__".ord($1)."__"/eg;
    return $title;
}

sub linkpage ($) {
    my $link=shift;
    my $chars = defined $config{wiki_file_chars} ? $config{wiki_file_chars} : "-[:alnum:]+/.:_";
    $link=~s/([^$chars])/$1 eq ' ' ? '_' : "__".ord($1)."__"/eg;
    return $link;
}

sub cgiurl (@) {
    my %params=@_;

    my $cgiurl=$config{cgiurl};
    if (exists $params{cgiurl}) {
        $cgiurl=$params{cgiurl};
        delete $params{cgiurl};
    }
    return $cgiurl."?".
        join("&amp;", map $_."=".uri_escape_utf8($params{$_}), keys %params);
}

sub baseurl (;$) {
    my $page=shift;

    return "$config{url}/" if ! defined $page;
    
    $page=htmlpage($page);
    $page=~s/[^\/]+$//;
    $page=~s/[^\/]+\//..\//g;
    return $page;
}

sub abs2rel ($$) {
    # Work around very innefficient behavior in File::Spec if abs2rel
    # is passed two relative paths. It's much faster if paths are
    # absolute! (Debian bug #376658; fixed in debian unstable now)
    my $path="/".shift;
    my $base="/".shift;

    require File::Spec;
    my $ret=File::Spec->abs2rel($path, $base);
    $ret=~s/^// if defined $ret;
    return $ret;
}

sub displaytime ($;$) {
    # Plugins can override this function to mark up the time to
    # display.
    return '<span class="date">'.formattime(@_).'</span>';
}

sub formattime ($;$) {
    # Plugins can override this function to format the time.
    my $time=shift;
    my $format=shift;
    if (! defined $format) {
        $format=$config{timeformat};
    }

    # strftime doesn't know about encodings, so make sure
    # its output is properly treated as utf8
    return decode_utf8(POSIX::strftime($format, localtime($time)));
}

sub beautify_urlpath ($) {
    my $url=shift;

    # Ensure url is not an empty link, and if necessary,
    # add ./ to avoid colon confusion.
    if ($url !~ /^\// && $url !~ /^\.\.?\//) {
        $url="./$url";
    }

    if ($config{usedirs}) {
        $url =~ s!/index.$config{htmlext}$!/!;
    }

    return $url;
}

sub urlto ($$;$) {
    my $to=shift;
    my $from=shift;
    my $absolute=shift;
    
    if (! length $to) {
        return beautify_urlpath(baseurl($from)."index.$config{htmlext}");
    }

    if (! $destsources{$to}) {
        $to=htmlpage($to);
    }

    if ($absolute) {
        return $config{url}.beautify_urlpath("/".$to);
    }

    my $link = abs2rel($to, dirname(htmlpage($from)));

    return beautify_urlpath($link);
}

sub htmllink ($$$;@) {
    my $lpage=shift; # the page doing the linking
    my $page=shift; # the page that will contain the link (different for inline)
    my $link=shift;
    my %opts=@_;

    $link=~s/\/$//;

    my $bestlink;
    if (! $opts{forcesubpage}) {
        $bestlink=bestlink($lpage, $link);
    }
    else {
        $bestlink="$lpage/".lc($link);
    }

    my $linktext;
    if (defined $opts{linktext}) {
        $linktext=$opts{linktext};
    }
    else {
        $linktext=pagetitle(basename($link));
    }
    
    return "<span class=\"selflink\">$linktext</span>"
        if length $bestlink && $page eq $bestlink &&
           ! defined $opts{anchor};
    
    if (! $destsources{$bestlink}) {
        $bestlink=htmlpage($bestlink);

        if (! $destsources{$bestlink}) {
            return $linktext unless length $config{cgiurl};
            return "<span class=\"createlink\"><a href=\"".
                cgiurl(
                    do => "create",
                    page => lc($link),
                    from => $lpage
                ).
                "\" rel=\"nofollow\">?</a>$linktext</span>"
        }
    }
    
    $bestlink=abs2rel($bestlink, dirname(htmlpage($page)));
    $bestlink=beautify_urlpath($bestlink);
    
    if (! $opts{noimageinline} && isinlinableimage($bestlink)) {
        return "<img src=\"$bestlink\" alt=\"$linktext\" />";
    }

    if (defined $opts{anchor}) {
        $bestlink.="#".$opts{anchor};
    }

    my @attrs;
    foreach my $attr (qw{rel class title}) {
        if (defined $opts{$attr}) {
            push @attrs, " $attr=\"$opts{$attr}\"";
        }
    }

    return "<a href=\"$bestlink\"@attrs>$linktext</a>";
}

sub userpage ($) {
    my $user=shift;
    return length $config{userdir} ? "$config{userdir}/$user" : $user;
}

sub openiduser ($) {
    my $user=shift;

    if ($user =~ m!^https?://! &&
        eval q{use Net::OpenID::VerifiedIdentity; 1} && !$@) {
        my $display;

        if (Net::OpenID::VerifiedIdentity->can("DisplayOfURL")) {
            $display = Net::OpenID::VerifiedIdentity::DisplayOfURL($user);
        }
        else {
            # backcompat with old version
            my $oid=Net::OpenID::VerifiedIdentity->new(identity => $user);
            $display=$oid->display;
        }

        # Convert "user.somehost.com" to "user [somehost.com]"
        # (also "user.somehost.co.uk")
        if ($display !~ /\[/) {
            $display=~s/^([-a-zA-Z0-9]+?)\.([-.a-zA-Z0-9]+\.[a-z]+)$/$1 [$2]/;
        }
        # Convert "http://somehost.com/user" to "user [somehost.com]".
        # (also "https://somehost.com/user/")
        if ($display !~ /\[/) {
            $display=~s/^https?:\/\/(.+)\/([^\/#?]+)\/?(?:[#?].*)?$/$2 [$1]/;
        }
        $display=~s!^https?://!!; # make sure this is removed
        eval q{use CGI 'escapeHTML'};
        error($@) if $@;
        return escapeHTML($display);
    }
    return;
}

sub htmlize ($$$$) {
    my $page=shift;
    my $destpage=shift;
    my $type=shift;
    my $content=shift;
    
    my $oneline = $content !~ /\n/;

    if (exists $hooks{htmlize}{$type}) {
        $content=$hooks{htmlize}{$type}{call}->(
            page => $page,
            content => $content,
        );
    }
    else {
        error("htmlization of $type not supported");
    }

    run_hooks(sanitize => sub {
        $content=shift->(
            page => $page,
            destpage => $destpage,
            content => $content,
        );
    });
    
    if ($oneline) {
        # hack to get rid of enclosing junk added by markdown
        # and other htmlizers
        $content=~s/^<p>//i;
        $content=~s/<\/p>$//i;
        chomp $content;
    }

    return $content;
}

sub linkify ($$$) {
    my $page=shift;
    my $destpage=shift;
    my $content=shift;

    run_hooks(linkify => sub {
        $content=shift->(
            page => $page,
            destpage => $destpage,
            content => $content,
        );
    });
    
    return $content;
}

our %preprocessing;
our $preprocess_preview=0;
sub preprocess ($$$;$$) {
    my $page=shift; # the page the data comes from
    my $destpage=shift; # the page the data will appear in (different for inline)
    my $content=shift;
    my $scan=shift;
    my $preview=shift;

    # Using local because it needs to be set within any nested calls
    # of this function.
    local $preprocess_preview=$preview if defined $preview;

    my $handle=sub {
        my $escape=shift;
        my $prefix=shift;
        my $command=shift;
        my $params=shift;
        $params="" if ! defined $params;

        if (length $escape) {
            return "[[$prefix$command $params]]";
        }
        elsif (exists $hooks{preprocess}{$command}) {
            return "" if $scan && ! $hooks{preprocess}{$command}{scan};
            # Note: preserve order of params, some plugins may
            # consider it significant.
            my @params;
            while ($params =~ m{
                (?:([-\w]+)=)?      # 1: named parameter key?
                (?:
                    """(.*?)""" # 2: triple-quoted value
                |
                    "([^"]*?)"  # 3: single-quoted value
                |
                    (\S+)       # 4: unquoted value
                )
                (?:\s+|$)       # delimiter to next param
            }sgx) {
                my $key=$1;
                my $val;
                if (defined $2) {
                    $val=$2;
                    $val=~s/\r\n/\n/mg;
                    $val=~s/^\n+//g;
                    $val=~s/\n+$//g;
                }
                elsif (defined $3) {
                    $val=$3;
                }
                elsif (defined $4) {
                    $val=$4;
                }

                if (defined $key) {
                    push @params, $key, $val;
                }
                else {
                    push @params, $val, '';
                }
            }
            if ($preprocessing{$page}++ > 3) {
                # Avoid loops of preprocessed pages preprocessing
                # other pages that preprocess them, etc.
                return "[[!$command <span class=\"error\">".
                    sprintf(gettext("preprocessing loop detected on %s at depth %i"),
                        $page, $preprocessing{$page}).
                    "</span>]]";
            }
            my $ret;
            if (! $scan) {
                $ret=eval {
                    $hooks{preprocess}{$command}{call}->(
                        @params,
                        page => $page,
                        destpage => $destpage,
                        preview => $preprocess_preview,
                    );
                };
                if ($@) {
                    my $error=$@;
                    chomp $error;
                    $ret="[[!$command <span class=\"error\">".
                        gettext("Error").": $error"."</span>]]";
                }
            }
            else {
                # use void context during scan pass
                eval {
                    $hooks{preprocess}{$command}{call}->(
                        @params,
                        page => $page,
                        destpage => $destpage,
                        preview => $preprocess_preview,
                    );
                };
                $ret="";
            }
            $preprocessing{$page}--;
            return $ret;
        }
        else {
            return "[[$prefix$command $params]]";
        }
    };
    
    my $regex;
    if ($config{prefix_directives}) {
        $regex = qr{
            (\\?)       # 1: escape?
            \[\[(!)     # directive open; 2: prefix
            ([-\w]+)    # 3: command
            (       # 4: the parameters..
                \s+ # Must have space if parameters present
                (?:
                    (?:[-\w]+=)?        # named parameter key?
                    (?:
                        """.*?"""   # triple-quoted value
                        |
                        "[^"]*?"    # single-quoted value
                        |
                        [^"\s\]]+   # unquoted value
                    )
                    \s*         # whitespace or end
                                # of directive
                )
            *)?     # 0 or more parameters
            \]\]        # directive closed
        }sx;
    }
    else {
        $regex = qr{
            (\\?)       # 1: escape?
            \[\[(!?)    # directive open; 2: optional prefix
            ([-\w]+)    # 3: command
            \s+
            (       # 4: the parameters..
                (?:
                    (?:[-\w]+=)?        # named parameter key?
                    (?:
                        """.*?"""   # triple-quoted value
                        |
                        "[^"]*?"    # single-quoted value
                        |
                        [^"\s\]]+   # unquoted value
                    )
                    \s*         # whitespace or end
                                # of directive
                )
            *)      # 0 or more parameters
            \]\]        # directive closed
        }sx;
    }

    $content =~ s{$regex}{$handle->($1, $2, $3, $4)}eg;
    return $content;
}

sub filter ($$$) {
    my $page=shift;
    my $destpage=shift;
    my $content=shift;

    run_hooks(filter => sub {
        $content=shift->(page => $page, destpage => $destpage, 
            content => $content);
    });

    return $content;
}

sub indexlink () {
    return "<a href=\"$config{url}\">$config{wikiname}</a>";
}

sub check_canedit ($$$;$) {
    my $page=shift;
    my $q=shift;
    my $session=shift;
    my $nonfatal=shift;
    
    my $canedit;
    run_hooks(canedit => sub {
        return if defined $canedit;
        my $ret=shift->($page, $q, $session);
        if (defined $ret) {
            if ($ret eq "") {
                $canedit=1;
            }
            elsif (ref $ret eq 'CODE') {
                $ret->() unless $nonfatal;
                $canedit=0;
            }
            elsif (defined $ret) {
                error($ret) unless $nonfatal;
                $canedit=0;
            }
        }
    });
    return defined $canedit ? $canedit : 1;
}

sub check_content (@) {
    my %params=@_;
    
    return 1 if ! exists $hooks{checkcontent}; # optimisation

    if (exists $pagesources{$params{page}}) {
        my @diff;
        my %old=map { $_ => 1 }
                split("\n", readfile(srcfile($pagesources{$params{page}})));
        foreach my $line (split("\n", $params{content})) {
            push @diff, $line if ! exists $old{$line};
        }
        $params{diff}=join("\n", @diff);
    }

    my $ok;
    run_hooks(checkcontent => sub {
        return if defined $ok;
        my $ret=shift->(%params);
        if (defined $ret) {
            if ($ret eq "") {
                $ok=1;
            }
            elsif (ref $ret eq 'CODE') {
                $ret->() unless $params{nonfatal};
                $ok=0;
            }
            elsif (defined $ret) {
                error($ret) unless $params{nonfatal};
                $ok=0;
            }
        }

    });
    return defined $ok ? $ok : 1;
}

my $wikilock;

sub lockwiki () {
    # Take an exclusive lock on the wiki to prevent multiple concurrent
    # run issues. The lock will be dropped on program exit.
    if (! -d $config{wikistatedir}) {
        mkdir($config{wikistatedir});
    }
    open($wikilock, '>', "$config{wikistatedir}/lockfile") ||
        error ("cannot write to $config{wikistatedir}/lockfile: $!");
    if (! flock($wikilock, 2)) { # LOCK_EX
        error("failed to get lock");
    }
    return 1;
}

sub unlockwiki () {
    POSIX::close($ENV{IKIWIKI_CGILOCK_FD}) if exists $ENV{IKIWIKI_CGILOCK_FD};
    return close($wikilock) if $wikilock;
    return;
}

my $commitlock;

sub commit_hook_enabled () {
    open($commitlock, '+>', "$config{wikistatedir}/commitlock") ||
        error("cannot write to $config{wikistatedir}/commitlock: $!");
    if (! flock($commitlock, 1 | 4)) { # LOCK_SH | LOCK_NB to test
        close($commitlock) || error("failed closing commitlock: $!");
        return 0;
    }
    close($commitlock) || error("failed closing commitlock: $!");
    return 1;
}

sub disable_commit_hook () {
    open($commitlock, '>', "$config{wikistatedir}/commitlock") ||
        error("cannot write to $config{wikistatedir}/commitlock: $!");
    if (! flock($commitlock, 2)) { # LOCK_EX
        error("failed to get commit lock");
    }
    return 1;
}

sub enable_commit_hook () {
    return close($commitlock) if $commitlock;
    return;
}

sub loadindex () {
    %oldrenderedfiles=%pagectime=();
    if (! $config{rebuild}) {
        %pagesources=%pagemtime=%oldlinks=%links=%depends=
        %destsources=%renderedfiles=%pagecase=%pagestate=
        %depends_simple=();
    }
    my $in;
    if (! open ($in, "<", "$config{wikistatedir}/indexdb")) {
        if (-e "$config{wikistatedir}/index") {
            system("ikiwiki-transition", "indexdb", $config{srcdir});
            open ($in, "<", "$config{wikistatedir}/indexdb") || return;
        }
        else {
            return;
        }
    }

    my $index=Storable::fd_retrieve($in);
    if (! defined $index) {
        return 0;
    }

    my $pages;
    if (exists $index->{version} && ! ref $index->{version}) {
        $pages=$index->{page};
        %wikistate=%{$index->{state}};
    }
    else {
        $pages=$index;
        %wikistate=();
    }

    foreach my $src (keys %$pages) {
        my $d=$pages->{$src};
        my $page=pagename($src);
        $pagectime{$page}=$d->{ctime};
        if (! $config{rebuild}) {
            $pagesources{$page}=$src;
            $pagemtime{$page}=$d->{mtime};
            $renderedfiles{$page}=$d->{dest};
            if (exists $d->{links} && ref $d->{links}) {
                $links{$page}=$d->{links};
                $oldlinks{$page}=[@{$d->{links}}];
            }
            if (ref $d->{depends_simple} eq 'ARRAY') {
                # old format
                $depends_simple{$page}={
                    map { $_ => 1 } @{$d->{depends_simple}}
                };
            }
            elsif (exists $d->{depends_simple}) {
                $depends_simple{$page}=$d->{depends_simple};
            }
            if (exists $d->{dependslist}) {
                # old format
                $depends{$page}={
                    map { $_ => $DEPEND_CONTENT }
                        @{$d->{dependslist}}
                };
            }
            elsif (exists $d->{depends} && ! ref $d->{depends}) {
                # old format
                $depends{$page}={$d->{depends} => $DEPEND_CONTENT };
            }
            elsif (exists $d->{depends}) {
                $depends{$page}=$d->{depends};
            }
            if (exists $d->{state}) {
                $pagestate{$page}=$d->{state};
            }
        }
        $oldrenderedfiles{$page}=[@{$d->{dest}}];
    }
    foreach my $page (keys %pagesources) {
        $pagecase{lc $page}=$page;
    }
    foreach my $page (keys %renderedfiles) {
        $destsources{$_}=$page foreach @{$renderedfiles{$page}};
    }
    return close($in);
}

sub saveindex () {
    run_hooks(savestate => sub { shift->() });

    my %hookids;
    foreach my $type (keys %hooks) {
        $hookids{$_}=1 foreach keys %{$hooks{$type}};
    }
    my @hookids=keys %hookids;

    if (! -d $config{wikistatedir}) {
        mkdir($config{wikistatedir});
    }
    my $newfile="$config{wikistatedir}/indexdb.new";
    my $cleanup = sub { unlink($newfile) };
    open (my $out, '>', $newfile) || error("cannot write to $newfile: $!", $cleanup);

    my %index;
    foreach my $page (keys %pagemtime) {
        next unless $pagemtime{$page};
        my $src=$pagesources{$page};

        $index{page}{$src}={
            ctime => $pagectime{$page},
            mtime => $pagemtime{$page},
            dest => $renderedfiles{$page},
            links => $links{$page},
        };

        if (exists $depends{$page}) {
            $index{page}{$src}{depends} = $depends{$page};
        }

        if (exists $depends_simple{$page}) {
            $index{page}{$src}{depends_simple} = $depends_simple{$page};
        }

        if (exists $pagestate{$page}) {
            foreach my $id (@hookids) {
                foreach my $key (keys %{$pagestate{$page}{$id}}) {
                    $index{page}{$src}{state}{$id}{$key}=$pagestate{$page}{$id}{$key};
                }
            }
        }
    }

    $index{state}={};
    foreach my $id (@hookids) {
        foreach my $key (keys %{$wikistate{$id}}) {
            $index{state}{$id}{$key}=$wikistate{$id}{$key};
        }
    }
    
    $index{version}="3";
    my $ret=Storable::nstore_fd(\%index, $out);
    return if ! defined $ret || ! $ret;
    close $out || error("failed saving to $newfile: $!", $cleanup);
    rename($newfile, "$config{wikistatedir}/indexdb") ||
        error("failed renaming $newfile to $config{wikistatedir}/indexdb", $cleanup);
    
    return 1;
}

sub template_file ($) {
    my $template=shift;

    foreach my $dir ($config{templatedir}, @{$config{templatedirs}},
                     "$installdir/share/ikiwiki/templates") {
        return "$dir/$template" if -e "$dir/$template";
    }
    return;
}

sub template_params (@) {
    my $filename=template_file(shift);

    if (! defined $filename) {
        return if wantarray;
        return "";
    }

    my @ret=(
        filter => sub {
            my $text_ref = shift;
            ${$text_ref} = decode_utf8(${$text_ref});
        },
        filename => $filename,
        loop_context_vars => 1,
        die_on_bad_params => 0,
        @_
    );
    return wantarray ? @ret : {@ret};
}

sub template ($;@) {
    require HTML::Template;
    return HTML::Template->new(template_params(@_));
}

sub misctemplate ($$;@) {
    my $title=shift;
    my $pagebody=shift;
    
    my $template=template("misc.tmpl");
    $template->param(
        title => $title,
        indexlink => indexlink(),
        wikiname => $config{wikiname},
        pagebody => $pagebody,
        baseurl => baseurl(),
        @_,
    );
    run_hooks(pagetemplate => sub {
        shift->(page => "", destpage => "", template => $template);
    });
    return $template->output;
}

sub hook (@) {
    my %param=@_;
    
    if (! exists $param{type} || ! ref $param{call} || ! exists $param{id}) {
        error 'hook requires type, call, and id parameters';
    }

    return if $param{no_override} && exists $hooks{$param{type}}{$param{id}};
    
    $hooks{$param{type}}{$param{id}}=\%param;
    return 1;
}

sub run_hooks ($$) {
    # Calls the given sub for each hook of the given type,
    # passing it the hook function to call.
    my $type=shift;
    my $sub=shift;

    if (exists $hooks{$type}) {
        my (@first, @middle, @last);
        foreach my $id (keys %{$hooks{$type}}) {
            if ($hooks{$type}{$id}{first}) {
                push @first, $id;
            }
            elsif ($hooks{$type}{$id}{last}) {
                push @last, $id;
            }
            else {
                push @middle, $id;
            }
        }
        foreach my $id (@first, @middle, @last) {
            $sub->($hooks{$type}{$id}{call});
        }
    }

    return 1;
}

sub rcs_update () {
    $hooks{rcs}{rcs_update}{call}->(@_);
}

sub rcs_prepedit ($) {
    $hooks{rcs}{rcs_prepedit}{call}->(@_);
}

sub rcs_commit ($$$;$$) {
    $hooks{rcs}{rcs_commit}{call}->(@_);
}

sub rcs_commit_staged ($$$) {
    $hooks{rcs}{rcs_commit_staged}{call}->(@_);
}

sub rcs_add ($) {
    $hooks{rcs}{rcs_add}{call}->(@_);
}

sub rcs_remove ($) {
    $hooks{rcs}{rcs_remove}{call}->(@_);
}

sub rcs_rename ($$) {
    $hooks{rcs}{rcs_rename}{call}->(@_);
}

sub rcs_recentchanges ($) {
    $hooks{rcs}{rcs_recentchanges}{call}->(@_);
}

sub rcs_diff ($) {
    $hooks{rcs}{rcs_diff}{call}->(@_);
}

sub rcs_getctime ($) {
    $hooks{rcs}{rcs_getctime}{call}->(@_);
}

sub rcs_receive () {
    $hooks{rcs}{rcs_receive}{call}->();
}

sub add_depends ($$;$) {
    my $page=shift;
    my $pagespec=shift;
    my $deptype=shift || $DEPEND_CONTENT;

    # Is the pagespec a simple page name?
    if ($pagespec =~ /$config{wiki_file_regexp}/ &&
        $pagespec !~ /[\s*?()!]/) {
        $depends_simple{$page}{lc $pagespec} |= $deptype;
        return 1;
    }

    # Add explicit dependencies for influences.
    my $sub=pagespec_translate($pagespec);
    return if $@;
    foreach my $p (keys %pagesources) {
        my $r=$sub->($p, location => $page);
        my $i=$r->influences;
        foreach my $k (keys %$i) {
            $depends_simple{$page}{lc $k} |= $i->{$k};
        }
        last if $r->influences_static;
    }

    $depends{$page}{$pagespec} |= $deptype;
    return 1;
}

sub deptype (@) {
    my $deptype=0;
    foreach my $type (@_) {
        if ($type eq 'presence') {
            $deptype |= $DEPEND_PRESENCE;
        }
        elsif ($type eq 'links') { 
            $deptype |= $DEPEND_LINKS;
        }
        elsif ($type eq 'content') {
            $deptype |= $DEPEND_CONTENT;
        }
    }
    return $deptype;
}

sub file_pruned ($;$) {
    my $file=shift;
    if (@_) {
        require File::Spec;
        $file=File::Spec->canonpath($file);
        my $base=File::Spec->canonpath(shift);
        return if $file eq $base;
        $file =~ s#^\Q$base\E/+##;
    }

    if (defined $config{include} && length $config{include}) {
        return 0 if $file =~ m/$config{include}/;
    }

    my $regexp='('.join('|', @{$config{wiki_file_prune_regexps}}).')';
    return $file =~ m/$regexp/;
}

sub define_gettext () {
    # If translation is needed, redefine the gettext function to do it.
    # Otherwise, it becomes a quick no-op.
    my $gettext_obj;
    my $getobj;
    if ((exists $ENV{LANG} && length $ENV{LANG}) ||
        (exists $ENV{LC_ALL} && length $ENV{LC_ALL}) ||
        (exists $ENV{LC_MESSAGES} && length $ENV{LC_MESSAGES})) {
            $getobj=sub {
            $gettext_obj=eval q{
                use Locale::gettext q{textdomain};
                Locale::gettext->domain('ikiwiki')
            };
        };
    }

    no warnings 'redefine';
    *gettext=sub {
        $getobj->() if $getobj;
        if ($gettext_obj) {
            $gettext_obj->get(shift);
        }
        else {
            return shift;
        }
    };
    *ngettext=sub {
        $getobj->() if $getobj;
        if ($gettext_obj) {
            $gettext_obj->nget(@_);
        }
        else {
            return ($_[2] == 1 ? $_[0] : $_[1])
        }
    };
}

sub gettext {
    define_gettext();
    gettext(@_);
}

sub ngettext {
    define_gettext();
    ngettext(@_);
}

sub yesno ($) {
    my $val=shift;

    return (defined $val && (lc($val) eq gettext("yes") || lc($val) eq "yes" || $val eq "1"));
}

sub inject {
    # Injects a new function into the symbol table to replace an
    # exported function.
    my %params=@_;

    # This is deep ugly perl foo, beware.
    no strict;
    no warnings;
    if (! defined $params{parent}) {
        $params{parent}='::';
        $params{old}=\&{$params{name}};
        $params{name}=~s/.*:://;
    }
    my $parent=$params{parent};
    foreach my $ns (grep /^\w+::/, keys %{$parent}) {
        $ns = $params{parent} . $ns;
        inject(%params, parent => $ns) unless $ns eq '::main::';
        *{$ns . $params{name}} = $params{call}
            if exists ${$ns}{$params{name}} &&
               \&{${$ns}{$params{name}}} == $params{old};
    }
    use strict;
    use warnings;
}

sub add_link ($$) {
    my $page=shift;
    my $link=shift;

    push @{$links{$page}}, $link
        unless grep { $_ eq $link } @{$links{$page}};
}

sub pagespec_translate ($) {
    my $spec=shift;

    # Convert spec to perl code.
    my $code="";
    my @data;
    while ($spec=~m{
        \s*     # ignore whitespace
        (       # 1: match a single word
            \!      # !
        |
            \(      # (
        |
            \)      # )
        |
            \w+\([^\)]*\)   # command(params)
        |
            [^\s()]+    # any other text
        )
        \s*     # ignore whitespace
    }gx) {
        my $word=$1;
        if (lc $word eq 'and') {
            $code.=' &';
        }
        elsif (lc $word eq 'or') {
            $code.=' |';
        }
        elsif ($word eq "(" || $word eq ")" || $word eq "!") {
            $code.=' '.$word;
        }
        elsif ($word =~ /^(\w+)\((.*)\)$/) {
            if (exists $IkiWiki::PageSpec::{"match_$1"}) {
                push @data, $2;
                $code.="IkiWiki::PageSpec::match_$1(\$page, \$data[$#data], \@_)";
            }
            else {
                push @data, qq{unknown function in pagespec "$word"};
                $code.="IkiWiki::ErrorReason->new(\$data[$#data])";
            }
        }
        else {
            push @data, $word;
            $code.=" IkiWiki::PageSpec::match_glob(\$page, \$data[$#data], \@_)";
        }
    }

    if (! length $code) {
        $code="IkiWiki::FailReason->new('empty pagespec')";
    }

    no warnings;
    return eval 'sub { my $page=shift; '.$code.' }';
}

sub pagespec_match ($$;@) {
    my $page=shift;
    my $spec=shift;
    my @params=@_;

    # Backwards compatability with old calling convention.
    if (@params == 1) {
        unshift @params, 'location';
    }

    my $sub=pagespec_translate($spec);
    return IkiWiki::ErrorReason->new("syntax error in pagespec \"$spec\"")
        if $@ || ! defined $sub;
    return $sub->($page, @params);
}

sub pagespec_match_list ($$;@) {
    my $page=shift;
    my $pagespec=shift;
    my %params=@_;

    # Backwards compatability with old calling convention.
    if (ref $page) {
        print STDERR "warning: a plugin (".caller().") is using pagespec_match_list in an obsolete way, and needs to be updated\n";
        $params{list}=$page;
        $page=$params{location}; # ugh!
    }

    my $sub=pagespec_translate($pagespec);
    error "syntax error in pagespec \"$pagespec\""
        if $@ || ! defined $sub;

    my @candidates;
    if (exists $params{list}) {
        @candidates=exists $params{filter}
            ? grep { ! $params{filter}->($_) } @{$params{list}}
            : @{$params{list}};
    }
    else {
        @candidates=exists $params{filter}
            ? grep { ! $params{filter}->($_) } keys %pagesources
            : keys %pagesources;
    }

    if (defined $params{sort}) {
        my $f;
        if ($params{sort} eq 'title') {
            $f=sub { pagetitle(basename($a)) cmp pagetitle(basename($b)) };
        }
        elsif ($params{sort} eq 'title_natural') {
            eval q{use Sort::Naturally};
            if ($@) {
                error(gettext("Sort::Naturally needed for title_natural sort"));
            }
            $f=sub { Sort::Naturally::ncmp(pagetitle(basename($a)), pagetitle(basename($b))) };
                }
        elsif ($params{sort} eq 'mtime') {
            $f=sub { $pagemtime{$b} <=> $pagemtime{$a} };
        }
        elsif ($params{sort} eq 'age') {
            $f=sub { $pagectime{$b} <=> $pagectime{$a} };
        }
        else {
            error sprintf(gettext("unknown sort type %s"), $params{sort});
        }
        @candidates = sort { &$f } @candidates;
    }

    @candidates=reverse(@candidates) if $params{reverse};
    
    $depends{$page}{$pagespec} |= ($params{deptype} || $DEPEND_CONTENT);
    
    # clear params, remainder is passed to pagespec
    my $num=$params{num};
    delete @params{qw{num deptype reverse sort filter list}};
    
    my @matches;
    my $firstfail;
    my $count=0;
    my $accum=IkiWiki::SuccessReason->new();
    foreach my $p (@candidates) {
        my $r=$sub->($p, %params, location => $page);
        error(sprintf(gettext("cannot match pages: %s"), $r))
            if $r->isa("IkiWiki::ErrorReason");
        $accum |= $r;
        if ($r) {
            push @matches, $p;
            last if defined $num && ++$count == $num;
        }
    }

    # Add simple dependencies for accumulated influences.
    my $i=$accum->influences;
    foreach my $k (keys %$i) {
        $depends_simple{$page}{lc $k} |= $i->{$k};
    }

    return @matches;
}

sub pagespec_valid ($) {
    my $spec=shift;

    my $sub=pagespec_translate($spec);
    return ! $@;
}

sub glob2re ($) {
    my $re=quotemeta(shift);
    $re=~s/\\\*/.*/g;
    $re=~s/\\\?/./g;
    return $re;
}

package IkiWiki::FailReason;

use overload (
    '""'    => sub { $_[0][0] },
    '0+'    => sub { 0 },
    '!' => sub { bless $_[0], 'IkiWiki::SuccessReason'},
    '&' => sub { $_[0]->merge_influences($_[1], 1); $_[0] },
    '|' => sub { $_[1]->merge_influences($_[0]); $_[1] },
    fallback => 1,
);

our @ISA = 'IkiWiki::SuccessReason';

package IkiWiki::SuccessReason;

use overload (
    '""'    => sub { $_[0][0] },
    '0+'    => sub { 1 },
    '!' => sub { bless $_[0], 'IkiWiki::FailReason'},
    '&' => sub { $_[1]->merge_influences($_[0], 1); $_[1] },
    '|' => sub { $_[0]->merge_influences($_[1]); $_[0] },
    fallback => 1,
);

sub new {
    my $class = shift;
    my $value = shift;
    return bless [$value, {@_}], $class;
}

sub influences {
    my $this=shift;
    $this->[1]={@_} if @_;
    my %i=%{$this->[1]};
    delete $i{""};
    return \%i;
}

sub influences_static {
    return ! $_[0][1]->{""};
}

sub merge_influences {
    my $this=shift;
    my $other=shift;
    my $anded=shift;

    if (! $anded || (($this || %{$this->[1]}) &&
                    ($other || %{$other->[1]}))) {
        foreach my $influence (keys %{$other->[1]}) {
            $this->[1]{$influence} |= $other->[1]{$influence};
        }
    }
    else {
        # influence blocker
        $this->[1]={};
    }
}

package IkiWiki::ErrorReason;

our @ISA = 'IkiWiki::FailReason';

package IkiWiki::PageSpec;

sub derel ($$) {
    my $path=shift;
    my $from=shift;

    if ($path =~ m!^\./!) {
        $from=~s#/?[^/]+$## if defined $from;
        $path=~s#^\./##;
        $path="$from/$path" if length $from;
    }

    return $path;
}

sub match_glob ($$;@) {
    my $page=shift;
    my $glob=shift;
    my %params=@_;
    
    $glob=derel($glob, $params{location});

    my $regexp=IkiWiki::glob2re($glob);
    if ($page=~/^$regexp$/i) {
        if (! IkiWiki::isinternal($page) || $params{internal}) {
            return IkiWiki::SuccessReason->new("$glob matches $page");
        }
        else {
            return IkiWiki::FailReason->new("$glob matches $page, but the page is an internal page");
        }
    }
    else {
        return IkiWiki::FailReason->new("$glob does not match $page");
    }
}

sub match_internal ($$;@) {
    return match_glob($_[0], $_[1], @_, internal => 1)
}

sub match_link ($$;@) {
    my $page=shift;
    my $link=lc(shift);
    my %params=@_;

    $link=derel($link, $params{location});
    my $from=exists $params{location} ? $params{location} : '';

    my $links = $IkiWiki::links{$page};
    return IkiWiki::FailReason->new("$page has no links", "" => 1)
        unless $links && @{$links};
    my $bestlink = IkiWiki::bestlink($from, $link);
    foreach my $p (@{$links}) {
        if (length $bestlink) {
            return IkiWiki::SuccessReason->new("$page links to $link", $page => $IkiWiki::DEPEND_LINKS, "" => 1)
                if $bestlink eq IkiWiki::bestlink($page, $p);
        }
        else {
            return IkiWiki::SuccessReason->new("$page links to page $p matching $link", $page => $IkiWiki::DEPEND_LINKS, "" => 1)
                if match_glob($p, $link, %params);
            my ($p_rel)=$p=~/^\/?(.*)/;
            $link=~s/^\///;
            return IkiWiki::SuccessReason->new("$page links to page $p_rel matching $link", $page => $IkiWiki::DEPEND_LINKS, "" => 1)
                if match_glob($p_rel, $link, %params);
        }
    }
    return IkiWiki::FailReason->new("$page does not link to $link", "" => 1);
}

sub match_backlink ($$;@) {
    my $ret=match_link($_[1], $_[0], @_);
    $ret->influences($_[1] => $IkiWiki::DEPEND_LINKS);
    return $ret;
}

sub match_created_before ($$;@) {
    my $page=shift;
    my $testpage=shift;
    my %params=@_;
    
    $testpage=derel($testpage, $params{location});

    if (exists $IkiWiki::pagectime{$testpage}) {
        if ($IkiWiki::pagectime{$page} < $IkiWiki::pagectime{$testpage}) {
            return IkiWiki::SuccessReason->new("$page created before $testpage", $testpage => $IkiWiki::DEPEND_PRESENCE);
        }
        else {
            return IkiWiki::FailReason->new("$page not created before $testpage", $testpage => $IkiWiki::DEPEND_PRESENCE);
        }
    }
    else {
        return IkiWiki::ErrorReason->new("$testpage does not exist", $testpage => $IkiWiki::DEPEND_PRESENCE);
    }
}

sub match_created_after ($$;@) {
    my $page=shift;
    my $testpage=shift;
    my %params=@_;
    
    $testpage=derel($testpage, $params{location});

    if (exists $IkiWiki::pagectime{$testpage}) {
        if ($IkiWiki::pagectime{$page} > $IkiWiki::pagectime{$testpage}) {
            return IkiWiki::SuccessReason->new("$page created after $testpage", $testpage => $IkiWiki::DEPEND_PRESENCE);
        }
        else {
            return IkiWiki::FailReason->new("$page not created after $testpage", $testpage => $IkiWiki::DEPEND_PRESENCE);
        }
    }
    else {
        return IkiWiki::ErrorReason->new("$testpage does not exist", $testpage => $IkiWiki::DEPEND_PRESENCE);
    }
}

sub match_creation_day ($$;@) {
    if ((gmtime($IkiWiki::pagectime{shift()}))[3] == shift) {
        return IkiWiki::SuccessReason->new('creation_day matched');
    }
    else {
        return IkiWiki::FailReason->new('creation_day did not match');
    }
}

sub match_creation_month ($$;@) {
    if ((gmtime($IkiWiki::pagectime{shift()}))[4] + 1 == shift) {
        return IkiWiki::SuccessReason->new('creation_month matched');
    }
    else {
        return IkiWiki::FailReason->new('creation_month did not match');
    }
}

sub match_creation_year ($$;@) {
    if ((gmtime($IkiWiki::pagectime{shift()}))[5] + 1900 == shift) {
        return IkiWiki::SuccessReason->new('creation_year matched');
    }
    else {
        return IkiWiki::FailReason->new('creation_year did not match');
    }
}

sub match_user ($$;@) {
    shift;
    my $user=shift;
    my %params=@_;
    
    my $regexp=IkiWiki::glob2re($user);
    
    if (! exists $params{user}) {
        return IkiWiki::ErrorReason->new("no user specified");
    }

    if (defined $params{user} && $params{user}=~/^$regexp$/i) {
        return IkiWiki::SuccessReason->new("user is $user");
    }
    elsif (! defined $params{user}) {
        return IkiWiki::FailReason->new("not logged in");
    }
    else {
        return IkiWiki::FailReason->new("user is $params{user}, not $user");
    }
}

sub match_admin ($$;@) {
    shift;
    shift;
    my %params=@_;
    
    if (! exists $params{user}) {
        return IkiWiki::ErrorReason->new("no user specified");
    }

    if (defined $params{user} && IkiWiki::is_admin($params{user})) {
        return IkiWiki::SuccessReason->new("user is an admin");
    }
    elsif (! defined $params{user}) {
        return IkiWiki::FailReason->new("not logged in");
    }
    else {
        return IkiWiki::FailReason->new("user is not an admin");
    }
}

sub match_ip ($$;@) {
    shift;
    my $ip=shift;
    my %params=@_;
    
    if (! exists $params{ip}) {
        return IkiWiki::ErrorReason->new("no IP specified");
    }

    if (defined $params{ip} && lc $params{ip} eq lc $ip) {
        return IkiWiki::SuccessReason->new("IP is $ip");
    }
    else {
        return IkiWiki::FailReason->new("IP is $params{ip}, not $ip");
    }
}

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