path: root/ikiwiki

#!/usr/bin/perl -T
$ENV{PATH}="/usr/local/bin:/usr/bin:/bin";

use warnings;
use strict;
use Memoize;
use File::Spec;
use HTML::Template;
use Getopt::Long;

my (%links, %oldlinks, %oldpagemtime, %renderedfiles, %pagesources);

# Holds global config settings, also used by some modules.
our %config=( #{{{
    wiki_file_prune_regexp => qr{((^|/).svn/|\.\.|^\.|\/\.|\.html?$)},
    wiki_link_regexp => qr/\[\[([^\s]+)\]\]/,
    wiki_file_regexp => qr/(^[-A-Za-z0-9_.:\/+]+$)/,
    verbose => 0,
    wikiname => "wiki",
    default_pageext => ".mdwn",
    cgi => 0,
    svn => 1,
    url => '',
    cgiurl => '',
    historyurl => '',
    anonok => 0,
    rebuild => 0,
    wrapper => undef,
    wrappermode => undef,
    srcdir => undef,
    destdir => undef,
    templatedir => undef,
    setup => undef,
); #}}}

GetOptions( #{{{
    "setup=s" => \$config{setup},
    "wikiname=s" => \$config{wikiname},
    "verbose|v!" => \$config{verbose},
    "rebuild!" => \$config{rebuild},
    "wrapper=s" => sub { $config{wrapper}=$_[1] ? $_[1] : "ikiwiki-wrap" },
    "wrappermode=i" => \$config{wrappermode},
    "svn!" => \$config{svn},
    "anonok!" => \$config{anonok},
    "cgi!" => \$config{cgi},
    "url=s" => \$config{url},
    "cgiurl=s" => \$config{cgiurl},
    "historyurl=s" => \$config{historyurl},
    "exclude=s@" => sub {
        $config{wiki_file_prune_regexp}=qr/$config{wiki_file_prune_regexp}|$_[1]/;
    },
) || usage();

if (! $config{setup}) {
    usage() unless @ARGV == 3;
    $config{srcdir} = possibly_foolish_untaint(shift);
    $config{templatedir} = possibly_foolish_untaint(shift);
    $config{destdir} = possibly_foolish_untaint(shift);
    if ($config{cgi} && ! length $config{url}) {
        error("Must specify url to wiki with --url when using --cgi");
    }
}
#}}}

sub usage { #{{{
    die "usage: ikiwiki [options] source templates dest\n";
} #}}}

sub error { #{{{
    if ($config{cgi}) {
        print "Content-type: text/html\n\n";
        print misctemplate("Error", "<p>Error: @_</p>");
    }
    die @_;
} #}}}

sub debug ($) { #{{{
    return unless $config{verbose};
    if (! $config{cgi}) {
        print "@_\n";
    }
    else {
        print STDERR "@_\n";
    }
} #}}}

sub mtime ($) { #{{{
    my $page=shift;
    
    return (stat($page))[9];
} #}}}

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

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

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

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

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

sub pagetype ($) { #{{{
    my $page=shift;
    
    if ($page =~ /\.mdwn$/) {
        return ".mdwn";
    }
    else {
        return "unknown";
    }
} #}}}

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

    my $type=pagetype($file);
    my $page=$file;
    $page=~s/\Q$type\E*$// unless $type eq 'unknown';
    return $page;
} #}}}

sub htmlpage ($) { #{{{
    my $page=shift;

    return $page.".html";
} #}}}

sub readfile ($) { #{{{
    my $file=shift;

    local $/=undef;
    open (IN, "$file") || error("failed to read $file: $!");
    my $ret=<IN>;
    close IN;
    return $ret;
} #}}}

sub writefile ($$) { #{{{
    my $file=shift;
    my $content=shift;

    my $dir=dirname($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: $!");
            }
        }
    }
    
    open (OUT, ">$file") || error("failed to write $file: $!");
    print OUT $content;
    close OUT;
} #}}}

sub findlinks ($$) { #{{{
    my $content=shift;
    my $page=shift;

    my @links;
    while ($content =~ /(?<!\\)$config{wiki_link_regexp}/g) {
        push @links, lc($1);
    }
    # Discussion links are a special case since they're not in the text
    # of the page, but on its template.
    return @links, "$page/discussion";
} #}}}

sub bestlink ($$) { #{{{
    # Given a page and the text of a link on the page, determine which
    # existing page that link best points to. Prefers pages under a
    # subdirectory with the same name as the source page, failing that
    # goes down the directory tree to the base looking for matching
    # pages.
    my $page=shift;
    my $link=lc(shift);
    
    my $cwd=$page;
    do {
        my $l=$cwd;
        $l.="/" if length $l;
        $l.=$link;

        if (exists $links{$l}) {
            #debug("for $page, \"$link\", use $l");
            return $l;
        }
    } while $cwd=~s!/?[^/]+$!!;

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

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

sub htmllink { #{{{
    my $page=shift;
    my $link=shift;
    my $noimageinline=shift; # don't turn links into inline html images
    my $forcesubpage=shift; # force a link to a subpage

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

    return $link if length $bestlink && $page eq $bestlink;
    
    # TODO BUG: %renderedfiles may not have it, if the linked to page
    # was also added and isn't yet rendered! Note that this bug is
    # masked by the bug mentioned below that makes all new files
    # be rendered twice.
    if (! grep { $_ eq $bestlink } values %renderedfiles) {
        $bestlink=htmlpage($bestlink);
    }
    if (! grep { $_ eq $bestlink } values %renderedfiles) {
        return "<a href=\"$config{cgiurl}?do=create&page=$link&from=$page\">?</a>$link"
    }
    
    $bestlink=File::Spec->abs2rel($bestlink, dirname($page));
    
    if (! $noimageinline && isinlinableimage($bestlink)) {
        return "<img src=\"$bestlink\">";
    }
    return "<a href=\"$bestlink\">$link</a>";
} #}}}

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

    $content =~ s{(\\?)$config{wiki_link_regexp}}{
        $1 ? "[[$2]]" : htmllink($page, $2)
    }eg;
    
    return $content;
} #}}}

sub htmlize ($$) { #{{{
    my $type=shift;
    my $content=shift;
    
    if (! $INC{"/usr/bin/markdown"}) {
        no warnings 'once';
        $blosxom::version="is a proper perl module too much to ask?";
        use warnings 'all';
        do "/usr/bin/markdown";
    }
    
    if ($type eq '.mdwn') {
        return Markdown::Markdown($content);
    }
    else {
        error("htmlization of $type not supported");
    }
} #}}}

sub backlinks ($) { #{{{
    my $page=shift;

    my @links;
    foreach my $p (keys %links) {
        next if bestlink($page, $p) eq $page;
        if (grep { length $_ && bestlink($p, $_) eq $page } @{$links{$p}}) {
            my $href=File::Spec->abs2rel(htmlpage($p), dirname($page));
            
            # Trim common dir prefixes from both pages.
            my $p_trimmed=$p;
            my $page_trimmed=$page;
            my $dir;
            1 while (($dir)=$page_trimmed=~m!^([^/]+/)!) &&
                    defined $dir &&
                    $p_trimmed=~s/^\Q$dir\E// &&
                    $page_trimmed=~s/^\Q$dir\E//;
                       
            push @links, { url => $href, page => $p_trimmed };
        }
    }

    return sort { $a->{page} cmp $b->{page} } @links;
} #}}}
    
sub parentlinks ($) { #{{{
    my $page=shift;
    
    my @ret;
    my $pagelink="";
    my $path="";
    my $skip=1;
    foreach my $dir (reverse split("/", $page)) {
        if (! $skip) {
            $path.="../";
            unshift @ret, { url => "$path$dir.html", page => $dir };
        }
        else {
            $skip=0;
        }
    }
    unshift @ret, { url => length $path ? $path : ".", page => $config{wikiname} };
    return @ret;
} #}}}

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

sub finalize ($$) { #{{{
    my $content=shift;
    my $page=shift;

    my $title=basename($page);
    $title=~s/_/ /g;
    
    my $template=HTML::Template->new(blind_cache => 1,
        filename => "$config{templatedir}/page.tmpl");
    
    if (length $config{cgiurl}) {
        $template->param(editurl => "$config{cgiurl}?do=edit&page=$page");
        if ($config{svn}) {
            $template->param(recentchangesurl => "$config{cgiurl}?do=recentchanges");
        }
    }

    if (length $config{historyurl}) {
        my $u=$config{historyurl};
        $u=~s/\[\[\]\]/$pagesources{$page}/g;
        $template->param(historyurl => $u);
    }
    
    $template->param(
        title => $title,
        wikiname => $config{wikiname},
        parentlinks => [parentlinks($page)],
        content => $content,
        backlinks => [backlinks($page)],
        discussionlink => htmllink($page, "Discussion", 1, 1),
    );
    
    return $template->output;
} #}}}

sub check_overwrite ($$) { #{{{
    # Important security check. Make sure to call this before saving
    # any files to the source directory.
    my $dest=shift;
    my $src=shift;
    
    if (! exists $renderedfiles{$src} && -e $dest && ! $config{rebuild}) {
        error("$dest already exists and was rendered from ".
            join(" ",(grep { $renderedfiles{$_} eq $dest } keys
                %renderedfiles)).
            ", before, so not rendering from $src");
    }
} #}}}

sub render ($) { #{{{
    my $file=shift;
    
    my $type=pagetype($file);
    my $content=readfile("$config{srcdir}/$file");
    if ($type ne 'unknown') {
        my $page=pagename($file);
        
        $links{$page}=[findlinks($content, $page)];
        
        $content=linkify($content, $page);
        $content=htmlize($type, $content);
        $content=finalize($content, $page);
        
        check_overwrite("$config{destdir}/".htmlpage($page), $page);
        writefile("$config{destdir}/".htmlpage($page), $content);
        $oldpagemtime{$page}=time;
        $renderedfiles{$page}=htmlpage($page);
    }
    else {
        $links{$file}=[];
        check_overwrite("$config{destdir}/$file", $file);
        writefile("$config{destdir}/$file", $content);
        $oldpagemtime{$file}=time;
        $renderedfiles{$file}=$file;
    }
} #}}}

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 "$config{srcdir}/.ikiwiki") {
        mkdir("$config{srcdir}/.ikiwiki");
    }
    open(WIKILOCK, ">$config{srcdir}/.ikiwiki/lockfile") || error ("cannot write to lockfile: $!");
    if (! flock(WIKILOCK, 2 | 4)) {
        debug("wiki seems to be locked, waiting for lock");
        my $wait=600; # arbitrary, but don't hang forever to 
                      # prevent process pileup
        for (1..600) {
            return if flock(WIKILOCK, 2 | 4);
            sleep 1;
        }
        error("wiki is locked; waited $wait seconds without lock being freed (possible stuck process or stale lock?)");
    }
} #}}}

sub lockwiki () { #{{{
    close WIKILOCK;
} #}}}

sub loadindex () { #{{{
    open (IN, "$config{srcdir}/.ikiwiki/index") || return;
    while (<IN>) {
        $_=possibly_foolish_untaint($_);
        chomp;
        my ($mtime, $file, $rendered, @links)=split(' ', $_);
        my $page=pagename($file);
        $pagesources{$page}=$file;
        $oldpagemtime{$page}=$mtime;
        $oldlinks{$page}=[@links];
        $links{$page}=[@links];
        $renderedfiles{$page}=$rendered;
    }
    close IN;
} #}}}

sub saveindex () { #{{{
    if (! -d "$config{srcdir}/.ikiwiki") {
        mkdir("$config{srcdir}/.ikiwiki");
    }
    open (OUT, ">$config{srcdir}/.ikiwiki/index") || error("cannot write to index: $!");
    foreach my $page (keys %oldpagemtime) {
        print OUT "$oldpagemtime{$page} $pagesources{$page} $renderedfiles{$page} ".
                join(" ", @{$links{$page}})."\n"
                if $oldpagemtime{$page};
    }
    close OUT;
} #}}}

sub rcs_update () { #{{{
    if (-d "$config{srcdir}/.svn") {
        if (system("svn", "update", "--quiet", $config{srcdir}) != 0) {
            warn("svn update failed\n");
        }
    }
} #}}}

sub rcs_commit ($) { #{{{
    my $message=shift;

    if (-d "$config{srcdir}/.svn") {
        if (system("svn", "commit", "--quiet", "-m",
                   possibly_foolish_untaint($message),
               $config{srcdir}) != 0) {
            warn("svn commit failed\n");
        }
    }
} #}}}

sub rcs_add ($) { #{{{
    my $file=shift;

    if (-d "$config{srcdir}/.svn") {
        my $parent=dirname($file);
        while (! -d "$config{srcdir}/$parent/.svn") {
            $file=$parent;
            $parent=dirname($file);
        }
        
        if (system("svn", "add", "--quiet", "$config{srcdir}/$file") != 0) {
            warn("svn add failed\n");
        }
    }
} #}}}

sub rcs_recentchanges ($) { #{{{
    my $num=shift;
    my @ret;
    
    eval q{use CGI 'escapeHTML'};
    eval q{use Date::Parse};
    eval q{use Time::Duration};
    
    if (-d "$config{srcdir}/.svn") {
        my $info=`LANG=C svn info $config{srcdir}`;
        my ($svn_url)=$info=~/^URL: (.*)$/m;

        # FIXME: currently assumes that the wiki is somewhere
        # under trunk in svn, doesn't support other layouts.
        my ($svn_base)=$svn_url=~m!(/trunk(?:/.*)?)$!;
        
        my $div=qr/^--------------------+$/;
        my $infoline=qr/^r(\d+)\s+\|\s+([^\s]+)\s+\|\s+(\d+-\d+-\d+\s+\d+:\d+:\d+\s+[-+]?\d+).*/;
        my $state='start';
        my ($rev, $user, $when, @pages, @message);
        foreach (`LANG=C svn log --limit $num -v '$svn_url'`) {
            chomp;
            if ($state eq 'start' && /$div/) {
                $state='header';
            }
            elsif ($state eq 'header' && /$infoline/) {
                $rev=$1;
                $user=$2;
                $when=concise(ago(time - str2time($3)));
                }
            elsif ($state eq 'header' && /^\s+[A-Z]\s+\Q$svn_base\E\/(.+)$/) {
                push @pages, { link => htmllink("", pagename($1), 1) }
                    if length $1;
            }
            elsif ($state eq 'header' && /^$/) {
                $state='body';
            }
            elsif ($state eq 'body' && /$div/) {
                my $committype="web";
                if (defined $message[0] &&
                    $message[0]->{line}=~/^web commit by (\w+):?(.*)/) {
                    $user="$1";
                    $message[0]->{line}=$2;
                }
                else {
                    $committype="svn";
                }
                
                push @ret, { rev => $rev,
                    user => htmllink("", $user, 1),
                    committype => $committype,
                    when => $when, message => [@message],
                    pages => [@pages] } if @pages;
                return @ret if @ret >= $num;
                
                $state='header';
                $rev=$user=$when=undef;
                @pages=@message=();
            }
            elsif ($state eq 'body') {
                push @message, {line => escapeHTML($_)},
            }
        }
    }

    return @ret;
} #}}}

sub prune ($) { #{{{
    my $file=shift;

    unlink($file);
    my $dir=dirname($file);
    while (rmdir($dir)) {
        $dir=dirname($dir);
    }
} #}}}

sub refresh () { #{{{
    # find existing pages
    my %exists;
    my @files;
    eval q{use File::Find};
    find({
        no_chdir => 1,
        wanted => sub {
            if (/$config{wiki_file_prune_regexp}/) {
                no warnings 'once';
                $File::Find::prune=1;
                use warnings "all";
            }
            elsif (! -d $_ && ! -l $_) {
                my ($f)=/$config{wiki_file_regexp}/; # untaint
                if (! defined $f) {
                    warn("skipping bad filename $_\n");
                }
                else {
                    $f=~s/^\Q$config{srcdir}\E\/?//;
                    push @files, $f;
                    $exists{pagename($f)}=1;
                }
            }
        },
    }, $config{srcdir});

    my %rendered;

    # check for added or removed pages
    my @add;
    foreach my $file (@files) {
        my $page=pagename($file);
        if (! $oldpagemtime{$page}) {
            debug("new page $page");
            push @add, $file;
            $links{$page}=[];
            $pagesources{$page}=$file;
        }
    }
    my @del;
    foreach my $page (keys %oldpagemtime) {
        if (! $exists{$page}) {
            debug("removing old page $page");
            push @del, $pagesources{$page};
            prune($config{destdir}."/".$renderedfiles{$page});
            delete $renderedfiles{$page};
            $oldpagemtime{$page}=0;
            delete $pagesources{$page};
        }
    }
    
    # render any updated files
    foreach my $file (@files) {
        my $page=pagename($file);
        
        if (! exists $oldpagemtime{$page} ||
            mtime("$config{srcdir}/$file") > $oldpagemtime{$page}) {
                debug("rendering changed file $file");
            render($file);
            $rendered{$file}=1;
        }
    }
    
    # if any files were added or removed, check to see if each page
    # needs an update due to linking to them
    # TODO: inefficient; pages may get rendered above and again here;
    # problem is the bestlink may have changed and we won't know until
    # now
    if (@add || @del) {
FILE:       foreach my $file (@files) {
            my $page=pagename($file);
            foreach my $f (@add, @del) {
                my $p=pagename($f);
                foreach my $link (@{$links{$page}}) {
                    if (bestlink($page, $link) eq $p) {
                        debug("rendering $file, which links to $p");
                        render($file);
                        $rendered{$file}=1;
                        next FILE;
                    }
                }
            }
        }
    }

    # handle backlinks; if a page has added/removed links, update the
    # pages it links to
    # TODO: inefficient; pages may get rendered above and again here;
    # problem is the backlinks could be wrong in the first pass render
    # above
    if (%rendered) {
        my %linkchanged;
        foreach my $file (keys %rendered, @del) {
            my $page=pagename($file);
            if (exists $links{$page}) {
                foreach my $link (map { bestlink($page, $_) } @{$links{$page}}) {
                    if (length $link &&
                        ! exists $oldlinks{$page} ||
                        ! grep { $_ eq $link } @{$oldlinks{$page}}) {
                        $linkchanged{$link}=1;
                    }
                }
            }
            if (exists $oldlinks{$page}) {
                foreach my $link (map { bestlink($page, $_) } @{$oldlinks{$page}}) {
                    if (length $link &&
                        ! exists $links{$page} ||
                        ! grep { $_ eq $link } @{$links{$page}}) {
                        $linkchanged{$link}=1;
                    }
                }
            }
        }
        foreach my $link (keys %linkchanged) {
                my $linkfile=$pagesources{$link};
            if (defined $linkfile) {
                debug("rendering $linkfile, to update its backlinks");
                render($linkfile);
            }
        }
    }
} #}}}

sub gen_wrapper (@) { #{{{
    my %config=(@_);
    eval q{use Cwd 'abs_path'};
    $config{srcdir}=abs_path($config{srcdir});
    $config{destdir}=abs_path($config{destdir});
    my $this=abs_path($0);
    if (! -x $this) {
        error("$this doesn't seem to be executable");
    }

    if ($config{setup}) {
        error("cannot create a wrapper that uses a setup file");
    }
    
    my @params=($config{srcdir}, $config{templatedir}, $config{destdir},
        "--wikiname=$config{wikiname}");
    push @params, "--verbose" if $config{verbose};
    push @params, "--rebuild" if $config{rebuild};
    push @params, "--nosvn" if !$config{svn};
    push @params, "--cgi" if $config{cgi};
    push @params, "--url=$config{url}" if length $config{url};
    push @params, "--cgiurl=$config{cgiurl}" if length $config{cgiurl};
    push @params, "--historyurl=$config{historyurl}" if length $config{historyurl};
    push @params, "--anonok" if $config{anonok};
    my $params=join(" ", @params);
    my $call='';
    foreach my $p ($this, $this, @params) {
        $call.=qq{"$p", };
    }
    $call.="NULL";
    
    my @envsave;
    push @envsave, qw{REMOTE_ADDR QUERY_STRING REQUEST_METHOD REQUEST_URI
                   CONTENT_TYPE CONTENT_LENGTH GATEWAY_INTERFACE
               HTTP_COOKIE} if $config{cgi};
    my $envsave="";
    foreach my $var (@envsave) {
        $envsave.=<<"EOF"
    if ((s=getenv("$var")))
        asprintf(&newenviron[i++], "%s=%s", "$var", s);
EOF
    }
    
    open(OUT, ">ikiwiki-wrap.c") || error("failed to write ikiwiki-wrap.c: $!");;
    print OUT <<"EOF";
/* A wrapper for ikiwiki, can be safely made suid. */
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

extern char **environ;

int main (int argc, char **argv) {
    /* Sanitize environment. */
    char *s;
    char *newenviron[$#envsave+3];
    int i=0;
$envsave
    newenviron[i++]="HOME=$ENV{HOME}";
    newenviron[i]=NULL;
    environ=newenviron;

    if (argc == 2 && strcmp(argv[1], "--params") == 0) {
        printf("$params\\n");
        exit(0);
    }
    
    execl($call);
    perror("failed to run $this");
    exit(1);
}
EOF
    close OUT;
    if (system("gcc", "ikiwiki-wrap.c", "-o", possibly_foolish_untaint($config{wrapper})) != 0) {
        error("failed to compile ikiwiki-wrap.c");
    }
    unlink("ikiwiki-wrap.c");
    if (defined $config{wrappermode} &&
        ! chmod(oct($config{wrappermode}), possibly_foolish_untaint($config{wrapper}))) {
        error("chmod $config{wrapper}: $!");
    }
    print "successfully generated $config{wrapper}\n";
} #}}}
        
sub misctemplate ($$) { #{{{
    my $title=shift;
    my $pagebody=shift;
    
    my $template=HTML::Template->new(
        filename => "$config{templatedir}/misc.tmpl"
    );
    $template->param(
        title => $title,
        indexlink => indexlink(),
        wikiname => $config{wikiname},
        pagebody => $pagebody,
    );
    return $template->output;
}#}}}

sub cgi_recentchanges ($) { #{{{
    my $q=shift;
    
    my $template=HTML::Template->new(
        filename => "$config{templatedir}/recentchanges.tmpl"
    );
    $template->param(
        title => "RecentChanges",
        indexlink => indexlink(),
        wikiname => $config{wikiname},
        changelog => [rcs_recentchanges(100)],
    );
    print $q->header, $template->output;
} #}}}

sub userinfo_get ($$) { #{{{
    my $user=shift;
    my $field=shift;

    eval q{use Storable};
    my $userdata=eval{ Storable::lock_retrieve("$config{srcdir}/.ikiwiki/userdb") };
    if (! defined $userdata || ! ref $userdata || 
        ! exists $userdata->{$user} || ! ref $userdata->{$user}) {
        return "";
    }
    return $userdata->{$user}->{$field};
} #}}}

sub userinfo_set ($$) { #{{{
    my $user=shift;
    my $info=shift;
    
    eval q{use Storable};
    my $userdata=eval{ Storable::lock_retrieve("$config{srcdir}/.ikiwiki/userdb") };
    if (! defined $userdata || ! ref $userdata) {
        $userdata={};
    }
    $userdata->{$user}=$info;
    my $oldmask=umask(077);
    my $ret=Storable::lock_store($userdata, "$config{srcdir}/.ikiwiki/userdb");
    umask($oldmask);
    return $ret;
} #}}}

sub cgi_signin ($$) { #{{{
    my $q=shift;
    my $session=shift;

    eval q{use CGI::FormBuilder};
    my $form = CGI::FormBuilder->new(
        title => "$config{wikiname} signin",
        fields => [qw(do page from name password confirm_password email)],
        header => 1,
        method => 'POST',
        validate => {
            confirm_password => {
                perl => q{eq $form->field("password")},
            },
            email => 'EMAIL',
        },
        required => 'NONE',
        javascript => 0,
        params => $q,
        action => $q->request_uri,
        header => 0,
        template => (-e "$config{templatedir}/signin.tmpl" ?
                      "$config{templatedir}/signin.tmpl" : "")
    );
    
    $form->field(name => "name", required => 0);
    $form->field(name => "do", type => "hidden");
    $form->field(name => "page", type => "hidden");
    $form->field(name => "from", type => "hidden");
    $form->field(name => "password", type => "password", required => 0);
    $form->field(name => "confirm_password", type => "password", required => 0);
    $form->field(name => "email", required => 0);
    if ($q->param("do") ne "signin") {
        $form->text("You need to log in before you can edit pages.");
    }
    
    if ($form->submitted) {
        # Set required fields based on how form was submitted.
        my %required=(
            "Login" => [qw(name password)],
            "Register" => [qw(name password confirm_password email)],
            "Mail Password" => [qw(name)],
        );
        foreach my $opt (@{$required{$form->submitted}}) {
            $form->field(name => $opt, required => 1);
        }
    
        # Validate password differently depending on how
        # form was submitted.
        if ($form->submitted eq 'Login') {
            $form->field(
                name => "password",
                validate => sub {
                    length $form->field("name") &&
                    shift eq userinfo_get($form->field("name"), 'password');
                },
            );
            $form->field(name => "name", validate => '/^\w+$/');
        }
        else {
            $form->field(name => "password", validate => 'VALUE');
        }
        # And make sure the entered name exists when logging
        # in or sending email, and does not when registering.
        if ($form->submitted eq 'Register') {
            $form->field(
                name => "name",
                validate => sub {
                    my $name=shift;
                    length $name &&
                    ! userinfo_get($name, "regdate");
                },
            );
        }
        else {
            $form->field(
                name => "name",
                validate => sub {
                    my $name=shift;
                    length $name &&
                    userinfo_get($name, "regdate");
                },
            );
        }
    }
    else {
        # First time settings.
        $form->field(name => "name", comment => "use FirstnameLastName");
        $form->field(name => "confirm_password", comment => "(only needed");
        $form->field(name => "email",            comment => "for registration)");
        if ($session->param("name")) {
            $form->field(name => "name", value => $session->param("name"));
        }
    }

    if ($form->submitted && $form->validate) {
        if ($form->submitted eq 'Login') {
            $session->param("name", $form->field("name"));
            if (defined $form->field("do") && 
                $form->field("do") ne 'signin') {
                print $q->redirect(
                    "$config{cgiurl}?do=".$form->field("do").
                    "&page=".$form->field("page").
                    "&from=".$form->field("from"));;
            }
            else {
                print $q->redirect($config{url});
            }
        }
        elsif ($form->submitted eq 'Register') {
            my $user_name=$form->field('name');
            if (userinfo_set($user_name, {
                           'email' => $form->field('email'),
                           'password' => $form->field('password'),
                           'regdate' => time
                         })) {
                $form->field(name => "confirm_password", type => "hidden");
                $form->field(name => "email", type => "hidden");
                $form->text("Registration successful. Now you can Login.");
                print $session->header();
                print misctemplate($form->title, $form->render(submit => ["Login"]));
            }
            else {
                error("Error saving registration.");
            }
        }
        elsif ($form->submitted eq 'Mail Password') {
            my $user_name=$form->field("name");
            my $template=HTML::Template->new(
                filename => "$config{templatedir}/passwordmail.tmpl"
            );
            $template->param(
                user_name => $user_name,
                user_password => userinfo_get($user_name, "password"),
                wikiurl => $config{url},
                wikiname => $config{wikiname},
                REMOTE_ADDR => $ENV{REMOTE_ADDR},
            );
            
            eval q{use Mail::Sendmail};
            my ($fromhost) = $config{cgiurl} =~ m!/([^/]+)!;
            sendmail(
                To => userinfo_get($user_name, "email"),
                From => "$config{wikiname} admin <".(getpwuid($>))[0]."@".$fromhost.">",
                Subject => "$config{wikiname} information",
                Message => $template->output,
            ) or error("Failed to send mail");
            
            $form->text("Your password has been emailed to you.");
            $form->field(name => "name", required => 0);
            print $session->header();
            print misctemplate($form->title, $form->render(submit => ["Login", "Register", "Mail Password"]));
        }
    }
    else {
        print $session->header();
        print misctemplate($form->title, $form->render(submit => ["Login", "Register", "Mail Password"]));
    }
} #}}}

sub cgi_editpage ($$) { #{{{
    my $q=shift;
    my $session=shift;

    eval q{use CGI::FormBuilder};
    my $form = CGI::FormBuilder->new(
        fields => [qw(do from page content comments)],
        header => 1,
        method => 'POST',
        validate => {
            content => '/.+/',
        },
        required => [qw{content}],
        javascript => 0,
        params => $q,
        action => $q->request_uri,
        table => 0,
        template => "$config{templatedir}/editpage.tmpl"
    );
    
    my ($page)=$form->param('page')=~/$config{wiki_file_regexp}/;
    if (! defined $page || ! length $page || $page ne $q->param('page') ||
        $page=~/$config{wiki_file_prune_regexp}/ || $page=~/^\//) {
        error("bad page name");
    }
    $page=lc($page);

    $form->field(name => "do", type => 'hidden');
    $form->field(name => "from", type => 'hidden');
    $form->field(name => "page", value => "$page", force => 1);
    $form->field(name => "comments", type => "text", size => 80);
    $form->field(name => "content", type => "textarea", rows => 20,
        cols => 80);
    
    if ($form->submitted eq "Cancel") {
        print $q->redirect("$config{url}/".htmlpage($page));
        return;
    }
    elsif ($form->submitted eq "Preview") {
        $form->tmpl_param("page_preview",
            htmlize($config{default_pageext},
                linkify($form->field('content'), $page)));
    }
    else {
        $form->tmpl_param("page_preview", "");
    }
    
    if (! $form->submitted || $form->submitted eq "Preview" || 
        ! $form->validate) {
        if ($form->field("do") eq "create") {
            if (exists $pagesources{lc($page)}) {
                # hmm, someone else made the page in the
                # meantime?
                print $q->redirect("$config{url}/".htmlpage($page));
                return;
            }
            
            my @page_locs;
            my $best_loc;
            my ($from)=$form->param('from')=~/$config{wiki_file_regexp}/;
            if (! defined $from || ! length $from ||
                $from ne $form->param('from') ||
                $from=~/$config{wiki_file_prune_regexp}/ || $from=~/^\//) {
                @page_locs=$best_loc=$page;
            }
            else {
                my $dir=$from."/";
                $dir=~s![^/]+/$!!;
                push @page_locs, $dir.$page;
                push @page_locs, "$from/$page";
                $best_loc="$from/$page";
                while (length $dir) {
                    $dir=~s![^/]+/$!!;
                    push @page_locs, $dir.$page;
                }

                @page_locs = grep { ! exists
                    $pagesources{lc($_)} } @page_locs;
            }

            $form->tmpl_param("page_select", 1);
            $form->field(name => "page", type => 'select',
                options => \@page_locs, value => $best_loc);
            $form->title("creating $page");
        }
        elsif ($form->field("do") eq "edit") {
            if (! length $form->field('content')) {
                my $content="";
                if (exists $pagesources{lc($page)}) {
                        $content=readfile("$config{srcdir}/$pagesources{lc($page)}");
                    $content=~s/\n/\r\n/g;
                }
                $form->field(name => "content", value => $content,
                    force => 1);
            }
            $form->tmpl_param("page_select", 0);
            $form->field(name => "page", type => 'hidden');
            $form->title("editing $page");
        }
        
        $form->tmpl_param("can_commit", $config{svn});
        $form->tmpl_param("indexlink", indexlink());
        print $form->render(submit => ["Save Page", "Preview", "Cancel"]);
    }
    else {
        # save page
        my $file=$page.$config{default_pageext};
        my $newfile=1;
        if (exists $pagesources{lc($page)}) {
            $file=$pagesources{lc($page)};
            $newfile=0;
        }
        
        my $content=$form->field('content');
        $content=~s/\r\n/\n/g;
        $content=~s/\r/\n/g;
        writefile("$config{srcdir}/$file", $content);
        
        my $message="web commit ";
        if ($session->param("name")) {
            $message.="by ".$session->param("name");
        }
        else {
            $message.="from $ENV{REMOTE_ADDR}";
        }
        if (defined $form->field('comments') &&
            length $form->field('comments')) {
            $message.=": ".$form->field('comments');
        }
        
        if ($config{svn}) {
            if ($newfile) {
                rcs_add($file);
            }
            # presumably the commit will trigger an update
            # of the wiki
            rcs_commit($message);
            unlock_wiki();
        }
        else {
            loadindex();
            refresh();
            saveindex();
        }
        
        # The trailing question mark tries to avoid broken
        # caches and get the most recent version of the page.
        print $q->redirect("$config{url}/".htmlpage($page)."?updated");
    }
} #}}}

sub cgi () { #{{{
    eval q{use CGI};
    eval q{use CGI::Session};
    
    my $q=CGI->new;
    
    my $do=$q->param('do');
    if (! defined $do || ! length $do) {
        error("\"do\" parameter missing");
    }
    
    # This does not need a session.
    if ($do eq 'recentchanges') {
        cgi_recentchanges($q);
        return;
    }
    
    CGI::Session->name("ikiwiki_session");

    my $oldmask=umask(077);
    my $session = CGI::Session->new("driver:db_file", $q,
        { FileName => "$config{srcdir}/.ikiwiki/sessions.db" });
    umask($oldmask);
    
    # Everything below this point needs the user to be signed in.
    if ((! $config{anonok} && ! defined $session->param("name") ||
        ! userinfo_get($session->param("name"), "regdate")) || $do eq 'signin') {
        cgi_signin($q, $session);
    
        # Force session flush with safe umask.
        my $oldmask=umask(077);
        $session->flush;
        umask($oldmask);
        
        return;
    }
    
    if ($do eq 'create' || $do eq 'edit') {
        cgi_editpage($q, $session);
    }
    else {
        error("unknown do parameter");
    }
} #}}}

sub setup () { # {{{
    my $setup=possibly_foolish_untaint($config{setup});
    delete $config{setup};
    open (IN, $setup) || error("read $setup: $!\n");
    local $/=undef;
    my $code=<IN>;
    ($code)=$code=~/(.*)/s;
    close IN;

    eval $code;
    error($@) if $@;
    exit;
} #}}}

# main {{{
lockwiki();
setup() if $config{setup};
if ($config{wrapper}) {
    gen_wrapper(%config);
    exit;
}
memoize('pagename');
memoize('bestlink');
loadindex() unless $config{rebuild};
if ($config{cgi}) {
    cgi();
}
else {
    rcs_update() if $config{svn};
    refresh();
    saveindex();
}
#}}}