IkiWiki/Plugin/external.pm

   1 #!/usr/bin/perl
   2 # Support for external plugins written in other languages.
   3 # Communication via XML RPC to a pipe.
   4 # See externaldemo for an example of a plugin that uses this.
   5 package IkiWiki::Plugin::external;
   6
   7 use warnings;
   8 use strict;
   9 use IkiWiki 3.00;
  10 use RPC::XML;
  11 use IPC::Open2;
  12 use IO::Handle;
  13
  14 my %plugins;
  15
  16 sub import {
  17         my $self=shift;
  18         my $plugin=shift;
  19         return unless defined $plugin;
  20
  21         my ($plugin_read, $plugin_write);
  22         my $pid = open2($plugin_read, $plugin_write,
  23                 IkiWiki::possibly_foolish_untaint($plugin));
  24
  25         # open2 doesn't respect "use open ':utf8'"
  26         binmode($plugin_read, ':utf8');
  27         binmode($plugin_write, ':utf8');
  28
  29         $plugins{$plugin}={in => $plugin_read, out => $plugin_write, pid => $pid,
  30                 accum => ""};
  31
  32         $RPC::XML::ENCODING="utf-8";
  33         $RPC::XML::FORCE_STRING_ENCODING="true";
  34
  35         rpc_call($plugins{$plugin}, "import");
  36 }
  37
  38 sub rpc_write ($$) {
  39         my $fh=shift;
  40         my $string=shift;
  41
  42         $fh->print($string."\n");
  43         $fh->flush;
  44 }
  45
  46 sub rpc_call ($$;@) {
  47         my $plugin=shift;
  48         my $command=shift;
  49
  50         # send the command
  51         my $req=RPC::XML::request->new($command, @_);
  52         rpc_write($plugin->{out}, $req->as_string);
  53
  54         # process incoming rpc until a result is available
  55         while ($_ = $plugin->{in}->getline) {
  56                 $plugin->{accum}.=$_;
  57                 while ($plugin->{accum} =~ /^\s*(<\?xml\s.*?<\/(?:methodCall|methodResponse)>)\n(.*)/s) {
  58                         $plugin->{accum}=$2;
  59                         my $parser;
  60                         eval q{
  61                                 use RPC::XML::ParserFactory;
  62                                 $parser = RPC::XML::ParserFactory->new;
  63                         };
  64                         if ($@) {
  65                                 # old interface
  66                                 eval q{
  67                                         use RPC::XML::Parser;
  68                                         $parser = RPC::XML::Parser->new;
  69                                 };
  70                         }
  71                         my $r=$parser->parse($1);
  72                         error("XML RPC parser failure: $r") unless ref $r;
  73                         if ($r->isa('RPC::XML::response')) {
  74                                 my $value=$r->value;
  75                                 if ($r->is_fault($value)) {
  76                                         # throw the error as best we can
  77                                         print STDERR $value->string."\n";
  78                                         return "";
  79                                 }
  80                                 elsif ($value->isa('RPC::XML::array')) {
  81                                         return @{$value->value};
  82                                 }
  83                                 elsif ($value->isa('RPC::XML::struct')) {
  84                                         my %hash=%{$value->value};
  85
  86                                         # XML-RPC v1 does not allow for
  87                                         # nil/null/None/undef values to be
  88                                         # transmitted. The <nil/> extension
  89                                         # is the right fix, but for
  90                                         # back-compat, let external plugins send
  91                                         # a hash with one key "null" pointing
  92                                         # to an empty string.
  93                                         if (exists $hash{null} &&
  94                                             $hash{null} eq "" &&
  95                                             int(keys(%hash)) == 1) {
  96                                                 return undef;
  97                                         }
  98
  99                                         return %hash;
 100                                 }
 101                                 else {
 102                                         return $value->value;
 103                                 }
 104                         }
 105
 106                         my $name=$r->name;
 107                         my @args=map { $_->value } @{$r->args};
 108
 109                         # When dispatching a function, first look in
 110                         # IkiWiki::RPC::XML. This allows overriding
 111                         # IkiWiki functions with RPC friendly versions.
 112                         my $ret;
 113                         if (exists $IkiWiki::RPC::XML::{$name}) {
 114                                 $ret=$IkiWiki::RPC::XML::{$name}($plugin, @args);
 115                         }
 116                         elsif (exists $IkiWiki::{$name}) {
 117                                 $ret=$IkiWiki::{$name}(@args);
 118                         }
 119                         else {
 120                                 error("XML RPC call error, unknown function: $name");
 121                         }
 122
 123                         # XML-RPC v1 does not allow for nil/null/None/undef
 124                         # values to be transmitted, so until XML::RPC::Parser
 125                         # honours v2 (<nil/>), send a hash with one key "null"
 126                         # pointing to an empty string.
 127                         if (! defined $ret) {
 128                                 $ret={"null" => ""};
 129                         }
 130
 131                         my $string=eval { RPC::XML::response->new($ret)->as_string };
 132                         if ($@ && ref $ret) {
 133                                 # One common reason for serialisation to
 134                                 # fail is a complex return type that cannot
 135                                 # be represented as an XML RPC response.
 136                                 # Handle this case by just returning 1.
 137                                 $string=eval { RPC::XML::response->new(1)->as_string };
 138                         }
 139                         if ($@) {
 140                                 error("XML response serialisation failed: $@");
 141                         }
 142                         rpc_write($plugin->{out}, $string);
 143                 }
 144         }
 145
 146         return undef;
 147 }
 148
 149 package IkiWiki::RPC::XML;
 150 use Memoize;
 151
 152 sub getvar ($$$) {
 153         my $plugin=shift;
 154         my $varname="IkiWiki::".shift;
 155         my $key=shift;
 156
 157         no strict 'refs';
 158         my $ret=$varname->{$key};
 159         use strict 'refs';
 160         return $ret;
 161 }
 162
 163 sub setvar ($$$;@) {
 164         my $plugin=shift;
 165         my $varname="IkiWiki::".shift;
 166         my $key=shift;
 167         my $value=shift;
 168
 169         no strict 'refs';
 170         my $ret=$varname->{$key}=$value;
 171         use strict 'refs';
 172         return $ret;
 173 }
 174
 175 sub getstate ($$$$) {
 176         my $plugin=shift;
 177         my $page=shift;
 178         my $id=shift;
 179         my $key=shift;
 180
 181         return $IkiWiki::pagestate{$page}{$id}{$key};
 182 }
 183
 184 sub setstate ($$$$;@) {
 185         my $plugin=shift;
 186         my $page=shift;
 187         my $id=shift;
 188         my $key=shift;
 189         my $value=shift;
 190
 191         return $IkiWiki::pagestate{$page}{$id}{$key}=$value;
 192 }
 193
 194 sub getargv ($) {
 195         my $plugin=shift;
 196
 197         return \@ARGV;
 198 }
 199
 200 sub setargv ($@) {
 201         my $plugin=shift;
 202         my $array=shift;
 203
 204         @ARGV=@$array;
 205 }
 206
 207 sub inject ($@) {
 208         # Bind a given perl function name to a particular RPC request.
 209         my $plugin=shift;
 210         my %params=@_;
 211
 212         if (! exists $params{name} || ! exists $params{call}) {
 213                 die "inject needs name and call parameters";
 214         }
 215         my $sub = sub {
 216                 IkiWiki::Plugin::external::rpc_call($plugin, $params{call}, @_)
 217         };
 218         $sub=memoize($sub) if $params{memoize};
 219
 220         # This will add it to the symbol table even if not present.
 221         no warnings;
 222         eval qq{*$params{name}=\$sub};
 223         use warnings;
 224
 225         # This will ensure that everywhere it was exported to sees
 226         # the injected version.
 227         IkiWiki::inject(name => $params{name}, call => $sub);
 228         return 1;
 229 }
 230
 231 sub hook ($@) {
 232         # the call parameter is a function name to call, since XML RPC
 233         # cannot pass a function reference
 234         my $plugin=shift;
 235         my %params=@_;
 236
 237         my $callback=$params{call};
 238         delete $params{call};
 239
 240         IkiWiki::hook(%params, call => sub {
 241                 IkiWiki::Plugin::external::rpc_call($plugin, $callback, @_);
 242         });
 243 }
 244
 245 sub pagespec_match ($@) {
 246         # convert return object into a XML RPC boolean
 247         my $plugin=shift;
 248         my $page=shift;
 249         my $spec=shift;
 250
 251         return RPC::XML::boolean->new(0 + IkiWiki::pagespec_match(
 252                         $page, $spec, @_));
 253 }
 254
 255 1