+# This library is free software; you can redistribute it and/or modify it
+# under the same terms as Perl itself, either Perl version 5.8.0 or, at
+# your option, any later version of Perl 5 you may have available.
+#
+# The license for this file differs from the rest of public-inbox.
+#
+# Workaround some bugs in upstream Mail::IMAPClient when
+# compression is enabled:
+# - reference cycle: https://rt.cpan.org/Ticket/Display.html?id=132654
+# - read starvation: https://rt.cpan.org/Ticket/Display.html?id=132720
+package PublicInbox::IMAPClient;
+use strict;
+use parent 'Mail::IMAPClient';
+use Errno qw(EAGAIN);
+
+# RFC4978 COMPRESS
+sub compress {
+ my ($self) = @_;
+
+ # BUG? strict check on capability commented out for now...
+ #my $can = $self->has_capability("COMPRESS")
+ #return undef unless $can and $can eq "DEFLATE";
+
+ $self->_imap_command("COMPRESS DEFLATE") or return undef;
+
+ my $zcl = $self->_load_module("Compress-Zlib") or return undef;
+
+ # give caller control of args if desired
+ $self->Compress(
+ [
+ -WindowBits => -$zcl->MAX_WBITS(),
+ -Level => $zcl->Z_BEST_SPEED()
+ ]
+ ) unless ( $self->Compress and ref( $self->Compress ) eq "ARRAY" );
+
+ my ( $rc, $do, $io );
+
+ ( $do, $rc ) = Compress::Zlib::deflateInit( @{ $self->Compress } );
+ unless ( $rc == $zcl->Z_OK ) {
+ $self->LastError("deflateInit failed (rc=$rc)");
+ return undef;
+ }
+
+ ( $io, $rc ) =
+ Compress::Zlib::inflateInit( -WindowBits => -$zcl->MAX_WBITS() );
+ unless ( $rc == $zcl->Z_OK ) {
+ $self->LastError("inflateInit failed (rc=$rc)");
+ return undef;
+ }
+
+ $self->{Prewritemethod} = sub {
+ my ( $self, $string ) = @_;
+
+ my ( $rc, $out1, $out2 );
+ ( $out1, $rc ) = $do->deflate($string);
+ ( $out2, $rc ) = $do->flush( $zcl->Z_PARTIAL_FLUSH() )
+ unless ( $rc != $zcl->Z_OK );
+
+ unless ( $rc == $zcl->Z_OK ) {
+ $self->LastError("deflate/flush failed (rc=$rc)");
+ return undef;
+ }
+
+ return $out1 . $out2;
+ };
+
+ # need to retain some state for Readmoremethod/Readmethod calls
+ my ( $Zbuf, $Ibuf ) = ( "", "" );
+
+ $self->{Readmoremethod} = sub {
+ my $self = shift;
+ return 1 if ( length($Zbuf) || length($Ibuf) );
+ $self->__read_more(@_);
+ };
+
+ $self->{Readmethod} = sub {
+ my ( $self, $fh, $buf, $len, $off ) = @_;
+
+ # get more data, but empty $Ibuf first if any data is left
+ my ( $lz, $li ) = ( length $Zbuf, length $Ibuf );
+ if ( $lz || !$li ) {
+ my $readlen = $self->Buffer || 4096;
+ my $ret = sysread( $fh, $Zbuf, $readlen, length $Zbuf );
+ $lz = length $Zbuf;
+ return $ret if ( !$ret && !$lz ); # $ret is undef or 0
+ }
+
+ # accumulate inflated data in $Ibuf
+ if ($lz) {
+ my ( $tbuf, $rc ) = $io->inflate( \$Zbuf );
+ unless ( $rc == $zcl->Z_OK ) {
+ $self->LastError("inflate failed (rc=$rc)");
+ return undef;
+ }
+ $Ibuf .= $tbuf;
+ $li = length $Ibuf;
+ }
+
+ if ( !$li ) {
+ # note: faking EAGAIN here is only safe with level-triggered
+ # I/O readiness notifications (select, poll). Refactoring
+ # callers will be needed in the unlikely case somebody wants
+ # to use edge-triggered notifications (EV_CLEAR, EPOLLET).
+ $! = EAGAIN;
+ return undef;
+ }
+
+ # pull desired length of data from $Ibuf
+ my $tbuf = substr( $Ibuf, 0, $len );
+ substr( $Ibuf, 0, $len ) = "";
+ substr( $$buf, $off ) = $tbuf;
+
+ return length $tbuf;
+ };
+
+ return $self;
+}
+
+1;