From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-4.0 required=3.0 tests=ALL_TRUSTED,BAYES_00 shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 6BF801F8C2 for ; Sat, 9 May 2020 08:27:38 +0000 (UTC) From: Eric Wong To: meta@public-inbox.org Subject: [PATCH 1/3] eml: reduce RE captures and possible side effects Date: Sat, 9 May 2020 08:27:36 +0000 Message-Id: <20200509082738.23602-2-e@yhbt.net> In-Reply-To: <20200509082738.23602-1-e@yhbt.net> References: <20200509082738.23602-1-e@yhbt.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: Since Perl 5.6, the `@-' (aka @LAST_MATCH_START) and `@+' (aka @LAST_MATCH_END) arrays provides integer offsets for every match as documented in perlvar(1), regardless of regexp modifiers. We can avoid relying on $1 in the epilogue scan, entirely. So use these instead of relying on m//g and pos(), since the `g' modifier can be affected by m//g matches performed in other places. Unrelated, but while we're in the area: remove some unnecessary use of (?:...), too. --- lib/PublicInbox/Eml.pm | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/lib/PublicInbox/Eml.pm b/lib/PublicInbox/Eml.pm index 4508bd84..80e7c1af 100644 --- a/lib/PublicInbox/Eml.pm +++ b/lib/PublicInbox/Eml.pm @@ -71,11 +71,11 @@ sub re_memo ($) { # compatible with our uses of Email::MIME sub new { my $ref = ref($_[1]) ? $_[1] : \(my $cpy = $_[1]); - if ($$ref =~ /(?:\r?\n(\r?\n))/gs) { # likely + if ($$ref =~ /\r?\n(\r?\n)/s) { # likely # This can modify $$ref in-place and to avoid memcpy/memmove # on a potentially large $$ref. It does need to make a # copy for $hdr, though. Idea stolen from Email::Simple - my $hdr = substr($$ref, 0, pos($$ref), ''); # sv_chop on $$ref + my $hdr = substr($$ref, 0, $+[0], ''); # sv_chop on $$ref substr($hdr, -(length($1))) = ''; # lower SvCUR bless { hdr => \$hdr, crlf => $1, bdy => $ref }, __PACKAGE__; } elsif ($$ref =~ /^[a-z0-9-]+[ \t]*:/ims && $$ref =~ /(\r?\n)\z/s) { @@ -90,8 +90,8 @@ sub new { sub new_sub { my (undef, $ref) = @_; # special case for messages like <85k5su9k59.fsf_-_@lola.goethe.zz> - $$ref =~ /\A(?:(\r?\n))/gs or goto &new; - my $hdr = substr($$ref, 0, pos($$ref), ''); # sv_chop on $$ref + $$ref =~ /\A(\r?\n)/s or goto &new; + my $hdr = substr($$ref, 0, $+[0], ''); # sv_chop on $$ref bless { hdr => \$hdr, crlf => $1, bdy => $ref }, __PACKAGE__; } @@ -132,8 +132,8 @@ sub mp_descend ($$) { # *sigh* just the regexp match alone seems to bump RSS by # length($$bdy) on a ~30M string: my $epilogue_missing; - if ($$bdy =~ /((?:\r?\n)?^--$bnd--[ \t]*\r?$)/gsm) { - substr($$bdy, pos($$bdy) - length($1)) = ''; + if ($$bdy =~ /(?:\r?\n)?^--$bnd--[ \t]*\r?$/sm) { + substr($$bdy, $-[0]) = ''; } else { $epilogue_missing = 1; }