From 22e0e4aa38a1545e5de719ecf235de1a3017d0d2 Mon Sep 17 00:00:00 2001
From: Andrew Ruthven <puck@catalyst.net.nz>
Date: Wed, 17 May 2017 11:06:29 +1200
Subject: [PATCH] Improve parsing of RFC5545 durations

The previous regex failed to parse PT15M which is a valid duration.

This version more correctly implements:
  https://tools.ietf.org/html/rfc5545#section-3.3.6

It isn't totally correct as it incorrectly allows:

  PT10H20S

Which is invalid due to no minutes being present. Oh well.
---
 inc/RRule.php | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/inc/RRule.php b/inc/RRule.php
index 4331229f..345029a6 100644
--- a/inc/RRule.php
+++ b/inc/RRule.php
@@ -72,7 +72,9 @@ class RepeatRuleTimeZone extends DateTimeZone {
 
 /**
  * Provide a useful way of dealing with RFC5545 duration strings of the form
- * ^-?P(\dW)|((\dD)?(T(\dH)?(\dM)?(\dS)?)?)$
+ * ^(-?)P(?:(\d+W)|(?:(?:(\d+)D)?(?:T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S?)?)?))$
+ * This doesn't fully implement the RFC, as it allows PT10H10S - which should
+ * be invalid as no minutes are present.
  */
 class Rfc5545Duration {
   private $epoch_seconds = null;
@@ -115,7 +117,7 @@ class Rfc5545Duration {
    */
   function asSeconds() {
     if ( !isset($this->epoch_seconds) ) {
-      if ( preg_match('{^(-?)P(\d+W)|(?:(\d+)D?(?:T(\d+)H?(\d+)M?(\d+)S?)?)$}i', $this->as_text, $matches) ) {
+      if ( preg_match('{^(-?)P(?:(\d+W)|(?:(?:(\d+)D)?(?:T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S?)?)?))$}i', $this->as_text, $matches) ) {
         // @printf("%s - %s - %s - %s - %s - %s\n", $matches[1], $matches[2], $matches[3], $matches[4], $matches[5], $matches[6]);
         $this->secs = 0;
         if ( !empty($matches[2]) ) {