Merge pull request #75 from wp-cli/65-check-for-pcre-error-on-return

Handle PCRE errors gracefully

Author: danielbachhuber

src/WP_CLI/SearchReplacer.php

@@ -2,6 +2,8 @@
 
 namespace WP_CLI;
 
+use Exception;
+
 class SearchReplacer {
 
 	private $from, $to;
@@ -102,7 +104,17 @@ private function _run( $data, $serialised, $recursion_level = 0, $visited_data =
 					$search_regex .= $this->from;
 					$search_regex .= $this->regex_delimiter;
 					$search_regex .= $this->regex_flags;
-					$data = preg_replace( $search_regex, $this->to, $data );
+
+					$result = preg_replace( $search_regex, $this->to, $data );
+					if ( null === $result || PREG_NO_ERROR !== preg_last_error() ) {
+						\WP_CLI::warning(
+							sprintf(
+								'The provided regular expression threw a PCRE error - %s',
+								$this->preg_error_message( $result )
+							)
+						);
+					}
+					$data = $result;
 				} else {
 					$data = str_replace( $this->from, $this->to, $data );
 				}
@@ -135,5 +147,21 @@ public function get_log_data() {
 	public function clear_log_data() {
 		$this->log_data = array();
 	}
+
+	/**
+	 * Get the PCRE error constant name from an error value.
+	 *
+	 * @param  integer $error Error code.
+	 * @return string         Error constant name.
+	 */
+	private function preg_error_message( $error ) {
+		$constants = get_defined_constants( true );
+		if ( ! array_key_exists( 'pcre', $constants ) ) {
+			return '<unknown error>';
+		}
+
+		$names = array_flip( $constants['pcre'] );
+		return isset( $names[ $error ] ) ? $names[ $error ] : '<unknown error>';
+	}
 }