run command with timeout

SeedDMS_Preview/Preview/Previewer.php

@@ -50,6 +50,39 @@ class SeedDMS_Preview_Previewer {
 		$this->width = intval($width);
 	}
 
+	static function execWithTimeout($cmd, $timeout=2) { /* {{{ */
+		$descriptorspec = array(
+			0 => array("pipe", "r"),
+			1 => array("pipe", "w"),
+			2 => array("pipe", "w")
+		);
+		$pipes = array();
+	 
+	  $timeout += time();
+		$process = proc_open($cmd, $descriptorspec, $pipes);
+		if (!is_resource($process)) {
+			throw new Exception("proc_open failed on: " . $cmd);
+		}
+			 
+		$output = '';
+		do {
+			$timeleft = $timeout - time();
+			$read = array($pipes[1]);
+			stream_select($read, $write = NULL, $exeptions = NULL, $timeleft, NULL);
+					 
+			if (!empty($read)) {
+				$output .= fread($pipes[1], 8192);
+													}
+		} while (!feof($pipes[1]) && $timeleft > 0);
+ 
+		if ($timeleft <= 0) {
+			proc_terminate($process);
+			throw new Exception("command timeout on: " . $cmd);
+		} else {
+			return $output;
+		}
+	} /* }}} */
+
 	/**
 	 * Retrieve the physical filename of the preview image on disk
 	 *
@@ -113,7 +146,11 @@ class SeedDMS_Preview_Previewer {
 					break;
 			}
 			if($cmd) {
-				exec($cmd);
+				//exec($cmd);
+				try {
+					self::execWithTimeout($cmd);
+				} catch(Exception $e) {
+				}
 			}
 			return true;
 		}