check extension dependency on shell commands

CHANGELOG

@@ -4,6 +4,7 @@
 - add hook additionalDocumentContentInfo
 - add restapi function 'statstotal'
 - custom attributes of type 'date' regard the date format
+- check extension dependency on shell commands
 
 --------------------------------------------------------------------------------
                      Changes in version 5.1.25

inc/inc.ClassExtensionMgr.php

@@ -441,6 +441,14 @@ class SeedDMS_Extension_Mgr {
 							}
 						}
 						break;
+					case 'cmd':
+						if(is_array($dval) && $dval) {
+							foreach($dval as $d) {
+								if(!commandExists($d))
+									$this->errmsgs[] = sprintf("Missing command '%s'", $d);
+							}
+						}
+						break;
 					default:
 						$tmp = explode('-', $dval, 2);
 						if(isset($this->extconf[$dkey]['version'])) {

inc/inc.Utils.php

@@ -696,6 +696,37 @@ function addDirSep($str) { /* {{{ */
 		return trim($str);
 } /* }}} */
 
+/**
+ * Determines if a command exists on the current environment
+ *
+ * @param string $command The command to check
+ * @return bool True if the command has been found ; otherwise, false.
+ */
+function commandExists ($command) {
+	$whereIsCommand = (PHP_OS == 'WINNT') ? 'where' : 'command -v';
+
+	$process = proc_open(
+		"$whereIsCommand $command",
+		array(
+			0 => array("pipe", "r"), //STDIN
+			1 => array("pipe", "w"), //STDOUT
+			2 => array("pipe", "w"), //STDERR
+		),
+		$pipes
+	);
+	if ($process !== false) {
+		$stdout = stream_get_contents($pipes[1]);
+		$stderr = stream_get_contents($pipes[2]);
+		fclose($pipes[1]);
+		fclose($pipes[2]);
+		proc_close($process);
+
+		return $stdout != '';
+	}
+
+	return false;
+}
+
 /**
  * Send a file from disk to the browser
  *