feat: add app-identifier for convenient

Signed-off-by: ComixHe <heyuming@deepin.org>

src/global.h

@@ -23,6 +23,7 @@
 #include <QUuid>
 #include <QLoggingCategory>
 #include <sys/stat.h>
+#include <sys/syscall.h>
 #include "constant.h"
 #include "config.h"
 
@@ -652,4 +653,9 @@ inline QString getObjectPathFromAppId(const QString &appId)
     return QString{DDEApplicationManager1ObjectPath} + "/" + QUuid::createUuid().toString(QUuid::Id128);
 }
 
+inline int pidfd_open(pid_t pid, uint flags)
+{
+    return syscall(SYS_pidfd_open, pid, flags);
+}
+
 #endif