Darwin syswrap: 1st arg of posix_spawn can be NULL

diff --git a/coregrind/m_syswrap/syswrap-darwin.c b/coregrind/m_syswrap/syswrap-darwin.c
index 1fa1de5429b5ac09fb6c22eba38207ad48a0c444..9d8ba22a3e838aec2507a94e0dbae04168079bd0 100644 (file)
--- a/coregrind/m_syswrap/syswrap-darwin.c
+++ b/coregrind/m_syswrap/syswrap-darwin.c
@@ -3852,7 +3852,9 @@ PRE(posix_spawn)
 
    PRE_REG_READ5(int, "posix_spawn", vki_pid_t*, pid, char*, path,
                  void*, file_actions, char**, argv, char**, envp );
-   PRE_MEM_WRITE("posix_spawn(pid)", ARG1, sizeof(vki_pid_t) );
+   if (ARG1 != 0) {
+      PRE_MEM_WRITE("posix_spawn(pid)", ARG1, sizeof(vki_pid_t) );
+   }
    PRE_MEM_RASCIIZ("posix_spawn(path)", ARG2);
    // DDD: check file_actions
    if (ARG4 != 0)