Provide IRT process interface

src/untrusted/nacl/posix_spawn.c

Index: src/untrusted/nacl/posix_spawn.c
diff --git a/src/untrusted/nacl/posix_spawn.c b/src/untrusted/nacl/posix_spawn.c
new file mode 100644
index 0000000000000000000000000000000000000000..2e2d45efc467856af73af3f0c49eb0500b20d3b6
--- /dev/null
+++ b/src/untrusted/nacl/posix_spawn.c
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2013 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <errno.h>
+#include <spawn.h>
+#include <sys/types.h>
+
+#include "native_client/src/untrusted/nacl/nacl_irt.h"
+
+int posix_spawn(pid_t *pid, const char *path,
+                const posix_spawn_file_actions_t *file_actions,
+                const posix_spawnattr_t *attrp,
+                char *const argv[], char *const envp[]) {
+  if (!__libnacl_irt_init_fn(&__libnacl_irt_dev_process.posix_spawn,
+                             __libnacl_irt_dev_process_init)) {
+    return -1;
+  }
+
+  int error = __libnacl_irt_dev_process.posix_spawn(pid, path, file_actions,
+                                                    attrp, argv, envp);
+  if (error) {
+    errno = error;
+    return -1;
+  }
+
+  return 0;
+}