Introduce PID_ERROR as an invalid exec return value.

[pintos-anon] / src / tests / userprog / shell.c

diff --git a/src/tests/userprog/shell.c b/src/tests/userprog/shell.c
index 905e18b0275570ce2f678cc9d87b8f72ee84bc03..7b9570ac9d564df88b3aef8c71d14600b1a481e6 100644 (file)
--- a/src/tests/userprog/shell.c
+++ b/src/tests/userprog/shell.c
@@ -23,6 +23,12 @@ main (void)
       
       /* Execute command. */
       if (cp > command) 
-        join (exec (command));
+        {
+          pid_t pid = exec (command);
+          if (pid != PID_ERROR)
+            join (pid);
+          else
+            printf ("exec failed\n");
+        }
     }
 }