prepare for lab 3

3 files changed, 28 insertions, 4 deletions

diff --git a/src/lib/pid_t.h b/src/lib/pid_t.h
new file mode 100644
index 0000000..c6d8e31
--- /dev/null
+++ b/src/lib/pid_t.h
@@ -0,0 +1,15 @@
+#ifndef LIB_PID_T_H
+#define LIB_PID_T_H
+
+/* Process identifier.
+   Moved from lib/user/syscall.h since both kernel-
+   and user-space want the same definition. */
+typedef int pid_t;
+
+#define PID_ERROR ((pid_t) -1)
+
+/* Format specifier for printf(), e.g.:
+   printf ("pid=%"PRPTd"\n", pid); */
+#define PRPTd d
+
+#endif /* lib/pid_t.h */
diff --git a/src/lib/user/syscall.h b/src/lib/user/syscall.h
index 8a9e0c0..a152dd1 100644
--- a/src/lib/user/syscall.h
+++ b/src/lib/user/syscall.h
@@ -4,9 +4,7 @@
 #include <stdbool.h>
 #include <debug.h>
 
-/* Process identifier. */
-typedef int pid_t;
-#define PID_ERROR ((pid_t) -1)
+#include "lib/pid_t.h"
 
 /* Map region identifier. */
 typedef int mapid_t;
diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 4ff0340..65ebc7e 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -8,6 +8,7 @@
 #include "filesys/file.h"
 #include "filesys/filesys.h"
 #include "filesys/off_t.h"
+#include "lib/pid_t.h"
 #include "threads/init.h"
 #include "threads/malloc.h"
 
@@ -67,7 +68,7 @@ get_fd (struct thread *thread, int fd_i)
 }
 
 static void
-exit (int status)
+exit (int status UNUSED)
 {
   struct thread *thread = thread_current ();
 
@@ -142,6 +143,12 @@ close (int fd_i)
   }
 }
 
+static pid_t
+exec (const char *file_name UNUSED)
+{
+  return -1;
+}
+
 // cast to TYPE and deref argument N from f->esp
 #define INTR_ESP(N, TYPE) *(TYPE *)(f->esp+(4*(N)))
 
@@ -158,6 +165,10 @@ syscall_handler (struct intr_frame *f UNUSED)
       // exit
       exit (INTR_ESP (1, int));
       break;
+    case 2:
+      // exec
+      f->eax = exec (INTR_ESP (1, char *));
+      break;
     case 4:
       // create
       f->eax = create (INTR_ESP (1, char *), INTR_ESP (2, off_t));