push child to parents list of children

2 files changed, 26 insertions, 1 deletions

diff --git a/src/threads/thread.c b/src/threads/thread.c
index 43dd8e3..3112a71 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -436,6 +436,9 @@ init_thread (struct thread *t, const char *name, int priority)
   strlcpy (t->name, name, sizeof t->name);
   t->stack = (uint8_t *) t + PGSIZE;
   t->priority = priority;
+#ifdef USERPROG
+  list_init (&t->children);
+#endif
   t->magic = THREAD_MAGIC;
 }
 
diff --git a/src/threads/thread.h b/src/threads/thread.h
index e3c426d..b822b64 100644
--- a/src/threads/thread.h
+++ b/src/threads/thread.h
@@ -4,6 +4,7 @@
 #include <debug.h>
 #include <list.h>
 #include <stdint.h>
+#include "threads/synch.h"
 
 #define MAX_FDS 128  /* Max number of file descriptors per thread */
 
@@ -21,6 +22,24 @@ enum thread_status
 typedef int tid_t;
 #define TID_ERROR ((tid_t) -1)          /* Error value for tid_t. */
 
+/* The relationship between a parent and child process.
+   It is setup by the child in 
+   The child reports its exit status by setting exit_status
+   and upping exit_sema. 
+   The parent places the parent_child element in its list of children.
+*/
+struct parent_child
+  {
+    struct list_elem elem; // owned by the parent
+
+    struct semaphore exit_sema;
+
+    struct lock l;
+    int exit_status;
+    int alive_count;
+
+  };
+
 /* Thread priorities. */
 #define PRI_MIN 0                       /* Lowest priority. */
 #define PRI_DEFAULT 31                  /* Default priority. */
@@ -98,7 +117,10 @@ struct thread
 #ifdef USERPROG
     /* Owned by userprog/process.c. */
     uint32_t *pagedir;                  /* Page directory. */
-    struct file **fds;                     /* Pointer to array of file descriptors. */
+    struct file **fds;                  /* Pointer to array of file descriptors. */
+
+    struct parent_child parent; // one parent
+    struct list children; // multiple children
 #endif
 
     /* Owned by thread.c. */