fix bug

defs.h

@@ -120,7 +120,7 @@ void            userinit(void);
 int             wait(void);
 void            wakeup(void*);
 void            yield(void);
-void            reparent(int);
+void            reparent(int,int);
 
 // swtch.S
 void            swtch(struct context**, struct context*);

proc.c

@@ -533,17 +533,27 @@ procdump(void)
   }
 }
 
-// Make init become the proc's parent (specified by pid)
+//Make parentpid become pid's parent
 void 
-reparent(int pid)
+reparent(int pid,int parentpid)
 {
   struct proc *p;
+  struct proc *parent = 0;
 
   acquire(&ptable.lock);
 
+  for (p = ptable.proc; p < &ptable.proc[NPROC];p++){
+    if(p->pid == parentpid)
+      parent = p;
+  }
+  if(parent == 0){
+    release(&ptable.lock);
+    return;
+  }
+
   for (p = ptable.proc; p < &ptable.proc[NPROC];p++){
     if(p->pid == pid){
-      myproc()->parent = p;
+      p->parent = parent;
       release(&ptable.lock);
       return;
     }

sh.c

@@ -92,7 +92,9 @@ fg(char* s)
   fgid = 0;
   while('0' <= *s && *s <= '9')
     fgid = fgid*10 + *s++ - '0';
-
+
+  int fgpid = 0;
+
 
 }
 // Execute cmd.  Never returns.

sysproc.c

@@ -94,9 +94,13 @@ int
 sys_reparent(void)
 {
   int pid;
+  int parent;
 
   if(argint(0, &pid) < 0)
     return -1;
-  reparent(pid);
+  if (argint(0, &parent) < 0)
+    return -1;
+
+  reparent(pid,parent);
   return 0;
 }