1 files changed, 42 insertions, 1 deletions
diff --git a/syscall.c b/syscall.c
index 0a017c7..31b6189 100644
--- a/syscall.c
+++ b/syscall.c
@@ -309,7 +309,8 @@ sys_mkdir(void)
     return -1;
 
   nip = mknod (cp->mem + arg0, T_DIR, 0, 0);
-
+  
+  memset (de.name, '\0', DIRSIZ);
   de.name[0] = '.';
   de.inum = nip->inum;
   writei (nip, (char *) &de, 0, sizeof(de));
@@ -324,6 +325,43 @@ sys_mkdir(void)
   return (nip == 0) ? -1 : 0;
 }
 
+
+int
+sys_chdir(void)
+{
+  struct proc *cp = curproc[cpu()];
+  struct inode *ip;
+    uint arg0;
+  int l;
+  
+  if(fetcharg(0, &arg0) < 0) 
+    return -1;
+
+  if((l = checkstring(arg0)) < 0)
+    return -1;
+
+  if(l >= DIRSIZ)
+    return -1;
+
+  if ((ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0)) == 0)
+    return -1;
+  
+  if (ip == cp->cwd) {
+    iput (ip);
+    return 0;
+  }
+
+  if (ip->type != T_DIR) {
+    iput(ip);
+    return 0;
+  }
+
+  idecref(cp->cwd);
+  cp->cwd = ip;
+  iunlock(cp->cwd);
+  return 0;
+}
+
 int
 sys_unlink(void)
 {
@@ -599,6 +637,9 @@ syscall(void)
   case SYS_mkdir:
     ret = sys_mkdir();
     break;
+  case SYS_chdir:
+    ret = sys_chdir();
+    break;
   default:
     cprintf("unknown sys call %d\n", num);
     // XXX fault