make new code like old code

Variable declarations at top of function,
separate from initialization.

Use == 0 instead of ! for checking pointers.

Consistent spacing around {, *, casts.

Declare 0-parameter functions as (void) not ().

Integer valued functions return -1 on failure, 0 on success.

sysfile.c

@@ -348,7 +348,7 @@ sys_exec(void)
   int i;
   uint uargv, uarg;
 
-  if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0) {
+  if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0){
     return -1;
   }
   memset(argv, 0, sizeof(argv));