stage2 更多的工具库 stage1 修复问题

stage2/sys/file.spl

@@ -34,12 +34,12 @@ fn write_byte(f: *File, b: u8): u64 {
     ret write(f, &tmp, 1);
 }
 
-fn read(f: *File, buf: *u8, n: u64): u64 {
+fn read(f: *File, buf: *u8, n: usize): usize {
     if f.handle == null { ret 0; }
     ret vm_fread(buf as *any, 1, n, f.handle);
 }
 
-fn size(f: *File): u64 {
+fn size(f: *File): usize {
     if f.handle == null { ret 0; }
     ret vm_fsize(f.handle);
 }
@@ -67,4 +67,4 @@ fn main(): void {
     @assert(n == msg.len, "write");
     putchar(46 as u8);
     putchar(10 as u8);
-}
+}