fix: some extra change

Author: Ivans-11

ch7/src/main.rs

@@ -434,9 +434,7 @@ mod impls {
             let current = PROCESSOR.get_mut().current().unwrap();
             let (read_end, write_end) = make_pipe();
             let read_fd = current.fd_table.len();
-            current.fd_table.push(Some(Mutex::new(read_end)));
-            let write_fd = current.fd_table.len();
-            current.fd_table.push(Some(Mutex::new(write_end)));
+            let write_fd = read_fd + 1;
             // 将 read_fd 写入 pipe[0]
             if let Some(mut ptr) = current
                 .address_space
@@ -455,6 +453,9 @@ mod impls {
             } else {
                 return -1;
             }
+            // 最后添加，避免中途写入异常导致浪费一个 fd
+            current.fd_table.push(Some(Mutex::new(read_end)));
+            current.fd_table.push(Some(Mutex::new(write_end)));
             0
         }
     }

ch8/src/main.rs

@@ -450,9 +450,7 @@ mod impls {
             let current = PROCESSOR.get_mut().get_current_proc().unwrap();
             let (read_end, write_end) = make_pipe();
             let read_fd = current.fd_table.len();
-            current.fd_table.push(Some(Mutex::new(read_end)));
-            let write_fd = current.fd_table.len();
-            current.fd_table.push(Some(Mutex::new(write_end)));
+            let write_fd = read_fd + 1;
             // 将 read_fd 写入 pipe[0]
             if let Some(mut ptr) = current
                 .address_space
@@ -471,6 +469,9 @@ mod impls {
             } else {
                 return -1;
             }
+            // 最后添加，避免中途写入异常导致浪费一个 fd
+            current.fd_table.push(Some(Mutex::new(read_end)));
+            current.fd_table.push(Some(Mutex::new(write_end)));
             0
         }
     }

tg-easy-fs/src/pipe.rs

@@ -17,14 +17,6 @@ enum RingBufferStatus {
     Normal,
 }
 
-/// 缓冲区快照，用于恢复状态
-#[derive(Copy, Clone)]
-pub struct BufferSnapshot {
-    head: usize,
-    tail: usize,
-    status: RingBufferStatus,
-}
-
 /// 管道环形缓冲区
 pub struct PipeRingBuffer {
     arr: [u8; RING_BUFFER_SIZE],
@@ -96,22 +88,6 @@ impl PipeRingBuffer {
     pub fn all_write_ends_closed(&self) -> bool {
         self.write_end.as_ref().unwrap().upgrade().is_none()
     }
-
-    /// 保存当前状态快照
-    pub fn save_state(&self) -> BufferSnapshot {
-        BufferSnapshot {
-            head: self.head,
-            tail: self.tail,
-            status: self.status,
-        }
-    }
-
-    /// 恢复到之前的状态
-    pub fn restore_state(&mut self, snapshot: BufferSnapshot) {
-        self.head = snapshot.head;
-        self.tail = snapshot.tail;
-        self.status = snapshot.status;
-    }
 }
 
 pub trait Pipe {