diff --git a/debug/2024-04.txt b/debug/2024-04.txt
index 914d7c4..565e054 100644
--- a/debug/2024-04.txt
+++ b/debug/2024-04.txt
@@ -17,7 +17,7 @@ Stack trace:
 使用了core crate中的String，导致最终调用了一个含有未正确链接的函数。
 
 ======== 04-23 13:55 ========
-Hit null pointer as 0x100351a.
+Hit null pointer at 0x100351a.
 Stack trace:
     0x00000000010054d0 -> metaverse::kernel::tty::tty::MessageBuilder::message_mut
     0x0000000001006170 -> <str as metaverse::libk::alloc::string::ToString>::to_string
@@ -27,3 +27,29 @@ Stack trace:
     0x0000000001003f60 -> alloc::alloc::alloc
     0x00000000010034f0 -> core::ptr::read_volatile::precondition_check
 使用了core crate的alloc函数，其中含有未正确链接的函数。
+
+======== 04-26 02:56 ========
+Hit null pointer in metaverse::libk::alloc::string::String::clone()
+Stack trace:
+    0x0000000001005520 -> metaverse::kernel::tty::tty::format_message
+    0x00000000010052f0 -> metaverse::kernel::tty::tty::MessageBuilder::message_mut
+    0x00000000010073f0 -> <metaverse::libk::alloc::string::String as metaverse::libk::alloc::string::ToString>::to_string
+    0x0000000001009a90 -> <metaverse::libk::alloc::string::String as core::clone::Clone>::clone
+使用了Clone的derive宏，含有未正确链接的函数。
+
+======== 04-26 15:55 ========
+Hit null pointer at 0x1003672.
+Stack trace:
+    0x0000000001007600 -> <u64 as metaverse::libk::alloc::string::ToString>::to_string
+    0x0000000001007030 -> metaverse::libk::alloc::string::String::insert
+    0x0000000001008330 -> metaverse::libk::alloc::vec::Vec::insert
+    0x0000000001007950 -> metaverse::libk::alloc::vec::Vec::extend_capacity
+    0x0000000001003630 -> core::intrinsics::copy::precondition_check
+将*mut u8转换为*mut T时调用了此函数，导致调用了一个未正确链接的函数。
+
+======== 04-27 16:06 ========
+Trapped into a infinite loop.
+Stack trace:
+    0x0000000001006c30 -> interrupt_req_DE
+    0x0000000001005420 -> metaverse::kernel::tty::tty::MessageBuilder::append
+    0x0000000001008410 -> metaverse::libk::alloc::vec::Vec::append
diff --git a/src/libk/alloc/string.rs b/src/libk/alloc/string.rs
index c106e0c..1676e4f 100644
--- a/src/libk/alloc/string.rs
+++ b/src/libk/alloc/string.rs
@@ -2,7 +2,7 @@ use core::ops::{Add, AddAssign};
 
 use super::vec::{Vec, VecIterator};
 
-#[derive(Clone, Default)]
+#[derive(Default)]
 pub struct String {
     data: Vec<char>,
     u8data: Vec<u8>,
@@ -75,6 +75,15 @@ impl AddAssign for String {
     }
 }
 
+impl Clone for String {
+    fn clone(&self) -> Self {
+        Self {
+            data: self.data.clone(),
+            u8data: self.u8data.clone(),
+        }
+    }
+}
+
 pub trait ToString {
     fn to_string(&self) -> String;
     fn to_octal_string(&self) -> String {
@@ -129,7 +138,7 @@ impl ToString for u8 {
         let mut num = *self;
         let mut res = String::new();
         while num != 0 {
-            res.insert(0, (tohex(num % 16) + b'0') as char);
+            res.insert(0, tohex(num % 16) as char);
             num /= 16;
         }
         res
@@ -144,6 +153,9 @@ impl ToString for u16 {
             res.insert(0, ((num % 10) as u8 + b'0') as char);
             num /= 10;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -154,6 +166,9 @@ impl ToString for u16 {
             res.insert(0, ((num % 8) as u8 + b'0') as char);
             num /= 8;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -168,12 +183,16 @@ impl ToString for u16 {
         let mut num = *self;
         let mut res = String::new();
         while num != 0 {
-            res.insert(0, (tohex(num % 16) + b'0') as char);
+            res.insert(0, tohex(num % 16) as char);
             num /= 16;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 }
+
 impl ToString for u32 {
     fn to_string(&self) -> String {
         let mut num = *self;
@@ -182,6 +201,9 @@ impl ToString for u32 {
             res.insert(0, ((num % 10) as u8 + b'0') as char);
             num /= 10;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -192,6 +214,9 @@ impl ToString for u32 {
             res.insert(0, ((num % 8) as u8 + b'0') as char);
             num /= 8;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -206,12 +231,16 @@ impl ToString for u32 {
         let mut num = *self;
         let mut res = String::new();
         while num != 0 {
-            res.insert(0, (tohex(num % 16) + b'0') as char);
+            res.insert(0, tohex(num % 16) as char);
             num /= 16;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 }
+
 impl ToString for u64 {
     fn to_string(&self) -> String {
         let mut num = *self;
@@ -220,6 +249,9 @@ impl ToString for u64 {
             res.insert(0, ((num % 10) as u8 + b'0') as char);
             num /= 10;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -230,6 +262,9 @@ impl ToString for u64 {
             res.insert(0, ((num % 8) as u8 + b'0') as char);
             num /= 8;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -244,12 +279,16 @@ impl ToString for u64 {
         let mut num = *self;
         let mut res = String::new();
         while num != 0 {
-            res.insert(0, (tohex(num % 16) + b'0') as char);
+            res.insert(0, tohex(num % 16) as char);
             num /= 16;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 }
+
 impl ToString for u128 {
     fn to_string(&self) -> String {
         let mut num = *self;
@@ -258,6 +297,9 @@ impl ToString for u128 {
             res.insert(0, ((num % 10) as u8 + b'0') as char);
             num /= 10;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -268,6 +310,9 @@ impl ToString for u128 {
             res.insert(0, ((num % 8) as u8 + b'0') as char);
             num /= 8;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 
@@ -282,9 +327,60 @@ impl ToString for u128 {
         let mut num = *self;
         let mut res = String::new();
         while num != 0 {
-            res.insert(0, (tohex(num % 16) + b'0') as char);
+            res.insert(0, tohex(num % 16) as char);
             num /= 16;
         }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
+        res
+    }
+}
+
+impl ToString for usize {
+    fn to_string(&self) -> String {
+        let mut num = *self;
+        let mut res = String::new();
+        while num != 0 {
+            res.insert(0, ((num % 10) as u8 + b'0') as char);
+            num /= 10;
+        }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
+        res
+    }
+
+    fn to_octal_string(&self) -> String {
+        let mut num = *self;
+        let mut res = String::new();
+        while num != 0 {
+            res.insert(0, ((num % 8) as u8 + b'0') as char);
+            num /= 8;
+        }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
+        res
+    }
+
+    fn to_hex_string(&self) -> String {
+        let tohex = |x| {
+            if x < 10 {
+                x as u8 + b'0'
+            } else {
+                x as u8 - 10 + b'a'
+            }
+        };
+        let mut num = *self;
+        let mut res = String::new();
+        while num != 0 {
+            res.insert(0, tohex(num % 16) as char);
+            num /= 16;
+        }
+        if res.len() == 0 {
+            res.insert(0, '0');
+        }
         res
     }
 }
diff --git a/src/libk/alloc/vec.rs b/src/libk/alloc/vec.rs
index 66df0b2..a33e2dc 100644
--- a/src/libk/alloc/vec.rs
+++ b/src/libk/alloc/vec.rs
@@ -1,11 +1,14 @@
 use core::{
     alloc::Layout,
     ops::{Index, IndexMut, Range, RangeFull},
-    ptr::{addr_of_mut, null_mut},
+    ptr::addr_of_mut,
     slice,
 };
 
-use crate::libk::alloc::alloc::{alloc, dealloc};
+use crate::libk::{
+    alloc::alloc::{alloc, dealloc},
+    core::ptr::PtrOptions,
+};
 
 pub struct Vec<T> {
     pointer: *mut T,
@@ -16,15 +19,15 @@ pub struct Vec<T> {
 impl<T: Default> Vec<T> {
     pub fn new() -> Self {
         Self {
-            pointer: null_mut(),
+            pointer: unsafe { alloc(Layout::array::<T>(4).unwrap()).cast() },
             length: 0,
-            capacity: 0,
+            capacity: 4,
         }
     }
 
     unsafe fn extend_capacity(&mut self) {
-        let newp = alloc(Layout::array::<T>(self.capacity * 2).unwrap()).cast();
-        self.pointer.copy_to(newp, self.length);
+        let newp: *mut T = alloc(Layout::array::<T>(self.capacity * 2).unwrap()).cast();
+        self.pointer.kcopy_to(newp, self.length);
         dealloc(
             self.pointer.cast(),
             Layout::array::<T>(self.capacity).unwrap(),
@@ -34,11 +37,6 @@ impl<T: Default> Vec<T> {
     }
 
     pub fn push(&mut self, item: T) {
-        if self.pointer.is_null() {
-            self.pointer = unsafe { alloc(Layout::array::<T>(4).unwrap()).cast() };
-            self.capacity = 4;
-            self.length = 0;
-        }
         if self.capacity == self.length {
             unsafe { self.extend_capacity() }
         }
@@ -54,11 +52,11 @@ impl<T: Default> Vec<T> {
         unsafe {
             if rearlen != 0 {
                 let tmp = alloc(Layout::array::<T>(rearlen).unwrap()).cast();
-                self.pointer.offset(index as isize).copy_to(tmp, rearlen);
+                self.pointer.offset(index as isize).kcopy_to(tmp, rearlen);
                 self.pointer.offset(index as isize).write(item);
                 self.pointer
                     .offset(index as isize + 1)
-                    .copy_from(tmp, rearlen);
+                    .kcopy_from(tmp, rearlen);
             } else {
                 self.pointer.offset(self.length as isize).write(item);
             }
@@ -73,7 +71,7 @@ impl<T: Default> Vec<T> {
         unsafe {
             self.pointer
                 .offset(self.length as isize)
-                .copy_from(v.pointer.cast_const(), v.length)
+                .kcopy_from(v.pointer.cast_const(), v.length)
         };
         self.length += v.length;
     }
@@ -108,8 +106,8 @@ impl<T: Default> Vec<T> {
         let mut t: T = T::default();
         let pt = addr_of_mut!(t);
         unsafe {
-            pt.copy_from(self.pointer.offset(index as isize).cast_const(), 1);
-            self.pointer.offset(index as isize).copy_from(
+            pt.kcopy_from(self.pointer.offset(index as isize).cast_const(), 1);
+            self.pointer.offset(index as isize).kcopy_from(
                 self.pointer.offset(index as isize + 1),
                 self.length - index - 1,
             );
@@ -172,7 +170,7 @@ impl<T: Default> Clone for Vec<T> {
         };
         unsafe {
             res.pointer
-                .copy_from(self.pointer.cast_const(), self.length)
+                .kcopy_from(self.pointer.cast_const(), self.length)
         };
         res
     }
@@ -264,7 +262,7 @@ impl<T: Default> Iterator for VecIter<T> {
             let res = unsafe {
                 self.pointer
                     .offset(self.index as isize)
-                    .copy_to(addr_of_mut!(t), 1);
+                    .kcopy_to(addr_of_mut!(t), 1);
                 Some(t)
             };
             self.index += 1;
diff --git a/src/libk/core/mod.rs b/src/libk/core/mod.rs
index e69de29..d0511c6 100644
--- a/src/libk/core/mod.rs
+++ b/src/libk/core/mod.rs
@@ -0,0 +1 @@
+pub mod ptr;
\ No newline at end of file
diff --git a/src/libk/core/ptr/mod.rs b/src/libk/core/ptr/mod.rs
new file mode 100644
index 0000000..4341346
--- /dev/null
+++ b/src/libk/core/ptr/mod.rs
@@ -0,0 +1,30 @@
+use core::mem::{size_of, transmute};
+
+extern "C" {
+    pub fn memset(des: *const u8, src: u8, len: usize);
+    pub fn memcpy(des: *const u8, src: *const u8, len: usize);
+    pub fn strlen(des: *const u8) -> usize;
+}
+
+pub trait PtrOptions<T> {
+    unsafe fn kcopy_from(self, src: *const T, count: usize);
+    unsafe fn kcopy_to(self, des: *const T, count: usize);
+}
+
+impl<T> PtrOptions<T> for *mut T {
+    unsafe fn kcopy_from(self, src: *const T, count: usize) {
+        memcpy(
+            transmute(self.cast_const()),
+            transmute(src),
+            count * size_of::<T>(),
+        );
+    }
+
+    unsafe fn kcopy_to(self, des: *const T, count: usize) {
+        memcpy(
+            transmute(des),
+            transmute(self.cast_const()),
+            count * size_of::<T>(),
+        );
+    }
+}