diff --git a/Makefile b/Makefile
index b7fb22d..ff2e30c 100644
--- a/Makefile
+++ b/Makefile
@@ -61,7 +61,7 @@ endif
 
 # riscv64-unknown-elf- or riscv64-linux-gnu-
 # perhaps in /opt/riscv/bin
-#TOOLPREFIX = 
+TOOLPREFIX = /opt/riscv/bin/riscv64-unknown-elf-
 
 # Try to infer the correct TOOLPREFIX if not set
 ifndef TOOLPREFIX
@@ -257,7 +257,8 @@ endif
 
 ifeq ($(LAB),fs)
 UPROGS += \
-	$U/_bigfile
+	$U/_bigfile\
+	$U/_symlinktest
 endif
 
 
diff --git a/gradelib.py b/gradelib.py
index f0d4934..21dd2bc 100644
--- a/gradelib.py
+++ b/gradelib.py
@@ -238,7 +238,7 @@ def make(*target):
     post_make()
 
 def show_command(cmd):
-    from pipes import quote
+    from shlex import quote
     print("\n$", " ".join(map(quote, cmd)))
 
 def maybe_unlink(*paths):
diff --git a/kernel/defs.h b/kernel/defs.h
index d1b6bb9..bed1531 100644
--- a/kernel/defs.h
+++ b/kernel/defs.h
@@ -187,3 +187,5 @@ void            virtio_disk_intr(void);
 
 // number of elements in fixed-size array
 #define NELEM(x) (sizeof(x)/sizeof((x)[0]))
+
+#define DEBUG()     printf("File: %s, Line: %d, Function: %s\n", __FILE__, __LINE__, __func__)
diff --git a/kernel/fcntl.h b/kernel/fcntl.h
index 44861b9..5aadb74 100644
--- a/kernel/fcntl.h
+++ b/kernel/fcntl.h
@@ -3,3 +3,4 @@
 #define O_RDWR    0x002
 #define O_CREATE  0x200
 #define O_TRUNC   0x400
+#define O_NOFOLLOW 0x004
\ No newline at end of file
diff --git a/kernel/file.h b/kernel/file.h
index b076d1d..5c4eb3a 100644
--- a/kernel/file.h
+++ b/kernel/file.h
@@ -26,7 +26,7 @@ struct inode {
   short minor;
   short nlink;
   uint size;
-  uint addrs[NDIRECT+1];
+  uint addrs[NDIRECT+2];
 };
 
 // map major device number to device functions.
diff --git a/kernel/fs.c b/kernel/fs.c
index c6bab15..d81e703 100644
--- a/kernel/fs.c
+++ b/kernel/fs.c
@@ -398,23 +398,59 @@ bmap(struct inode *ip, uint bn)
 
   if(bn < NINDIRECT){
     // Load indirect block, allocating if necessary.
-    if((addr = ip->addrs[NDIRECT]) == 0){
-      addr = balloc(ip->dev);
-      if(addr == 0)
-        return 0;
-      ip->addrs[NDIRECT] = addr;
-    }
-    bp = bread(ip->dev, addr);
-    a = (uint*)bp->data;
-    if((addr = a[bn]) == 0){
-      addr = balloc(ip->dev);
-      if(addr){
-        a[bn] = addr;
-        log_write(bp);
+    if(bn<NINDIRECT1){
+      if((addr = ip->addrs[NDIRECT]) == 0){
+        addr = balloc(ip->dev);
+        if(addr == 0)
+          return 0;
+        ip->addrs[NDIRECT] = addr;
       }
+      bp = bread(ip->dev, addr);
+      a = (uint*)bp->data;
+      if((addr = a[bn]) == 0){
+        addr = balloc(ip->dev);
+        if(addr){
+          a[bn] = addr;
+          log_write(bp);
+        }
+      }
+      brelse(bp);
+      return addr;
+    }else{
+      bn-=NINDIRECT1;
+      if((addr = ip->addrs[NDIRECT+1])==0){
+        addr = balloc(ip->dev);
+        if(addr == 0)
+          return 0;
+        ip->addrs[NDIRECT+1] = addr;
+      }
+      bp=bread(ip->dev,addr);
+      a = (uint *)bp->data;
+      const uint offset=bn%NINDIRECT1;
+      bn/=NINDIRECT1;
+      if((addr = a[bn])==0){
+        addr=balloc(ip->dev);
+        if(addr){
+          a[bn] = addr;
+          log_write(bp);
+        }
+      }
+      {
+        struct buf *bp=bread(ip->dev,addr);
+        a = (uint *)bp->data;
+        if((addr = a[offset])==0){
+          addr=balloc(ip->dev);
+          if(addr){
+            a[offset]=addr;
+            log_write(bp);
+          }
+        }
+        brelse(bp);
+      }
+      brelse(bp);
+      return addr;
     }
-    brelse(bp);
-    return addr;
+
   }
 
   panic("bmap: out of range");
@@ -439,7 +475,7 @@ itrunc(struct inode *ip)
   if(ip->addrs[NDIRECT]){
     bp = bread(ip->dev, ip->addrs[NDIRECT]);
     a = (uint*)bp->data;
-    for(j = 0; j < NINDIRECT; j++){
+    for(j = 0; j < NINDIRECT1; j++){
       if(a[j])
         bfree(ip->dev, a[j]);
     }
@@ -447,7 +483,25 @@ itrunc(struct inode *ip)
     bfree(ip->dev, ip->addrs[NDIRECT]);
     ip->addrs[NDIRECT] = 0;
   }
-
+  if(ip->addrs[NDIRECT+1]){
+    bp = bread(ip->dev,ip->addrs[NDIRECT+1]);
+    a = (uint*)bp->data;
+    for(j = 0;j<NINDIRECT1;++j){
+      if(a[j]){
+        struct buf *bp=bread(ip->dev,a[j]);
+        for(int j=0;j<NINDIRECT1;++j){
+          uint *a=(uint*)bp->data;
+          if(a[j])
+            bfree(ip->dev,a[j]);
+        }
+        brelse(bp);
+        bfree(ip->dev,a[j]);
+      }
+    }
+    brelse(bp);
+    bfree(ip->dev,ip->addrs[NDIRECT+1]);
+    ip->addrs[NDIRECT+1] = 0;
+  }
   ip->size = 0;
   iupdate(ip);
 }
@@ -508,11 +562,12 @@ writei(struct inode *ip, int user_src, uint64 src, uint off, uint n)
   uint tot, m;
   struct buf *bp;
 
-  if(off > ip->size || off + n < off)
+  if(off > ip->size || off + n < off){
     return -1;
-  if(off + n > MAXFILE*BSIZE)
+  }
+  if(off + n > MAXFILE*BSIZE){
     return -1;
-
+  }
   for(tot=0; tot<n; tot+=m, off+=m, src+=m){
     uint addr = bmap(ip, off/BSIZE);
     if(addr == 0)
diff --git a/kernel/fs.h b/kernel/fs.h
index 139dcc9..33a8337 100644
--- a/kernel/fs.h
+++ b/kernel/fs.h
@@ -24,8 +24,9 @@ struct superblock {
 
 #define FSMAGIC 0x10203040
 
-#define NDIRECT 12
-#define NINDIRECT (BSIZE / sizeof(uint))
+#define NDIRECT 11
+#define NINDIRECT1 (BSIZE / sizeof(uint))
+#define NINDIRECT (NINDIRECT1 + NINDIRECT1 * NINDIRECT1)
 #define MAXFILE (NDIRECT + NINDIRECT)
 
 // On-disk inode structure
@@ -35,7 +36,7 @@ struct dinode {
   short minor;          // Minor device number (T_DEVICE only)
   short nlink;          // Number of links to inode in file system
   uint size;            // Size of file (bytes)
-  uint addrs[NDIRECT+1];   // Data block addresses
+  uint addrs[NDIRECT+2];   // Data block addresses
 };
 
 // Inodes per block.
diff --git a/kernel/stat.h b/kernel/stat.h
index 19543af..bd8fe00 100644
--- a/kernel/stat.h
+++ b/kernel/stat.h
@@ -1,7 +1,7 @@
 #define T_DIR     1   // Directory
 #define T_FILE    2   // File
 #define T_DEVICE  3   // Device
-
+#define T_SYMLINK 4
 struct stat {
   int dev;     // File system's disk device
   uint ino;    // Inode number
diff --git a/kernel/syscall.c b/kernel/syscall.c
index ed65409..5e8f1ed 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -101,7 +101,7 @@ extern uint64 sys_unlink(void);
 extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
-
+extern uint64 sys_symlink(void);
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
 static uint64 (*syscalls[])(void) = {
@@ -126,6 +126,7 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
+[SYS_symlink] sys_symlink
 };
 
 void
diff --git a/kernel/syscall.h b/kernel/syscall.h
index bc5f356..0fbf6ed 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -20,3 +20,4 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+#define SYS_symlink 22
\ No newline at end of file
diff --git a/kernel/sysfile.c b/kernel/sysfile.c
index 16b668c..d8eb96b 100644
--- a/kernel/sysfile.c
+++ b/kernel/sysfile.c
@@ -327,6 +327,27 @@ sys_open(void)
       end_op();
       return -1;
     }
+    int dep=0;
+    if((omode & O_NOFOLLOW)==0){
+      while(1){
+        ilock(ip);
+        if(ip->type!=T_SYMLINK){
+          iunlock(ip);
+          break;
+        }
+        readi(ip,0,(uint64)path,0,MAXPATH);
+        iunlockput(ip);
+        if((ip = namei(path)) == 0){
+          end_op();
+          return -1;
+        }
+        ++dep;
+        if(dep>=10){
+          end_op();
+          return -1;
+        }
+      }
+    }
     ilock(ip);
     if(ip->type == T_DIR && omode != O_RDONLY){
       iunlockput(ip);
@@ -348,7 +369,7 @@ sys_open(void)
     end_op();
     return -1;
   }
-
+  
   if(ip->type == T_DEVICE){
     f->type = FD_DEVICE;
     f->major = ip->major;
@@ -474,6 +495,31 @@ sys_exec(void)
   return -1;
 }
 
+uint64 sys_symlink(){
+  char target[MAXPATH],path[MAXPATH];
+  if(argstr(0, target, MAXPATH) < 0 || argstr(1, path, MAXPATH) < 0)
+    goto ERR1;
+  begin_op();
+  struct inode *ip;
+  if((ip = namei(path)) == 0){
+    if((ip = create(path, T_SYMLINK,0,0))==0)
+      goto ERR2;
+  }else
+    ilock(ip);
+  if(writei(ip,0,(uint64)target,0,MAXPATH)<0){
+    goto ERR3;
+  }
+  iunlockput(ip);
+  end_op();
+  return 0;
+  ERR3:
+  iunlockput(ip);
+  ERR2:
+  end_op();
+  ERR1:
+  return -1;
+}
+
 uint64
 sys_pipe(void)
 {
diff --git a/time.txt b/time.txt
new file mode 100644
index 0000000..1e8b314
--- /dev/null
+++ b/time.txt
@@ -0,0 +1 @@
+6
diff --git a/user/symlinktest.c b/user/symlinktest.c
index 781fc9e..632f90c 100644
--- a/user/symlinktest.c
+++ b/user/symlinktest.c
@@ -135,10 +135,10 @@ testsymlink(void)
   if(c!=c2)
     fail("Value read from 4 differed from value written to 1\n");
 
+
   close(fd1);
   close(fd2);
   fd1 = fd2 = -1;
-
   //
   // check that many symlinks can co-exist.
   //
diff --git a/user/user.h b/user/user.h
index f16fe27..5c8290c 100644
--- a/user/user.h
+++ b/user/user.h
@@ -22,7 +22,7 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
-
+int symlink(const char *,const char *);
 // ulib.c
 int stat(const char*, struct stat*);
 char* strcpy(char*, const char*);
diff --git a/user/usys.pl b/user/usys.pl
index 01e426e..65a8d6b 100755
--- a/user/usys.pl
+++ b/user/usys.pl
@@ -36,3 +36,4 @@ entry("getpid");
 entry("sbrk");
 entry("sleep");
 entry("uptime");
+entry("symlink");
\ No newline at end of file