diff --git a/1.c b/1.c
new file mode 100644
index 0000000..db89bad
--- /dev/null
+++ b/1.c
@@ -0,0 +1,401 @@
+/*
+ *  linux/kernel/sys.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+
+#include <linux/sched.h>	//调度程序头文件。定义了任务结构task_struct,任务0的数据,
+							//还有一些有关描述符参数设置和获取的嵌入式汇编函数宏语言
+#include <linux/tty.h>
+#include <linux/kernel.h>	//内核头文件
+#include <asm/segment.h>
+#include <sys/times.h>
+#include <sys/utsname.h>	//系统名称结构头文件
+
+#include <fcntl.h>
+int sys_ftime()
+{
+	return -ENOSYS;
+}
+
+int sys_break()
+{
+	return -ENOSYS;
+}
+
+int sys_ptrace()
+{
+	return -ENOSYS;
+}
+
+int sys_stty()
+{
+	return -ENOSYS;
+}
+
+int sys_gtty()
+{
+	return -ENOSYS;
+}
+
+int sys_rename()
+{
+	return -ENOSYS;
+}
+
+int sys_prof()
+{
+	return -ENOSYS;
+}
+
+int sys_setregid(int rgid, int egid)
+{
+	if (rgid>0) {
+		if ((current->gid == rgid) || 
+		    suser())
+			current->gid = rgid;
+		else
+			return(-EPERM);
+	}
+	if (egid>0) {
+		if ((current->gid == egid) ||
+		    (current->egid == egid) ||
+		    suser()) {
+			current->egid = egid;
+			current->sgid = egid;
+		} else
+			return(-EPERM);
+	}
+	return 0;
+}
+//设置进程组号
+int sys_setgid(int gid)
+{
+/*	return(sys_setregid(gid, gid)); */
+	if (suser())
+		current->gid = current->egid = current->sgid = gid;
+	else if ((gid == current->gid) || (gid == current->sgid))
+		current->egid = gid;
+	else
+		return -EPERM;
+	return 0;
+}
+
+int sys_acct()
+{
+	return -ENOSYS;
+}
+
+int sys_phys()
+{
+	return -ENOSYS;
+}
+
+int sys_lock()
+{
+	return -ENOSYS;
+}
+
+int sys_mpx()
+{
+	return -ENOSYS;
+}
+
+int sys_ulimit()
+{
+	return -ENOSYS;
+}
+//返回从1970年1月1号 开始记时的时间值(s)
+int sys_time(long * tloc)
+{
+	int i;
+
+	i = CURRENT_TIME;
+	if (tloc) {
+		verify_area(tloc,4);
+		put_fs_long(i,(unsigned long *)tloc);	//把时间值存储到用户空间
+		//段寄存器fs被默认地指向用户数据空间，因此此函数可利用fs段寄存器来访问用户空间中的值
+	}
+	return i;
+}
+
+/*
+ * Unprivileged users may change the real user id to the effective uid
+ * or vice versa.
+ */
+int sys_setreuid(int ruid, int euid)
+{
+	int old_ruid = current->uid;
+	
+	if (ruid>0) {
+		if ((current->euid==ruid) ||
+                    (old_ruid == ruid) ||
+		    suser())
+			current->uid = ruid;
+		else
+			return(-EPERM);
+	}
+	if (euid>0) {
+		if ((old_ruid == euid) ||
+                    (current->euid == euid) ||
+		    suser()) {
+			current->euid = euid;
+			current->suid = euid;
+		} else {
+			current->uid = old_ruid;
+			return(-EPERM);
+		}
+	}
+	return 0;
+}
+
+int sys_setuid(int uid)
+{
+/*	return(sys_setreuid(uid, uid)); */
+	if (suser())
+		current->uid = current->euid = current->suid = uid;
+	else if ((uid == current->uid) || (uid == current->suid))
+		current->euid = uid;
+	else
+		return -EPERM;
+	return(0);
+}
+
+int sys_stime(long * tptr)
+{
+	if (!suser())
+		return -EPERM;
+	startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;
+	return 0;
+}
+//获取当前任务运行时间统计值
+int sys_times(struct tms * tbuf)
+{
+	if (tbuf) {
+		verify_area(tbuf,sizeof *tbuf);
+		put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
+		put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
+		put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
+		put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
+	}
+	return jiffies;
+}
+//设置程序在内存中的末端位置
+int sys_brk(unsigned long end_data_seg)
+{
+	//如果参数值大于代码结尾，并且小于（堆栈-16kb），则设置新数据段结尾值
+	if (end_data_seg >= current->end_code &&
+	    end_data_seg < current->start_stack - 16384)
+		current->brk = end_data_seg;
+	return current->brk;
+}
+
+/*
+ * This needs some heave checking ...
+ * I just haven't get the stomach for it. I also don't fully
+ * understand sessions/pgrp etc. Let somebody who does explain it.
+ */
+int sys_setpgid(int pid, int pgid)
+{
+	int i;
+
+	if (!pid)
+		pid = current->pid;
+	if (!pgid)
+		pgid = current->pid;
+	for (i=0 ; i<NR_TASKS ; i++)
+		if (task[i] && task[i]->pid==pid) {
+			if (task[i]->leader)
+				return -EPERM;
+			if (task[i]->session != current->session)
+				return -EPERM;
+			task[i]->pgrp = pgid;
+			return 0;
+		}
+	return -ESRCH;
+}
+
+int sys_getpgrp(void)
+{
+	return current->pgrp;
+}
+
+int sys_setsid(void)
+{
+	if (current->leader && !suser())
+		return -EPERM;
+	current->leader = 1;
+	current->session = current->pgrp = current->pid;
+	current->tty = -1;
+	return current->pgrp;
+}
+
+int sys_getgroups()
+{
+	return -ENOSYS;
+}
+
+int sys_setgroups()
+{
+	return -ENOSYS;
+}
+
+int sys_uname(struct utsname * name)
+{
+	static struct utsname thisname = {
+		"linux .0","nodename","release ","version ","machine "
+	};
+	int i;
+
+	if (!name) return -ERROR;
+	verify_area(name,sizeof *name);
+	for(i=0;i<sizeof *name;i++)
+		put_fs_byte(((char *) &thisname)[i],i+(char *) name);	//用来访问用户程序的数据
+	return 0;
+}
+
+int sys_sethostname()
+{
+	return -ENOSYS;
+}
+
+int sys_getrlimit()
+{
+	return -ENOSYS;
+}
+
+int sys_setrlimit()
+{
+	return -ENOSYS;
+}
+
+int sys_getrusage()
+{
+	return -ENOSYS;
+}
+
+int sys_gettimeofday()
+{
+	return -ENOSYS;
+}
+
+int sys_settimeofday()
+{
+	return -ENOSYS;
+}
+
+
+int sys_umask(int mask)
+{
+	int old = current->umask;
+
+	current->umask = mask & 0777;
+	return (old);
+}
+
+int sys_pipe2(void){
+	return 0;
+}
+
+int sys_sleep(unsigned int seconds){
+	sys_signal(SIGALRM,SIG_IGN);
+	sys_alarm(seconds);
+	sys_pause();
+	return 0;
+}
+
+int sys_execve2(){
+	return 0;
+}
+/*获取目录的目录项*/
+/*fd指目录描述符，dirp指目录信息，count指目录信息大小*/
+int sys_getdents(unsigned int fd,struct linux_dirent *dirp,unsigned int count)
+{
+	struct file *file;
+    struct m_inode *inode;
+	struct buffer_head *bh;
+    struct dir_entry *de;
+    struct linux_dirent *temp;
+    char * buf;
+    int i,len = 0,ret = 0;
+
+    if(!count)return -1;							
+    if(fd>=NR_OPEN)return -1;					/*fd超过进程最多打开文件数20*/
+    
+    file=current->filp[fd];
+    if(!file)return -1;
+    inode = file->f_inode;
+    temp = (struct linux_dirent *)malloc(sizeof(struct linux_dirent)); //目录信息
+    buf = (char*)malloc(sizeof(struct linux_dirent)); 
+	bh = bread(inode->i_dev , inode->i_zone[0]);	//读取指向的数据块
+
+    for (;ret<inode->i_size;ret += sizeof(struct dir_entry)){
+        if (len >= count-sizeof(struct linux_dirent))
+            break; /* full */
+        de = (struct dir_entry *)(bh->b_data + ret);/*de更新为当前目录项*/
+        if (!de->inode )/*如果节点号为空，就退出*/
+            continue;            
+        /*用temp保存当前目录项信息*/
+        temp->d_ino = de->inode;
+        temp->d_off = 0; 
+        temp->d_reclen = sizeof(struct linux_dirent);
+        strcpy(temp->d_name,de->name);
+        /*将数据写回到用户*/
+        memcpy(buf, temp, sizeof(struct linux_dirent));
+        for (i=0;i < sizeof(struct linux_dirent);i++){
+            put_fs_byte(*(buf+i), ((char*)dirp)+len+i); 	//用来访问用户程序的数据
+        }
+        len += sizeof(struct linux_dirent);
+    }
+    return len;
+}
+//参考find_entry
+int sys_getcwd(char* buf,size_t size){
+	struct buffer_head *bh;
+	struct dir_entry*de,*p_de;
+
+    unsigned current_depth = 0;
+    struct m_inode* current_ino;
+    struct m_inode* parent_ino;
+	char* t_buf;
+	int ret = 0;
+	t_buf = (char*)malloc(256);
+	strcpy(t_buf,"");
+	buf = malloc(size);
+	if(!buf)return -1;
+
+    for(;;){
+        current_ino = namei(".");
+        parent_ino = namei("..");
+        if(current_ino == parent_ino)		//找到了根节点
+            break;
+        sys_chdir("..");
+        //read_inode(current_ino);		这是个静态函数
+        //buf[current_depth++] = read_inode(current_ino);//根据节点号，在当前目录查找文件read_inode
+		bh = bread(parent_ino->i_dev,parent_ino->i_zone[0]);
+		for(;ret<parent_ino->i_size;ret+=sizeof(struct dir_entry))
+		{
+			de = (struct dir_entry*)(bh->b_data + ret);
+			if(!de->inode)break;
+			if(de->inode == (current_ino->i_num)){
+				memcpy(t_buf,de->name,NAME_LEN);
+				current_depth += NAME_LEN;
+				break;
+			}
+		}
+		//current_depth++;
+    }
+    // int i = current_depth-1;
+    // for(i;i >= 0;i--){
+    //     printk("/%s",buf[i]);
+    // }
+    // printk("%s\n",current_depth==0?"/":"");
+    // //复制过来
+	int i;
+	for(i = 0;t_buf[i];i++){
+		put_fs_byte(t_buf[i],buf+i);
+	}
+    return (int)buf;
+}