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p6a8nelzg 2 years ago
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sys.c
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/*
* 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 <asm/io.h>
#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;
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,* tmp;
// int ret = 0;
// t_buf = (char*)malloc(256);
// strcpy(t_buf,"");
// 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)){
// strcpy(tmp,"/");
// strcat(tmp,de->name);
// strcat(tmp,t_buf);
// strcpy(t_buf,tmp);
// current_depth += NAME_LEN;
// break;
// }
// }
// //current_depth++;
// }
// int i;
// for(i = 0;t_buf[i];i++){
// put_fs_byte(t_buf[i],buf+i);
// }
// return (int)buf;
// }
#define BUF_MAX 256
int sys_getcwd(char * buf, size_t size)
{
char temp[BUF_MAX], t_buf[BUF_MAX];
int flag,len;
struct m_inode *parent_ino,*current_ino,*root;
struct super_block *sb;
struct dir_entry *de,*p_de;
int i;
sb = (struct super_block *)bread(current->pwd->i_dev,1);
current_ino = current->pwd;
root = current->root;
while(current_ino->i_num != root->i_num)
{
de = (struct dir_entry *)bread(current_ino->i_dev,current_ino->i_zone[0])->b_data;
int de_num = current_ino->i_size/sizeof(struct dir_entry);//当前目录的目录项数量
flag = 0;
for(i=0;i<de_num;i++){
if(!strcmp((de+i)->name,"..")){
flag = 1;
parent_ino = iget(current_ino->i_dev,(de + i)->inode); //寻找父目录节点
break;
}
}
if(!flag) {
return NULL;
}
p_de = (struct dir_entry *)bread(parent_ino->i_dev,parent_ino->i_zone[0])->b_data;
int p_de_num = parent_ino->i_size/sizeof(struct dir_entry); //父目录的目录项数量
flag = 0;
for(i=0;i<p_de_num;i++){
if((p_de+i)->inode == current_ino->i_num){ //比对当前节点的节点号相同，则记录，并回溯
memset(temp, 0, sizeof(temp));
strcat(temp,"/");
strcat(temp,(p_de+i)->name);
strcat(temp,t_buf);
strncpy(t_buf,temp,BUF_MAX);
flag = 1;
break;
}
}
if(!flag){
return NULL;
}
current_ino = parent_ino;
}
for(i=0;i<strlen(t_buf);i++){
put_fs_byte(t_buf[i],buf+i);
}
return (int)buf;
}
/*
start:映射起始位置
len:长度
prot:映射的内存保护⽅式，可取：PROT_EXEC, PROT_READ, PROT_WRITE, PROT_NONE
flags:映射是否与其他进程共享的标志，可取：MAP_FILE, MAP_SHARED, MAP_PRIVATE
fd:⽂件句柄，文件描述符，代表要映射的文件
off:⽂件偏移量
返回值:成功返回已映射区域的指针，失败返回-1;
内存映射函数mmap, 负责把文件内容映射到进程的虚拟内存空间, 通过对这段内存的读取和修改，
来实现对文件的读取和修改,而不需要再调用read，write等操作。
PROT_EXEC: 映射区可被执行
PROT_READ: 映射区可被读取
PROT_WRITE: 映射区可被写入
MAP_SHARED:写入映射区的数据会复制回文件, 且允许其他映射该文件的进程共享。
MAP_PRIVATE:对映射区的写入操作会产生一个映射区的复制(copy-on-write),
对此区域所做的修改不会写回原文件。
*/
// typedef struct { unsigned long pgprot; } pgprot_t;
// struct vm_area_struct{
// unsigned long vm_start; //虚拟内存起始地址
// unsigned long vm_end;
// unsigned long vm_flags; //该区域的标志
// pgprot_t vm_page_prot;
// };
// int memdev_mmap(struct file*filp,struct vm_area_struct *vma){
// vma->vm_flags |= VM_IO;
// vma->vm_flags |= VM_RESEVED;
// if(remap_pfn_range(vma,vma->vm_start,virt_to_phys(dev->data)>>PAGE_SHIFT,
// size,vma->vm_page_prot))
// return -EAGAIN;
// return 0;
// }
int sys_mmap(void* start,size_t len,int prot,int flags,
int fd,off_t off){
return 0;
};
#define vga_graph_memstart 0xA0000
#define vga_graph_memsize 64000
#define cursor_side 6
#define width 320
#define height 200
//#define barrier_width 10
int volatile jumpp;
int flag=0;
int sys_init_graphics()
{
int i,j,x,y;
char *p=vga_graph_memstart;
x = 20;y = 20;
if(flag==0)
{
/* 图形控制器，拼接器有关寄存器端口是0x3CE和0x3C4 */
/* 先往寄存器端口写索引号，端口地址下一个写命令或读入数据 */
/* 在0x3CE端口中有对应索引号0x06的寄存器，
第0位用来控制字符模式,1启动图形模式;2,3位决定显存位置*/
/* 0x3CE中索引号0x05的寄存器，
第六位设置为1，设定为256色*/
outb(0x05,0x3CE);
outb(0x40,0x3CF);/* 设定256色，且取出方式为移动拼装*/
/*显存区域 A0000H - AFFFFH(64KB) */
outb(0x06,0x3CE);
outb(0x05,0x3CF);/*设定现存的地址区域，禁止字符模式*/
/*0x4C4下的索引号为0x04的寄存器
第四位为chain4，用于将4个显存片连在一起*/
outb(0x04,0x3C4);
outb(0x08,0x3C5);/*设定将4个现存片连在一起*/
/*设置End Horizontal Display 为79*/
/*用于控制在屏幕上显示的扫描线长度 */
outb(0x01,0x3D4);
outb(0x4F,0x3D5);
/*0x03寄存器,0-4位表示End Horizontal Blanking
5,6位表示Display Enable Skew;7位表示EVRA*/
outb(0x03,0x3D4);
outb(0x82,0x3D5); //设置Skew 为0
outb(0x07,0x3D4);
outb(0x1F,0x3D5);/*vertical display end No8,9 bit=1,0*/
outb(0x12,0x3D4);
outb(0x8F,0x3D5);/*vertical display end low 7b =0x8F*/
/*CRT控制器中索引号为0x17的寄存器中的SLDIV位设置为1,
Scanline Counter加一的周期为两个扫描周期*/
outb(0x17,0x3D4);
outb(0xA3,0x3D5);/*SLDIV=1 ,scanline clock/2*/
outb(0x14,0x3D4);
outb(0x40,0x3D5);/*DW=1*/
/*移动距离 = 2*Memory Address Size
* Offset Register/Pixels Per Address*/
outb(0x13,0x3D4);
outb(0x28,0x3D5);/*Offset=40, 20:bian chang*/
/*开始绘制屏幕*/
outb(0x0C,0x3D4);
outb(0x00,0x3D5);
outb(0x0D,0x3D4);
outb(0x00,0x3D5);/*Start Address=0xA0000*/
flag=1;
}
for(i=0;i<vga_graph_memsize;i++) *p++=3; //背景为蓝色
//3-blue 4-red 12-purple
for(i=x-cursor_side;i<=x+cursor_side;i++)
for(j=y-cursor_side;j<=y+cursor_side;j++){
p=(char *) vga_graph_memstart+j*width+i;
*p=12; //鼠标为红色
}
return 0;
}
int sys_get_message(){
return 0;
}
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