linux_lab_os_exp2/linux/kernel/sys.c

/*
 *  linux/kernel/sys.c
 *
 *  (C) 1991  Linus Torvalds
 */
#include <stdarg.h>
 
#include <linux/config.h>
#include <asm/system.h>
#include <asm/io.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <sys/times.h>
#include <sys/utsname.h>
#include <stdarg.h>
#include <new.h>
#include <mm.h>
//ADD FOR getcwd    

long sys_getcwd(char *buf,size_t size)
{
	int block=current->pwd->i_zone[0];	
	int idev=current->pwd->i_dev;
	int flag=0;
	struct buffer_head * bh;
	struct dir_entry * de;
	struct m_inode *dir=current->pwd,*rdir=current->root;
	if(dir==rdir) 
	{
		flag=1;
		goto mytag;
	}
	unsigned short curinode,finode,tempfi;
	char name[128],base[128];
	int entries,i;

	if (!(block = current->pwd->i_zone[0]))
		return NULL;
	if (!(bh = bread(current->pwd->i_dev,block)))
		return NULL;
	de = (struct dir_entry *) bh->b_data;
	curinode=de->inode;
	de++;
	finode=de->inode; 
	while (rdir!=dir)
	{
		//update father
		dir=iget(idev,finode); 
		if (!(block = dir->i_zone[0]))
			return NULL;
		if (!(bh = bread(dir->i_dev,block)))
			return NULL;
		i = 0;
		entries = dir->i_size / (sizeof (struct dir_entry));
		de = (struct dir_entry *) bh->b_data;
		tempfi=(de+1)->inode;
		while (i < entries) {
			if ((char *)de >= BLOCK_SIZE+bh->b_data) {
				brelse(bh);
				bh = NULL;
				if (!(block = bmap(dir,i/DIR_ENTRIES_PER_BLOCK)) ||
					!(bh = bread(dir->i_dev,block))) {
					i += DIR_ENTRIES_PER_BLOCK;
					continue;
				}
				de = (struct dir_entry *) bh->b_data;
			}
				if(de->inode==curinode)
				{
					memset(base,'\0',sizeof(base));
					strcat(base,"/");
					strcat(base,de->name);
					strcat(base,name);
					strcpy(name,base);
					break;
				}
			de++;
			i++;
		}
		curinode=finode;
		finode=tempfi;
	}
mytag:
	if(flag) strcpy(name,"/");
	size_t len=strlen(name);
	if(size<len && buf!=NULL)
	{
		errno=ERANGE;
		return NULL;
	}
	if(!buf)
		buf=(char*)malloc(len);
	char *p1=buf;
	char *p2=name;
	while(len--)
		put_fs_byte(*(p2++),p1++);
	return buf;
}
//THE END 
int sys_getdents(unsigned int fd,struct linux_dirent *dirp,unsigned int count)
{
	struct m_inode	*filenode =current->filp[fd]->f_inode;
	int block,i,entries,sizdir=sizeof(struct dir_entry);
	struct buffer_head * bh;
	struct dir_entry * de;
	struct linux_dirent *initmp,*temp;
	if(!(temp=(struct linux_dirent *)malloc(count+64)))
		return -1;
	initmp=temp;
	int size=sizeof(long)+sizeof(off_t)+sizeof(unsigned short);
	
	if (!(block = filenode->i_zone[0]))
		return -1;
	if (!(bh = bread(filenode->i_dev,block)))
		return -1;
	de = (struct dir_entry *) bh->b_data;
	entries=filenode->i_size/(sizeof(struct dir_entry));
	i=0;
	int nread=0,pos=0;
	while(i<entries)
	{
		if ((char *)de >= BLOCK_SIZE+bh->b_data) {
				brelse(bh);
				bh = NULL;
				if (!(block = bmap(filenode,i/DIR_ENTRIES_PER_BLOCK)) ||
					!(bh = bread(filenode->i_dev,block))) {
					i += DIR_ENTRIES_PER_BLOCK;
					continue;
				}
				pos+=((char*) bh->b_data-(char*)(de));
				de = (struct dir_entry *) bh->b_data;
			}
		temp->d_ino=de->inode;
		temp->d_off=pos;
		strcpy(temp->d_name,de->name);
		temp->d_reclen=sizeof(de);
		nread+=temp->d_reclen;
		temp=(struct linux_dirent*)((char*)temp+temp->d_reclen);
		de++;
		pos+=sizdir;
		i++;
	}
	if(count<nread)
	{
		errno=ERANGE;
		return -1;
	}//printk("%d",nread);
	i=nread;
	char *p1=dirp;
	char *p2=initmp;
	while(i--)
		put_fs_byte(*(p2++),p1++);
	free(initmp);
	return nread;
}
int sys_pipe2()
{
	return -1;
}
unsigned int sys_sleep(unsigned int seconds)
{
	struct sigaction tmp;
	tmp.sa_handler = (void (*)(int)) SIG_IGN;
	tmp.sa_mask = 0;
	tmp.sa_flags = SA_ONESHOT | SA_NOMASK;
	tmp.sa_restorer = (void (*)(void)) NULL;
	current->sigaction[SIGALRM-1] = tmp;
	current->alarm=(seconds>0)?(jiffies+HZ*seconds):0;
	current->state=TASK_INTERRUPTIBLE;
	current->counter=(current->counter>>1)+current->priority;
	schedule();
	return 0;
}

int sys_clone()
{

	return -1;
}

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;
}

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;
}

int sys_time(long * tloc)
{
	int i;

	i = CURRENT_TIME;
	if (tloc) {
		verify_area(tloc,4);
		put_fs_long(i,(unsigned long *)tloc);
	}
	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;
}

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;
}

int sys_brk(unsigned long end_data_seg)
{
	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);
	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);
}

static int my_share(unsigned long address, struct task_struct * p)
{
	unsigned long from;
	unsigned long to;
	unsigned long from_page;
	unsigned long to_page;
	unsigned long phys_addr;

	from_page = to_page = ((address>>20) & 0xffc);
	from_page += ((current->start_code>>20) & 0xffc);
	to_page += ((p->start_code>>20) & 0xffc);

	from = *(unsigned long *) from_page;
	from &= 0xfffff000;
	from_page = from + ((address>>10) & 0xffc);
	phys_addr = *(unsigned long *) from_page;
	to = *(unsigned long *) to_page;
	if (!(to & 1))
		if (to = get_free_page())
			*(unsigned long *) to_page = to | 7;
		else
			return 0;
	to &= 0xfffff000;
	to_page = to + ((address>>10) & 0xffc);
	if (1 & *(unsigned long *) to_page)
		return 0;
	/* share them: write-protect */
	*(unsigned long *) to_page = *(unsigned long *) from_page;
	phys_addr -= LOW_MEM;
	phys_addr >>= 12;
	mem_map[phys_addr]++;
	return 1;
}

// rememeber to sync when munmap exit manual 

long sys_mmap(void * start,size_t len,...)// int prot,int flags,int fd,off_t off
{
	printk("start mmaping\n");
	/* va_list args;
	va_start(args,len); */
	int prot=3,flags=1,fd=3,off=0;
	/* prot=va_arg(args,int);flags=va_arg(args,int);fd=va_arg(args,int);
	off_t off=va_arg(args,off_t);
	int *ll=&len;printk("%d,%d,%d,%d,%d\n",*ll,*(ll+1),*(ll+2),*(ll+3),*(ll+4));
	va_end(args);
	printk("%d,%d,%d,%ld\n",prot,flags,fd,off); */
	
	int block;
	size_t l=len;
	struct buffer_head * bh;
	char *temp,*p1,*p2;
	void * buf=start;
	int tempprot=0;
	
	//因为new.h和namei.c定义不一样，要修改
	if(prot &PROT_READ) tempprot |=4;
	if(prot &PROT_EXEC) tempprot |=1;
	if(prot &PROT_WRITE) tempprot |=2;

	//特殊量len>0 off%4096==0 prot至少有read权限
	if(len<=0 ||  off<0 || (off%PAGE_SIZE)) 
	{
		if(len<=0) 
			printk("the len of the wanting bytes must be positive");
		else
			printk("offset must be the mul of 4096");
		return MAP_FAILED;
	}	
	if(!(prot& PROT_READ)) return MAP_FAILED;

	//permissions of the file ,搬运函数namei.c::permissions
	printk("fd: %d\n",fd);
	struct m_inode *inode=current->filp[fd]->f_inode;
	printk("end of permissions\n");
	int mode = inode->i_mode;
	if (inode->i_dev && !inode->i_nlinks)
		{printk("end of permissions1\n");return MAP_FAILED;}
	else if (current->euid==inode->i_uid)
		mode >>= 6;
	else if (current->egid==inode->i_gid)
		mode >>= 3;
	if (!(((mode & tempprot & 0007) == tempprot) || suser()))
	{
		printk("error permission.");
		return MAP_FAILED;
	}
	//end of permission check
	printk("end of permissions\n");
	
	//设置用户空间的虚拟地址，初始为32MB处，这样写在brk增长至32MB时会有bug,我们忽略
	//同时，当栈向下增长到一定程度时，也会和当前地址冲突，我们忽略
	if(start<=current->brk || start>=current->start_stack-0x8000 || start==NULL) 
	{
		if(!current->mmap_tail)
			buf=0x2000000;
		else
			buf=current->mmap_tail->endaddr;
	}
	//申请mmap
	struct mmap_struct *mmap=(struct mmap_struct *)malloc(sizeof(struct mmap_struct));
	mmap->address=buf;
	mmap->size=len;
	mmap->endaddr=(unsigned long)buf+(len + 0xfff)&0xfffff000;
	mmap->rw=prot;
	mmap->ps=flags;
	mmap->next=NULL;
	//加入current->mmap
	if(!current->mmap) 
		{current->mmap=current->mmap_tail=mmap;}
	else 
		current->mmap_tail->next=mmap;
	printk("buf: %x\n",(unsigned long )buf);
	
	//分配物理页

	unsigned long from;
	unsigned long to;
	unsigned long from_page;
	unsigned long to_page;
	unsigned long phys_addr;
	unsigned long tpage;
	unsigned long address=mmap->address;
	while(address<mmap->endaddr)
	{
		from_page =  ((mmap->address>>20) & 0xffc);
		from_page += ((current->start_code>>20) & 0xffc);//页目录
		if(!(*(unsigned long *)from_page&1))  //页表项不存在，申请页面
			if(!(tpage=get_free_page()))
			{
				printk("out of memory.\n");
				return MAP_FAILED;
			}
			else
				*(unsigned long *)from_page= tpage | 7;
		from=*(unsigned long *)from_page;	//页表项
		from &= 0xfffff000;
		from_page = from + ((address>>10) & 0xffc);
		if(!(*(unsigned long *)from_page & 1))	//物理页不存在
			if(!(tpage=get_free_page()))
			{
				printk("out of memory.\n");
				return MAP_FAILED;
			}
			else
				*(unsigned long *)from_page= tpage | 7; 
		*(unsigned long *)from_page &= (prot&PROT_WRITE); //分配读写权限
		if(flags & MAP_SHARED)
		{
			struct task_struct ** p;

			for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
				if (!*p)
					continue;
				if (current == *p)
					continue;
				if(!my_share(address,*p))
					printk("share failed at task:pid=%d",(*p)->pid);
			}
		}
		address+=PAGE_SIZE;
	}
		
	//read and put in 
	if (!(block = inode->i_zone[0]))
		return NULL;
	if (!(bh = bread(inode->i_dev,block)))
		return NULL;
	temp = (char *) bh->b_data;
	p1=temp;p2=buf;
	while(l--)
		put_fs_byte(*(p1++),p2++);
	printk("%s\n",temp);
	return buf;
}
int sys_munmap()
{

	return -1;
}