哈工大操作系统试验 7 proc文件系统的实现

特别鸣谢成武同学提供的代码~

//==============================================================================

1.cpu的占用律 cupinfo,可以更好的了解cpu的使用情况。
2.是变化前的，f_pos为0时才会更新psinfo内容。

//==============================================================================

这次试验没有想象中那么难

需要修改

linux-0.11/include/sys/stat.h

linux-0.11/init/main.c

linux-0.11/fs/read_write.c

linux-0.11/fs/namei.c

这几个文件

自己写一个

linux-0.11/fs/proc.c

文件

不要忘记把fs中的makefile改掉，要不然你自己新写的proc.c是不会被编译进去的。

或者你比较懒，可以到测试脚本中找makefile.c直接粘贴过来也行。

修改的部分试验指导书写的很清楚，按图索骥就可以改好

stat.h   修改成这样，完全按照指导书来就行。需要定义一个字符数组。用处见proc.c

#ifndef _SYS_STAT_H
#define _SYS_STAT_H

#include <sys/types.h>

struct stat {
	dev_t	st_dev;
	ino_t	st_ino;
	umode_t	st_mode;
	nlink_t	st_nlink;
	uid_t	st_uid;
	gid_t	st_gid;
	dev_t	st_rdev;
	off_t	st_size;
	time_t	st_atime;
	time_t	st_mtime;
	time_t	st_ctime;
};

#define S_IFMT  00170000
#define S_IFREG  0100000
#define S_IFBLK  0060000
#define S_IFDIR  0040000
#define S_IFPROC 0050000
#define S_IFCHR  0020000
#define S_IFIFO  0010000
#define S_ISUID  0004000
#define S_ISGID  0002000
#define S_ISVTX  0001000


#define S_ISREG(m)	(((m) & S_IFMT) == S_IFREG)
#define S_ISDIR(m)	(((m) & S_IFMT) == S_IFDIR)
#define S_ISCHR(m)	(((m) & S_IFMT) == S_IFCHR)
#define S_ISBLK(m)	(((m) & S_IFMT) == S_IFBLK)
#define S_ISPROC(m) (((m) & S_IFMT) == S_IFPROC)
#define S_ISFIFO(m)	(((m) & S_IFMT) == S_IFIFO)


#define S_IRWXU 00700
#define S_IRUSR 00400
#define S_IWUSR 00200
#define S_IXUSR 00100

#define S_IRWXG 00070
#define S_IRGRP 00040
#define S_IWGRP 00020
#define S_IXGRP 00010

#define S_IRWXO 00007
#define S_IROTH 00004
#define S_IWOTH 00002
#define S_IXOTH 00001 

char psbuffer[1024];
extern int chmod(const char *_path, mode_ta mode);
extern int fstat(int fildes, struct stat *stat_buf);
extern int mkdir(const char *_path, mode_t mode);
extern int mkfifo(const char *_path, mode_t mode);
extern int stat(const char *filename, struct stat *stat_buf);
extern mode_t umask(mode_t mask);

#endif

main.c 这样改 吧mknod和mkdir的宏加在开头

然后在init函数中调用一下就可以了，参数神马的指导书里也有详细讲解。

/*
 *  linux/init/main.c
 *
 *  (C) 1991  Linus Torvalds
 */

#define __LIBRARY__
#include <unistd.h>
#include <time.h>
#include <sys/stat.h>

/*
 * we need this inline - forking from kernel space will result
 * in NO COPY ON WRITE (!!!), until an execve is executed. This
 * is no problem, but for the stack. This is handled by not letting
 * main() use the stack at all after fork(). Thus, no function
 * calls - which means inline code for fork too, as otherwise we
 * would use the stack upon exit from 'fork()'.
 *
 * Actually only pause and fork are needed inline, so that there
 * won't be any messing with the stack from main(), but we define
 * some others too.
 */
static inline _syscall0(int,fork)
static inline _syscall0(int,pause)
static inline _syscall1(int,setup,void *,BIOS)
static inline _syscall0(int,sync)
_syscall2(int,mkdir,const char*,name,mode_t,mode)
_syscall3(int,mknod,const char*,filename,mode_t,mode,dev_t,dev)
 
#include <linux/tty.h>
#include <linux/sched.h>
#include <linux/head.h>
#include <asm/system.h>
#include <asm/io.h>

#include <stddef.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>

#include <linux/fs.h>

static char printbuf[1024];

extern int vsprintf();
extern void init(void);
extern void blk_dev_init(void);
extern void chr_dev_init(void);
extern void hd_init(void);
extern void floppy_init(void);
extern void mem_init(long start, long end);
extern long rd_init(long mem_start, int length);
extern long kernel_mktime(struct tm * tm);
extern long startup_time;

/*
 * This is set up by the setup-routine at boot-time
 */
#define EXT_MEM_K (*(unsigned short *)0x90002)
#define DRIVE_INFO (*(struct drive_info *)0x90080)
#define ORIG_ROOT_DEV (*(unsigned short *)0x901FC)

/*
 * Yeah, yeah, it's ugly, but I cannot find how to do this correctly
 * and this seems to work. I anybody has more info on the real-time
 * clock I'd be interested. Most of this was trial and error, and some
 * bios-listing reading. Urghh.
 */

#define CMOS_READ(addr) ({ \
outb_p(0x80|addr,0x70); \
inb_p(0x71); \
})

#define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)

static void time_init(void)
{
	struct tm time;

	do {
		time.tm_sec = CMOS_READ(0);
		time.tm_min = CMOS_READ(2);
		time.tm_hour = CMOS_READ(4);
		time.tm_mday = CMOS_READ(7);
		time.tm_mon = CMOS_READ(8);
		time.tm_year = CMOS_READ(9);
	} while (time.tm_sec != CMOS_READ(0));
	BCD_TO_BIN(time.tm_sec);
	BCD_TO_BIN(time.tm_min);
	BCD_TO_BIN(time.tm_hour);
	BCD_TO_BIN(time.tm_mday);
	BCD_TO_BIN(time.tm_mon);
	BCD_TO_BIN(time.tm_year);
	time.tm_mon--;
	startup_time = kernel_mktime(&time);
}

static long memory_end = 0;
static long buffer_memory_end = 0;
static long main_memory_start = 0;

struct drive_info { char dummy[32]; } drive_info;

void main(void)		/* This really IS void, no error here. */
{			/* The startup routine assumes (well, ...) this */
/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
 	ROOT_DEV = ORIG_ROOT_DEV;
 	drive_info = DRIVE_INFO;
	memory_end = (1<<20) + (EXT_MEM_K<<10);
	memory_end &= 0xfffff000;
	if (memory_end > 16*1024*1024)
		memory_end = 16*1024*1024;
	if (memory_end > 12*1024*1024) 
		buffer_memory_end = 4*1024*1024;
	else if (memory_end > 6*1024*1024)
		buffer_memory_end = 2*1024*1024;
	else
		buffer_memory_end = 1*1024*1024;
	main_memory_start = buffer_memory_end;
#ifdef RAMDISK
	main_memory_start += rd_init(main_memory_start, RAMDISK*1024);
#endif
	mem_init(main_memory_start,memory_end);
	trap_init();
	blk_dev_init();
	chr_dev_init();
	tty_init();
	time_init();
	sched_init();
	buffer_init(buffer_memory_end);
	hd_init();
	floppy_init();
	sti();
	move_to_user_mode();
	if (!fork()) {		/* we count on this going ok */
		init();
	}
/*
 *   NOTE!!   For any other task 'pause()' would mean we have to get a
 * signal to awaken, but task0 is the sole exception (see 'schedule()')
 * as task 0 gets activated at every idle moment (when no other tasks
 * can run). For task0 'pause()' just means we go check if some other
 * task can run, and if not we return here.
 */
	for(;;) pause();
}

static int printf(const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	write(1,printbuf,i=vsprintf(printbuf, fmt, args));
	va_end(args);
	return i;
}

static char * argv_rc[] = { "/bin/sh", NULL };
static char * envp_rc[] = { "HOME=/", NULL };

static char * argv[] = { "-/bin/sh",NULL };
static char * envp[] = { "HOME=/usr/root", NULL };

void init(void)
{
	int pid,i;

	setup((void *) &drive_info);
	(void) open("/dev/tty0",O_RDWR,0);
	(void) dup(0);
	(void) dup(0);
	mkdir("/proc",0755);
	mknod("/proc/psinfo",S_IFPROC|0444,0);
	printf("%d buffers = %d bytes buffer space\n\r",NR_BUFFERS,
		NR_BUFFERS*BLOCK_SIZE);
	printf("Free mem: %d bytes\n\r",memory_end-main_memory_start);
	if (!(pid=fork())) {
		close(0);
		if (open("/etc/rc",O_RDONLY,0))
			_exit(1);
		execve("/bin/sh",argv_rc,envp_rc);
		_exit(2);
	}
	if (pid>0)
		while (pid != wait(&i))
			/* nothing */;
	while (1) {
		if ((pid=fork())<0) {
			printf("Fork failed in init\r\n");
			continue;
		}
		if (!pid) {
			close(0);close(1);close(2);
			setsid();
			(void) open("/dev/tty0",O_RDWR,0);
			(void) dup(0);
			(void) dup(0);
			_exit(execve("/bin/sh",argv,envp));
		}
		while (1)
			if (pid == wait(&i))
				break;
		printf("\n\rchild %d died with code %04x\n\r",pid,i);
		sync();
	}
	_exit(0);	/* NOTE! _exit, not exit() */
}

namei.c 只需要修改mknod函数中的一行代码就好了~

/*
 *  linux/fs/namei.c
 *
 *  (C) 1991  Linus Torvalds
 */

/*
 * Some corrections by tytso.
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <asm/segment.h>

#include <string.h> 
#include <fcntl.h>
#include <errno.h>
#include <const.h>
#include <sys/stat.h>

#define ACC_MODE(x) ("\004\002\006\377"[(x)&O_ACCMODE])

/*
 * comment out this line if you want names > NAME_LEN chars to be
 * truncated. Else they will be disallowed.
 */
/* #define NO_TRUNCATE */

#define MAY_EXEC 1
#define MAY_WRITE 2
#define MAY_READ 4

/*
 *	permission()
 *
 * is used to check for read/write/execute permissions on a file.
 * I don't know if we should look at just the euid or both euid and
 * uid, but that should be easily changed.
 */
static int permission(struct m_inode * inode,int mask)
{
	int mode = inode->i_mode;

/* special case: not even root can read/write a deleted file */
	if (inode->i_dev && !inode->i_nlinks)
		return 0;
	else if (current->euid==inode->i_uid)
		mode >>= 6;
	else if (current->egid==inode->i_gid)
		mode >>= 3;
	if (((mode & mask & 0007) == mask) || suser())
		return 1;
	return 0;
}

/*
 * ok, we cannot use strncmp, as the name is not in our data space.
 * Thus we'll have to use match. No big problem. Match also makes
 * some sanity tests.
 *
 * NOTE! unlike strncmp, match returns 1 for success, 0 for failure.
 */
static int match(int len,const char * name,struct dir_entry * de)
{
	register int same ;

	if (!de || !de->inode || len > NAME_LEN)
		return 0;
	if (len < NAME_LEN && de->name[len])
		return 0;
	__asm__("cld\n\t"
		"fs ; repe ; cmpsb\n\t"
		"setz %%al"
		:"=a" (same)
		:"0" (0),"S" ((long) name),"D" ((long) de->name),"c" (len)
		);
	return same;
}

/*
 *	find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the cache buffer in which the entry was found, and the entry
 * itself (as a parameter - res_dir). It does NOT read the inode of the
 * entry - you'll have to do that yourself if you want to.
 *
 * This also takes care of the few special cases due to '..'-traversal
 * over a pseudo-root and a mount point.
 */
static struct buffer_head * find_entry(struct m_inode ** dir,
	const char * name, int namelen, struct dir_entry ** res_dir)
{
	int entries;
	int block,i;
	struct buffer_head * bh;
	struct dir_entry * de;
	struct super_block * sb;

#ifdef NO_TRUNCATE
	if (namelen > NAME_LEN)
		return NULL;
#else
	if (namelen > NAME_LEN)
		namelen = NAME_LEN;
#endif
	entries = (*dir)->i_size / (sizeof (struct dir_entry));
	*res_dir = NULL;
	if (!namelen)
		return NULL;
/* check for '..', as we might have to do some "magic" for it */
	if (namelen==2 && get_fs_byte(name)=='.' && get_fs_byte(name+1)=='.') {
/* '..' in a pseudo-root results in a faked '.' (just change namelen) */
		if ((*dir) == current->root)
			namelen=1;
		else if ((*dir)->i_num == ROOT_INO) {
/* '..' over a mount-point results in 'dir' being exchanged for the mounted
   directory-inode. NOTE! We set mounted, so that we can iput the new dir */
			sb=get_super((*dir)->i_dev);
			if (sb->s_imount) {
				iput(*dir);
				(*dir)=sb->s_imount;
				(*dir)->i_count++;
			}
		}
	}
	if (!(block = (*dir)->i_zone[0]))
		return NULL;
	if (!(bh = bread((*dir)->i_dev,block)))
		return NULL;
	i = 0;
	de = (struct dir_entry *) bh->b_data;
	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 (match(namelen,name,de)) {
			*res_dir = de;
			return bh;
		}
		de++;
		i++;
	}
	brelse(bh);
	return NULL;
}

/*
 *	add_entry()
 *
 * adds a file entry to the specified directory, using the same
 * semantics as find_entry(). It returns NULL if it failed.
 *
 * NOTE!! The inode part of 'de' is left at 0 - which means you
 * may not sleep between calling this and putting something into
 * the entry, as someone else might have used it while you slept.
 */
static struct buffer_head * add_entry(struct m_inode * dir,
	const char * name, int namelen, struct dir_entry ** res_dir)
{
	int block,i;
	struct buffer_head * bh;
	struct dir_entry * de;

	*res_dir = NULL;
#ifdef NO_TRUNCATE
	if (namelen > NAME_LEN)
		return NULL;
#else
	if (namelen > NAME_LEN)
		namelen = NAME_LEN;
#endif
	if (!namelen)
		return NULL;
	if (!(block = dir->i_zone[0]))
		return NULL;
	if (!(bh = bread(dir->i_dev,block)))
		return NULL;
	i = 0;
	de = (struct dir_entry *) bh->b_data;
	while (1) {
		if ((char *)de >= BLOCK_SIZE+bh->b_data) {
			brelse(bh);
			bh = NULL;
			block = create_block(dir,i/DIR_ENTRIES_PER_BLOCK);
			if (!block)
				return NULL;
			if (!(bh = bread(dir->i_dev,block))) {
				i += DIR_ENTRIES_PER_BLOCK;
				continue;
			}
			de = (struct dir_entry *) bh->b_data;
		}
		if (i*sizeof(struct dir_entry) >= dir->i_size) {
			de->inode=0;
			dir->i_size = (i+1)*sizeof(struct dir_entry);
			dir->i_dirt = 1;
			dir->i_ctime = CURRENT_TIME;
		}
		if (!de->inode) {
			dir->i_mtime = CURRENT_TIME;
			for (i=0; i < NAME_LEN ; i++)
				de->name[i]=(i<namelen)?get_fs_byte(name+i):0;
			bh->b_dirt = 1;
			*res_dir = de;
			return bh;
		}
		de++;
		i++;
	}
	brelse(bh);
	return NULL;
}

/*
 *	get_dir()
 *
 * Getdir traverses the pathname until it hits the topmost directory.
 * It returns NULL on failure.
 */
static struct m_inode * get_dir(const char * pathname)
{
	char c;
	const char * thisname;
	struct m_inode * inode;
	struct buffer_head * bh;
	int namelen,inr,idev;
	struct dir_entry * de;

	if (!current->root || !current->root->i_count)
		panic("No root inode");
	if (!current->pwd || !current->pwd->i_count)
		panic("No cwd inode");
	if ((c=get_fs_byte(pathname))=='/') {
		inode = current->root;
		pathname++;
	} else if (c)
		inode = current->pwd;
	else
		return NULL;	/* empty name is bad */
	inode->i_count++;
	while (1) {
		thisname = pathname;
		if (!S_ISDIR(inode->i_mode) || !permission(inode,MAY_EXEC)) {
			iput(inode);
			return NULL;
		}
		for(namelen=0;(c=get_fs_byte(pathname++))&&(c!='/');namelen++)
			/* nothing */ ;
		if (!c)
			return inode;
		if (!(bh = find_entry(&inode,thisname,namelen,&de))) {
			iput(inode);
			return NULL;
		}
		inr = de->inode;
		idev = inode->i_dev;
		brelse(bh);
		iput(inode);
		if (!(inode = iget(idev,inr)))
			return NULL;
	}
}

/*
 *	dir_namei()
 *
 * dir_namei() returns the inode of the directory of the
 * specified name, and the name within that directory.
 */
static struct m_inode * dir_namei(const char * pathname,
	int * namelen, const char ** name)
{
	char c;
	const char * basename;
	struct m_inode * dir;

	if (!(dir = get_dir(pathname)))
		return NULL;
	basename = pathname;
	while ((c=get_fs_byte(pathname++)))
		if (c=='/')
			basename=pathname;
	*namelen = pathname-basename-1;
	*name = basename;
	return dir;
}

/*
 *	namei()
 *
 * is used by most simple commands to get the inode of a specified name.
 * Open, link etc use their own routines, but this is enough for things
 * like 'chmod' etc.
 */
struct m_inode * namei(const char * pathname)
{
	const char * basename;
	int inr,dev,namelen;
	struct m_inode * dir;
	struct buffer_head * bh;
	struct dir_entry * de;

	if (!(dir = dir_namei(pathname,&namelen,&basename)))
		return NULL;
	if (!namelen)			/* special case: '/usr/' etc */
		return dir;
	bh = find_entry(&dir,basename,namelen,&de);
	if (!bh) {
		iput(dir);
		return NULL;
	}
	inr = de->inode;
	dev = dir->i_dev;
	brelse(bh);
	iput(dir);
	dir=iget(dev,inr);
	if (dir) {
		dir->i_atime=CURRENT_TIME;
		dir->i_dirt=1;
	}
	return dir;
}

/*
 *	open_namei()
 *
 * namei for open - this is in fact almost the whole open-routine.
 */
int open_namei(const char * pathname, int flag, int mode,
	struct m_inode ** res_inode)
{
	const char * basename;
	int inr,dev,namelen;
	struct m_inode * dir, *inode;
	struct buffer_head * bh;
	struct dir_entry * de;

	if ((flag & O_TRUNC) && !(flag & O_ACCMODE))
		flag |= O_WRONLY;
	mode &= 0777 & ~current->umask;
	mode |= I_REGULAR;
	if (!(dir = dir_namei(pathname,&namelen,&basename)))
		return -ENOENT;
	if (!namelen) {			/* special case: '/usr/' etc */
		if (!(flag & (O_ACCMODE|O_CREAT|O_TRUNC))) {
			*res_inode=dir;
			return 0;
		}
		iput(dir);
		return -EISDIR;
	}
	bh = find_entry(&dir,basename,namelen,&de);
	if (!bh) {
		if (!(flag & O_CREAT)) {
			iput(dir);
			return -ENOENT;
		}
		if (!permission(dir,MAY_WRITE)) {
			iput(dir);
			return -EACCES;
		}
		inode = new_inode(dir->i_dev);
		if (!inode) {
			iput(dir);
			return -ENOSPC;
		}
		inode->i_uid = current->euid;
		inode->i_mode = mode;
		inode->i_dirt = 1;
		bh = add_entry(dir,basename,namelen,&de);
		if (!bh) {
			inode->i_nlinks--;
			iput(inode);
			iput(dir);
			return -ENOSPC;
		}
		de->inode = inode->i_num;
		bh->b_dirt = 1;
		brelse(bh);
		iput(dir);
		*res_inode = inode;
		return 0;
	}
	inr = de->inode;
	dev = dir->i_dev;
	brelse(bh);
	iput(dir);
	if (flag & O_EXCL)
		return -EEXIST;
	if (!(inode=iget(dev,inr)))
		return -EACCES;
	if ((S_ISDIR(inode->i_mode) && (flag & O_ACCMODE)) ||
	    !permission(inode,ACC_MODE(flag))) {
		iput(inode);
		return -EPERM;
	}
	inode->i_atime = CURRENT_TIME;
	if (flag & O_TRUNC)
		truncate(inode);
	*res_inode = inode;
	return 0;
}

int sys_mknod(const char * filename, int mode, int dev)
{
	const char * basename;
	int namelen;
	struct m_inode * dir, * inode;
	struct buffer_head * bh;
	struct dir_entry * de;
	
	if (!suser())
		return -EPERM;
	if (!(dir = dir_namei(filename,&namelen,&basename)))
		return -ENOENT;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (!permission(dir,MAY_WRITE)) {
		iput(dir);
		return -EPERM;
	}
	bh = find_entry(&dir,basename,namelen,&de);
	if (bh) {
		brelse(bh);
		iput(dir);
		return -EEXIST;
	}
	inode = new_inode(dir->i_dev);
	if (!inode) {
		iput(dir);
		return -ENOSPC;
	}
	inode->i_mode = mode;
	if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISPROC(mode))
		inode->i_zone[0] = dev;
	inode->i_mtime = inode->i_atime = CURRENT_TIME;
	inode->i_dirt = 1;
	bh = add_entry(dir,basename,namelen,&de);
	if (!bh) {
		iput(dir);
		inode->i_nlinks=0;
		iput(inode);
		return -ENOSPC;
	}
	de->inode = inode->i_num;
	bh->b_dirt = 1;
	iput(dir);
	iput(inode);
	brelse(bh);
	return 0;
}

int sys_mkdir(const char * pathname, int mode)
{
	const char * basename;
	int namelen;
	struct m_inode * dir, * inode;
	struct buffer_head * bh, *dir_block;
	struct dir_entry * de;

	if (!suser())
		return -EPERM;
	if (!(dir = dir_namei(pathname,&namelen,&basename)))
		return -ENOENT;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (!permission(dir,MAY_WRITE)) {
		iput(dir);
		return -EPERM;
	}
	bh = find_entry(&dir,basename,namelen,&de);
	if (bh) {
		brelse(bh);
		iput(dir);
		return -EEXIST;
	}
	inode = new_inode(dir->i_dev);
	if (!inode) {
		iput(dir);
		return -ENOSPC;
	}
	inode->i_size = 32;
	inode->i_dirt = 1;
	inode->i_mtime = inode->i_atime = CURRENT_TIME;
	if (!(inode->i_zone[0]=new_block(inode->i_dev))) {
		iput(dir);
		inode->i_nlinks--;
		iput(inode);
		return -ENOSPC;
	}
	inode->i_dirt = 1;
	if (!(dir_block=bread(inode->i_dev,inode->i_zone[0]))) {
		iput(dir);
		free_block(inode->i_dev,inode->i_zone[0]);
		inode->i_nlinks--;
		iput(inode);
		return -ERROR;
	}
	de = (struct dir_entry *) dir_block->b_data;
	de->inode=inode->i_num;
	strcpy(de->name,".");
	de++;
	de->inode = dir->i_num;
	strcpy(de->name,"..");
	inode->i_nlinks = 2;
	dir_block->b_dirt = 1;
	brelse(dir_block);
	inode->i_mode = I_DIRECTORY | (mode & 0777 & ~current->umask);
	inode->i_dirt = 1;
	bh = add_entry(dir,basename,namelen,&de);
	if (!bh) {
		iput(dir);
		free_block(inode->i_dev,inode->i_zone[0]);
		inode->i_nlinks=0;
		iput(inode);
		return -ENOSPC;
	}
	de->inode = inode->i_num;
	bh->b_dirt = 1;
	dir->i_nlinks++;
	dir->i_dirt = 1;
	iput(dir);
	iput(inode);
	brelse(bh);
	return 0;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
static int empty_dir(struct m_inode * inode)
{
	int nr,block;
	int len;
	struct buffer_head * bh;
	struct dir_entry * de;

	len = inode->i_size / sizeof (struct dir_entry);
	if (len<2 || !inode->i_zone[0] ||
	    !(bh=bread(inode->i_dev,inode->i_zone[0]))) {
	    	printk("warning - bad directory on dev %04x\n",inode->i_dev);
		return 0;
	}
	de = (struct dir_entry *) bh->b_data;
	if (de[0].inode != inode->i_num || !de[1].inode || 
	    strcmp(".",de[0].name) || strcmp("..",de[1].name)) {
	    	printk("warning - bad directory on dev %04x\n",inode->i_dev);
		return 0;
	}
	nr = 2;
	de += 2;
	while (nr<len) {
		if ((void *) de >= (void *) (bh->b_data+BLOCK_SIZE)) {
			brelse(bh);
			block=bmap(inode,nr/DIR_ENTRIES_PER_BLOCK);
			if (!block) {
				nr += DIR_ENTRIES_PER_BLOCK;
				continue;
			}
			if (!(bh=bread(inode->i_dev,block)))
				return 0;
			de = (struct dir_entry *) bh->b_data;
		}
		if (de->inode) {
			brelse(bh);
			return 0;
		}
		de++;
		nr++;
	}
	brelse(bh);
	return 1;
}

int sys_rmdir(const char * name)
{
	const char * basename;
	int namelen;
	struct m_inode * dir, * inode;
	struct buffer_head * bh;
	struct dir_entry * de;

	if (!suser())
		return -EPERM;
	if (!(dir = dir_namei(name,&namelen,&basename)))
		return -ENOENT;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (!permission(dir,MAY_WRITE)) {
		iput(dir);
		return -EPERM;
	}
	bh = find_entry(&dir,basename,namelen,&de);
	if (!bh) {
		iput(dir);
		return -ENOENT;
	}
	if (!(inode = iget(dir->i_dev, de->inode))) {
		iput(dir);
		brelse(bh);
		return -EPERM;
	}
	if ((dir->i_mode & S_ISVTX) && current->euid &&
	    inode->i_uid != current->euid) {
		iput(dir);
		iput(inode);
		brelse(bh);
		return -EPERM;
	}
	if (inode->i_dev != dir->i_dev || inode->i_count>1) {
		iput(dir);
		iput(inode);
		brelse(bh);
		return -EPERM;
	}
	if (inode == dir) {	/* we may not delete ".", but "../dir" is ok */
		iput(inode);
		iput(dir);
		brelse(bh);
		return -EPERM;
	}
	if (!S_ISDIR(inode->i_mode)) {
		iput(inode);
		iput(dir);
		brelse(bh);
		return -ENOTDIR;
	}
	if (!empty_dir(inode)) {
		iput(inode);
		iput(dir);
		brelse(bh);
		return -ENOTEMPTY;
	}
	if (inode->i_nlinks != 2)
		printk("empty directory has nlink!=2 (%d)",inode->i_nlinks);
	de->inode = 0;
	bh->b_dirt = 1;
	brelse(bh);
	inode->i_nlinks=0;
	inode->i_dirt=1;
	dir->i_nlinks--;
	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	dir->i_dirt=1;
	iput(dir);
	iput(inode);
	return 0;
}

int sys_unlink(const char * name)
{
	const char * basename;
	int namelen;
	struct m_inode * dir, * inode;
	struct buffer_head * bh;
	struct dir_entry * de;

	if (!(dir = dir_namei(name,&namelen,&basename)))
		return -ENOENT;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (!permission(dir,MAY_WRITE)) {
		iput(dir);
		return -EPERM;
	}
	bh = find_entry(&dir,basename,namelen,&de);
	if (!bh) {
		iput(dir);
		return -ENOENT;
	}
	if (!(inode = iget(dir->i_dev, de->inode))) {
		iput(dir);
		brelse(bh);
		return -ENOENT;
	}
	if ((dir->i_mode & S_ISVTX) && !suser() &&
	    current->euid != inode->i_uid &&
	    current->euid != dir->i_uid) {
		iput(dir);
		iput(inode);
		brelse(bh);
		return -EPERM;
	}
	if (S_ISDIR(inode->i_mode)) {
		iput(inode);
		iput(dir);
		brelse(bh);
		return -EPERM;
	}
	if (!inode->i_nlinks) {
		printk("Deleting nonexistent file (%04x:%d), %d\n",
			inode->i_dev,inode->i_num,inode->i_nlinks);
		inode->i_nlinks=1;
	}
	de->inode = 0;
	bh->b_dirt = 1;
	brelse(bh);
	inode->i_nlinks--;
	inode->i_dirt = 1;
	inode->i_ctime = CURRENT_TIME;
	iput(inode);
	iput(dir);
	return 0;
}

int sys_link(const char * oldname, const char * newname)
{
	struct dir_entry * de;
	struct m_inode * oldinode, * dir;
	struct buffer_head * bh;
	const char * basename;
	int namelen;

	oldinode=namei(oldname);
	if (!oldinode)
		return -ENOENT;
	if (S_ISDIR(oldinode->i_mode)) {
		iput(oldinode);
		return -EPERM;
	}
	dir = dir_namei(newname,&namelen,&basename);
	if (!dir) {
		iput(oldinode);
		return -EACCES;
	}
	if (!namelen) {
		iput(oldinode);
		iput(dir);
		return -EPERM;
	}
	if (dir->i_dev != oldinode->i_dev) {
		iput(dir);
		iput(oldinode);
		return -EXDEV;
	}
	if (!permission(dir,MAY_WRITE)) {
		iput(dir);
		iput(oldinode);
		return -EACCES;
	}
	bh = find_entry(&dir,basename,namelen,&de);
	if (bh) {
		brelse(bh);
		iput(dir);
		iput(oldinode);
		return -EEXIST;
	}
	bh = add_entry(dir,basename,namelen,&de);
	if (!bh) {
		iput(dir);
		iput(oldinode);
		return -ENOSPC;
	}
	de->inode = oldinode->i_num;
	bh->b_dirt = 1;
	brelse(bh);
	iput(dir);
	oldinode->i_nlinks++;
	oldinode->i_ctime = CURRENT_TIME;
	oldinode->i_dirt = 1;
	iput(oldinode);
	return 0;
}

read_write.c 试验指导书上也是直接给代码了，修改sys_read函数就可以啦~

/*
 *  linux/fs/read_write.c
 *
 *  (C) 1991  Linus Torvalds
 */

#include <sys/stat.h>
#include <errno.h>
#include <sys/types.h>

#include <linux/kernel.h>
#include <linux/sched.h>
#include <asm/segment.h>

extern int rw_char(int rw,int dev, char * buf, int count, off_t * pos);
extern int read_pipe(struct m_inode * inode, char * buf, int count);
extern int write_pipe(struct m_inode * inode, char * buf, int count);
extern int block_read(int dev, off_t * pos, char * buf, int count);
extern int block_write(int dev, off_t * pos, char * buf, int count);
extern int file_read(struct m_inode * inode, struct file * filp,
		char * buf, int count);
extern int file_write(struct m_inode * inode, struct file * filp,
		char * buf, int count);
extern int psread(int dev,char * buf,int count,off_t * f_pos);

int sys_lseek(unsigned int fd,off_t offset, int origin)
{
	struct file * file;
	int tmp;

	if (fd >= NR_OPEN || !(file=current->filp[fd]) || !(file->f_inode)
	   || !IS_SEEKABLE(MAJOR(file->f_inode->i_dev)))
		return -EBADF;
	if (file->f_inode->i_pipe)
		return -ESPIPE;
	switch (origin) {
		case 0:
			if (offset<0) return -EINVAL;
			file->f_pos=offset;
			break;
		case 1:
			if (file->f_pos+offset<0) return -EINVAL;
			file->f_pos += offset;
			break;
		case 2:
			if ((tmp=file->f_inode->i_size+offset) < 0)
				return -EINVAL;
			file->f_pos = tmp;
			break;
		default:
			return -EINVAL;
	}
	return file->f_pos;
}

int sys_read(unsigned int fd,char * buf,int count)
{
	struct file * file; 
	struct m_inode * inode;

	if (fd>=NR_OPEN || count<0 || !(file=current->filp[fd]))
		return -EINVAL;
	if (!count)
		return 0;
	verify_area(buf,count);
	inode = file->f_inode;
	if (inode->i_pipe)
		return (file->f_mode&1)?read_pipe(inode,buf,count):-EIO;
	if (S_ISCHR(inode->i_mode))
		return rw_char(READ,inode->i_zone[0],buf,count,&file->f_pos);
	if (S_ISBLK(inode->i_mode))
		return block_read(inode->i_zone[0],&file->f_pos,buf,count);
   	if (S_ISPROC(inode->i_mode))
	    return psread(inode->i_zone[0],buf,count,&file->f_pos);
	if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode)) {
		if (count+file->f_pos > inode->i_size)
			count = inode->i_size - file->f_pos;
		if (count<=0)
			return 0;
		return file_read(inode,file,buf,count);
	}
	printk("(Read)inode->i_mode=%06o\n\r",inode->i_mode);
	return -EINVAL;
}

int sys_write(unsigned int fd,char * buf,int count)
{
	struct file * file;
	struct m_inode * inode;
	
	if (fd>=NR_OPEN || count <0 || !(file=current->filp[fd]))
		return -EINVAL;
	if (!count)
		return 0;
	inode=file->f_inode;
	if (inode->i_pipe)
		return (file->f_mode&2)?write_pipe(inode,buf,count):-EIO;
	if (S_ISCHR(inode->i_mode))
		return rw_char(WRITE,inode->i_zone[0],buf,count,&file->f_pos);
	if (S_ISBLK(inode->i_mode))
		return block_write(inode->i_zone[0],&file->f_pos,buf,count);
	if (S_ISREG(inode->i_mode))
		return file_write(inode,file,buf,count);
	printk("(Write)inode->i_mode=%06o\n\r",inode->i_mode);
	return -EINVAL;
}

proc.c这样写  要用到put_fs_byte函数，这个试验2用到过。

如果和指导书截图一样把上面的名字也打出来，排版上可能会比较麻烦，我就没写。

刚刚在stat.h里面定义了一个字符数组psbuffer。用处是这样的。

如果把这个数组定义在proc.c里面,因为一次cat可能要调用多次这个处理函数，

这样的话每次调用数据都得更新～～很明显不行的嘛。so，只要在

cat后的第一次调用这个处理函数的时候更新就行了。

如果谁有好的方法，请留言告知。

#include <asm/segment.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
int i,j,k,pid; 

void addNum(int num){
	char c;
	if (num==0){
		psbuffer[j]='0';
		j++;
		psbuffer[j]='\t';
		j++;		
		return;
	}
	if (num<0){
		psbuffer[j]='-';
		j++;
		num=-num;
	}
	while (num%10){
		psbuffer[j]=(char)((num%10)+'0');
		num=num/10;
		j++;
	}
	psbuffer[j]='\t';
	j++;
}
int psread(int dev,char * buf,int count,off_t * f_pos)
{
	struct task_struct * p;
  
  if(!(*f_pos))
    {       
        j=0;       
        for(k=0;k<1024;k++)              
                 psbuffer[k]='\0';
    	for(i=0;i<64;i++)
	{
	    p=task[i];
		if(p != NULL)
		{
		    	pid = p->pid;
			addNum(p->pid);
			addNum(p->state);
			addNum(p->father);
			addNum(p->counter);
			addNum(p->start_time);
			psbuffer[j]='\n';
			j++;
                }          
    }    
}
	
    for(k=0;k<count;k++)
	{
	    if(psbuffer[k+(*f_pos)] == '\0')
		  break;
        put_fs_byte(psbuffer[k+(*f_pos)],buf+k+(*f_pos));	
    }
	(*f_pos) = (*f_pos)+k;
	
	return k;
}

至于指导书上的sprintf函数，懒得改了，下面评论的小伙子说的很清楚了。～～