base.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

	struct files_struct * files;

	retval = 0;
	pid = p->pid;

	fd = filp->f_pos;
	switch (fd) {
		case 0:
			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
				goto out;
			filp->f_pos++;
		case 1:
			ino = fake_ino(pid, PROC_PID_INO);
			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
				goto out;
			filp->f_pos++;
		default:
			task_lock(p);
			files = p->files;
			if (files)
				atomic_inc(&files->count);
			task_unlock(p);
			if (!files)
				goto out;
			read_lock(&files->file_lock);
			for (fd = filp->f_pos-2;
			     fd < files->max_fds;
			     fd++, filp->f_pos++) {
				unsigned int i,j;

				if (!fcheck_files(files, fd))
					continue;
				read_unlock(&files->file_lock);

				j = NUMBUF;
				i = fd;
				do {
					j--;
					buf[j] = '0' + (i % 10);
					i /= 10;
				} while (i);

				ino = fake_ino(pid, PROC_PID_FD_DIR + fd);
				if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino, DT_LNK) < 0) {
					read_lock(&files->file_lock);
					break;
				}
				read_lock(&files->file_lock);
			}
			read_unlock(&files->file_lock);
			put_files_struct(files);
	}
out:
	return retval;
}

static int proc_base_readdir(struct file * filp,
	void * dirent, filldir_t filldir)
{
	int i;
	int pid;
	struct inode *inode = filp->f_dentry->d_inode;
	struct pid_entry *p;

	pid = inode->u.proc_i.task->pid;
	if (!pid)
		return -ENOENT;
	i = filp->f_pos;
	switch (i) {
		case 0:
			if (filldir(dirent, ".", 1, i, inode->i_ino, DT_DIR) < 0)
				return 0;
			i++;
			filp->f_pos++;
			/* fall through */
		case 1:
			if (filldir(dirent, "..", 2, i, PROC_ROOT_INO, DT_DIR) < 0)
				return 0;
			i++;
			filp->f_pos++;
			/* fall through */
		default:
			i -= 2;
			if (i>=sizeof(base_stuff)/sizeof(base_stuff[0]))
				return 1;
			p = base_stuff + i;
			while (p->name) {
				if (filldir(dirent, p->name, p->len, filp->f_pos,
					    fake_ino(pid, p->type), p->mode >> 12) < 0)
					return 0;
				filp->f_pos++;
				p++;
			}
	}
	return 1;
}

/* building an inode */

static int task_dumpable(struct task_struct *task)
{
	int dumpable = 0;
	struct mm_struct *mm;

	task_lock(task);
	mm = task->mm;
	if (mm)
		dumpable = mm->dumpable;
	task_unlock(task);
	return dumpable;
}


static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task, int ino)
{
	struct inode * inode;

	/* We need a new inode */
	
	inode = new_inode(sb);
	if (!inode)
		goto out;

	/* Common stuff */

	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	inode->i_ino = fake_ino(task->pid, ino);

	if (!task->pid)
		goto out_unlock;

	/*
	 * grab the reference to task.
	 */
	get_task_struct(task);
	inode->u.proc_i.task = task;
	inode->i_uid = 0;
	inode->i_gid = 0;
	if (ino == PROC_PID_INO || task_dumpable(task)) {
		inode->i_uid = task->euid;
		inode->i_gid = task->egid;
	}

out:
	return inode;

out_unlock:
	iput(inode);
	return NULL;
}

/* dentry stuff */

static int pid_fd_revalidate(struct dentry * dentry, int flags)
{
	return 0;
}

/*
 *	Exceptional case: normally we are not allowed to unhash a busy
 * directory. In this case, however, we can do it - no aliasing problems
 * due to the way we treat inodes.
 */
static int pid_base_revalidate(struct dentry * dentry, int flags)
{
	if (dentry->d_inode->u.proc_i.task->pid)
		return 1;
	d_drop(dentry);
	return 0;
}

static int pid_delete_dentry(struct dentry * dentry)
{
	return 1;
}

static struct dentry_operations pid_fd_dentry_operations =
{
	d_revalidate:	pid_fd_revalidate,
	d_delete:	pid_delete_dentry,
};

static struct dentry_operations pid_dentry_operations =
{
	d_delete:	pid_delete_dentry,
};

static struct dentry_operations pid_base_dentry_operations =
{
	d_revalidate:	pid_base_revalidate,
	d_delete:	pid_delete_dentry,
};

/* Lookups */
#define MAX_MULBY10	((~0U-9)/10)

static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry)
{
	unsigned int fd, c;
	struct task_struct *task = dir->u.proc_i.task;
	struct file * file;
	struct files_struct * files;
	struct inode *inode;
	const char *name;
	int len;

	fd = 0;
	len = dentry->d_name.len;
	name = dentry->d_name.name;
	if (len > 1 && *name == '0') goto out;
	while (len-- > 0) {
		c = *name - '0';
		name++;
		if (c > 9)
			goto out;
		if (fd >= MAX_MULBY10)
			goto out;
		fd *= 10;
		fd += c;
	}

	inode = proc_pid_make_inode(dir->i_sb, task, PROC_PID_FD_DIR+fd);
	if (!inode)
		goto out;
	task_lock(task);
	files = task->files;
	if (files)
		atomic_inc(&files->count);
	task_unlock(task);
	if (!files)
		goto out_unlock;
	read_lock(&files->file_lock);
	file = inode->u.proc_i.file = fcheck_files(files, fd);
	if (!file)
		goto out_unlock2;
	get_file(file);
	read_unlock(&files->file_lock);
	put_files_struct(files);
	inode->i_op = &proc_pid_link_inode_operations;
	inode->i_size = 64;
	inode->i_mode = S_IFLNK;
	inode->u.proc_i.op.proc_get_link = proc_fd_link;
	if (file->f_mode & 1)
		inode->i_mode |= S_IRUSR | S_IXUSR;
	if (file->f_mode & 2)
		inode->i_mode |= S_IWUSR | S_IXUSR;
	dentry->d_op = &pid_fd_dentry_operations;
	d_add(dentry, inode);
	return NULL;

out_unlock2:
	put_files_struct(files);
	read_unlock(&files->file_lock);
out_unlock:
	iput(inode);
out:
	return ERR_PTR(-ENOENT);
}

static struct file_operations proc_fd_operations = {
	read:		generic_read_dir,
	readdir:	proc_readfd,
};

/*
 * proc directories can do almost nothing..
 */
static struct inode_operations proc_fd_inode_operations = {
	lookup:		proc_lookupfd,
	permission:	proc_permission,
};

static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode;
	int error;
	struct task_struct *task = dir->u.proc_i.task;
	struct pid_entry *p;

	error = -ENOENT;
	inode = NULL;

	for (p = base_stuff; p->name; p++) {
		if (p->len != dentry->d_name.len)
			continue;
		if (!memcmp(dentry->d_name.name, p->name, p->len))
			break;
	}
	if (!p->name)
		goto out;

	error = -EINVAL;
	inode = proc_pid_make_inode(dir->i_sb, task, p->type);
	if (!inode)
		goto out;

	inode->i_mode = p->mode;
	/*
	 * Yes, it does not scale. And it should not. Don't add
	 * new entries into /proc/<pid>/ without very good reasons.
	 */
	switch(p->type) {
		case PROC_PID_FD:
			inode->i_nlink = 2;
			inode->i_op = &proc_fd_inode_operations;
			inode->i_fop = &proc_fd_operations;
			break;
		case PROC_PID_EXE:
			inode->i_op = &proc_pid_link_inode_operations;
			inode->u.proc_i.op.proc_get_link = proc_exe_link;
			break;
		case PROC_PID_CWD:
			inode->i_op = &proc_pid_link_inode_operations;
			inode->u.proc_i.op.proc_get_link = proc_cwd_link;
			break;
		case PROC_PID_ROOT:
			inode->i_op = &proc_pid_link_inode_operations;
			inode->u.proc_i.op.proc_get_link = proc_root_link;
			break;
		case PROC_PID_ENVIRON:
			inode->i_fop = &proc_info_file_operations;
			inode->u.proc_i.op.proc_read = proc_pid_environ;
			break;
		case PROC_PID_STATUS:
			inode->i_fop = &proc_info_file_operations;
			inode->u.proc_i.op.proc_read = proc_pid_status;
			break;
		case PROC_PID_STAT:
			inode->i_fop = &proc_info_file_operations;
			inode->u.proc_i.op.proc_read = proc_pid_stat;
			break;
		case PROC_PID_CMDLINE:
			inode->i_fop = &proc_info_file_operations;
			inode->u.proc_i.op.proc_read = proc_pid_cmdline;
			break;
		case PROC_PID_STATM:
			inode->i_fop = &proc_info_file_operations;
			inode->u.proc_i.op.proc_read = proc_pid_statm;
			break;
		case PROC_PID_MAPS:
			inode->i_fop = &proc_maps_operations;
			break;
#ifdef CONFIG_SMP
		case PROC_PID_CPU:
			inode->i_fop = &proc_info_file_operations;
			inode->u.proc_i.op.proc_read = proc_pid_cpu;
			break;
#endif
		case PROC_PID_MEM:
			inode->i_op = &proc_mem_inode_operations;
			inode->i_fop = &proc_mem_operations;
			break;
		default:
			printk("procfs: impossible type (%d)",p->type);
			iput(inode);
			return ERR_PTR(-EINVAL);
	}
	dentry->d_op = &pid_dentry_operations;
	d_add(dentry, inode);
	return NULL;

out:
	return ERR_PTR(error);
}

static struct file_operations proc_base_operations = {
	read:		generic_read_dir,
	readdir:	proc_base_readdir,
};

static struct inode_operations proc_base_inode_operations = {
	lookup:		proc_base_lookup,
};

/*
 * /proc/self:
 */
static int proc_self_readlink(struct dentry *dentry, char *buffer, int buflen)
{
	char tmp[30];
	sprintf(tmp, "%d", current->pid);
	return vfs_readlink(dentry,buffer,buflen,tmp);
}

static int proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	char tmp[30];
	sprintf(tmp, "%d", current->pid);
	return vfs_follow_link(nd,tmp);
}	

static struct inode_operations proc_self_inode_operations = {
	readlink:	proc_self_readlink,
	follow_link:	proc_self_follow_link,
};

struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry)
{
	unsigned int pid, c;
	struct task_struct *task;
	const char *name;
	struct inode *inode;
	int len;

	pid = 0;
	name = dentry->d_name.name;
	len = dentry->d_name.len;
	if (len == 4 && !memcmp(name, "self", 4)) {
		inode = new_inode(dir->i_sb);
		if (!inode)
			return ERR_PTR(-ENOMEM);
		inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
		inode->i_ino = fake_ino(0, PROC_PID_INO);
		inode->u.proc_i.file = NULL;
		inode->u.proc_i.task = NULL;
		inode->i_mode = S_IFLNK|S_IRWXUGO;
		inode->i_uid = inode->i_gid = 0;
		inode->i_size = 64;
		inode->i_op = &proc_self_inode_operations;
		d_add(dentry, inode);
		return NULL;
	}
	while (len-- > 0) {
		c = *name - '0';
		name++;
		if (c > 9)
			goto out;
		if (pid >= MAX_MULBY10)
			goto out;
		pid *= 10;
		pid += c;
		if (!pid)
			goto out;
	}

	read_lock(&tasklist_lock);
	task = find_task_by_pid(pid);
	if (task)
		get_task_struct(task);
	read_unlock(&tasklist_lock);
	if (!task)
		goto out;

	inode = proc_pid_make_inode(dir->i_sb, task, PROC_PID_INO);

	free_task_struct(task);

	if (!inode)
		goto out;
	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
	inode->i_op = &proc_base_inode_operations;
	inode->i_fop = &proc_base_operations;
	inode->i_nlink = 3;
	inode->i_flags|=S_IMMUTABLE;

	dentry->d_op = &pid_base_dentry_operations;
	d_add(dentry, inode);
	return NULL;
out:
	return ERR_PTR(-ENOENT);
}

void proc_pid_delete_inode(struct inode *inode)
{
	if (inode->u.proc_i.file)
		fput(inode->u.proc_i.file);
	if (inode->u.proc_i.task)
		free_task_struct(inode->u.proc_i.task);
}

#define PROC_NUMBUF 10
#define PROC_MAXPIDS 20

/*
 * Get a few pid's to return for filldir - we need to hold the
 * tasklist lock while doing this, and we must release it before
 * we actually do the filldir itself, so we use a temp buffer..
 */
static int get_pid_list(int index, unsigned int *pids)
{
	struct task_struct *p;
	int nr_pids = 0;

	index--;
	read_lock(&tasklist_lock);
	for_each_task(p) {
		int pid = p->pid;
		if (!pid)
			continue;
		if (--index >= 0)
			continue;
		pids[nr_pids] = pid;
		nr_pids++;
		if (nr_pids >= PROC_MAXPIDS)
			break;
	}
	read_unlock(&tasklist_lock);
	return nr_pids;
}

int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	unsigned int pid_array[PROC_MAXPIDS];
	char buf[PROC_NUMBUF];
	unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
	unsigned int nr_pids, i;

	if (!nr) {
		ino_t ino = fake_ino(0,PROC_PID_INO);
		if (filldir(dirent, "self", 4, filp->f_pos, ino, DT_LNK) < 0)
			return 0;
		filp->f_pos++;
		nr++;
	}

	nr_pids = get_pid_list(nr, pid_array);

	for (i = 0; i < nr_pids; i++) {
		int pid = pid_array[i];
		ino_t ino = fake_ino(pid,PROC_PID_INO);
		unsigned long j = PROC_NUMBUF;

		do buf[--j] = '0' + (pid % 10); while (pid/=10);

		if (filldir(dirent, buf+j, PROC_NUMBUF-j, filp->f_pos, ino, DT_DIR) < 0)
			break;
		filp->f_pos++;
	}
	return 0;
}