namei.c

LINUX 1.0 内核c源代码,是一份精简的linux内核源代码

		   return error;
	      }
	      inode->i_dirt = 1;
	}
	*res_inode = inode;
	return 0;
}

int do_mknod(const char * filename, int mode, dev_t dev)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	mode &= ~current->umask;
	error = dir_namei(filename,&namelen,&basename, NULL, &dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if (!permission(dir,MAY_WRITE | MAY_EXEC)) {
		iput(dir);
		return -EACCES;
	}
	if (!dir->i_op || !dir->i_op->mknod) {
		iput(dir);
		return -EPERM;
	}
	down(&dir->i_sem);
	error = dir->i_op->mknod(dir,basename,namelen,mode,dev);
	up(&dir->i_sem);
	return error;
}

asmlinkage int sys_mknod(const char * filename, int mode, dev_t dev)
{
	int error;
	char * tmp;

	if (S_ISDIR(mode) || (!S_ISFIFO(mode) && !suser()))
		return -EPERM;
	switch (mode & S_IFMT) {
	case 0:
		mode |= S_IFREG;
		break;
	case S_IFREG: case S_IFCHR: case S_IFBLK: case S_IFIFO:
		break;
	default:
		return -EINVAL;
	}
	error = getname(filename,&tmp);
	if (!error) {
		error = do_mknod(tmp,mode,dev);
		putname(tmp);
	}
	return error;
}

static int do_mkdir(const char * pathname, int mode)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	error = dir_namei(pathname,&namelen,&basename,NULL,&dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if (!permission(dir,MAY_WRITE | MAY_EXEC)) {
		iput(dir);
		return -EACCES;
	}
	if (!dir->i_op || !dir->i_op->mkdir) {
		iput(dir);
		return -EPERM;
	}
	down(&dir->i_sem);
	error = dir->i_op->mkdir(dir,basename,namelen,mode);
	up(&dir->i_sem);
	return error;
}

asmlinkage int sys_mkdir(const char * pathname, int mode)
{
	int error;
	char * tmp;

	error = getname(pathname,&tmp);
	if (!error) {
		error = do_mkdir(tmp,mode);
		putname(tmp);
	}
	return error;
}

static int do_rmdir(const char * name)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	error = dir_namei(name,&namelen,&basename,NULL,&dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if (!permission(dir,MAY_WRITE | MAY_EXEC)) {
		iput(dir);
		return -EACCES;
	}
	if (!dir->i_op || !dir->i_op->rmdir) {
		iput(dir);
		return -EPERM;
	}
	return dir->i_op->rmdir(dir,basename,namelen);
}

asmlinkage int sys_rmdir(const char * pathname)
{
	int error;
	char * tmp;

	error = getname(pathname,&tmp);
	if (!error) {
		error = do_rmdir(tmp);
		putname(tmp);
	}
	return error;
}

static int do_unlink(const char * name)
{
	const char * basename;
	int namelen, error;
	struct inode * dir;

	error = dir_namei(name,&namelen,&basename,NULL,&dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -EPERM;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if (!permission(dir,MAY_WRITE | MAY_EXEC)) {
		iput(dir);
		return -EACCES;
	}
	if (!dir->i_op || !dir->i_op->unlink) {
		iput(dir);
		return -EPERM;
	}
	return dir->i_op->unlink(dir,basename,namelen);
}

asmlinkage int sys_unlink(const char * pathname)
{
	int error;
	char * tmp;

	error = getname(pathname,&tmp);
	if (!error) {
		error = do_unlink(tmp);
		putname(tmp);
	}
	return error;
}

static int do_symlink(const char * oldname, const char * newname)
{
	struct inode * dir;
	const char * basename;
	int namelen, error;

	error = dir_namei(newname,&namelen,&basename,NULL,&dir);
	if (error)
		return error;
	if (!namelen) {
		iput(dir);
		return -ENOENT;
	}
	if (IS_RDONLY(dir)) {
		iput(dir);
		return -EROFS;
	}
	if (!permission(dir,MAY_WRITE | MAY_EXEC)) {
		iput(dir);
		return -EACCES;
	}
	if (!dir->i_op || !dir->i_op->symlink) {
		iput(dir);
		return -EPERM;
	}
	down(&dir->i_sem);
	error = dir->i_op->symlink(dir,basename,namelen,oldname);
	up(&dir->i_sem);
	return error;
}

asmlinkage int sys_symlink(const char * oldname, const char * newname)
{
	int error;
	char * from, * to;

	error = getname(oldname,&from);
	if (!error) {
		error = getname(newname,&to);
		if (!error) {
			error = do_symlink(from,to);
			putname(to);
		}
		putname(from);
	}
	return error;
}

static int do_link(struct inode * oldinode, const char * newname)
{
	struct inode * dir;
	const char * basename;
	int namelen, error;

	error = dir_namei(newname,&namelen,&basename,NULL,&dir);
	if (error) {
		iput(oldinode);
		return error;
	}
	if (!namelen) {
		iput(oldinode);
		iput(dir);
		return -EPERM;
	}
	if (IS_RDONLY(dir)) {
		iput(oldinode);
		iput(dir);
		return -EROFS;
	}
	if (dir->i_dev != oldinode->i_dev) {
		iput(dir);
		iput(oldinode);
		return -EXDEV;
	}
	if (!permission(dir,MAY_WRITE | MAY_EXEC)) {
		iput(dir);
		iput(oldinode);
		return -EACCES;
	}
	if (!dir->i_op || !dir->i_op->link) {
		iput(dir);
		iput(oldinode);
		return -EPERM;
	}
	down(&dir->i_sem);
	error = dir->i_op->link(oldinode, dir, basename, namelen);
	up(&dir->i_sem);
	return error;
}

asmlinkage int sys_link(const char * oldname, const char * newname)
{
	int error;
	char * to;
	struct inode * oldinode;

	error = namei(oldname, &oldinode);
	if (error)
		return error;
	error = getname(newname,&to);
	if (error) {
		iput(oldinode);
		return error;
	}
	error = do_link(oldinode,to);
	putname(to);
	return error;
}

static int do_rename(const char * oldname, const char * newname)
{
	struct inode * old_dir, * new_dir;
	const char * old_base, * new_base;
	int old_len, new_len, error;

	error = dir_namei(oldname,&old_len,&old_base,NULL,&old_dir);
	if (error)
		return error;
	if (!permission(old_dir,MAY_WRITE | MAY_EXEC)) {
		iput(old_dir);
		return -EACCES;
	}
	if (!old_len || (old_base[0] == '.' &&
	    (old_len == 1 || (old_base[1] == '.' &&
	     old_len == 2)))) {
		iput(old_dir);
		return -EPERM;
	}
	error = dir_namei(newname,&new_len,&new_base,NULL,&new_dir);
	if (error) {
		iput(old_dir);
		return error;
	}
	if (!permission(new_dir,MAY_WRITE | MAY_EXEC)) {
		iput(old_dir);
		iput(new_dir);
		return -EACCES;
	}
	if (!new_len || (new_base[0] == '.' &&
	    (new_len == 1 || (new_base[1] == '.' &&
	     new_len == 2)))) {
		iput(old_dir);
		iput(new_dir);
		return -EPERM;
	}
	if (new_dir->i_dev != old_dir->i_dev) {
		iput(old_dir);
		iput(new_dir);
		return -EXDEV;
	}
	if (IS_RDONLY(new_dir) || IS_RDONLY(old_dir)) {
		iput(old_dir);
		iput(new_dir);
		return -EROFS;
	}
	if (!old_dir->i_op || !old_dir->i_op->rename) {
		iput(old_dir);
		iput(new_dir);
		return -EPERM;
	}
	down(&new_dir->i_sem);
	error = old_dir->i_op->rename(old_dir, old_base, old_len, 
		new_dir, new_base, new_len);
	up(&new_dir->i_sem);
	return error;
}

asmlinkage int sys_rename(const char * oldname, const char * newname)
{
	int error;
	char * from, * to;

	error = getname(oldname,&from);
	if (!error) {
		error = getname(newname,&to);
		if (!error) {
			error = do_rename(from,to);
			putname(to);
		}
		putname(from);
	}
	return error;
}