Re: Compiling C++ modules

Al Viro
2006-05-02T14:13:10Z

On Tue, May 02, 2006 at 04:52:53PM +0300, Avi Kivity wrote:
> static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> size_t count, loff_t max)
> {
> loff_t pos;
> ssize_t retval;
>
> /*
> * Get input file, and verify that it is ok..
> */
> light_file_ptr in_file(in_fd);

*snerk*
Good luck defining copying and conversion to file * for that puppy.

> if (!in_file.valid())
> return -EBADF;
> if (!in_file->readable())
> return -EBADF;
> retval = -EINVAL;
> struct inode *in_inode = in_file->dentry()->inode();

Lovely. Let's expose all fields as methods?

> if (!in_inode)
> return -EINVAL;

BTW, that can't happen. Applies to the original as well.

> // I'm assuming here that the default sendfile() returns -EINVAL
> if (!ppos)
> ppos = &in_file->f_pos;
> else
> if (!(in_file->mode() & FMODE_PREAD))
> return -ESPIPE;

As opposed to ->readable() for checking FMODE_READ?

> light_file_ptr out_file(out_fd);
> if (!out_file)
> return -EBADF;

?

> if (!max)
> max = min(in_inode->i_sb->s_maxbytes,
> out_inode->i_sb->s_maxbytes);

While we are at it, that's the only place where in_inode and out_inode
are used. Also... how does one remember which of ->dentry, ->inode
and ->i_sb are methods and which are public fields?

> // now, with exceptions
> static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> size_t count, loff_t max)
> {
> loff_t pos;
>
> /*
> * Get input file, and verify that it is ok..
> */
> light_file_ptr in_file(in_fd);
> in_file->verify_readable();

That assumes that error value returned in that case is the same everywhere.
It isn't.