Re: Splicing to/from a tty

[Al Viro]

On Wed, Jan 20, 2021 at 04:26:08PM +0000, Al Viro wrote:

> [1] yes, it is possible to have O_APPEND opened pipes - open a FIFO with
> O_APPEND and you've got it.  We are not quite consistent in handling
> those - sendfile() to such is rejected, splice() is not.

BTW, according to manpages of splice(2) and sendfile(2), we have
       EINVAL [snip] target file is opened in append mode [snip]
and
       EINVAL out_fd has the O_APPEND flag set.  This is not currently supported by sendfile().

However, splice(2) to FIFO opened with O_APPEND works just fine.  So
it doesn't match the manpage either.

Why do we care about O_APPEND on anything without FMODE_PWRITE (including
pipes), anyway?  All writes there ignore position, after all...