Re: Wrong file position after writing 65537 bytes to block device

[Steven Penny <svnpenn at gmail dot com>]

On Mon, 18 Dec 2017 14:10:35, Corinna Vinschen wrote:
> In general, the writes on disk devices is sector-oriented.  Howewver,
> in this case ftell should have returned 65536.  The problem here is
> that the newlib implmentation of ftell/ftello performs an fflush
> when called on a write stream since about 2008 to adjust for appending
> streams.  Given your example (thanks for the testcase!) this seems
> pretty wrong.  Looking further it turns out that neither glibc nor BSD
> actually calls fflush in this case.  There's only a special case for
> appending streams, but this calls lseek, not fflush.
>
> Looks like a patch is required.  Stay tuned.

is it though? he says "write 65536 + 1 bytes", but as far as i can tell, you
cant do that. quoting myself:

> Seeking, reading and writing must all be done in multiples of sector size, in
> my case 512 bytes

http://web.archive.org/web/stackoverflow.com/questions/37228874/how-to-fwrite-to-removable-volume

so it would make sense that the position becomes "65536 + 512"


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple