Re: [PATCH] tee: recover from EAGAIN returned from fwrite()

[Pádraig Brady]

On 06/09/18 07:28, Kamil Dudka wrote:
> tee expects the output descriptors to operate in blocking mode but this
> assumption might be invalidated by other programs connected to the same
> terminal, as in the following example:
> 
> $ telnet ... | tee log_file
> 
> telnet calls ioctl(stdin, FIONBIO, [1]), which causes the O_NONBLOCK
> flag to be set on tee's output, which is connected to the same terminal.
> 
> This patch has zero impact unless EAGAIN returns from fwrite().  In that
> case we try to reset the O_NONBLOCK flag on the output file descriptor
> and retry the call to fwrite().

Not sure about this.

Would that not be changing the tty to blocking, which is not what telnet wants?
Also this would be a general issue. Why treat tee specially here?
Also would `cat | telnet ... | tee blah` be a workaround?

thanks for the patch,
Pádraig