CVSROOT:        /cvs
Module name:    src
Changes by:     d...@cvs.openbsd.org    2021/05/18 19:24:05

Modified files:
        usr.bin/ssh    : channels.c channels.h clientloop.c mux.c 
                         nchan.c ssh.c 

Log message:
restore blocking status on stdio fds before close

ssh(1) needs to set file descriptors to non-blocking mode to operate
but it was not restoring the original state on exit. This could cause
problems with fds shared with other programs via the shell, e.g.

> $ cat > test.sh << _EOF
> #!/bin/sh
> {
>         ssh -Fnone -oLogLevel=verbose ::1 hostname
>         cat /usr/share/dict/words
> } | sleep 10
> _EOF
> $ ./test.sh
> Authenticated to ::1 ([::1]:22).
> Transferred: sent 2352, received 2928 bytes, in 0.1 seconds
> Bytes per second: sent 44338.9, received 55197.4
> cat: stdout: Resource temporarily unavailable

This restores the blocking status for fds 0,1,2 (stdio) before ssh(1)
abandons/closes them.

This was reported as bz3280 and GHPR246; ok dtucker@

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