Re: proposal - psql - use pager for \watch command

From: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: proposal - psql - use pager for \watch command
Date: 2021-03-22 12:13:11
Message-ID: CA+hUKGLsd9afMbDog8Bc6xfuTu8w0qJV06mtJmDDPZ7uw8=RbA@mail.gmail.com
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On Mon, Mar 22, 2021 at 5:10 PM Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> probably there will not be an issue inside ncurses - the most complex part of get_event is polling of input sources - tty and some other. The pspg should not to stop there on tty reading.

The problem is that Apple's /dev/tty device is defective, and doesn't
work in poll(). It always returns immediately with revents=POLLNVAL,
but pspg assumes that data is ready and tries to read the keyboard and
then blocks until I press a key. This seems to fix it:

+#ifndef __APPLE__
+ /* macOS can't use poll() on /dev/tty */
state.tty = fopen("/dev/tty", "r+");
+#endif
if (!state.tty)
state.tty = fopen(ttyname(fileno(stdout)), "r");

A minor problem is that on macOS, _GNU_SOURCE doesn't seem to imply
NCURSES_WIDECHAR, so I suspect Unicode will be broken unless you
manually add -DNCURSES_WIDECHAR=1, though I didn't check.

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