Re: [PATCH] rebase: fix garbled progress display with '-x'

From: SZEDER Gábor <szeder.dev@gmail.com>
Date: Jun 11, 2019, 12:38 UTC
Message-ID: <20190611123811.GF4012@szeder.dev>
In-Reply-To: <20190501231640.GD14763@szeder.dev>

On Thu, May 02, 2019 at 01:16:40AM +0200, SZEDER Gábor wrote:

> On Tue, Apr 30, 2019 at 06:25:35PM -0400, Johannes Schindelin wrote:
> > > Make sure that the previously displayed "Rebasing (N/M)" line is
> > > completely covered up by printing a terminal width worth of space
> > > characters.

Show 15 quoted lines

> > > +			if (!opts->verbose)
> > > +				/*
> > > +				 * Fully cover the previous "Rebasing (n/m)"
> > > +				 * progress line.
> > > +				 */
> > > +				fprintf(stderr, "%*s\r", term_columns(), "");
> > 
> > IIRC there are terminals (`cmd.exe`?) that would advance to the next row
> > automatically when printing the exact number of columns in a row. So this
> > would not work.
> 
> Hrm, I though about using 'term_columns()-1', or moving the '\r' from
> the format string to the string to be printed, but in the end didn't
> do either, because it seemed to work well as it is in the two
> terminals that I tried (on Linux).

And I would have been wrong doing so, because that fprintf'ed string ends with '\r', not '\n', and therefore it is actually necessary to write as many space characters as the width of the terminal, or the last character in the previously displayed line won't get overwritten.