Re: [dev] [libsl] crashes when redering emojis

From: Hiltjo Posthuma <>
Date: Wed, 18 Jan 2017 18:36:33 +0100

On Tue, Jan 17, 2017 at 08:47:09PM +0100, Sören Tempel wrote:
> Hello there,
> I believe I found a bug in libsl. The drw_text function from libsl
> crashes with an X Error when the passed text contains an emoji. The
> exact error message is the following:
> X Error of failed request: BadLength (poly request too large or internal Xlib length error)
> Major opcode of failed request: 138 (RENDER)
> Minor opcode of failed request: 20 (RenderAddGlyphs)
> Serial number of failed request: 28
> Current serial number in output stream: 29
> I reproduced this bug with dwm and dmenu. When using dmenu you can
> reproduce this bug in the following way: First of all you will need to
> have a font installed which actually supports emojis. I used Googles
> noto emoji font [1]. After installing such a font it will be
> automatically picked up by libsl as a fallback font for emojis (assuming
> that the font you configured in config.h doesn't support them).
> To reproduce the error message shown above you will then just need to
> pass an emoji to dmenu over stdin. I used the clown face (U+1F921) but
> different emojis should also work.
> Even though the instructions above are limited to dmenu it also effects
> other suckless software using libsl, for instance dwm. Among other
> things dwm uses drw_text to display the title of the current window in
> the topbar. This is somewhat annoying because if you open a webpage
> containing an emoji in its title (assuming your web browser sets the
> window title to the page title) your entire window manager will crash.
> I tried to resolve the issue myself the only thing I managed to figure
> out is that the Xlib function causing the crash is XftTextExtentsUtf8
> which is called from drw_font_getexts (called from drw_text). However, I
> I am too inexperienced with Xlib myself to come up with a patch.
> Sören.
> [1]:

I cannot reproduce this issue, but it has been reported before.

Do you use the latest git version for dmenu? Do you have any custom patches or
changes applied?

What OS / distro and library versions do you use?

Can you provide your config.h, font configuration files and command you used
to generate the text?

Kind regards,
Received on Wed Jan 18 2017 - 18:36:33 CET

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