Fix handling of non V1.5 XRandr. #364

SteveJones · 2017-08-24T20:26:08Z

Due to the way Xlib handles errors XRRGetMonitors will cause dunst to exit if
the server doesn't support version 1.5 of Randr. The check for null is
effectively dead code. Change the code to fetch the Randr version and fallback
if the version is less than 1.5 when getting monitors.

tsipinakis

Sorry for the delay in reviewing this, I wasn't home for the past few days.

tsipinakis · 2017-08-27T06:51:09Z

src/x11/screen.c

@@ -82,27 +82,33 @@ void alloc_screen_ar(int n)

 int randr_event_base = 0;

+static int randr_major_version = 1;


Why default these to 1 and 5? I think setting them to 0 would be a better choice.

This was me reading the protocol docs which say that the client has to send the version it expects, but the xrandr code sends this itself, it doesn't use the initial value of the pointers you pass in. I'll fix this.

This was me reading the protocol docs which say that the client has to send the version it expects

Where does it say that? It's not mentioned anywhere in the xrandr man page?

It's in the protocol specification, but the library API doesn't match that.

Found it, JFTR in this document search for QueryVersion.

The client sends the highest supported version to the server
and the server sends the highest version it supports, but no
higher than the requested version. Major versions changes can
introduce incompatibilities in existing functionality, minor
version changes introduce only backward compatible changes.
It is the clients responsibility to ensure that the server
supports a version which is compatible with its expectations.

In that case it should probably be left in even though it's not doing anything currently and the change is trivial I think it's best to go with the spec.

tsipinakis · 2017-08-27T06:52:47Z

src/x11/screen.c

-        int n;
-        XRRMonitorInfo *m = XRRGetMonitors(xctx.dpy, RootWindow(xctx.dpy, DefaultScreen(xctx.dpy)), true, &n);
-
-        if (m == NULL || n == -1) {


In xrandr.c I see that there's an error check for n == -1 so this check should probably stay and have a separate check for version.

Hmm, looking at https://cgit.freedesktop.org/xorg/lib/libXrandr/tree/src/XrrMonitor.c it's checking a weird edge case where the server returns 0 monitors, but I guess that's possible. I'll put the check back.

tsipinakis · 2017-08-27T06:55:19Z

src/x11/screen.c

-        XRRMonitorInfo *m = XRRGetMonitors(xctx.dpy, RootWindow(xctx.dpy, DefaultScreen(xctx.dpy)), true, &n);
-
-        if (m == NULL || n == -1) {
+        if (randr_minor_version < 5) {


You're only checking for minor < 5 here which is going to break at the next major version. A more complete check would be randr_major_version < 1 || (randr_major_version == 1 && randr_minor_version < 5)

Additionally, there should probably be a more descriptive error message mentioning the outdated version.

Good point.

tsipinakis · 2017-09-06T17:42:42Z

@SteveJones Ping, are you still active?

SteveJones · 2017-09-06T22:42:28Z

Hi yeah, sorry this slipped my mind. I'll try and get this fixed up in the next day or so.

tsipinakis · 2017-09-11T12:46:26Z

Looks like you misspelled the major version variable.

Have you tested this in a system with an outdated xrandr version (and probably on one with no xrandr installed at all)? Just to confirm that it works as intended.

SteveJones · 2017-09-13T13:23:38Z

That'll teach me to add in a cosmetic change after testing it builds (it won't).

I've tested it on outdated, XRandR, it's why I wrote it.

tsipinakis

Just a minor mistake after that this should be ready to be merged

Can you squash the commits to avoid polluting the history?

PS: Sorry for the delay (again) you caught me both times on days that I was out.

tsipinakis · 2017-09-17T14:29:33Z

src/x11/screen.c

@@ -98,7 +98,8 @@ void randr_init()

 void randr_update()
 {
-        if (randr_minor_version < 5) {
+	if (randr_major_version > 1


Noticed this just as I was about to click merge:

We're checking for the error condition so it should be randr_major_version < 1

SteveJones · 2017-09-17T20:45:56Z

Right, fixed that and squashed. Tests just passed. It builds and seems happy. Should be good to go.

tsipinakis · 2017-09-18T17:32:54Z

It builds and seems happy. Should be good to go.

Apparently not :p Just realised you used tabs, we're using 8 spaces for indentation. should be a quick fix.

bebehei · 2017-09-18T17:36:27Z

Apparently not :p Just realised you used tabs, we're using 8 spaces for indentation. should be a quick fix.

If we're so nitpicky now, please also remove the last point on your commit headline. It's a common standard.

tsipinakis · 2017-09-18T17:43:21Z

If we're so nitpicky now

That's not a nitpick in my opinion, it's adhering to the projects code style else it just becomes a mess.

The commit message format is generally up to the contributor and I don't interfere with that, just give hints about the correct standards (and I didn't actually notice the period this time).

tsipinakis · 2017-10-21T17:56:00Z

Ping @SteveJones

@SteveJones

Due to the way Xlib handles errors XRRGetMonitors will cause dunst to exit if the server doesn't support version 1.5 of RandR. The check for null is effectively dead code but in theory the number of monitors can be < 1 so treat this as an error. Change the code to fetch the RandR version and fallback if the version is less than 1.5 when getting monitors. This fix was brought up by @SteveJones on GitHub

Albeit it's possible to run with XRandR extension < 1.5, dunst needs the headers of libxrandr 1.5.

bebehei · 2017-11-02T14:32:41Z

I misused my privileges the first time now pushed the stylefixes to this PR.

Fix handling of non V1.5 XRandr.

tsipinakis requested changes Aug 27, 2017

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tsipinakis requested changes Sep 17, 2017

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bebehei mentioned this pull request Oct 15, 2017

failed with old xorg #413

Closed

bebehei added 2 commits November 2, 2017 15:31

Require XRandR 1.5 in pkg-config to compile

4cf9114

Albeit it's possible to run with XRandR extension < 1.5, dunst needs the headers of libxrandr 1.5.

bebehei requested a review from tsipinakis November 2, 2017 22:59

tsipinakis approved these changes Nov 4, 2017

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tsipinakis merged commit fd81bd1 into dunst-project:master Nov 4, 2017

karlicoss pushed a commit to karlicoss/dunst that referenced this pull request Mar 21, 2019

Merge pull request dunst-project#364 from SteveJones/master

d7ba78a

Fix handling of non V1.5 XRandr.

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Fix handling of non V1.5 XRandr. #364

Fix handling of non V1.5 XRandr. #364

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bebehei commented Nov 2, 2017

		@@ -82,27 +82,33 @@ void alloc_screen_ar(int n)

		int randr_event_base = 0;

		static int randr_major_version = 1;

Fix handling of non V1.5 XRandr. #364

Fix handling of non V1.5 XRandr. #364

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