[PATCH 2/2] vbox: Fix starting domains

[Martin Kletzander]

On Mon, Jan 23, 2023 at 10:31:53AM +0100, Michal Privoznik wrote:
>When starting a VirtualBox domain, we try to guess which frontend
>to use. While the whole algorithm looks a bit outdated, it may
>happen that we tell VirtualBox to use "gui" frontend, but not
>which DISPLAY= to use.
>
>I haven't found any documentation on the algorithm we use, but if
>I make us fallback onto DISPLAY=:0 when no other configuration is
>found then I'm able to start my guests just fine.
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> src/vbox/vbox_common.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
>diff --git a/src/vbox/vbox_common.c b/src/vbox/vbox_common.c
>index bd77641d39..5269f9b23f 100644
>--- a/src/vbox/vbox_common.c
>+++ b/src/vbox/vbox_common.c
>@@ -2121,13 +2121,12 @@ vboxStartMachine(virDomainPtr dom, int maxDomID, IMachine *machine, vboxIID *iid
>     VBOX_UTF8_FREE(valueDisplayUtf8);
>
>     if (guiPresent) {
>-        if (guiDisplay) {
>-            char *displayutf8;
>-            displayutf8 = g_strdup_printf("DISPLAY=%s", guiDisplay);
>-            VBOX_UTF8_TO_UTF16(displayutf8, &env);
>-            VIR_FREE(displayutf8);
>-            VIR_FREE(guiDisplay);
>-        }
>+        char *displayutf8;
>+
>+        displayutf8 = g_strdup_printf("DISPLAY=%s", guiDisplay ? guiDisplay : ":0");
>+        VBOX_UTF8_TO_UTF16(displayutf8, &env);

This might get overwritten when using SDL couple lines below.  I suggest
you default to :0 only if none other option remains.  It feels dirty
just guessing the display number, but let's say that's something we'll
have to live with in the vbox driver.

>+        VIR_FREE(displayutf8);
>+        VIR_FREE(guiDisplay);
>
>         VBOX_UTF8_TO_UTF16("gui", &sessionType);
>     }
>-- 
>2.39.1
>
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