[PATCH] xf86Crtc: handle no outputs with no modes harder.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

If you started an X server with no connected outputs, we pick a default
1024x768 mode, however if you then ran an xvidmode using app against that
server it would segfault the server due to not finding any valid modes.

This was due to the no output mode set code, only adding the modes to the
scrn->modes once, when something called randr 1.2 xf86SetScrnInfoModes would
get called and remove all the modes and we'd end up with 0.

This change fixes xf86SetScrnInfoModes to always report a scrn mode of at
least 1024x768, and pushes the initial configuration to just call it instead
of setting up the mode itself.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=746926

I've seen other bugs like this on other distros so it might also actually fix them.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 hw/xfree86/modes/xf86Crtc.c |   41 +++++++++++++++++++----------------------
 1 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/hw/xfree86/modes/xf86Crtc.c b/hw/xfree86/modes/xf86Crtc.c
index cbe0b5c..fc34a6b 100644
--- a/hw/xfree86/modes/xf86Crtc.c
+++ b/hw/xfree86/modes/xf86Crtc.c
@@ -1915,19 +1915,25 @@ xf86SetScrnInfoModes (ScrnInfoPtr scrn)
 		break;
     }
 
-    if (scrn->modes != NULL) {
-	/* For some reason, scrn->modes is circular, unlike the other mode
-	 * lists.  How great is that?
-	 */
-	for (last = scrn->modes; last && last->next; last = last->next)
-	    ;
-	last->next = scrn->modes;
-	scrn->modes->prev = last;
-	if (mode) {
-	    while (scrn->modes != mode)
-		scrn->modes = scrn->modes->next;
-	}
+    if (!scrn->modes) {
+	scrn->modes = xf86ModesAdd(scrn->modes,
+				   xf86CVTMode(scrn->display->virtualX,
+					       scrn->display->virtualY,
+					       60, 0, 0));
+    }
+
+    /* For some reason, scrn->modes is circular, unlike the other mode
+     * lists.  How great is that?
+     */
+    for (last = scrn->modes; last && last->next; last = last->next)
+	;
+    last->next = scrn->modes;
+    scrn->modes->prev = last;
+    if (mode) {
+	while (scrn->modes != mode)
+	    scrn->modes = scrn->modes->next;
     }
+
     scrn->currentMode = scrn->modes;
 #ifdef XFreeXDGA
     if (scrn->pScreen)
@@ -2514,16 +2520,7 @@ xf86InitialConfiguration (ScrnInfoPtr scrn, Bool canGrow)
 			      width, height);
     }
 
-    if (have_outputs) {
-	/* Mirror output modes to scrn mode list */
-	xf86SetScrnInfoModes (scrn);
-    } else {
-	/* Clear any existing modes from scrn->modes */
-	while (scrn->modes != NULL)
-	    xf86DeleteMode(&scrn->modes, scrn->modes);
-	scrn->modes = xf86ModesAdd(scrn->modes,
-				   xf86CVTMode(width, height, 60, 0, 0));
-    }
+    xf86SetScrnInfoModes (scrn);
 
     success = TRUE;
  bailout:
-- 
1.7.6.4