[PATCH xserver] glamor: restore vfunc handlers on init failure

[Olivier Fourdan]

In glamor_init(), if the minimum requirements are not met, glamor may
fail after setting up its own CloseScreen() and DestroyPixmap()
routines, leading to a crash when either of the two routines is called
if glamor failed to complete its initialization, e.g:

  (EE) Backtrace:
  (EE) 0:  Xwayland (OsSigHandler+0x29)
  (EE) 1: /lib64/libpthread.so.0 (__restore_rt+0x0)
  (EE) 2: Xwayland (glamor_sync_close+0x2a)
  (EE) 3: Xwayland (glamor_close_screen+0x52)
  (EE) 4: Xwayland (CursorCloseScreen+0x88)
  (EE) 5: Xwayland (AnimCurCloseScreen+0xa4)
  (EE) 6: Xwayland (present_close_screen+0x42)
  (EE) 7: Xwayland (dix_main+0x4f9)
  (EE) 8: /lib64/libc.so.6 (__libc_start_main+0xf1)
  (EE) 9:  Xwayland (_start+0x2a)

Restore the previous CloseScreen() and DestroyPixmap() vfunc handlers in
case of failure when checking for the minimum requirements, so that if
any of the requirement is not met we don't leave the CloseScreen() and
DestroyPixmap() from glamor handlers in place.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1390018

Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>
---
 glamor/glamor.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/glamor/glamor.c b/glamor/glamor.c
index b771832..c54cf3b 100644
--- a/glamor/glamor.c
+++ b/glamor/glamor.c
@@ -470,7 +470,7 @@ glamor_init(ScreenPtr screen, unsigned int flags)
         LogMessage(X_WARNING,
                    "glamor%d: Failed to allocate screen private\n",
                    screen->myNum);
-        goto fail;
+        goto free_glamor_private;
     }
 
     glamor_set_screen_private(screen, glamor_priv);
@@ -480,7 +480,7 @@ glamor_init(ScreenPtr screen, unsigned int flags)
         LogMessage(X_WARNING,
                    "glamor%d: Failed to allocate pixmap private\n",
                    screen->myNum);
-        goto fail;
+        goto free_glamor_private;
     }
 
     if (!dixRegisterPrivateKey(&glamor_gc_private_key, PRIVATE_GC,
@@ -488,7 +488,7 @@ glamor_init(ScreenPtr screen, unsigned int flags)
         LogMessage(X_WARNING,
                    "glamor%d: Failed to allocate gc private\n",
                    screen->myNum);
-        goto fail;
+        goto free_glamor_private;
     }
 
     glamor_priv->saved_procs.close_screen = screen->CloseScreen;
@@ -731,6 +731,11 @@ glamor_init(ScreenPtr screen, unsigned int flags)
     return TRUE;
 
  fail:
+    /* Restore default CloseScreen and DestroyPixmap handlers */
+    screen->CloseScreen = glamor_priv->saved_procs.close_screen;
+    screen->DestroyPixmap = glamor_priv->saved_procs.destroy_pixmap;
+
+ free_glamor_private:
     free(glamor_priv);
     glamor_set_screen_private(screen, NULL);
     return FALSE;
-- 
2.9.3