xwayland: Check for duplicate output names

Even though the name provided by either xdg-output or wl_output are
guaranteed to be unique, that might not be the case with output names
between different protocols, such as the one offered for DRM lease.

To avoid running into name conflicts, check that no other existing
output of the same name exists prior to changing the output name.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1492>

1 files changed, 21 insertions, 0 deletions

diff --git a/hw/xwayland/xwayland-output.c b/hw/xwayland/xwayland-output.c
index 2690fa0e3..7c8ebd49a 100644
--- a/hw/xwayland/xwayland-output.c
+++ b/hw/xwayland/xwayland-output.c
@@ -687,6 +687,9 @@ void
 xwl_output_set_name(struct xwl_output *xwl_output, const char *name)
 {
     struct xwl_screen *xwl_screen = xwl_output->xwl_screen;
+    rrScrPrivPtr pScrPriv;
+    RRLeasePtr lease;
+    int i;
 
     if (xwl_output->randr_output == NULL)
         return; /* rootful */
@@ -697,6 +700,24 @@ xwl_output_set_name(struct xwl_output *xwl_output, const char *name)
         return;
     }
 
+    /* Check for duplicate names to be safe */
+    pScrPriv = rrGetScrPriv(xwl_screen->screen);
+    for (i = 0; i < pScrPriv->numOutputs; i++) {
+        if (!strcmp(name, pScrPriv->outputs[i]->name)) {
+            ErrorF("An output named '%s' already exists", name);
+            return;
+        }
+    }
+    /* And leases' names as well */
+    xorg_list_for_each_entry(lease, &pScrPriv->leases, list) {
+        for (i = 0; i < lease->numOutputs; i++) {
+            if (!strcmp(name, pScrPriv->outputs[i]->name)) {
+                ErrorF("A lease output named '%s' already exists", name);
+                return;
+            }
+        }
+    }
+
     snprintf(xwl_output->randr_output->name, MAX_OUTPUT_NAME, "%s", name);
     xwl_output->randr_output->nameLength = strlen(xwl_output->randr_output->name);