server: Fix returned error when creating an existing symlink.

dlls/ntdll/tests/om.c

@@ -1408,8 +1408,14 @@ static void test_symboliclink(void)
     pNtClose(link);
 
     RtlInitUnicodeString(&str, L"\\");
+    attr.Attributes = OBJ_OPENIF;
     status = pNtCreateSymbolicLinkObject(&h, SYMBOLIC_LINK_QUERY, &attr, &target);
-    todo_wine ok(status == STATUS_OBJECT_TYPE_MISMATCH,
+    ok(status == STATUS_OBJECT_TYPE_MISMATCH,
+       "NtCreateSymbolicLinkObject should have failed with STATUS_OBJECT_TYPE_MISMATCH got(%08lx)\n", status);
+    attr.Attributes = 0;
+    status = pNtCreateSymbolicLinkObject(&h, SYMBOLIC_LINK_QUERY, &attr, &target);
+    todo_wine
+    ok(status == STATUS_OBJECT_TYPE_MISMATCH,
        "NtCreateSymbolicLinkObject should have failed with STATUS_OBJECT_TYPE_MISMATCH got(%08lx)\n", status);
 
     RtlInitUnicodeString( &target, L"->Somewhere");
@@ -1480,6 +1486,16 @@ static void test_symboliclink(void)
     ok(status == STATUS_SUCCESS, "Got unexpected status %#lx.\n", status);
     pNtClose(h);
 
+    attr.Attributes = OBJ_OPENIF;
+    status = pNtCreateSymbolicLinkObject( &h, SYMBOLIC_LINK_QUERY, &attr, &target );
+    ok(status == STATUS_SUCCESS || broken( status == STATUS_OBJECT_NAME_EXISTS ), /* <= win10 1507 */
+       "Got unexpected status %#lx.\n", status);
+    pNtClose(h);
+    attr.Attributes = 0;
+    status = pNtCreateSymbolicLinkObject( &h, SYMBOLIC_LINK_QUERY, &attr, &target );
+    ok(status == STATUS_OBJECT_NAME_COLLISION, "Got unexpected status %#lx.\n", status);
+    pNtClose(h);
+
     InitializeObjectAttributes(&attr, &str, 0, 0, NULL);
     RtlInitUnicodeString( &str, L"\\BaseNamedObjects\\om.c-test\\" );
     status = NtCreateFile(&h, GENERIC_READ | SYNCHRONIZE, &attr, &iosb, NULL, 0,

server/symlink.c

@@ -155,13 +155,18 @@ struct object *create_symlink( struct object *root, const struct unicode_str *na
         set_error( STATUS_INVALID_PARAMETER );
         return NULL;
     }
-    if (!(symlink = create_named_object( root, &symlink_ops, name, attr, sd ))) return NULL;
-    if (get_error() != STATUS_OBJECT_NAME_EXISTS && !(symlink->target = memdup( target->str, target->len )))
+    if (!(symlink = create_named_object( root, &symlink_ops, name, attr | OBJ_OPENLINK, sd ))) return NULL;
+    if (get_error() != STATUS_OBJECT_NAME_EXISTS)
+    {
+        symlink->len = target->len;
+        if (!(symlink->target = memdup( target->str, target->len )))
         {
             release_object( symlink );
             return NULL;
         }
-    symlink->len = target->len;
+    }
+    else clear_error();
+
     return &symlink->obj;
 }