libudev: enumerate - allow to filter-out not-already-initialized devices

[elogind.git] / libudev / libudev-enumerate.c

diff --git a/libudev/libudev-enumerate.c b/libudev/libudev-enumerate.c
index 363d445f90a5f63a569cf4d1d15378456b119180..e46bc087fa31879573a3107f189be62b6191d9d5 100644 (file)
--- a/libudev/libudev-enumerate.c
+++ b/libudev/libudev-enumerate.c
@@ -57,6 +57,7 @@ struct udev_enumerate {
        unsigned int devices_cur;
        unsigned int devices_max;
        bool devices_uptodate:1;
+       bool match_is_initialized;
 };
 
 /**
@@ -456,6 +457,32 @@ int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const ch
        return 0;
 }
 
+/**
+ * udev_enumerate_add_match_is_initialized:
+ * @udev_enumerate: context
+ *
+ * Match only devices which udev has set up already. This makes
+ * sure, that the device node permissions and context are properly set
+ * and that network devices are fully renamed.
+ *
+ * Usually, devices which are found in the kernel but not already
+ * handled by udev, have still pending events. Services should subscribe
+ * to monitor events and wait for these devices to become ready, instead
+ * of using uninitialized devices.
+ *
+ * For now, this will not affect devices which do not have a device node
+ * and are not network interfaces.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate)
+{
+       if (udev_enumerate == NULL)
+               return -EINVAL;
+       udev_enumerate->match_is_initialized = true;
+       return 0;
+}
+
 /**
  * udev_enumerate_add_match_sysname:
  * @udev_enumerate: context
@@ -601,6 +628,21 @@ static int scan_dir_and_add_devices(struct udev_enumerate *udev_enumerate,
                if (dev == NULL)
                        continue;
 
+               if (udev_enumerate->match_is_initialized) {
+                       /*
+                        * All devices with a device node or network interfaces
+                        * possibly need udev to adjust the device node permission
+                        * or context, or rename the interface before it can be
+                        * reliably used from other processes.
+                        *
+                        * For now, we can only check these types of devices, we
+                        * might not store a database, and have no way to find out
+                        * for all other types of devices.
+                        */
+                       if (!udev_device_get_is_initialized(dev) &&
+                           (major(udev_device_get_devnum(dev)) > 0 || udev_device_get_ifindex(dev) > 0))
+                               goto nomatch;
+               }
                if (!match_tag(udev_enumerate, dev))
                        goto nomatch;
                if (!match_property(udev_enumerate, dev))