[PATCH 2/3] base-manager: handle NULL physical device more gracefully

[Ben Chan]

find_device_by_physdev_uid() expects a non-NULL UID of the physical
device. However, mm_kernel_device_get_physdev_uid() could potentially
return NULL on MMKernelDeviceUdev if find_physical_gudevdevice() in
mm-kernel-device-udev.c fails to find the physical device. When a NULL
physical device UID is passed to find_device_by_physdev_uid() and used
in g_hash_table_lookup(), it leads to a crash in g_str_hash(), which is
a bit obscure.

This patch updates find_device_by_physdev_uid() to handle the case when
mm_kernel_device_get_physdev_uid() fails to return a valid UID, and also
moves the assertion on non-NULL UID to find_device_by_physdev_uid() in
order to ensure find_device_by_physdev_uid() is properly used by future
callers.
---
 src/mm-base-manager.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/mm-base-manager.c b/src/mm-base-manager.c
index 66096130..d5049b12 100644
--- a/src/mm-base-manager.c
+++ b/src/mm-base-manager.c
@@ -127,6 +127,8 @@ static MMDevice *
 find_device_by_physdev_uid (MMBaseManager *self,
                             const gchar   *physdev_uid)
 {
+    g_assert (physdev_uid != NULL);
+
     return g_hash_table_lookup (self->priv->devices, physdev_uid);
 }
 
@@ -134,7 +136,12 @@ static MMDevice *
 find_device_by_kernel_device (MMBaseManager  *manager,
                               MMKernelDevice *kernel_device)
 {
-    return find_device_by_physdev_uid (manager, mm_kernel_device_get_physdev_uid (kernel_device));
+    const gchar *physdev_uid;
+
+    physdev_uid = mm_kernel_device_get_physdev_uid (kernel_device);
+    g_return_val_if_fail (physdev_uid != NULL, NULL);
+
+    return find_device_by_physdev_uid (manager, physdev_uid);
 }
 
 /*****************************************************************************/
@@ -277,7 +284,6 @@ device_added (MMBaseManager  *manager,
     /* Get the port's physical device's uid. All ports of the same physical
      * device will share the same uid. */
     physdev_uid = mm_kernel_device_get_physdev_uid (port);
-    g_assert (physdev_uid);
 
     /* See if we already created an object to handle ports in this device */
     device = find_device_by_physdev_uid (manager, physdev_uid);
-- 
2.11.0.483.g087da7b7c-goog