* added code to catch some more error conditions

* slightly changed the structure of the block device cache

src/cryptobox/core/blockdevice.py

@@ -173,7 +173,7 @@ class Blockdevice:
         @param empty_cache: Whether to discard the cached information or not.
         """
         if empty_cache:
-            CACHE.reset(["blockdevice_info", self.name])
+            CACHE.reset(["blockdevice_info", (self.major, self.minor)])
         self.size = self.__get_size()
         self.size_human = self.__get_size_human()
         self.range = self.__get_device_range()
@@ -181,6 +181,14 @@ class Blockdevice:
         self.holders = self.__get_dev_related("holders")
         self.children = self.__get_children()
         self.devnodes = self.__get_device_nodes()
+        if self.get_device() is None:
+            CACHE.reset(["blockdevice_nodes"])
+            self.devnodes = self.__get_device_nodes()
+            if self.get_device() is None:
+                LOGGER.warning("No suitable device nodes found for: %s" % \
+                        self.devdir)
+                # the following code would fail without device node -> skip it
+                return
         attributes = self.__get_blkid_attributes()
         self.label = attributes["label"]
         self.type_id = attributes["type_id"]
@@ -237,7 +245,7 @@ class Blockdevice:
         @return: 'True' for a device usable as a storage
         """
         ## check the cache first
-        cache_link = ["blockdevice_info", self.name, "is_storage"]
+        cache_link = ["blockdevice_info", (self.major, self.minor), "is_storage"]
         cached = CACHE.get(cache_link)
         if not cached is None:
             return cached
@@ -282,7 +290,7 @@ class Blockdevice:
         """return if the device is a physical volume of a LVM
         """
         ## check the cache first
-        cache_link = ["blockdevice_info", self.name, "is_lvm_pv"]
+        cache_link = ["blockdevice_info", (self.major, self.minor), "is_lvm_pv"]
         cached = CACHE.get(cache_link)
         if not cached is None:
             return cached
@@ -300,7 +308,7 @@ class Blockdevice:
         """return if the device is a logical volume of a LVM
         """
         ## check the cache first
-        cache_link = ["blockdevice_info", self.name, "is_lvm_lv"]
+        cache_link = ["blockdevice_info", (self.major, self.minor), "is_lvm_lv"]
         cached = CACHE.get(cache_link)
         if not cached is None:
             return cached
@@ -325,7 +333,7 @@ class Blockdevice:
         """check if the device is the base of a md raid device
         """
         ## check the cache first
-        cache_link = ["blockdevice_info", self.name, "is_md_raid"]
+        cache_link = ["blockdevice_info", (self.major, self.minor), "is_md_raid"]
         cached = CACHE.get(cache_link)
         if not cached is None:
             return cached
@@ -352,7 +360,7 @@ class Blockdevice:
         """check if the device is a luks container
         """
         ## check the cache first
-        cache_link = ["blockdevice_info", self.name, "is_luks"]
+        cache_link = ["blockdevice_info", (self.major, self.minor), "is_luks"]
         cached = CACHE.get(cache_link)
         if not cached is None:
             return cached
@@ -388,7 +396,7 @@ class Blockdevice:
         """check if the device is marked as 'removable'
         """
         ## check the cache first
-        cache_link = ["blockdevice_info", self.name, "is_removable"]
+        cache_link = ["blockdevice_info", (self.major, self.minor), "is_removable"]
         cached = CACHE.get(cache_link)
         if not cached is None:
             return cached
@@ -690,10 +698,10 @@ class BlockdeviceCache:
         self.reset()
 
 
-    def reset(self, link=None):
+    def reset(self, target=None):
         """empty the cache and reset the expire time
         """
-        if not link:
+        if target is None:
             self.values = {}
             try:
                 self.partitions_save = file(CACHE_MONITOR_FILE).read()
@@ -702,9 +710,15 @@ class BlockdeviceCache:
                         (CACHE_MONITOR_FILE, err_msg))
                 self.partitions_save = ""
             self.expires = int(time.time()) + CACHE_EXPIRE_SECONDS
+        elif type(target) == types.ListType:
+            # we do not reset the expire date
+            self.set(target, {})
+        elif isinstance(target, Blockdevice):
+            # we do not reset the expire date
+            self.set(["blockdevice_info", (target.major, target.minor)], {})
         else:
-            ## we do no reset the expire date
+            LOGGER.log.warn("Invalid argument type for reset: %s" % \
-            self.set(link, {})
+                    str(type(target)))
 
 
     def __is_expired(self):
@@ -811,7 +825,9 @@ def __get_major_minor(dev):
 def get_blockdevice(dev,
         sysblock_dir=DEFAULT_SYSBLOCK_DIR,
         devnode_dir=DEFAULT_DEVNODE_DIR, retry_once=True):
-    if isinstance(dev, Blockdevice):
+    if dev is None:
+        return None
+    elif isinstance(dev, Blockdevice):
         # it is already a blockdevice
         major_minor = (dev.major, dev.minor)
     elif type(dev) is types.TupleType: