Fix database path

- Don't use ~/.cache, it's intended to store non-essential data
  files and may be purged at any time
- Instead, follow XDG and use $XDG_DATA_HOME or ~/.local/share/buku
- Fallback to current directory if HOME is not defined (Windows?)

buku

@@ -102,6 +102,18 @@ class BMHTMLParser(HTMLParser.HTMLParser):
 
 
 
+def getDataPath():
+    data_home = os.environ.get('XDG_DATA_HOME')
+    if data_home is None:
+        if os.environ.get('HOME') is None:
+            data_home = '.'
+        else:
+            data_home = os.path.join(os.environ.get('HOME'), '.local', 'share')
+
+    return os.path.join(data_home, 'buku')
+
+
+
 def initdb():
     """Initialize the database connection. Create DB file and/or bookmarks table
     if they don't exist. Alert on encryption options on first execution.
@@ -109,7 +121,7 @@ def initdb():
     Returns: connection, cursor
     """
 
-    dbpath = os.path.join(os.environ.get('HOME'), '.cache', 'buku')
+    dbpath = getDataPath()
     if not os.path.exists(dbpath):
         os.makedirs(dbpath)
 
@@ -663,7 +675,7 @@ def get_filehash(filepath):
 def encrypt_file():
     """Encrypt the bookmarks database file"""
 
-    dbpath = os.path.join(os.environ.get('HOME'), '.cache', 'buku', 'bookmarks.db')
+    dbpath = os.path.join(getDataPath(), 'bookmarks.db')
     encpath = dbpath + '.enc'
     if not os.path.exists(dbpath):
         print("%s missing. Already encrypted?" % dbpath)
@@ -724,7 +736,7 @@ def encrypt_file():
 def decrypt_file():
     """Decrypt the bookmarks database file"""
 
-    dbpath = os.path.join(os.environ.get('HOME'), '.cache', 'buku', 'bookmarks.db')
+    dbpath = os.path.join(getDataPath(), 'bookmarks.db')
     encpath = dbpath + '.enc'
     if not os.path.exists(encpath):
         printmsg((encpath + " missing"), "ERROR")