Fix selection of overlapping patterns (#197)

- closes #137 (thanks to @ilario for the first steps)
- closes #22
- normally selection patterns not relative to the root path lead to an error,
  but 'selection' was accepted for 'select' because they start alike.
- test accordingly added to testing/selection.py

src/rdiff_backup/selection.py

@@ -86,6 +86,7 @@ def __init__(self, rootrp):
         self.selection_functions = []
         self.rpath = rootrp
         self.prefix = self.rpath.path
+        self.prefixindex = tuple([x for x in self.prefix.split(b"/") if x])
 
     def set_iter(self, sel_func=None):
         """Initialize more variables, get ready to iterate
@@ -185,6 +186,17 @@ def Iterate(self, rp, rec_func, sel_func):
         else:
             assert 0, "Invalid selection result %s" % (str(s), )
 
+    def get_relative_index(self, filename):
+        """return the index of a file relative to the current prefix
+        or fail if they're not relative to each other"""
+
+        fileindex = tuple([x for x in filename.split(b"/") if x])
+
+        # are the first elements of the path the same?
+        if fileindex[:len(self.prefixindex)] != self.prefixindex:
+            raise FilePrefixError(filename)
+        return fileindex[len(self.prefixindex):]
+
     def listdir(self, dir_rp):
         """List directory rpath with error logging"""
 
@@ -420,10 +432,7 @@ def filelist_parse_line(self, line, include):
             include = 0
             line = line[2:]
 
-        if not line.startswith(self.prefix):
-            raise FilePrefixError(line)
-        line = line[len(self.prefix):]  # Discard prefix
-        index = tuple([x for x in line.split(b"/") if x])  # remove empties
+        index = self.get_relative_index(line)
         return (index, include)
 
     def filelist_pair_match(self, rp, pair):
@@ -616,10 +625,7 @@ def glob_get_filename_sf(self, filename, include):
         globbing characters are used.
 
         """
-        if not filename.startswith(self.prefix):
-            raise FilePrefixError(filename)
-        index = tuple(
-            [x for x in filename[len(self.prefix):].split(b"/") if x])
+        index = self.get_relative_index(filename)
         return self.glob_get_tuple_sf(index, include)
 
     def glob_get_tuple_sf(self, tuple, include):

testing/selectiontest.py

@@ -41,6 +41,10 @@ def testTupleInclude(self):
         """Test include selection function made from a regular filename"""
         self.assertRaises(FilePrefixError, self.Select.glob_get_filename_sf,
                           b"foo", 1)
+        self.assertRaises(FilePrefixError, self.Select.glob_get_filename_sf,
+                          b"rdiff-backup_testfiles/sel", 1)
+        self.assertRaises(FilePrefixError, self.Select.glob_get_filename_sf,
+                          b"rdiff-backup_testfiles/selection", 1)
 
         sf2 = self.Select.glob_get_sf(
             "rdiff-backup_testfiles/select/usr/local/bin/", 1)
@@ -55,6 +59,10 @@ def testTupleExclude(self):
         """Test exclude selection function made from a regular filename"""
         self.assertRaises(FilePrefixError, self.Select.glob_get_filename_sf,
                           b"foo", 0)
+        self.assertRaises(FilePrefixError, self.Select.glob_get_filename_sf,
+                          b"rdiff-backup_testfiles/sel", 0)
+        self.assertRaises(FilePrefixError, self.Select.glob_get_filename_sf,
+                          b"rdiff-backup_testfiles/selection", 0)
 
         sf2 = self.Select.glob_get_sf(
             "rdiff-backup_testfiles/select/usr/local/bin/", 0)