Apply patch from Valery to fix FUSE read

Patch by Valery Yundin. He gave the following recipe to verify it
works:

  * set "ObnamFuseFile.keep_cache" to False
  * backup
  * mount
  * diff -r the original and via FUSE

Before the patch this failed for me if the original file was large
enough, on the order of two to a hundred megs. It works after the
patch.

Someday I will have to really write a test suite for this.

2 files changed, 5 insertions, 6 deletions

diff --git a/obnamlib/plugins/fuse_plugin.py b/obnamlib/plugins/fuse_plugin.py
index 5d736a67..0e9b12bc 100644
--- a/obnamlib/plugins/fuse_plugin.py
+++ b/obnamlib/plugins/fuse_plugin.py
@@ -171,15 +171,14 @@ class ObnamFuseFile(object):
                 size_cache[chunkid] = len(contents)
             size = size_cache[chunkid]
 
-            if chunk_pos_in_file + size > offset:
-                start = offset - chunk_pos_in_file
-                n = length - output_length
+            if chunk_pos_in_file + size > offset + output_length:
+                start = offset + output_length - chunk_pos_in_file
+                n = min(length - output_length, size - start)
                 if contents is None:
                     contents = self.fuse_fs.obnam.repo.get_chunk_content(
                         chunkid)
-                data = contents[start : start+n]
-                output.append(data)
-                output_length += len(data)
+                output.append(contents[start : start+n])
+                output_length += n
                 assert output_length <= length
                 if output_length == length:
                     break
diff --git a/test-gpghome/random_seed b/test-gpghome/random_seed
index 6a8dce29..f4ad4794 100644
--- a/test-gpghome/random_seed
+++ b/test-gpghome/random_seed