file.py: wrote two new functions -- write_shards(), read_shards()

modified:   file.py
modified:   tests/test_file.py

1 files changed, 33 insertions, 0 deletions

diff --git a/combox/file.py b/combox/file.py
index ab76315..ec0372e 100644
--- a/combox/file.py
+++ b/combox/file.py
@@ -18,6 +18,7 @@
 
 from os import path
 from sys import exit
+from glob import glob
 
 
 def split_data(data, n):
@@ -92,3 +93,35 @@ def write_file(filename, filecontent):
     except IOError:
         print "ERROR: creating and writing content to %s" % (filename)
         exit(1)
+
+def write_shards(shards, directory, shard_basename):
+    """Write shards to respective files respective files.
+
+    shard: list of strings (ciphers or data).
+    directory: absolute path of directory to which it shards must be written to.
+    shard_basename: base name of the shard.
+    """
+
+    # partial filename of the shard
+    p_filename =  path.join(directory, shard_basename)
+    shard_no = 0
+    for shard in shards:
+        shard_name =  "%s.shard%s" % (p_filename, shard_no)
+        write_file(shard_name, shard)
+        shard_no += 1
+
+def read_shards(directory, shard_basename):
+    """Read the shards from directory and return it as a list.
+
+    directory: absolute path of directory from which to read the shards.
+    shard_basename: base name of the shard.
+    """
+
+    shards = []
+    # partial filename of the shard
+    p_filename = "%s.shard*" % path.join(directory, shard_basename)
+    for shard_file in sorted(glob(p_filename)):
+        shard_content = read_file(shard_file)
+        shards.append(shard_content)
+
+    return shards