added back combox/file.py

1 files changed, 127 insertions, 0 deletions

diff --git a/combox/file.py b/combox/file.py
new file mode 100644
index 0000000..ec0372e
--- /dev/null
+++ b/combox/file.py
@@ -0,0 +1,127 @@
+#    Copyright (C) 2014 Combox author(s). See AUTHORS.
+#
+#    This file is part of Combox.
+#
+#   Combox is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   Combox is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#   General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with Combox (see COPYING).  If not, see
+#   <http://www.gnu.org/licenses/>.
+
+from os import path
+from sys import exit
+from glob import glob
+
+
+def split_data(data, n):
+    """Split data into `n' parts and return them as an array.
+
+    data: Stream of bytes or string
+    n: Number of parts the file has to be split.
+    """
+
+    d_parts = []
+    # File size in bytes.
+    data_size = len(data)
+    # No. of bytes for each data part.
+    part_size =  data_size / n
+    # Take note of remaining bytes; this is non-zero when data_size is
+    # not divisible by `n'.
+    rem_bytes = data_size % n
+
+    start = 0
+    end = part_size
+    while end <= data_size:
+        d_parts.append(data[start:end])
+        start = end
+        end = end + part_size
+
+    # read the remaining bytes into the last data part.
+    end += start + rem_bytes
+    d_parts[n-1] += data[start:end]
+
+    return d_parts
+
+
+def glue_data(d_parts):
+    """Glue different parts of the data to one.
+
+    d_parts: Array containing different parts of the data. Each part
+    is a sequence of bytes.
+    """
+
+    data = ''
+    for part in d_parts:
+        data += part
+
+    return data
+
+
+def read_file(filename):
+    """Read file and return it as a string.
+
+    filename: Absolute pathname of the file.
+    """
+    file_ = None
+    try:
+      file_   = open(filename, 'rb')
+    except IOError:
+        print "ERROR: opening %s" % (filename)
+        exit(1)
+
+    return file_.read()
+
+
+def write_file(filename, filecontent):
+    """Write `filecontent' to `filename'.
+
+    filename: Absolute pathname of the file.
+    filecontent: String/bytstream to write to filename.
+    """
+    file_ = None
+    try:
+      file_   = open(filename, 'wb')
+      file_.write(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