===========
mkmasfimage
===========

Create a MASF (Metadata and Small Files) image of a folder.

It essentially creates a snapshot of the given folder, without
the file contents.

This can be useful when you need to know the contents of a drive
that is not easily accessible (e.g. an external hard drive), without
keeping a complete copy of it.

In addition, a size threshold (for all files, or for specific file
extensions) can be set so that they are also included in the image.
For example, all "*.txt" and "*.py" files that are smaller than 10k
may be included.

In essence, the file hierarchy, permissions, file sizes, and the small
files are preserved, to create a tiny image of the target folder.

The image is compressed using the squashfs tools.

For usage details, run the command "mkmasfimage -h".

Requirements
============
* squashfs-tools

Implementation Details
======================
All the files, except the excluded files, are copied to a temporary
folder (which is usually /tmp, stored in the RAM) with the
copystat function of the shutil module. This copies everything about a
file, except the contents, therefore the file size is zero.

Optionally, os.truncate is used to set the file sizes. This function
sets the file size without changing its size on the file system, therefore
the files can be larger than the underlying file system.
The file contents become all zero, which is easily compressed by the
squashfs-tools.

The excluded files are copied normally. squashfs-tools still compress them,
but these files can be completely available inside the image file.