= Introduction

The ruby-ole library provides a variety of functions primarily for
working with OLE2 structured storage files, such as those produced by
Microsoft Office - eg *.doc, *.msg etc.

= Example Usage

Here are some examples of how to use the library functionality,
categorised roughly by purpose.

1. Reading and writing files within an OLE container

   The recommended way to manipulate the contents is via the
   "file_system" API, whereby you use Ole::Storage instance methods
   similar to the regular File and Dir class methods.

     ole = Ole::Storage.open('oleWithDirs.ole', 'rb+')
     p ole.dir.entries('.') # => [".", "..", "dir1", "dir2", "file1"]
     p ole.file.read('file1')[0, 25] # => "this is the entry 'file1'"
     ole.dir.mkdir('newdir')

2. Accessing OLE meta data

   Some convenience functions are provided for (currently read only)
   access to OLE property sets and other sources of meta data.

     ole = Ole::Storage.open('test_word_95.doc')
     p ole.meta_data.file_format # => "MSWordDoc"
     p ole.meta_data.mime_type # => "application/msword"
     p ole.meta_data.doc_author.split.first # => "Charles"

3. Raw access to underlying OLE internals

   This is probably of little interest to most developers using the
   library, but for some use cases you may need to drop down to the
   lower level API on which the "file_system" API is constructed,
   which exposes more of the format details.

   <tt>Ole::Storage</tt> files can have multiple files with the same name,
   or with a slash in the name, and other things that are probably
   strictly invalid. This API is the only way to access those files.

   You can access the header object directly:

     p ole.header.num_sbat # => 1
     p ole.header.magic.unpack('H*') # => ["d0cf11e0a1b11ae1"]

   You can directly access the array of all Dirent objects,
   including the root:

     p ole.dirents.length # => 5
     puts ole.root.to_tree
     # =>
     - #<Dirent:"Root Entry">
       |- #<Dirent:"\001Ole" size=20 data="\001\000\000\002\000...">
       |- #<Dirent:"\001CompObj" size=98 data="\001\000\376\377\003...">
       |- #<Dirent:"WordDocument" size=2574 data="\334\245e\000-...">
       \- #<Dirent:"\005SummaryInformation" size=54788 data="\376\377\000\000\001...">

   You can access (through RangesIO methods, or by using the
   relevant Dirent and AllocationTable methods) information like where within
   the container a stream is located (these are offset/length pairs):

     p ole.root["\001CompObj"].open { |io| io.ranges } # => [[0, 64], [64, 34]]

See the documentation for each class for more details.

= Thanks

* The code contained in this project was initially based on chicago's libole
  (source available at http://prdownloads.sf.net/chicago/ole.tgz).

* It was later augmented with some corrections by inspecting pole, and (purely
  for header definitions) gsf.

* The property set parsing code came from the apache java project POIFS.

* The excellent idea for using a pseudo file system style interface by providing
  #file and #dir methods which mimic File and Dir, was borrowed (along with almost
  unchanged tests!) from Thomas Sondergaard's rubyzip.
