fileutil::magic::rt(n) file utilities fileutil::magic::rt(n) 







fileutil::magic::rt - Runtime core for file type recognition
    engines written in pure Tcl








package require Tcl 8.4


package require fileutil::magic::rt ?1.0?


::fileutil::magic::rt::open filename


::fileutil::magic::rt::close


::fileutil::magic::rt::file_start name


::fileutil::magic::rt::result ?msg?


::fileutil::magic::rt::resultv ?msg?


::fileutil::magic::rt::emit msg


::fileutil::magic::rt::offset where


::fileutil::magic::rt::Nv type offset
    ?qual?


::fileutil::magic::rt::N type offset
    comp val ?qual?


::fileutil::magic::rt::Nvx atlevel type
    offset ?qual?


::fileutil::magic::rt::Nx atlevel type
    offset comp val ?qual?


::fileutil::magic::rt::S offset comp
    val ?qual?


::fileutil::magic::rt::Sx atlevel offset
    comp val ?qual?


::fileutil::magic::rt::L newlevel


::fileutil::magic::rt::I base type
    delta


::fileutil::magic::rt::R offset












This package provides the runtime core for file type recognition
    engines written in pure Tcl and is thus used by all other packages in this
    module, i.e. the two frontend packages fileutil::magic::mimetypes and
    fileutil::magic::filetypes, and the two engine compiler packages
    fileutil::magic::cgen and fileutil::magic::cfront.









  
::fileutil::magic::rt::open filename

  
This command initializes the runtime and prepares the file filename
      for use by the system. This command has to be invoked first, before any
      other command of this package.
    
The command returns the channel handle of the opened file as
        its result.

  

  
::fileutil::magic::rt::close

  
This command closes the last file opened via
      ::fileutil::magic::rt::open and shuts the runtime down. This
      command has to be invoked last, after the file has been dealt with
      completely. Afterward another invokation of
      ::fileutil::magic::rt::open is required to process another file.
    
This command returns the empty string as its result.

  

  
::fileutil::magic::rt::file_start name

  
This command marks the start of a magic file when debugging. It returns
      the empty string as its result.

  
::fileutil::magic::rt::result ?msg?

  
This command returns the current result and stops processing.
    
If msg is specified its text is added to the result
        before it is returned. See ::fileutil::magic::rt::emit for the
        allowed special character sequences.

  

  
::fileutil::magic::rt::resultv ?msg?

  
This command returns the current result. In contrast to
      ::fileutil::magic::rt::result processing continues.
    
If msg is specified its text is added to the result
        before it is returned. See ::fileutil::magic::rt::emit for the
        allowed special character sequences.

  

  
::fileutil::magic::rt::emit msg

  
This command adds the text msg to the result buffer. The message
      may contain the following special character sequences. They will be
      replaced with buffered values before the message is added to the result.
      The command returns the empty string as its result.







  
\b

  
This sequence is removed

  
%s

  
Replaced with the last buffered string value.

  
%ld

  
Replaced with the last buffered numeric value.

  
%d

  
See above.







  
::fileutil::magic::rt::Nv type offset
    ?qual?

  
This command fetches the numeric value with type from the absolute
      location offset and returns it as its result. The fetched value is
      further stored in the numeric buffer.
    
If qual is specified it is considered to be a mask and
        applied to the fetched value before it is stored and returned. It has to
        have the form of a partial Tcl bit-wise expression, i.e.

    
	& number
    

    For example:
    
	Nv lelong 0 &0x8080ffff
    

    For the possible types see section NUMERIC TYPES.

  
::fileutil::magic::rt::N type offset comp
    val ?qual?

  
This command behaves mostly like ::fileutil::magic::rt::Nv, except
      that it compares the fetched and masked value against val as
      specified with comp and returns the result of that comparison.
    
The argument comp has to contain one of Tcl's
        comparison operators, and the comparison made will be

    
	<val> <comp> <fetched-and-masked-value>
    

    
The special comparison operator x signals that no
        comparison should be done, or, in other words, that the fetched value
        will always match val.

  

  
::fileutil::magic::rt::Nvx atlevel type offset
    ?qual?

  
This command behaves like ::fileutil::magic::rt::Nv, except that it
      additionally remembers the location in the file after the fetch in the
      calling context, for the level atlevel, for later use by
      ::fileutil::magic::rt::R.

  
::fileutil::magic::rt::Nx atlevel type offset
    comp val ?qual?

  
This command behaves like ::fileutil::magic::rt::N, except that it
      additionally remembers the location in the file after the fetch in the
      calling context, for the level atlevel, for later use by
      ::fileutil::magic::rt::R.

  
::fileutil::magic::rt::S offset comp val
    ?qual?

  
This command behaves like ::fileutil::magic::rt::N, except that it
      fetches and compares strings, not numeric data. The fetched value is also
      stored in the internal string buffer instead of the numeric buffer.

  
::fileutil::magic::rt::Sx atlevel offset comp
    val ?qual?

  
This command behaves like ::fileutil::magic::rt::S, except that it
      additionally remembers the location in the file after the fetch in the
      calling context, for the level atlevel, for later use by
      ::fileutil::magic::rt::R.

  
::fileutil::magic::rt::L newlevel

  
This command sets the current level in the calling context to
      newlevel. The command returns the empty string as its result.

  
::fileutil::magic::rt::I base type delta

  
This command handles base locations specified indirectly through the
      contents of the inspected file. It returns the sum of delta and the
      value of numeric type fetched from the absolute location
      base.
    
For the possible types see section NUMERIC TYPES.

  

  
::fileutil::magic::rt::R offset

  
This command handles base locations specified relative to the end of the
      last field one level above.
    
In other words, the command computes an absolute location in
        the file based on the relative offset and returns it as its
        result. The base the offset is added to is the last location remembered
        for the level in the calling context.

  











  

  
8-bit integer

  

  
16-bit integer, stored in native endianess

  

  
see above, stored in big endian

  

  
see above, stored in small/little endian

  

  
32-bit integer, stored in native endianess

  

  
see above, stored in big endian

  

  
see above, stored in small/little endian




All of the types above exit in an unsigned form as well. The type
    names are the same, with the character "u" added as prefix.



  

  
32-bit integer timestamp, stored in native endianess

  

  
see above, stored in big endian

  

  
see above, stored in small/little endian

  

  
32-bit integer timestamp, stored in native endianess

  

  
see above, stored in big endian

  

  
see above, stored in small/little endian










This document, and the package it describes, will undoubtedly
    contain bugs and other problems. Please report such in the category
    fileutil :: magic of the Tcllib SF Trackers
    [http://sourceforge.net/tracker/?group_id=12883]. Please also report any
    ideas for enhancements you may have for either package and/or
  documentation.








file(1), fileutil, magic(5)








file recognition, file type, file utilities, mime, type








Programming tools







  

    1.0
    fumagic