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



____________________________________________________________________________________________________________

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

SYNOPSIS
       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

____________________________________________________________________________________________________________

DESCRIPTION
       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::mime-types fileutil::magic::mimetypes
       types  and fileutil::magic::filetypes, and the two engine compiler packages fileutil::magic::cgen and
       fileutil::magic::cfront.

COMMANDS
       ::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 ::fileu-til::magic::rt::emit ::fileutil::magic::rt::emit
              til::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  pro-cessing processing
              cessing continues.

              If  msg  is  specified  its  text  is  added to the result before it is returned. See ::fileu-til::magic::rt::emit ::fileutil::magic::rt::emit
              til::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.


NUMERIC TYPES
       byte   8-bit integer

       short  16-bit integer, stored in native endianess

       beshort
              see above, stored in big endian

       leshort
              see above, stored in small/little endian

       long   32-bit integer, stored in native endianess

       belong see above, stored in big endian

       lelong 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  char-acter character
       acter "u" added as prefix.

       date   32-bit integer timestamp, stored in native endianess

       bedate see above, stored in big endian

       ledate see above, stored in small/little endian

       ldate  32-bit integer timestamp, stored in native endianess

       beldate
              see above, stored in big endian

       leldate
              see above, stored in small/little endian


BUGS, IDEAS, FEEDBACK
       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://source -
       forge.net/tracker/? group_id=12883].   Please  also report any ideas for enhancements you may have for
       either package and/or documentation.

SEE ALSO
       file(1), fileutil, magic(5)

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

CATEGORY
       Programming tools



fumagic                                              1.0                              fileutil::magic::rt(n)