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

NAME

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

SYNOPSIS

       package require Tcl  8.5

       package require fileutil::magic::rt  ?2.0?

       ::fileutil::magic::rt::>

       ::fileutil::magic::rt::<

       ::fileutil::magic::rt::new chan named analyze

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

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

       ::fileutil::magic::rt::O where

       ::fileutil::magic::rt::R where

       ::fileutil::magic::rt::Nv type offset compinvert comp expected

       ::fileutil::magic::rt::N type offset testinvert compinvert mod mand comp expected

       ::fileutil::magic::rt::S type offset testinvert mod mand comp val

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

       ::fileutil::magic::rt::I offset it ioi ioo iir io

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

       ::fileutil::magic::rt::U fileindex name

_________________________________________________________________________________________________

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   such   as
       fileutil::magic::filetype   and   the  two  compiler  packages  fileutil::magic::cgen  and
       fileutil::magic::cfront.

COMMANDS

::fileutil::magic::rt::>
Increment the level and perform related housekeeping

::fileutil::magic::rt::<
Decrement the level and perform related housekeeping

::fileutil::magic::rt::new chan named analyze
Create a new command which returns one description of the file each time it is
called, and a code of break when there are no more descriptions. chan is the
channel containing the data to describe. The channel configuration is then managed
as needed. named is a dictionary of named tests, as generated by
fileutil::magic::cfront::compile. test is a command prefix for a routine composed
of the list of commands as returned by fileutil::magic::cfront::compile.

::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::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.

${x:...?...}
Substitute one string if the file is executable, and another string
otherwise.

::fileutil::magic::rt::O where
Produce an offset from where, relative to the cursor one level up. Produce an
offset from where, relative to the offset one level up.

::fileutil::magic::rt::Nv type offset compinvert comp expected
A limited form of ::fileutile::magic::rt::N that only checks for equality and can't
be told to invert the test.

::fileutil::magic::rt::N type offset testinvert compinvert mod mand comp expected
Fetch the numeric value with type from the absolute location offset, compare it
with expected using comp as the comparision operator, and returns the result.

The argument comp must be one of Tcl's comparison operators.

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::S type offset testinvert mod mand comp val
Like ::fileutil::magic::rt::N except that it fetches and compares string types ,
not numeric data.

::fileutil::magic::rt::L newlevel
Sets the current level in the calling context to newlevel. The command returns the
empty string as its result.

::fileutil::magic::rt::I offset it ioi ioo iir io
Calculates an offset based on an initial offset and the provided modifiers.

::fileutil::magic::rt::R offset
Given an initial offset, calculates an offset relative to the cursor at the next
level up. The cursor is the position in the data one character after the data
extracted from the file one level up.

::fileutil::magic::rt::U fileindex name
Add a level and use a named test script.

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 character "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  Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you
       may have for either package and/or documentation.

       When proposing code changes, please provide unified diffs, i.e the output of diff -u.

       Note further that attachments are strongly preferred over inlined patches. Attachments can
       be  made  by going to the Edit form of the ticket immediately after its creation, and then
       using the left-most button in the secondary navigation bar.

KEYWORDS

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