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.
- 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
This document, and the package it describes, will undoubtedly contain
bugs and other problems.
Please report such in the category
fileutil :: magic of the
http://sourceforge.net/tracker/?group_id=12883.
Please also report any ideas for enhancements you may have for either
package and/or documentation.
fileutil, file(1), magic(5)
type, mime, file utilities, file type, file recognition