[//000000001]: # (fileutil::magic::rt \- file utilities) [//000000002]: # (Generated from file 'rtcore\.man' by tcllib/doctools with format 'markdown') [//000000003]: # (fileutil::magic::rt$n$ 2\.0 tcllib "file utilities")

# NAME fileutil::magic::rt \- Runtime core for file type recognition engines written in pure Tcl # Table Of Contents - [Table Of Contents](#toc) - [Synopsis](#synopsis) - [Description](#section1) - [COMMANDS](#section2) - [NUMERIC TYPES](#section3) - [Bugs, Ideas, Feedback](#section4) - [See Also](#seealso) - [Keywords](#keywords) - [Category](#category) # SYNOPSIS package require Tcl 8\.5 package require fileutil::magic::rt ?2\.0? [__::fileutil::magic::rt::>__](#1) [__::fileutil::magic::rt::<__](#2) [__::fileutil::magic::rt::new__ *chan* *named* *analyze*](#3) [__::fileutil::magic::rt::file\_start__ *name*](#4) [__::fileutil::magic::rt::emit__ *msg*](#5) [__::fileutil::magic::rt::O__ *where*](#6) [__::fileutil::magic::rt::R__ *where*](#7) [__::fileutil::magic::rt::Nv__ *type* *offset* *compinvert* *comp* *expected*](#8) [__::fileutil::magic::rt::N__ *type* *offset* *testinvert* *compinvert* *mod* *mand* *comp* *expected*](#9) [__::fileutil::magic::rt::S__ *type* *offset* *testinvert* *mod* *mand* *comp* *val*](#10) [__::fileutil::magic::rt::L__ *newlevel*](#11) [__::fileutil::magic::rt::I__ *offset* *it* *ioi* *ioo* *iir* *io*](#12) [__::fileutil::magic::rt::R__ *offset*](#13) [__::fileutil::magic::rt::U__ *fileindex* *name*](#14) # 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](filetypes\.md)__ and the two compiler packages __[fileutil::magic::cgen](cgen\.md)__ and __[fileutil::magic::cfront](cfront\.md)__\. # 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\. - __::fileutil::magic::rt::R__ *where* 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\. # SEE ALSO file$1$, [fileutil](\.\./fileutil/fileutil\.md), magic$5$ # KEYWORDS [file recognition](\.\./\.\./\.\./\.\./index\.md\#file\_recognition), [file type](\.\./\.\./\.\./\.\./index\.md\#file\_type), [file utilities](\.\./\.\./\.\./\.\./index\.md\#file\_utilities), [mime](\.\./\.\./\.\./\.\./index\.md\#mime), [type](\.\./\.\./\.\./\.\./index\.md\#type) # CATEGORY Programming tools