'\"
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.TH "fileutil::magic::rt" 3tcl 1\&.0 tcllib "file utilities"
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See the \\*(So manual entry for details on the standard options.
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Command-Line Name:	\\fB\\$1\\fR
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.BS
.SH NAME
fileutil::magic::rt \- Runtime core for file type recognition engines written in pure Tcl
.SH SYNOPSIS
package require \fBTcl  8\&.4\fR
.sp
package require \fBfileutil::magic::rt  ?1\&.0?\fR
.sp
\fB::fileutil::magic::rt::open\fR \fIfilename\fR
.sp
\fB::fileutil::magic::rt::close\fR
.sp
\fB::fileutil::magic::rt::file_start\fR \fIname\fR
.sp
\fB::fileutil::magic::rt::result\fR ?\fImsg\fR?
.sp
\fB::fileutil::magic::rt::resultv\fR ?\fImsg\fR?
.sp
\fB::fileutil::magic::rt::emit\fR \fImsg\fR
.sp
\fB::fileutil::magic::rt::offset\fR \fIwhere\fR
.sp
\fB::fileutil::magic::rt::Nv\fR \fItype\fR \fIoffset\fR ?\fIqual\fR?
.sp
\fB::fileutil::magic::rt::N\fR \fItype\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
.sp
\fB::fileutil::magic::rt::Nvx\fR \fIatlevel\fR \fItype\fR \fIoffset\fR ?\fIqual\fR?
.sp
\fB::fileutil::magic::rt::Nx\fR \fIatlevel\fR \fItype\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
.sp
\fB::fileutil::magic::rt::S\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
.sp
\fB::fileutil::magic::rt::Sx\fR \fIatlevel\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
.sp
\fB::fileutil::magic::rt::L\fR \fInewlevel\fR
.sp
\fB::fileutil::magic::rt::I\fR \fIbase\fR \fItype\fR \fIdelta\fR
.sp
\fB::fileutil::magic::rt::R\fR \fIoffset\fR
.sp
.BE
.SH DESCRIPTION
.PP
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
\fBfileutil::magic::mimetypes\fR and
\fBfileutil::magic::filetypes\fR, and the two engine compiler
packages \fBfileutil::magic::cgen\fR and
\fBfileutil::magic::cfront\fR\&.
.SH COMMANDS
.TP
\fB::fileutil::magic::rt::open\fR \fIfilename\fR
This command initializes the runtime and prepares the file
\fIfilename\fR for use by the system\&.
This command has to be invoked first, before any other command of this
package\&.
.sp
The command returns the channel handle of the opened file as its
result\&.
.TP
\fB::fileutil::magic::rt::close\fR
This command closes the last file opened via
\fB::fileutil::magic::rt::open\fR and shuts the runtime down\&.
This command has to be invoked last, after the file has been dealt
with completely\&.
Afterward another invokation of \fB::fileutil::magic::rt::open\fR  is
required to process another file\&.
.sp
This command returns the empty string as its result\&.
.TP
\fB::fileutil::magic::rt::file_start\fR \fIname\fR
This command marks the start of a magic file when debugging\&. It
returns the empty string as its result\&.
.TP
\fB::fileutil::magic::rt::result\fR ?\fImsg\fR?
This command returns the current result and stops processing\&.
.sp
If \fImsg\fR is specified its text is added to the result before it is
returned\&. See \fB::fileutil::magic::rt::emit\fR for the allowed
special character sequences\&.
.TP
\fB::fileutil::magic::rt::resultv\fR ?\fImsg\fR?
This command returns the current result\&.
In contrast to \fB::fileutil::magic::rt::result\fR processing
continues\&.
.sp
If \fImsg\fR is specified its text is added to the result before it is
returned\&. See \fB::fileutil::magic::rt::emit\fR for the allowed
special character sequences\&.
.TP
\fB::fileutil::magic::rt::emit\fR \fImsg\fR
This command adds the text \fImsg\fR 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\&.
.RS
.TP
\fB\\b\fR
This sequence is removed
.TP
\fB%s\fR
Replaced with the last buffered string value\&.
.TP
\fB%ld\fR
Replaced with the last buffered numeric value\&.
.TP
\fB%d\fR
See above\&.
.RE
.TP
\fB::fileutil::magic::rt::Nv\fR \fItype\fR \fIoffset\fR ?\fIqual\fR?
This command fetches the numeric value with \fItype\fR from the
absolute location \fIoffset\fR and returns it as its result\&. The
fetched value is further stored in the numeric buffer\&.
.sp
If \fIqual\fR 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\&.
.CS


	& number

.CE
.IP
For example:
.CS


	Nv lelong 0 &0x8080ffff

.CE
.IP
For the possible types see section \fBNUMERIC TYPES\fR\&.
.TP
\fB::fileutil::magic::rt::N\fR \fItype\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
This command behaves mostly like \fB::fileutil::magic::rt::Nv\fR,
except that it compares the fetched and masked value against \fIval\fR
as specified with \fIcomp\fR and returns the result of that
comparison\&.
.sp
The argument \fIcomp\fR has to contain one of Tcl's comparison
operators, and the comparison made will be
.CS


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

.CE
.sp
The special comparison operator \fBx\fR signals that no comparison
should be done, or, in other words, that the fetched value will always
match \fIval\fR\&.
.TP
\fB::fileutil::magic::rt::Nvx\fR \fIatlevel\fR \fItype\fR \fIoffset\fR ?\fIqual\fR?
This command behaves like \fB::fileutil::magic::rt::Nv\fR, except that
it additionally remembers the location in the file after the fetch in
the calling context, for the level \fIatlevel\fR, for later use by
\fB::fileutil::magic::rt::R\fR\&.
.TP
\fB::fileutil::magic::rt::Nx\fR \fIatlevel\fR \fItype\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
This command behaves like \fB::fileutil::magic::rt::N\fR, except that
it additionally remembers the location in the file after the fetch in
the calling context, for the level \fIatlevel\fR, for later use by
\fB::fileutil::magic::rt::R\fR\&.
.TP
\fB::fileutil::magic::rt::S\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
This command behaves like \fB::fileutil::magic::rt::N\fR, 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\&.
.TP
\fB::fileutil::magic::rt::Sx\fR \fIatlevel\fR \fIoffset\fR \fIcomp\fR \fIval\fR ?\fIqual\fR?
This command behaves like \fB::fileutil::magic::rt::S\fR, except that
it additionally remembers the location in the file after the fetch in
the calling context, for the level \fIatlevel\fR, for later use by
\fB::fileutil::magic::rt::R\fR\&.
.TP
\fB::fileutil::magic::rt::L\fR \fInewlevel\fR
This command sets the current level in the calling context to
\fInewlevel\fR\&. The command returns the empty string as its result\&.
.TP
\fB::fileutil::magic::rt::I\fR \fIbase\fR \fItype\fR \fIdelta\fR
This command handles base locations specified indirectly through the
contents of the inspected file\&. It returns the sum of \fIdelta\fR and
the value of numeric \fItype\fR fetched from the absolute location
\fIbase\fR\&.
.sp
For the possible types see section \fBNUMERIC TYPES\fR\&.
.TP
\fB::fileutil::magic::rt::R\fR \fIoffset\fR
This command handles base locations specified relative to the end of
the last field one level above\&.
.sp
In other words, the command computes an absolute location in the file
based on the relative \fIoffset\fR 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\&.
.PP
.SH "NUMERIC TYPES"
.TP
\fBbyte\fR
8-bit integer
.TP
\fBshort\fR
16-bit integer, stored in native endianess
.TP
\fBbeshort\fR
see above, stored in big endian
.TP
\fBleshort\fR
see above, stored in small/little endian
.TP
\fBlong\fR
32-bit integer, stored in native endianess
.TP
\fBbelong\fR
see above, stored in big endian
.TP
\fBlelong\fR
see above, stored in small/little endian
.PP
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\&.
.TP
\fBdate\fR
32-bit integer timestamp, stored in native endianess
.TP
\fBbedate\fR
see above, stored in big endian
.TP
\fBledate\fR
see above, stored in small/little endian
.TP
\fBldate\fR
32-bit integer timestamp, stored in native endianess
.TP
\fBbeldate\fR
see above, stored in big endian
.TP
\fBleldate\fR
see above, stored in small/little endian
.PP
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIfileutil :: magic\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.SH "SEE ALSO"
file(1), fileutil, magic(5)
.SH KEYWORDS
file recognition, file type, file utilities, mime, type
.SH CATEGORY
Programming tools