1fileutil::magic::rt(n) file utilities fileutil::magic::rt(n)
2______________________________________________________________________________
6
8 fileutil::magic::rt - Runtime core for file type recognition engines
9 written in pure Tcl
10
12 package require Tcl 8.4
13 package require fileutil::magic::rt ?1.0?
15 ::fileutil::magic::rt::open filename
17 ::fileutil::magic::rt::close
19 ::fileutil::magic::rt::file_start name
21 ::fileutil::magic::rt::result ?msg?
23 ::fileutil::magic::rt::resultv ?msg?
25 ::fileutil::magic::rt::emit msg
27 ::fileutil::magic::rt::offset where
29 ::fileutil::magic::rt::Nv type offset ?qual?
31 ::fileutil::magic::rt::N type offset comp val ?qual?
33 ::fileutil::magic::rt::Nvx atlevel type offset ?qual?
35 ::fileutil::magic::rt::Nx atlevel type offset comp val ?qual?
37 ::fileutil::magic::rt::S offset comp val ?qual?
39 ::fileutil::magic::rt::Sx atlevel offset comp val ?qual?
41 ::fileutil::magic::rt::L newlevel
43 ::fileutil::magic::rt::I base type delta
45 ::fileutil::magic::rt::R offset
47_________________________________________________________________
49
51 This package provides the runtime core for file type recognition
52 engines written in pure Tcl and is thus used by all other packages in
53 this module, i.e. the two frontend packages fileutil::magic::mimetypes
54 and fileutil::magic::filetypes, and the two engine compiler packages
55 fileutil::magic::cgen and fileutil::magic::cfront.
56
58 ::fileutil::magic::rt::open filename
59 This command initializes the runtime and prepares the file file‐
60 name for use by the system. This command has to be invoked
61 first, before any other command of this package.
62 The command returns the channel handle of the opened file as its
64 result.
65 ::fileutil::magic::rt::close
67 This command closes the last file opened via ::fileu‐
68 til::magic::rt::open and shuts the runtime down. This command
69 has to be invoked last, after the file has been dealt with com‐
70 pletely. Afterward another invokation of ::fileu‐
71 til::magic::rt::open is required to process another file.
72 This command returns the empty string as its result.
74 ::fileutil::magic::rt::file_start name
76 This command marks the start of a magic file when debugging. It
77 returns the empty string as its result.
78 ::fileutil::magic::rt::result ?msg?
80 This command returns the current result and stops processing.
81 If msg is specified its text is added to the result before it is
83 returned. See ::fileutil::magic::rt::emit for the allowed spe‐
84 cial character sequences.
85 ::fileutil::magic::rt::resultv ?msg?
87 This command returns the current result. In contrast to
88 ::fileutil::magic::rt::result processing continues.
89 If msg is specified its text is added to the result before it is
91 returned. See ::fileutil::magic::rt::emit for the allowed spe‐
92 cial character sequences.
93 ::fileutil::magic::rt::emit msg
95 This command adds the text msg to the result buffer. The message
96 may contain the following special character sequences. They will
97 be replaced with buffered values before the message is added to
98 the result. The command returns the empty string as its result.
99 \b This sequence is removed
101 %s Replaced with the last buffered string value.
103 %ld Replaced with the last buffered numeric value.
105 %d See above.
107 ::fileutil::magic::rt::Nv type offset ?qual?
109 This command fetches the numeric value with type from the abso‐
110 lute location offset and returns it as its result. The fetched
111 value is further stored in the numeric buffer.
112 If qual is specified it is considered to be a mask and applied
114 to the fetched value before it is stored and returned. It has to
115 have the form of a partial Tcl bit-wise expression, i.e.
116 & number
118 For example:
120 Nv lelong 0 &0x8080ffff
122 For the possible types see section NUMERIC TYPES.
124 ::fileutil::magic::rt::N type offset comp val ?qual?
126 This command behaves mostly like ::fileutil::magic::rt::Nv,
127 except that it compares the fetched and masked value against val
128 as specified with comp and returns the result of that compari‐
129 son.
130 The argument comp has to contain one of Tcl's comparison opera‐
132 tors, and the comparison made will be
133 <val> <comp> <fetched-and-masked-value>
135 The special comparison operator x signals that no comparison
138 should be done, or, in other words, that the fetched value will
139 always match val.
140 ::fileutil::magic::rt::Nvx atlevel type offset ?qual?
142 This command behaves like ::fileutil::magic::rt::Nv, except that
143 it additionally remembers the location in the file after the
144 fetch in the calling context, for the level atlevel, for later
145 use by ::fileutil::magic::rt::R.
146 ::fileutil::magic::rt::Nx atlevel type offset comp val ?qual?
148 This command behaves like ::fileutil::magic::rt::N, except that
149 it additionally remembers the location in the file after the
150 fetch in the calling context, for the level atlevel, for later
151 use by ::fileutil::magic::rt::R.
152 ::fileutil::magic::rt::S offset comp val ?qual?
154 This command behaves like ::fileutil::magic::rt::N, except that
155 it fetches and compares strings, not numeric data. The fetched
156 value is also stored in the internal string buffer instead of
157 the numeric buffer.
158 ::fileutil::magic::rt::Sx atlevel offset comp val ?qual?
160 This command behaves like ::fileutil::magic::rt::S, except that
161 it additionally remembers the location in the file after the
162 fetch in the calling context, for the level atlevel, for later
163 use by ::fileutil::magic::rt::R.
164 ::fileutil::magic::rt::L newlevel
166 This command sets the current level in the calling context to
167 newlevel. The command returns the empty string as its result.
168 ::fileutil::magic::rt::I base type delta
170 This command handles base locations specified indirectly through
171 the contents of the inspected file. It returns the sum of delta
172 and the value of numeric type fetched from the absolute location
173 base.
174 For the possible types see section NUMERIC TYPES.
176 ::fileutil::magic::rt::R offset
178 This command handles base locations specified relative to the
179 end of the last field one level above.
180 In other words, the command computes an absolute location in the
182 file based on the relative offset and returns it as its result.
183 The base the offset is added to is the last location remembered
184 for the level in the calling context.
185
187 byte 8-bit integer
188 short 16-bit integer, stored in native endianess
190 beshort
192 see above, stored in big endian
193 leshort
195 see above, stored in small/little endian
196 long 32-bit integer, stored in native endianess
198 belong see above, stored in big endian
200 lelong see above, stored in small/little endian
202 All of the types above exit in an unsigned form as well. The type names
204 are the same, with the character "u" added as prefix.
205 date 32-bit integer timestamp, stored in native endianess
207 bedate see above, stored in big endian
209 ledate see above, stored in small/little endian
211 ldate 32-bit integer timestamp, stored in native endianess
213 beldate
215 see above, stored in big endian
216 leldate
218 see above, stored in small/little endian
219
221 This document, and the package it describes, will undoubtedly contain
222 bugs and other problems. Please report such in the category fileutil
223 :: magic of the Tcllib SF Trackers [http://source‐
224 forge.net/tracker/?group_id=12883]. Please also report any ideas for
225 enhancements you may have for either package and/or documentation.
226
228 file(1), fileutil, magic(5)
229
231 file recognition, file type, file utilities, mime, type
232fumagic 1.0 fileutil::magic::rt(n)