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 8.5
13 package require fileutil::magic::rt ?2.0?
15 ::fileutil::magic::rt::>
17 ::fileutil::magic::rt::<
19 ::fileutil::magic::rt::open filename
21 ::fileutil::magic::rt::close
23 ::fileutil::magic::rt::file_start name
25 ::fileutil::magic::rt::result ?msg?
27 ::fileutil::magic::rt::resultv ?msg?
29 ::fileutil::magic::rt::emit msg
31 ::fileutil::magic::rt::offset where
33 ::fileutil::magic::rt::Nv type offset ?qual?
35 ::fileutil::magic::rt::N type offset comp val ?qual?
37 ::fileutil::magic::rt::Nvx type offset ?qual?
39 ::fileutil::magic::rt::Nx type offset comp val ?qual?
41 ::fileutil::magic::rt::S offset comp val ?qual?
43 ::fileutil::magic::rt::Sx offset comp val ?qual?
45 ::fileutil::magic::rt::L newlevel
47 ::fileutil::magic::rt::I base type delta
49 ::fileutil::magic::rt::R offset
51 ::fileutil::magic::rt::U fileindex name
53______________________________________________________________________________
55
57 This package provides the runtime core for file type recognition en‐
58 gines written in pure Tcl and is thus used by all other packages in
59 this module, i.e. the two frontend packages fileutil::magic::mimetypes
60 and fileutil::magic::filetypes, and the two engine compiler packages
61 fileutil::magic::cgen and fileutil::magic::cfront.
62
64 ::fileutil::magic::rt::>
65 Shorthand for incr level.
66 ::fileutil::magic::rt::<
68 Shorthand for incr level -1.
69 ::fileutil::magic::rt::open filename
71 This command initializes the runtime and prepares the file file‐
72 name for use by the system. This command has to be invoked
73 first, before any other command of this package.
74 The command returns the channel handle of the opened file as its
76 result.
77 ::fileutil::magic::rt::close
79 This command closes the last file opened via ::fileu‐
80 til::magic::rt::open and shuts the runtime down. This command
81 has to be invoked last, after the file has been dealt with com‐
82 pletely. Afterward another invokation of ::fileu‐
83 til::magic::rt::open is required to process another file.
84 This command returns the empty string as its result.
86 ::fileutil::magic::rt::file_start name
88 This command marks the start of a magic file when debugging. It
89 returns the empty string as its result.
90 ::fileutil::magic::rt::result ?msg?
92 This command returns the current result and stops processing.
93 If msg is specified its text is added to the result before it is
95 returned. See ::fileutil::magic::rt::emit for the allowed spe‐
96 cial character sequences.
97 ::fileutil::magic::rt::resultv ?msg?
99 This command returns the current result. In contrast to
100 ::fileutil::magic::rt::result processing continues.
101 If msg is specified its text is added to the result before it is
103 returned. See ::fileutil::magic::rt::emit for the allowed spe‐
104 cial character sequences.
105 ::fileutil::magic::rt::emit msg
107 This command adds the text msg to the result buffer. The message
108 may contain the following special character sequences. They will
109 be replaced with buffered values before the message is added to
110 the result. The command returns the empty string as its result.
111 \b This sequence is removed
113 %s Replaced with the last buffered string value.
115 %ld Replaced with the last buffered numeric value.
117 %d See above.
119 ::fileutil::magic::rt::Nv type offset ?qual?
121 This command fetches the numeric value with type from the abso‐
122 lute location offset and returns it as its result. The fetched
123 value is further stored in the numeric buffer.
124 If qual is specified it is considered to be a mask and applied
126 to the fetched value before it is stored and returned. It has to
127 have the form of a partial Tcl bit-wise expression, i.e.
128 & number
131 For example:
134 Nv lelong 0 &0x8080ffff
137 For the possible types see section NUMERIC TYPES.
140 ::fileutil::magic::rt::N type offset comp val ?qual?
142 This command behaves mostly like ::fileutil::magic::rt::Nv, ex‐
143 cept that it compares the fetched and masked value against val
144 as specified with comp and returns the result of that compari‐
145 son.
146 The argument comp has to contain one of Tcl's comparison opera‐
148 tors, and the comparison made will be
149 <val> <comp> <fetched-and-masked-value>
152 The special comparison operator x signals that no comparison should be
155 done, or, in other words, that the fetched value will always match val.
156 ::fileutil::magic::rt::Nvx type offset ?qual?
158 This command behaves like ::fileutil::magic::rt::Nv, except that
159 it additionally remembers the location in the file after the
160 fetch in the calling context, for the current level, for later
161 use by ::fileutil::magic::rt::R.
162 ::fileutil::magic::rt::Nx type offset comp val ?qual?
164 This command behaves like ::fileutil::magic::rt::N, except that
165 it additionally remembers the location in the file after the
166 fetch in the calling context, for the current, for later use by
167 ::fileutil::magic::rt::R.
168 ::fileutil::magic::rt::S offset comp val ?qual?
170 This command behaves like ::fileutil::magic::rt::N, except that
171 it fetches and compares strings, not numeric data. The fetched
172 value is also stored in the internal string buffer instead of
173 the numeric buffer.
174 ::fileutil::magic::rt::Sx offset comp val ?qual?
176 This command behaves like ::fileutil::magic::rt::S, except that
177 it additionally remembers the location in the file after the
178 fetch in the calling context, for the current level, for later
179 use by ::fileutil::magic::rt::R.
180 ::fileutil::magic::rt::L newlevel
182 This command sets the current level in the calling context to
183 newlevel. The command returns the empty string as its result.
184 ::fileutil::magic::rt::I base type delta
186 This command handles base locations specified indirectly through
187 the contents of the inspected file. It returns the sum of delta
188 and the value of numeric type fetched from the absolute location
189 base.
190 For the possible types see section NUMERIC TYPES.
192 ::fileutil::magic::rt::R offset
194 This command handles base locations specified relative to the
195 end of the last field one level above.
196 In other words, the command computes an absolute location in the
198 file based on the relative offset and returns it as its result.
199 The base the offset is added to is the last location remembered
200 for the level in the calling context.
201 ::fileutil::magic::rt::U fileindex name
203 Use a named test script at the current level.
204
206 byte 8-bit integer
207 short 16-bit integer, stored in native endianess
209 beshort
211 see above, stored in big endian
212 leshort
214 see above, stored in small/little endian
215 long 32-bit integer, stored in native endianess
217 belong see above, stored in big endian
219 lelong see above, stored in small/little endian
221 All of the types above exit in an unsigned form as well. The type names
223 are the same, with the character "u" added as prefix.
224 date 32-bit integer timestamp, stored in native endianess
226 bedate see above, stored in big endian
228 ledate see above, stored in small/little endian
230 ldate 32-bit integer timestamp, stored in native endianess
232 beldate
234 see above, stored in big endian
235 leldate
237 see above, stored in small/little endian
238
240 This document, and the package it describes, will undoubtedly contain
241 bugs and other problems. Please report such in the category fileutil
242 :: magic of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist].
243 Please also report any ideas for enhancements you may have for either
244 package and/or documentation.
245 When proposing code changes, please provide unified diffs, i.e the out‐
247 put of diff -u.
248 Note further that attachments are strongly preferred over inlined
250 patches. Attachments can be made by going to the Edit form of the
251 ticket immediately after its creation, and then using the left-most
252 button in the secondary navigation bar.
253
255 file(1), fileutil, magic(5)
256
258 file recognition, file type, file utilities, mime, type
259
261 Programming tools
262tcllib 2.0 fileutil::magic::rt(n)