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1 | package Opcode; |
2 | |
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3 | use 5.006_001; |
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4 | |
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5 | use strict; |
6 | |
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7 | our($VERSION, $XS_VERSION, @ISA, @EXPORT_OK); |
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8 | |
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9 | $VERSION = "1.07"; |
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10 | $XS_VERSION = "1.03"; |
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11 | |
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12 | use Carp; |
13 | use Exporter (); |
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14 | use XSLoader (); |
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15 | |
16 | BEGIN { |
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17 | @ISA = qw(Exporter); |
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18 | @EXPORT_OK = qw( |
19 | opset ops_to_opset |
20 | opset_to_ops opset_to_hex invert_opset |
21 | empty_opset full_opset |
22 | opdesc opcodes opmask define_optag |
23 | opmask_add verify_opset opdump |
24 | ); |
25 | } |
26 | |
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27 | sub opset (;@); |
28 | sub opset_to_hex ($); |
29 | sub opdump (;$); |
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30 | use subs @EXPORT_OK; |
31 | |
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32 | XSLoader::load 'Opcode', $XS_VERSION; |
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33 | |
34 | _init_optags(); |
35 | |
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36 | sub ops_to_opset { opset @_ } # alias for old name |
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37 | |
38 | sub opset_to_hex ($) { |
39 | return "(invalid opset)" unless verify_opset($_[0]); |
40 | unpack("h*",$_[0]); |
41 | } |
42 | |
43 | sub opdump (;$) { |
44 | my $pat = shift; |
45 | # handy utility: perl -MOpcode=opdump -e 'opdump File' |
46 | foreach(opset_to_ops(full_opset)) { |
47 | my $op = sprintf " %12s %s\n", $_, opdesc($_); |
48 | next if defined $pat and $op !~ m/$pat/i; |
49 | print $op; |
50 | } |
51 | } |
52 | |
53 | |
54 | |
55 | sub _init_optags { |
56 | my(%all, %seen); |
57 | @all{opset_to_ops(full_opset)} = (); # keys only |
58 | |
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59 | local($_); |
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60 | local($/) = "\n=cut"; # skip to optags definition section |
61 | <DATA>; |
62 | $/ = "\n="; # now read in 'pod section' chunks |
63 | while(<DATA>) { |
64 | next unless m/^item\s+(:\w+)/; |
65 | my $tag = $1; |
66 | |
67 | # Split into lines, keep only indented lines |
68 | my @lines = grep { m/^\s/ } split(/\n/); |
69 | foreach (@lines) { s/--.*// } # delete comments |
70 | my @ops = map { split ' ' } @lines; # get op words |
71 | |
72 | foreach(@ops) { |
73 | warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_}; |
74 | $seen{$_} = $tag; |
75 | delete $all{$_}; |
76 | } |
77 | # opset will croak on invalid names |
78 | define_optag($tag, opset(@ops)); |
79 | } |
80 | close(DATA); |
81 | warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all; |
82 | } |
83 | |
84 | |
85 | 1; |
86 | |
87 | __DATA__ |
88 | |
89 | =head1 NAME |
90 | |
91 | Opcode - Disable named opcodes when compiling perl code |
92 | |
93 | =head1 SYNOPSIS |
94 | |
95 | use Opcode; |
96 | |
97 | |
98 | =head1 DESCRIPTION |
99 | |
100 | Perl code is always compiled into an internal format before execution. |
101 | |
102 | Evaluating perl code (e.g. via "eval" or "do 'file'") causes |
103 | the code to be compiled into an internal format and then, |
104 | provided there was no error in the compilation, executed. |
105 | The internal format is based on many distinct I<opcodes>. |
106 | |
107 | By default no opmask is in effect and any code can be compiled. |
108 | |
109 | The Opcode module allow you to define an I<operator mask> to be in |
110 | effect when perl I<next> compiles any code. Attempting to compile code |
111 | which contains a masked opcode will cause the compilation to fail |
112 | with an error. The code will not be executed. |
113 | |
114 | =head1 NOTE |
115 | |
116 | The Opcode module is not usually used directly. See the ops pragma and |
117 | Safe modules for more typical uses. |
118 | |
119 | =head1 WARNING |
120 | |
121 | The authors make B<no warranty>, implied or otherwise, about the |
122 | suitability of this software for safety or security purposes. |
123 | |
124 | The authors shall not in any case be liable for special, incidental, |
125 | consequential, indirect or other similar damages arising from the use |
126 | of this software. |
127 | |
128 | Your mileage will vary. If in any doubt B<do not use it>. |
129 | |
130 | |
131 | =head1 Operator Names and Operator Lists |
132 | |
133 | The canonical list of operator names is the contents of the array |
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134 | PL_op_name defined and initialised in file F<opcode.h> of the Perl |
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135 | source distribution (and installed into the perl library). |
136 | |
137 | Each operator has both a terse name (its opname) and a more verbose or |
138 | recognisable descriptive name. The opdesc function can be used to |
139 | return a list of descriptions for a list of operators. |
140 | |
141 | Many of the functions and methods listed below take a list of |
142 | operators as parameters. Most operator lists can be made up of several |
143 | types of element. Each element can be one of |
144 | |
145 | =over 8 |
146 | |
147 | =item an operator name (opname) |
148 | |
149 | Operator names are typically small lowercase words like enterloop, |
150 | leaveloop, last, next, redo etc. Sometimes they are rather cryptic |
151 | like gv2cv, i_ncmp and ftsvtx. |
152 | |
153 | =item an operator tag name (optag) |
154 | |
155 | Operator tags can be used to refer to groups (or sets) of operators. |
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156 | Tag names always begin with a colon. The Opcode module defines several |
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157 | optags and the user can define others using the define_optag function. |
158 | |
159 | =item a negated opname or optag |
160 | |
161 | An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir. |
162 | Negating an opname or optag means remove the corresponding ops from the |
163 | accumulated set of ops at that point. |
164 | |
165 | =item an operator set (opset) |
166 | |
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167 | An I<opset> as a binary string of approximately 44 bytes which holds a |
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168 | set or zero or more operators. |
169 | |
170 | The opset and opset_to_ops functions can be used to convert from |
171 | a list of operators to an opset and I<vice versa>. |
172 | |
173 | Wherever a list of operators can be given you can use one or more opsets. |
174 | See also Manipulating Opsets below. |
175 | |
176 | =back |
177 | |
178 | |
179 | =head1 Opcode Functions |
180 | |
181 | The Opcode package contains functions for manipulating operator names |
182 | tags and sets. All are available for export by the package. |
183 | |
184 | =over 8 |
185 | |
186 | =item opcodes |
187 | |
188 | In a scalar context opcodes returns the number of opcodes in this |
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189 | version of perl (around 350 for perl-5.7.0). |
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190 | |
191 | In a list context it returns a list of all the operator names. |
192 | (Not yet implemented, use @names = opset_to_ops(full_opset).) |
193 | |
194 | =item opset (OP, ...) |
195 | |
196 | Returns an opset containing the listed operators. |
197 | |
198 | =item opset_to_ops (OPSET) |
199 | |
200 | Returns a list of operator names corresponding to those operators in |
201 | the set. |
202 | |
203 | =item opset_to_hex (OPSET) |
204 | |
205 | Returns a string representation of an opset. Can be handy for debugging. |
206 | |
207 | =item full_opset |
208 | |
209 | Returns an opset which includes all operators. |
210 | |
211 | =item empty_opset |
212 | |
213 | Returns an opset which contains no operators. |
214 | |
215 | =item invert_opset (OPSET) |
216 | |
217 | Returns an opset which is the inverse set of the one supplied. |
218 | |
219 | =item verify_opset (OPSET, ...) |
220 | |
221 | Returns true if the supplied opset looks like a valid opset (is the |
222 | right length etc) otherwise it returns false. If an optional second |
223 | parameter is true then verify_opset will croak on an invalid opset |
224 | instead of returning false. |
225 | |
226 | Most of the other Opcode functions call verify_opset automatically |
227 | and will croak if given an invalid opset. |
228 | |
229 | =item define_optag (OPTAG, OPSET) |
230 | |
231 | Define OPTAG as a symbolic name for OPSET. Optag names always start |
232 | with a colon C<:>. |
233 | |
234 | The optag name used must not be defined already (define_optag will |
235 | croak if it is already defined). Optag names are global to the perl |
236 | process and optag definitions cannot be altered or deleted once |
237 | defined. |
238 | |
239 | It is strongly recommended that applications using Opcode should use a |
240 | leading capital letter on their tag names since lowercase names are |
241 | reserved for use by the Opcode module. If using Opcode within a module |
242 | you should prefix your tags names with the name of your module to |
243 | ensure uniqueness and thus avoid clashes with other modules. |
244 | |
245 | =item opmask_add (OPSET) |
246 | |
247 | Adds the supplied opset to the current opmask. Note that there is |
248 | currently I<no> mechanism for unmasking ops once they have been masked. |
249 | This is intentional. |
250 | |
251 | =item opmask |
252 | |
253 | Returns an opset corresponding to the current opmask. |
254 | |
255 | =item opdesc (OP, ...) |
256 | |
257 | This takes a list of operator names and returns the corresponding list |
258 | of operator descriptions. |
259 | |
260 | =item opdump (PAT) |
261 | |
262 | Dumps to STDOUT a two column list of op names and op descriptions. |
263 | If an optional pattern is given then only lines which match the |
264 | (case insensitive) pattern will be output. |
265 | |
266 | It's designed to be used as a handy command line utility: |
267 | |
268 | perl -MOpcode=opdump -e opdump |
269 | perl -MOpcode=opdump -e 'opdump Eval' |
270 | |
271 | =back |
272 | |
273 | =head1 Manipulating Opsets |
274 | |
275 | Opsets may be manipulated using the perl bit vector operators & (and), | (or), |
276 | ^ (xor) and ~ (negate/invert). |
277 | |
278 | However you should never rely on the numerical position of any opcode |
279 | within the opset. In other words both sides of a bit vector operator |
280 | should be opsets returned from Opcode functions. |
281 | |
282 | Also, since the number of opcodes in your current version of perl might |
283 | not be an exact multiple of eight, there may be unused bits in the last |
284 | byte of an upset. This should not cause any problems (Opcode functions |
285 | ignore those extra bits) but it does mean that using the ~ operator |
286 | will typically not produce the same 'physical' opset 'string' as the |
287 | invert_opset function. |
288 | |
289 | |
290 | =head1 TO DO (maybe) |
291 | |
292 | $bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv |
293 | |
294 | $yes = opset_can($opset, @ops) true if $opset has all @ops set |
295 | |
296 | @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...) |
297 | |
298 | =cut |
299 | |
300 | # the =cut above is used by _init_optags() to get here quickly |
301 | |
302 | =head1 Predefined Opcode Tags |
303 | |
304 | =over 5 |
305 | |
306 | =item :base_core |
307 | |
308 | null stub scalar pushmark wantarray const defined undef |
309 | |
310 | rv2sv sassign |
311 | |
312 | rv2av aassign aelem aelemfast aslice av2arylen |
313 | |
314 | rv2hv helem hslice each values keys exists delete |
315 | |
316 | preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec |
317 | int hex oct abs pow multiply i_multiply divide i_divide |
318 | modulo i_modulo add i_add subtract i_subtract |
319 | |
320 | left_shift right_shift bit_and bit_xor bit_or negate i_negate |
321 | not complement |
322 | |
323 | lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp |
324 | slt sgt sle sge seq sne scmp |
325 | |
326 | substr vec stringify study pos length index rindex ord chr |
327 | |
328 | ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp |
329 | |
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330 | match split qr |
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331 | |
332 | list lslice splice push pop shift unshift reverse |
333 | |
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334 | cond_expr flip flop andassign orassign dorassign and or dor xor |
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335 | |
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336 | warn die lineseq nextstate scope enter leave setstate |
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337 | |
338 | rv2cv anoncode prototype |
339 | |
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340 | entersub leavesub leavesublv return method method_named -- XXX loops via recursion? |
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341 | |
342 | leaveeval -- needed for Safe to operate, is safe without entereval |
343 | |
344 | =item :base_mem |
345 | |
346 | These memory related ops are not included in :base_core because they |
347 | can easily be used to implement a resource attack (e.g., consume all |
348 | available memory). |
349 | |
350 | concat repeat join range |
351 | |
352 | anonlist anonhash |
353 | |
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354 | Note that despite the existence of this optag a memory resource attack |
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355 | may still be possible using only :base_core ops. |
356 | |
357 | Disabling these ops is a I<very> heavy handed way to attempt to prevent |
358 | a memory resource attack. It's probable that a specific memory limit |
359 | mechanism will be added to perl in the near future. |
360 | |
361 | =item :base_loop |
362 | |
363 | These loop ops are not included in :base_core because they can easily be |
364 | used to implement a resource attack (e.g., consume all available CPU time). |
365 | |
366 | grepstart grepwhile |
367 | mapstart mapwhile |
368 | enteriter iter |
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369 | enterloop leaveloop unstack |
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370 | last next redo |
371 | goto |
372 | |
373 | =item :base_io |
374 | |
375 | These ops enable I<filehandle> (rather than filename) based input and |
376 | output. These are safe on the assumption that only pre-existing |
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377 | filehandles are available for use. Usually, to create new filehandles |
378 | other ops such as open would need to be enabled, if you don't take into |
379 | account the magical open of ARGV. |
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380 | |
381 | readline rcatline getc read |
382 | |
383 | formline enterwrite leavewrite |
384 | |
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385 | print sysread syswrite send recv |
386 | |
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387 | eof tell seek sysseek |
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388 | |
389 | readdir telldir seekdir rewinddir |
390 | |
391 | =item :base_orig |
392 | |
393 | These are a hotchpotch of opcodes still waiting to be considered |
394 | |
395 | gvsv gv gelem |
396 | |
397 | padsv padav padhv padany |
398 | |
399 | rv2gv refgen srefgen ref |
400 | |
401 | bless -- could be used to change ownership of objects (reblessing) |
402 | |
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403 | pushre regcmaybe regcreset regcomp subst substcont |
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404 | |
405 | sprintf prtf -- can core dump |
406 | |
407 | crypt |
408 | |
409 | tie untie |
410 | |
411 | dbmopen dbmclose |
412 | sselect select |
413 | pipe_op sockpair |
414 | |
415 | getppid getpgrp setpgrp getpriority setpriority localtime gmtime |
416 | |
417 | entertry leavetry -- can be used to 'hide' fatal errors |
418 | |
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419 | custom -- where should this go |
420 | |
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421 | =item :base_math |
422 | |
423 | These ops are not included in :base_core because of the risk of them being |
424 | used to generate floating point exceptions (which would have to be caught |
425 | using a $SIG{FPE} handler). |
426 | |
427 | atan2 sin cos exp log sqrt |
428 | |
429 | These ops are not included in :base_core because they have an effect |
430 | beyond the scope of the compartment. |
431 | |
432 | rand srand |
433 | |
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434 | =item :base_thread |
435 | |
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436 | These ops are related to multi-threading. |
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437 | |
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438 | lock threadsv |
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439 | |
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440 | =item :default |
441 | |
442 | A handy tag name for a I<reasonable> default set of ops. (The current ops |
443 | allowed are unstable while development continues. It will change.) |
444 | |
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445 | :base_core :base_mem :base_loop :base_orig :base_thread |
446 | |
447 | This list used to contain :base_io prior to Opcode 1.07. |
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448 | |
449 | If safety matters to you (and why else would you be using the Opcode module?) |
450 | then you should not rely on the definition of this, or indeed any other, optag! |
451 | |
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452 | =item :filesys_read |
453 | |
454 | stat lstat readlink |
455 | |
456 | ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread |
457 | ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned |
458 | ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx |
459 | |
460 | fttext ftbinary |
461 | |
462 | fileno |
463 | |
464 | =item :sys_db |
465 | |
466 | ghbyname ghbyaddr ghostent shostent ehostent -- hosts |
467 | gnbyname gnbyaddr gnetent snetent enetent -- networks |
468 | gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols |
469 | gsbyname gsbyport gservent sservent eservent -- services |
470 | |
471 | gpwnam gpwuid gpwent spwent epwent getlogin -- users |
472 | ggrnam ggrgid ggrent sgrent egrent -- groups |
473 | |
474 | =item :browse |
475 | |
476 | A handy tag name for a I<reasonable> default set of ops beyond the |
477 | :default optag. Like :default (and indeed all the other optags) its |
478 | current definition is unstable while development continues. It will change. |
479 | |
480 | The :browse tag represents the next step beyond :default. It it a |
481 | superset of the :default ops and adds :filesys_read the :sys_db. |
482 | The intent being that scripts can access more (possibly sensitive) |
483 | information about your system but not be able to change it. |
484 | |
485 | :default :filesys_read :sys_db |
486 | |
487 | =item :filesys_open |
488 | |
489 | sysopen open close |
490 | umask binmode |
491 | |
492 | open_dir closedir -- other dir ops are in :base_io |
493 | |
494 | =item :filesys_write |
495 | |
496 | link unlink rename symlink truncate |
497 | |
498 | mkdir rmdir |
499 | |
500 | utime chmod chown |
501 | |
502 | fcntl -- not strictly filesys related, but possibly as dangerous? |
503 | |
504 | =item :subprocess |
505 | |
506 | backtick system |
507 | |
508 | fork |
509 | |
510 | wait waitpid |
511 | |
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512 | glob -- access to Cshell via <`rm *`> |
513 | |
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514 | =item :ownprocess |
515 | |
516 | exec exit kill |
517 | |
518 | time tms -- could be used for timing attacks (paranoid?) |
519 | |
520 | =item :others |
521 | |
522 | This tag holds groups of assorted specialist opcodes that don't warrant |
523 | having optags defined for them. |
524 | |
525 | SystemV Interprocess Communications: |
526 | |
527 | msgctl msgget msgrcv msgsnd |
528 | |
529 | semctl semget semop |
530 | |
531 | shmctl shmget shmread shmwrite |
532 | |
533 | =item :still_to_be_decided |
534 | |
535 | chdir |
536 | flock ioctl |
537 | |
538 | socket getpeername ssockopt |
539 | bind connect listen accept shutdown gsockopt getsockname |
540 | |
541 | sleep alarm -- changes global timer state and signal handling |
542 | sort -- assorted problems including core dumps |
543 | tied -- can be used to access object implementing a tie |
544 | pack unpack -- can be used to create/use memory pointers |
545 | |
546 | entereval -- can be used to hide code from initial compile |
547 | require dofile |
548 | |
549 | caller -- get info about calling environment and args |
550 | |
551 | reset |
552 | |
553 | dbstate -- perl -d version of nextstate(ment) opcode |
554 | |
555 | =item :dangerous |
556 | |
557 | This tag is simply a bucket for opcodes that are unlikely to be used via |
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558 | a tag name but need to be tagged for completeness and documentation. |
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559 | |
560 | syscall dump chroot |
561 | |
562 | |
563 | =back |
564 | |
565 | =head1 SEE ALSO |
566 | |
567 | ops(3) -- perl pragma interface to Opcode module. |
568 | |
569 | Safe(3) -- Opcode and namespace limited execution compartments |
570 | |
571 | =head1 AUTHORS |
572 | |
573 | Originally designed and implemented by Malcolm Beattie, |
574 | mbeattie@sable.ox.ac.uk as part of Safe version 1. |
575 | |
576 | Split out from Safe module version 1, named opcode tags and other |
7b8d334a |
577 | changes added by Tim Bunce. |
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578 | |
579 | =cut |
580 | |