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Add padcv to Opcode.pm
[perl5.git] / ext / Opcode / Opcode.pm
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1package Opcode;
2
3b825e41 3use 5.006_001;
6badd1a5 4
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5use strict;
6
4eb3f1b8 7our($VERSION, @ISA, @EXPORT_OK);
6badd1a5 8
440292d7 9$VERSION = "1.24";
6badd1a5 10
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11use Carp;
12use Exporter ();
da4061d3 13use XSLoader;
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14
15BEGIN {
b75c8c73 16 @ISA = qw(Exporter);
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17 @EXPORT_OK = qw(
18 opset ops_to_opset
19 opset_to_ops opset_to_hex invert_opset
20 empty_opset full_opset
21 opdesc opcodes opmask define_optag
22 opmask_add verify_opset opdump
23 );
24}
25
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26sub opset (;@);
27sub opset_to_hex ($);
28sub opdump (;$);
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29use subs @EXPORT_OK;
30
da4061d3 31XSLoader::load();
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32
33_init_optags();
34
68dc0745 35sub ops_to_opset { opset @_ } # alias for old name
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36
37sub opset_to_hex ($) {
38 return "(invalid opset)" unless verify_opset($_[0]);
39 unpack("h*",$_[0]);
40}
41
42sub opdump (;$) {
43 my $pat = shift;
44 # handy utility: perl -MOpcode=opdump -e 'opdump File'
45 foreach(opset_to_ops(full_opset)) {
46 my $op = sprintf " %12s %s\n", $_, opdesc($_);
47 next if defined $pat and $op !~ m/$pat/i;
48 print $op;
49 }
50}
51
52
53
54sub _init_optags {
55 my(%all, %seen);
56 @all{opset_to_ops(full_opset)} = (); # keys only
57
7a57407b 58 local($_);
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59 local($/) = "\n=cut"; # skip to optags definition section
60 <DATA>;
61 $/ = "\n="; # now read in 'pod section' chunks
62 while(<DATA>) {
63 next unless m/^item\s+(:\w+)/;
64 my $tag = $1;
65
66 # Split into lines, keep only indented lines
67 my @lines = grep { m/^\s/ } split(/\n/);
be1d34d7 68 foreach (@lines) { s/(?:\t|--).*// } # delete comments
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69 my @ops = map { split ' ' } @lines; # get op words
70
71 foreach(@ops) {
72 warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_};
73 $seen{$_} = $tag;
74 delete $all{$_};
75 }
76 # opset will croak on invalid names
77 define_optag($tag, opset(@ops));
78 }
79 close(DATA);
80 warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all;
81}
82
83
841;
85
86__DATA__
87
88=head1 NAME
89
90Opcode - Disable named opcodes when compiling perl code
91
92=head1 SYNOPSIS
93
94 use Opcode;
95
96
97=head1 DESCRIPTION
98
99Perl code is always compiled into an internal format before execution.
100
101Evaluating perl code (e.g. via "eval" or "do 'file'") causes
102the code to be compiled into an internal format and then,
103provided there was no error in the compilation, executed.
104The internal format is based on many distinct I<opcodes>.
105
106By default no opmask is in effect and any code can be compiled.
107
108The Opcode module allow you to define an I<operator mask> to be in
109effect when perl I<next> compiles any code. Attempting to compile code
110which contains a masked opcode will cause the compilation to fail
111with an error. The code will not be executed.
112
113=head1 NOTE
114
115The Opcode module is not usually used directly. See the ops pragma and
116Safe modules for more typical uses.
117
118=head1 WARNING
119
120The authors make B<no warranty>, implied or otherwise, about the
121suitability of this software for safety or security purposes.
122
123The authors shall not in any case be liable for special, incidental,
124consequential, indirect or other similar damages arising from the use
125of this software.
126
127Your mileage will vary. If in any doubt B<do not use it>.
128
129
130=head1 Operator Names and Operator Lists
131
132The canonical list of operator names is the contents of the array
4369b173 133PL_op_name defined and initialised in file F<opcode.h> of the Perl
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134source distribution (and installed into the perl library).
135
136Each operator has both a terse name (its opname) and a more verbose or
137recognisable descriptive name. The opdesc function can be used to
138return a list of descriptions for a list of operators.
139
140Many of the functions and methods listed below take a list of
141operators as parameters. Most operator lists can be made up of several
142types of element. Each element can be one of
143
144=over 8
145
146=item an operator name (opname)
147
148Operator names are typically small lowercase words like enterloop,
149leaveloop, last, next, redo etc. Sometimes they are rather cryptic
150like gv2cv, i_ncmp and ftsvtx.
151
152=item an operator tag name (optag)
153
154Operator tags can be used to refer to groups (or sets) of operators.
7b8d334a 155Tag names always begin with a colon. The Opcode module defines several
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156optags and the user can define others using the define_optag function.
157
158=item a negated opname or optag
159
160An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir.
161Negating an opname or optag means remove the corresponding ops from the
162accumulated set of ops at that point.
163
164=item an operator set (opset)
165
7c011d3a 166An I<opset> as a binary string of approximately 44 bytes which holds a
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167set or zero or more operators.
168
169The opset and opset_to_ops functions can be used to convert from
170a list of operators to an opset and I<vice versa>.
171
172Wherever a list of operators can be given you can use one or more opsets.
173See also Manipulating Opsets below.
174
175=back
176
177
178=head1 Opcode Functions
179
180The Opcode package contains functions for manipulating operator names
181tags and sets. All are available for export by the package.
182
183=over 8
184
185=item opcodes
186
187In a scalar context opcodes returns the number of opcodes in this
7c011d3a 188version of perl (around 350 for perl-5.7.0).
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189
190In a list context it returns a list of all the operator names.
191(Not yet implemented, use @names = opset_to_ops(full_opset).)
192
193=item opset (OP, ...)
194
195Returns an opset containing the listed operators.
196
197=item opset_to_ops (OPSET)
198
199Returns a list of operator names corresponding to those operators in
200the set.
201
202=item opset_to_hex (OPSET)
203
204Returns a string representation of an opset. Can be handy for debugging.
205
206=item full_opset
207
208Returns an opset which includes all operators.
209
210=item empty_opset
211
212Returns an opset which contains no operators.
213
214=item invert_opset (OPSET)
215
216Returns an opset which is the inverse set of the one supplied.
217
218=item verify_opset (OPSET, ...)
219
220Returns true if the supplied opset looks like a valid opset (is the
221right length etc) otherwise it returns false. If an optional second
222parameter is true then verify_opset will croak on an invalid opset
223instead of returning false.
224
225Most of the other Opcode functions call verify_opset automatically
226and will croak if given an invalid opset.
227
228=item define_optag (OPTAG, OPSET)
229
230Define OPTAG as a symbolic name for OPSET. Optag names always start
231with a colon C<:>.
232
233The optag name used must not be defined already (define_optag will
234croak if it is already defined). Optag names are global to the perl
235process and optag definitions cannot be altered or deleted once
236defined.
237
238It is strongly recommended that applications using Opcode should use a
239leading capital letter on their tag names since lowercase names are
240reserved for use by the Opcode module. If using Opcode within a module
241you should prefix your tags names with the name of your module to
242ensure uniqueness and thus avoid clashes with other modules.
243
244=item opmask_add (OPSET)
245
246Adds the supplied opset to the current opmask. Note that there is
247currently I<no> mechanism for unmasking ops once they have been masked.
248This is intentional.
249
250=item opmask
251
252Returns an opset corresponding to the current opmask.
253
254=item opdesc (OP, ...)
255
256This takes a list of operator names and returns the corresponding list
257of operator descriptions.
258
259=item opdump (PAT)
260
261Dumps to STDOUT a two column list of op names and op descriptions.
262If an optional pattern is given then only lines which match the
263(case insensitive) pattern will be output.
264
265It's designed to be used as a handy command line utility:
266
267 perl -MOpcode=opdump -e opdump
268 perl -MOpcode=opdump -e 'opdump Eval'
269
270=back
271
272=head1 Manipulating Opsets
273
274Opsets may be manipulated using the perl bit vector operators & (and), | (or),
275^ (xor) and ~ (negate/invert).
276
277However you should never rely on the numerical position of any opcode
278within the opset. In other words both sides of a bit vector operator
279should be opsets returned from Opcode functions.
280
281Also, since the number of opcodes in your current version of perl might
282not be an exact multiple of eight, there may be unused bits in the last
283byte of an upset. This should not cause any problems (Opcode functions
284ignore those extra bits) but it does mean that using the ~ operator
285will typically not produce the same 'physical' opset 'string' as the
286invert_opset function.
287
288
289=head1 TO DO (maybe)
290
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291 $bool = opset_eq($opset1, $opset2) true if opsets are logically
292 equivalent
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293 $yes = opset_can($opset, @ops) true if $opset has all @ops set
294
295 @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...)
296
297=cut
298
299# the =cut above is used by _init_optags() to get here quickly
300
301=head1 Predefined Opcode Tags
302
303=over 5
304
305=item :base_core
306
307 null stub scalar pushmark wantarray const defined undef
308
309 rv2sv sassign
310
93bad3fd 311 rv2av aassign aelem aelemfast aelemfast_lex aslice av2arylen
6badd1a5 312
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313 rv2hv helem hslice each values keys exists delete aeach akeys
314 avalues reach rvalues rkeys
6badd1a5 315
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316 preinc i_preinc predec i_predec postinc i_postinc
317 postdec i_postdec int hex oct abs pow multiply i_multiply
318 divide i_divide modulo i_modulo add i_add subtract i_subtract
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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
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328 ucfirst lcfirst uc lc fc quotemeta trans transr chop schop
329 chomp schomp
6badd1a5 330
8782bef2 331 match split qr
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332
333 list lslice splice push pop shift unshift reverse
334
c963b151 335 cond_expr flip flop andassign orassign dorassign and or dor xor
6badd1a5 336
5edb5b2a 337 warn die lineseq nextstate scope enter leave
6badd1a5 338
deb8a388 339 rv2cv anoncode prototype coreargs
6badd1a5 340
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341 entersub leavesub leavesublv return method method_named
342 -- XXX loops via recursion?
6badd1a5 343
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344 leaveeval -- needed for Safe to operate, is safe
345 without entereval
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346
347=item :base_mem
348
349These memory related ops are not included in :base_core because they
350can easily be used to implement a resource attack (e.g., consume all
351available memory).
352
353 concat repeat join range
354
355 anonlist anonhash
356
3c4b39be 357Note that despite the existence of this optag a memory resource attack
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358may still be possible using only :base_core ops.
359
360Disabling these ops is a I<very> heavy handed way to attempt to prevent
361a memory resource attack. It's probable that a specific memory limit
362mechanism will be added to perl in the near future.
363
364=item :base_loop
365
366These loop ops are not included in :base_core because they can easily be
367used to implement a resource attack (e.g., consume all available CPU time).
368
369 grepstart grepwhile
370 mapstart mapwhile
371 enteriter iter
e897d888 372 enterloop leaveloop unstack
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373 last next redo
374 goto
375
376=item :base_io
377
378These ops enable I<filehandle> (rather than filename) based input and
379output. These are safe on the assumption that only pre-existing
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380filehandles are available for use. Usually, to create new filehandles
381other ops such as open would need to be enabled, if you don't take into
382account the magical open of ARGV.
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383
384 readline rcatline getc read
385
386 formline enterwrite leavewrite
387
0d863452 388 print say sysread syswrite send recv
96e4d5b1 389
8903cb82 390 eof tell seek sysseek
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391
392 readdir telldir seekdir rewinddir
393
394=item :base_orig
395
396These are a hotchpotch of opcodes still waiting to be considered
397
398 gvsv gv gelem
399
9ccb8d54 400 padsv padav padhv padcv padany
6badd1a5 401
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402 once
403
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404 rv2gv refgen srefgen ref
405
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406 bless -- could be used to change ownership of objects
407 (reblessing)
6badd1a5 408
2cd61cdb 409 pushre regcmaybe regcreset regcomp subst substcont
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410
411 sprintf prtf -- can core dump
412
413 crypt
414
415 tie untie
416
417 dbmopen dbmclose
418 sselect select
419 pipe_op sockpair
420
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421 getppid getpgrp setpgrp getpriority setpriority
422 localtime gmtime
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423
424 entertry leavetry -- can be used to 'hide' fatal errors
425
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426 entergiven leavegiven
427 enterwhen leavewhen
428 break continue
429 smartmatch
430
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431 custom -- where should this go
432
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433=item :base_math
434
435These ops are not included in :base_core because of the risk of them being
436used to generate floating point exceptions (which would have to be caught
437using a $SIG{FPE} handler).
438
439 atan2 sin cos exp log sqrt
440
441These ops are not included in :base_core because they have an effect
442beyond the scope of the compartment.
443
444 rand srand
445
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446=item :base_thread
447
554b3eca 448These ops are related to multi-threading.
1f5895a1 449
5b9081af 450 lock
1f5895a1 451
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452=item :default
453
454A handy tag name for a I<reasonable> default set of ops. (The current ops
455allowed are unstable while development continues. It will change.)
456
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457 :base_core :base_mem :base_loop :base_orig :base_thread
458
459This list used to contain :base_io prior to Opcode 1.07.
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460
461If safety matters to you (and why else would you be using the Opcode module?)
462then you should not rely on the definition of this, or indeed any other, optag!
463
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464=item :filesys_read
465
466 stat lstat readlink
467
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468 ftatime ftblk ftchr ftctime ftdir fteexec fteowned
469 fteread ftewrite ftfile ftis ftlink ftmtime ftpipe
470 ftrexec ftrowned ftrread ftsgid ftsize ftsock ftsuid
471 fttty ftzero ftrwrite ftsvtx
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472
473 fttext ftbinary
474
475 fileno
476
477=item :sys_db
478
479 ghbyname ghbyaddr ghostent shostent ehostent -- hosts
480 gnbyname gnbyaddr gnetent snetent enetent -- networks
481 gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols
482 gsbyname gsbyport gservent sservent eservent -- services
483
484 gpwnam gpwuid gpwent spwent epwent getlogin -- users
485 ggrnam ggrgid ggrent sgrent egrent -- groups
486
487=item :browse
488
489A handy tag name for a I<reasonable> default set of ops beyond the
490:default optag. Like :default (and indeed all the other optags) its
491current definition is unstable while development continues. It will change.
492
493The :browse tag represents the next step beyond :default. It it a
494superset of the :default ops and adds :filesys_read the :sys_db.
495The intent being that scripts can access more (possibly sensitive)
496information about your system but not be able to change it.
497
498 :default :filesys_read :sys_db
499
500=item :filesys_open
501
502 sysopen open close
503 umask binmode
504
505 open_dir closedir -- other dir ops are in :base_io
506
507=item :filesys_write
508
509 link unlink rename symlink truncate
510
511 mkdir rmdir
512
513 utime chmod chown
514
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515 fcntl -- not strictly filesys related, but possibly as
516 dangerous?
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517
518=item :subprocess
519
520 backtick system
521
522 fork
523
524 wait waitpid
525
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526 glob -- access to Cshell via <`rm *`>
527
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528=item :ownprocess
529
530 exec exit kill
531
532 time tms -- could be used for timing attacks (paranoid?)
533
534=item :others
535
536This tag holds groups of assorted specialist opcodes that don't warrant
537having optags defined for them.
538
539SystemV Interprocess Communications:
540
541 msgctl msgget msgrcv msgsnd
542
543 semctl semget semop
544
545 shmctl shmget shmread shmwrite
546
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547=item :load
548
549This tag holds opcodes related to loading modules and getting information
550about calling environment and args.
551
552 require dofile
84ed0108 553 caller runcv
6e8b06a8 554
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555=item :still_to_be_decided
556
557 chdir
558 flock ioctl
559
560 socket getpeername ssockopt
561 bind connect listen accept shutdown gsockopt getsockname
562
563 sleep alarm -- changes global timer state and signal handling
564 sort -- assorted problems including core dumps
565 tied -- can be used to access object implementing a tie
566 pack unpack -- can be used to create/use memory pointers
567
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568 hintseval -- constant op holding eval hints
569
6badd1a5 570 entereval -- can be used to hide code from initial compile
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571
572 reset
573
574 dbstate -- perl -d version of nextstate(ment) opcode
575
576=item :dangerous
577
578This tag is simply a bucket for opcodes that are unlikely to be used via
3c4b39be 579a tag name but need to be tagged for completeness and documentation.
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580
581 syscall dump chroot
582
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583=back
584
585=head1 SEE ALSO
586
86780939 587L<ops> -- perl pragma interface to Opcode module.
6badd1a5 588
86780939 589L<Safe> -- Opcode and namespace limited execution compartments
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590
591=head1 AUTHORS
592
593Originally designed and implemented by Malcolm Beattie,
594mbeattie@sable.ox.ac.uk as part of Safe version 1.
595
596Split out from Safe module version 1, named opcode tags and other
7b8d334a 597changes added by Tim Bunce.
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598
599=cut
600