This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
New opcode category :load, for require, dofile and caller.
[perl5.git] / ext / Opcode / Opcode.pm
CommitLineData
6badd1a5
PP
1package Opcode;
2
3b825e41 3use 5.006_001;
6badd1a5 4
b75c8c73
MS
5use strict;
6
4eb3f1b8 7our($VERSION, @ISA, @EXPORT_OK);
6badd1a5 8
6e8b06a8 9$VERSION = "1.11";
6badd1a5 10
6badd1a5
PP
11use Carp;
12use Exporter ();
9426adcd 13use XSLoader ();
6badd1a5
PP
14
15BEGIN {
b75c8c73 16 @ISA = qw(Exporter);
6badd1a5
PP
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
68dc0745
PP
26sub opset (;@);
27sub opset_to_hex ($);
28sub opdump (;$);
6badd1a5
PP
29use subs @EXPORT_OK;
30
4eb3f1b8 31XSLoader::load 'Opcode', $VERSION;
6badd1a5
PP
32
33_init_optags();
34
68dc0745 35sub ops_to_opset { opset @_ } # alias for old name
6badd1a5
PP
36
37sub opset_to_hex ($) {
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 $op;
49 }
50}
51
52
53
54sub _init_optags {
55 my(%all, %seen);
56 @all{opset_to_ops(full_opset)} = (); # keys only
57
7a57407b 58 local($_);
6badd1a5
PP
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 = $1;
65
66 # Split into lines, keep only indented lines
67 my @lines = grep { m/^\s/ } split(/\n/);
68 foreach (@lines) { s/--.*// } # delete comments
69 my @ops = map { split ' ' } @lines; # get op words
70
71 foreach(@ops) {
72 warn "$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
6badd1a5
PP
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
6badd1a5
PP
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
6badd1a5
PP
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).
6badd1a5
PP
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
291 $bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv
292
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
311 rv2av aassign aelem aelemfast aslice av2arylen
312
313 rv2hv helem hslice each values keys exists delete
314
315 preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec
316 int hex oct abs pow multiply i_multiply divide i_divide
317 modulo i_modulo add i_add subtract i_subtract
318
319 left_shift right_shift bit_and bit_xor bit_or negate i_negate
320 not complement
321
322 lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
323 slt sgt sle sge seq sne scmp
324
325 substr vec stringify study pos length index rindex ord chr
326
327 ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp
328
8782bef2 329 match split qr
6badd1a5
PP
330
331 list lslice splice push pop shift unshift reverse
332
c963b151 333 cond_expr flip flop andassign orassign dorassign and or dor xor
6badd1a5 334
7399586d 335 warn die lineseq nextstate scope enter leave setstate
6badd1a5
PP
336
337 rv2cv anoncode prototype
338
cd06dffe 339 entersub leavesub leavesublv return method method_named -- XXX loops via recursion?
6badd1a5
PP
340
341 leaveeval -- needed for Safe to operate, is safe without entereval
342
343=item :base_mem
344
345These memory related ops are not included in :base_core because they
346can easily be used to implement a resource attack (e.g., consume all
347available memory).
348
349 concat repeat join range
350
351 anonlist anonhash
352
3c4b39be 353Note that despite the existence of this optag a memory resource attack
6badd1a5
PP
354may still be possible using only :base_core ops.
355
356Disabling these ops is a I<very> heavy handed way to attempt to prevent
357a memory resource attack. It's probable that a specific memory limit
358mechanism will be added to perl in the near future.
359
360=item :base_loop
361
362These loop ops are not included in :base_core because they can easily be
363used to implement a resource attack (e.g., consume all available CPU time).
364
365 grepstart grepwhile
366 mapstart mapwhile
367 enteriter iter
e897d888 368 enterloop leaveloop unstack
6badd1a5
PP
369 last next redo
370 goto
371
372=item :base_io
373
374These ops enable I<filehandle> (rather than filename) based input and
375output. These are safe on the assumption that only pre-existing
e866b74b
RGS
376filehandles are available for use. Usually, to create new filehandles
377other ops such as open would need to be enabled, if you don't take into
378account the magical open of ARGV.
6badd1a5
PP
379
380 readline rcatline getc read
381
382 formline enterwrite leavewrite
383
0d863452 384 print say sysread syswrite send recv
96e4d5b1 385
8903cb82 386 eof tell seek sysseek
6badd1a5
PP
387
388 readdir telldir seekdir rewinddir
389
390=item :base_orig
391
392These are a hotchpotch of opcodes still waiting to be considered
393
394 gvsv gv gelem
395
396 padsv padav padhv padany
397
87fc0556
NC
398 once
399
6badd1a5
PP
400 rv2gv refgen srefgen ref
401
402 bless -- could be used to change ownership of objects (reblessing)
403
2cd61cdb 404 pushre regcmaybe regcreset regcomp subst substcont
6badd1a5
PP
405
406 sprintf prtf -- can core dump
407
408 crypt
409
410 tie untie
411
412 dbmopen dbmclose
413 sselect select
414 pipe_op sockpair
415
416 getppid getpgrp setpgrp getpriority setpriority localtime gmtime
417
418 entertry leavetry -- can be used to 'hide' fatal errors
419
0d863452
RH
420 entergiven leavegiven
421 enterwhen leavewhen
422 break continue
423 smartmatch
424
53e06cf0
SC
425 custom -- where should this go
426
6badd1a5
PP
427=item :base_math
428
429These ops are not included in :base_core because of the risk of them being
430used to generate floating point exceptions (which would have to be caught
431using a $SIG{FPE} handler).
432
433 atan2 sin cos exp log sqrt
434
435These ops are not included in :base_core because they have an effect
436beyond the scope of the compartment.
437
438 rand srand
439
1f5895a1
MB
440=item :base_thread
441
554b3eca 442These ops are related to multi-threading.
1f5895a1 443
5b9081af 444 lock
1f5895a1 445
6badd1a5
PP
446=item :default
447
448A handy tag name for a I<reasonable> default set of ops. (The current ops
449allowed are unstable while development continues. It will change.)
450
e866b74b
RGS
451 :base_core :base_mem :base_loop :base_orig :base_thread
452
453This list used to contain :base_io prior to Opcode 1.07.
6badd1a5
PP
454
455If safety matters to you (and why else would you be using the Opcode module?)
456then you should not rely on the definition of this, or indeed any other, optag!
457
6badd1a5
PP
458=item :filesys_read
459
460 stat lstat readlink
461
462 ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread
463 ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned
464 ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx
465
466 fttext ftbinary
467
468 fileno
469
470=item :sys_db
471
472 ghbyname ghbyaddr ghostent shostent ehostent -- hosts
473 gnbyname gnbyaddr gnetent snetent enetent -- networks
474 gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols
475 gsbyname gsbyport gservent sservent eservent -- services
476
477 gpwnam gpwuid gpwent spwent epwent getlogin -- users
478 ggrnam ggrgid ggrent sgrent egrent -- groups
479
480=item :browse
481
482A handy tag name for a I<reasonable> default set of ops beyond the
483:default optag. Like :default (and indeed all the other optags) its
484current definition is unstable while development continues. It will change.
485
486The :browse tag represents the next step beyond :default. It it a
487superset of the :default ops and adds :filesys_read the :sys_db.
488The intent being that scripts can access more (possibly sensitive)
489information about your system but not be able to change it.
490
491 :default :filesys_read :sys_db
492
493=item :filesys_open
494
495 sysopen open close
496 umask binmode
497
498 open_dir closedir -- other dir ops are in :base_io
499
500=item :filesys_write
501
502 link unlink rename symlink truncate
503
504 mkdir rmdir
505
506 utime chmod chown
507
508 fcntl -- not strictly filesys related, but possibly as dangerous?
509
510=item :subprocess
511
512 backtick system
513
514 fork
515
516 wait waitpid
517
f812a825
PP
518 glob -- access to Cshell via <`rm *`>
519
6badd1a5
PP
520=item :ownprocess
521
522 exec exit kill
523
524 time tms -- could be used for timing attacks (paranoid?)
525
526=item :others
527
528This tag holds groups of assorted specialist opcodes that don't warrant
529having optags defined for them.
530
531SystemV Interprocess Communications:
532
533 msgctl msgget msgrcv msgsnd
534
535 semctl semget semop
536
537 shmctl shmget shmread shmwrite
538
6e8b06a8
RGS
539=item :load
540
541This tag holds opcodes related to loading modules and getting information
542about calling environment and args.
543
544 require dofile
545 caller
546
6badd1a5
PP
547=item :still_to_be_decided
548
549 chdir
550 flock ioctl
551
552 socket getpeername ssockopt
553 bind connect listen accept shutdown gsockopt getsockname
554
555 sleep alarm -- changes global timer state and signal handling
556 sort -- assorted problems including core dumps
557 tied -- can be used to access object implementing a tie
558 pack unpack -- can be used to create/use memory pointers
559
560 entereval -- can be used to hide code from initial compile
6badd1a5
PP
561
562 reset
563
564 dbstate -- perl -d version of nextstate(ment) opcode
565
566=item :dangerous
567
568This tag is simply a bucket for opcodes that are unlikely to be used via
3c4b39be 569a tag name but need to be tagged for completeness and documentation.
6badd1a5
PP
570
571 syscall dump chroot
572
6badd1a5
PP
573=back
574
575=head1 SEE ALSO
576
86780939 577L<ops> -- perl pragma interface to Opcode module.
6badd1a5 578
86780939 579L<Safe> -- Opcode and namespace limited execution compartments
6badd1a5
PP
580
581=head1 AUTHORS
582
583Originally designed and implemented by Malcolm Beattie,
584mbeattie@sable.ox.ac.uk as part of Safe version 1.
585
586Split out from Safe module version 1, named opcode tags and other
7b8d334a 587changes added by Tim Bunce.
6badd1a5
PP
588
589=cut
590