7 our($VERSION, @ISA, @EXPORT_OK);
19 opset_to_ops opset_to_hex invert_opset
20 empty_opset full_opset
21 opdesc opcodes opmask define_optag
22 opmask_add verify_opset opdump
35 sub ops_to_opset { opset @_ } # alias for old name
37 sub opset_to_hex ($) {
38 return "(invalid opset)" unless verify_opset($_[0]);
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;
56 @all{opset_to_ops(full_opset)} = (); # keys only
59 local($/) = "\n=cut"; # skip to optags definition section
61 $/ = "\n="; # now read in 'pod section' chunks
63 next unless m/^item\s+(:\w+)/;
66 # Split into lines, keep only indented lines
67 my @lines = grep { m/^\s/ } split(/\n/);
68 foreach (@lines) { s/(?:\t|--).*// } # delete comments
69 my @ops = map { split ' ' } @lines; # get op words
72 warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_};
76 # opset will croak on invalid names
77 define_optag($tag, opset(@ops));
80 warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all;
90 Opcode - Disable named opcodes when compiling perl code
99 Perl code is always compiled into an internal format before execution.
101 Evaluating perl code (e.g. via "eval" or "do 'file'") causes
102 the code to be compiled into an internal format and then,
103 provided there was no error in the compilation, executed.
104 The internal format is based on many distinct I<opcodes>.
106 By default no opmask is in effect and any code can be compiled.
108 The Opcode module allow you to define an I<operator mask> to be in
109 effect when perl I<next> compiles any code. Attempting to compile code
110 which contains a masked opcode will cause the compilation to fail
111 with an error. The code will not be executed.
115 The Opcode module is not usually used directly. See the ops pragma and
116 Safe modules for more typical uses.
120 The authors make B<no warranty>, implied or otherwise, about the
121 suitability of this software for safety or security purposes.
123 The authors shall not in any case be liable for special, incidental,
124 consequential, indirect or other similar damages arising from the use
127 Your mileage will vary. If in any doubt B<do not use it>.
130 =head1 Operator Names and Operator Lists
132 The canonical list of operator names is the contents of the array
133 PL_op_name defined and initialised in file F<opcode.h> of the Perl
134 source distribution (and installed into the perl library).
136 Each operator has both a terse name (its opname) and a more verbose or
137 recognisable descriptive name. The opdesc function can be used to
138 return a list of descriptions for a list of operators.
140 Many of the functions and methods listed below take a list of
141 operators as parameters. Most operator lists can be made up of several
142 types of element. Each element can be one of
146 =item an operator name (opname)
148 Operator names are typically small lowercase words like enterloop,
149 leaveloop, last, next, redo etc. Sometimes they are rather cryptic
150 like gv2cv, i_ncmp and ftsvtx.
152 =item an operator tag name (optag)
154 Operator tags can be used to refer to groups (or sets) of operators.
155 Tag names always begin with a colon. The Opcode module defines several
156 optags and the user can define others using the define_optag function.
158 =item a negated opname or optag
160 An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir.
161 Negating an opname or optag means remove the corresponding ops from the
162 accumulated set of ops at that point.
164 =item an operator set (opset)
166 An I<opset> as a binary string of approximately 44 bytes which holds a
167 set or zero or more operators.
169 The opset and opset_to_ops functions can be used to convert from
170 a list of operators to an opset and I<vice versa>.
172 Wherever a list of operators can be given you can use one or more opsets.
173 See also Manipulating Opsets below.
178 =head1 Opcode Functions
180 The Opcode package contains functions for manipulating operator names
181 tags and sets. All are available for export by the package.
187 In a scalar context opcodes returns the number of opcodes in this
188 version of perl (around 350 for perl-5.7.0).
190 In a list context it returns a list of all the operator names.
191 (Not yet implemented, use @names = opset_to_ops(full_opset).)
193 =item opset (OP, ...)
195 Returns an opset containing the listed operators.
197 =item opset_to_ops (OPSET)
199 Returns a list of operator names corresponding to those operators in
202 =item opset_to_hex (OPSET)
204 Returns a string representation of an opset. Can be handy for debugging.
208 Returns an opset which includes all operators.
212 Returns an opset which contains no operators.
214 =item invert_opset (OPSET)
216 Returns an opset which is the inverse set of the one supplied.
218 =item verify_opset (OPSET, ...)
220 Returns true if the supplied opset looks like a valid opset (is the
221 right length etc) otherwise it returns false. If an optional second
222 parameter is true then verify_opset will croak on an invalid opset
223 instead of returning false.
225 Most of the other Opcode functions call verify_opset automatically
226 and will croak if given an invalid opset.
228 =item define_optag (OPTAG, OPSET)
230 Define OPTAG as a symbolic name for OPSET. Optag names always start
233 The optag name used must not be defined already (define_optag will
234 croak if it is already defined). Optag names are global to the perl
235 process and optag definitions cannot be altered or deleted once
238 It is strongly recommended that applications using Opcode should use a
239 leading capital letter on their tag names since lowercase names are
240 reserved for use by the Opcode module. If using Opcode within a module
241 you should prefix your tags names with the name of your module to
242 ensure uniqueness and thus avoid clashes with other modules.
244 =item opmask_add (OPSET)
246 Adds the supplied opset to the current opmask. Note that there is
247 currently I<no> mechanism for unmasking ops once they have been masked.
252 Returns an opset corresponding to the current opmask.
254 =item opdesc (OP, ...)
256 This takes a list of operator names and returns the corresponding list
257 of operator descriptions.
261 Dumps to STDOUT a two column list of op names and op descriptions.
262 If an optional pattern is given then only lines which match the
263 (case insensitive) pattern will be output.
265 It's designed to be used as a handy command line utility:
267 perl -MOpcode=opdump -e opdump
268 perl -MOpcode=opdump -e 'opdump Eval'
272 =head1 Manipulating Opsets
274 Opsets may be manipulated using the perl bit vector operators & (and), | (or),
275 ^ (xor) and ~ (negate/invert).
277 However you should never rely on the numerical position of any opcode
278 within the opset. In other words both sides of a bit vector operator
279 should be opsets returned from Opcode functions.
281 Also, since the number of opcodes in your current version of perl might
282 not be an exact multiple of eight, there may be unused bits in the last
283 byte of an upset. This should not cause any problems (Opcode functions
284 ignore those extra bits) but it does mean that using the ~ operator
285 will typically not produce the same 'physical' opset 'string' as the
286 invert_opset function.
291 $bool = opset_eq($opset1, $opset2) true if opsets are logically
293 $yes = opset_can($opset, @ops) true if $opset has all @ops set
295 @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...)
299 # the =cut above is used by _init_optags() to get here quickly
301 =head1 Predefined Opcode Tags
307 null stub scalar pushmark wantarray const defined undef
311 rv2av aassign aelem aelemfast aelemfast_lex aslice kvaslice
314 rv2hv helem hslice kvhslice each values keys exists delete
315 aeach akeys avalues multideref
317 preinc i_preinc predec i_predec postinc i_postinc
318 postdec i_postdec int hex oct abs pow multiply i_multiply
319 divide i_divide modulo i_modulo add i_add subtract i_subtract
321 left_shift right_shift bit_and bit_xor bit_or nbit_and
322 nbit_xor nbit_or sbit_and sbit_xor sbit_or negate i_negate not
323 complement ncomplement scomplement
325 lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
326 slt sgt sle sge seq sne scmp
328 substr vec stringify study pos length index rindex ord chr
330 ucfirst lcfirst uc lc fc quotemeta trans transr chop schop
335 list lslice splice push pop shift unshift reverse
337 cond_expr flip flop andassign orassign dorassign and or dor xor
339 warn die lineseq nextstate scope enter leave
341 rv2cv anoncode prototype coreargs anonconst
343 entersub leavesub leavesublv return method method_named
344 method_super method_redir method_redir_super
345 -- XXX loops via recursion?
347 leaveeval -- needed for Safe to operate, is safe
352 These memory related ops are not included in :base_core because they
353 can easily be used to implement a resource attack (e.g., consume all
356 concat repeat join range
360 Note that despite the existence of this optag a memory resource attack
361 may still be possible using only :base_core ops.
363 Disabling these ops is a I<very> heavy handed way to attempt to prevent
364 a memory resource attack. It's probable that a specific memory limit
365 mechanism will be added to perl in the near future.
369 These loop ops are not included in :base_core because they can easily be
370 used to implement a resource attack (e.g., consume all available CPU time).
375 enterloop leaveloop unstack
381 These ops enable I<filehandle> (rather than filename) based input and
382 output. These are safe on the assumption that only pre-existing
383 filehandles are available for use. Usually, to create new filehandles
384 other ops such as open would need to be enabled, if you don't take into
385 account the magical open of ARGV.
387 readline rcatline getc read
389 formline enterwrite leavewrite
391 print say sysread syswrite send recv
393 eof tell seek sysseek
395 readdir telldir seekdir rewinddir
399 These are a hotchpotch of opcodes still waiting to be considered
403 padsv padav padhv padcv padany padrange introcv clonecv
407 rv2gv refgen srefgen ref refassign lvref lvrefslice lvavref
409 bless -- could be used to change ownership of objects
412 pushre regcmaybe regcreset regcomp subst substcont
414 sprintf prtf -- can core dump
424 getppid getpgrp setpgrp getpriority setpriority
427 entertry leavetry -- can be used to 'hide' fatal errors
429 entergiven leavegiven
434 custom -- where should this go
438 These ops are not included in :base_core because of the risk of them being
439 used to generate floating point exceptions (which would have to be caught
440 using a $SIG{FPE} handler).
442 atan2 sin cos exp log sqrt
444 These ops are not included in :base_core because they have an effect
445 beyond the scope of the compartment.
451 These ops are related to multi-threading.
457 A handy tag name for a I<reasonable> default set of ops. (The current ops
458 allowed are unstable while development continues. It will change.)
460 :base_core :base_mem :base_loop :base_orig :base_thread
462 This list used to contain :base_io prior to Opcode 1.07.
464 If safety matters to you (and why else would you be using the Opcode module?)
465 then you should not rely on the definition of this, or indeed any other, optag!
471 ftatime ftblk ftchr ftctime ftdir fteexec fteowned
472 fteread ftewrite ftfile ftis ftlink ftmtime ftpipe
473 ftrexec ftrowned ftrread ftsgid ftsize ftsock ftsuid
474 fttty ftzero ftrwrite ftsvtx
482 ghbyname ghbyaddr ghostent shostent ehostent -- hosts
483 gnbyname gnbyaddr gnetent snetent enetent -- networks
484 gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols
485 gsbyname gsbyport gservent sservent eservent -- services
487 gpwnam gpwuid gpwent spwent epwent getlogin -- users
488 ggrnam ggrgid ggrent sgrent egrent -- groups
492 A handy tag name for a I<reasonable> default set of ops beyond the
493 :default optag. Like :default (and indeed all the other optags) its
494 current definition is unstable while development continues. It will change.
496 The :browse tag represents the next step beyond :default. It it a
497 superset of the :default ops and adds :filesys_read the :sys_db.
498 The intent being that scripts can access more (possibly sensitive)
499 information about your system but not be able to change it.
501 :default :filesys_read :sys_db
508 open_dir closedir -- other dir ops are in :base_io
512 link unlink rename symlink truncate
518 fcntl -- not strictly filesys related, but possibly as
529 glob -- access to Cshell via <`rm *`>
535 time tms -- could be used for timing attacks (paranoid?)
539 This tag holds groups of assorted specialist opcodes that don't warrant
540 having optags defined for them.
542 SystemV Interprocess Communications:
544 msgctl msgget msgrcv msgsnd
548 shmctl shmget shmread shmwrite
552 This tag holds opcodes related to loading modules and getting information
553 about calling environment and args.
558 =item :still_to_be_decided
563 socket getpeername ssockopt
564 bind connect listen accept shutdown gsockopt getsockname
566 sleep alarm -- changes global timer state and signal handling
567 sort -- assorted problems including core dumps
568 tied -- can be used to access object implementing a tie
569 pack unpack -- can be used to create/use memory pointers
571 hintseval -- constant op holding eval hints
573 entereval -- can be used to hide code from initial compile
577 dbstate -- perl -d version of nextstate(ment) opcode
581 This tag is simply a bucket for opcodes that are unlikely to be used via
582 a tag name but need to be tagged for completeness and documentation.
590 L<ops> -- perl pragma interface to Opcode module.
592 L<Safe> -- Opcode and namespace limited execution compartments
596 Originally designed and implemented by Malcolm Beattie,
597 mbeattie@sable.ox.ac.uk as part of Safe version 1.
599 Split out from Safe module version 1, named opcode tags and other
600 changes added by Tim Bunce.