5 use vars qw($VERSION @ISA @EXPORT_OK);
13 @ISA = qw(Exporter DynaLoader);
18 opset_to_ops opset_to_hex invert_opset
19 empty_opset full_opset
20 opdesc opcodes opmask define_optag
21 opmask_add verify_opset opdump
27 bootstrap Opcode $VERSION;
32 *ops_to_opset = \&opset; # alias for old name
35 sub opset_to_hex ($) {
36 return "(invalid opset)" unless verify_opset($_[0]);
42 # handy utility: perl -MOpcode=opdump -e 'opdump File'
43 foreach(opset_to_ops(full_opset)) {
44 my $op = sprintf " %12s %s\n", $_, opdesc($_);
45 next if defined $pat and $op !~ m/$pat/i;
54 @all{opset_to_ops(full_opset)} = (); # keys only
56 local($/) = "\n=cut"; # skip to optags definition section
58 $/ = "\n="; # now read in 'pod section' chunks
60 next unless m/^item\s+(:\w+)/;
63 # Split into lines, keep only indented lines
64 my @lines = grep { m/^\s/ } split(/\n/);
65 foreach (@lines) { s/--.*// } # delete comments
66 my @ops = map { split ' ' } @lines; # get op words
69 warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_};
73 # opset will croak on invalid names
74 define_optag($tag, opset(@ops));
77 warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all;
87 Opcode - Disable named opcodes when compiling perl code
96 Perl code is always compiled into an internal format before execution.
98 Evaluating perl code (e.g. via "eval" or "do 'file'") causes
99 the code to be compiled into an internal format and then,
100 provided there was no error in the compilation, executed.
101 The internal format is based on many distinct I<opcodes>.
103 By default no opmask is in effect and any code can be compiled.
105 The Opcode module allow you to define an I<operator mask> to be in
106 effect when perl I<next> compiles any code. Attempting to compile code
107 which contains a masked opcode will cause the compilation to fail
108 with an error. The code will not be executed.
112 The Opcode module is not usually used directly. See the ops pragma and
113 Safe modules for more typical uses.
117 The authors make B<no warranty>, implied or otherwise, about the
118 suitability of this software for safety or security purposes.
120 The authors shall not in any case be liable for special, incidental,
121 consequential, indirect or other similar damages arising from the use
124 Your mileage will vary. If in any doubt B<do not use it>.
127 =head1 Operator Names and Operator Lists
129 The canonical list of operator names is the contents of the array
130 op_name defined and initialised in file F<opcode.h> of the Perl
131 source distribution (and installed into the perl library).
133 Each operator has both a terse name (its opname) and a more verbose or
134 recognisable descriptive name. The opdesc function can be used to
135 return a list of descriptions for a list of operators.
137 Many of the functions and methods listed below take a list of
138 operators as parameters. Most operator lists can be made up of several
139 types of element. Each element can be one of
143 =item an operator name (opname)
145 Operator names are typically small lowercase words like enterloop,
146 leaveloop, last, next, redo etc. Sometimes they are rather cryptic
147 like gv2cv, i_ncmp and ftsvtx.
149 =item an operator tag name (optag)
151 Operator tags can be used to refer to groups (or sets) of operators.
152 Tag names always being with a colon. The Opcode module defines several
153 optags and the user can define others using the define_optag function.
155 =item a negated opname or optag
157 An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir.
158 Negating an opname or optag means remove the corresponding ops from the
159 accumulated set of ops at that point.
161 =item an operator set (opset)
163 An I<opset> as a binary string of approximately 43 bytes which holds a
164 set or zero or more operators.
166 The opset and opset_to_ops functions can be used to convert from
167 a list of operators to an opset and I<vice versa>.
169 Wherever a list of operators can be given you can use one or more opsets.
170 See also Manipulating Opsets below.
175 =head1 Opcode Functions
177 The Opcode package contains functions for manipulating operator names
178 tags and sets. All are available for export by the package.
184 In a scalar context opcodes returns the number of opcodes in this
185 version of perl (around 340 for perl5.002).
187 In a list context it returns a list of all the operator names.
188 (Not yet implemented, use @names = opset_to_ops(full_opset).)
190 =item opset (OP, ...)
192 Returns an opset containing the listed operators.
194 =item opset_to_ops (OPSET)
196 Returns a list of operator names corresponding to those operators in
199 =item opset_to_hex (OPSET)
201 Returns a string representation of an opset. Can be handy for debugging.
205 Returns an opset which includes all operators.
209 Returns an opset which contains no operators.
211 =item invert_opset (OPSET)
213 Returns an opset which is the inverse set of the one supplied.
215 =item verify_opset (OPSET, ...)
217 Returns true if the supplied opset looks like a valid opset (is the
218 right length etc) otherwise it returns false. If an optional second
219 parameter is true then verify_opset will croak on an invalid opset
220 instead of returning false.
222 Most of the other Opcode functions call verify_opset automatically
223 and will croak if given an invalid opset.
225 =item define_optag (OPTAG, OPSET)
227 Define OPTAG as a symbolic name for OPSET. Optag names always start
230 The optag name used must not be defined already (define_optag will
231 croak if it is already defined). Optag names are global to the perl
232 process and optag definitions cannot be altered or deleted once
235 It is strongly recommended that applications using Opcode should use a
236 leading capital letter on their tag names since lowercase names are
237 reserved for use by the Opcode module. If using Opcode within a module
238 you should prefix your tags names with the name of your module to
239 ensure uniqueness and thus avoid clashes with other modules.
241 =item opmask_add (OPSET)
243 Adds the supplied opset to the current opmask. Note that there is
244 currently I<no> mechanism for unmasking ops once they have been masked.
249 Returns an opset corresponding to the current opmask.
251 =item opdesc (OP, ...)
253 This takes a list of operator names and returns the corresponding list
254 of operator descriptions.
258 Dumps to STDOUT a two column list of op names and op descriptions.
259 If an optional pattern is given then only lines which match the
260 (case insensitive) pattern will be output.
262 It's designed to be used as a handy command line utility:
264 perl -MOpcode=opdump -e opdump
265 perl -MOpcode=opdump -e 'opdump Eval'
269 =head1 Manipulating Opsets
271 Opsets may be manipulated using the perl bit vector operators & (and), | (or),
272 ^ (xor) and ~ (negate/invert).
274 However you should never rely on the numerical position of any opcode
275 within the opset. In other words both sides of a bit vector operator
276 should be opsets returned from Opcode functions.
278 Also, since the number of opcodes in your current version of perl might
279 not be an exact multiple of eight, there may be unused bits in the last
280 byte of an upset. This should not cause any problems (Opcode functions
281 ignore those extra bits) but it does mean that using the ~ operator
282 will typically not produce the same 'physical' opset 'string' as the
283 invert_opset function.
288 $bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv
290 $yes = opset_can($opset, @ops) true if $opset has all @ops set
292 @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...)
296 # the =cut above is used by _init_optags() to get here quickly
298 =head1 Predefined Opcode Tags
304 null stub scalar pushmark wantarray const defined undef
308 rv2av aassign aelem aelemfast aslice av2arylen
310 rv2hv helem hslice each values keys exists delete
312 preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec
313 int hex oct abs pow multiply i_multiply divide i_divide
314 modulo i_modulo add i_add subtract i_subtract
316 left_shift right_shift bit_and bit_xor bit_or negate i_negate
319 lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
320 slt sgt sle sge seq sne scmp
322 substr vec stringify study pos length index rindex ord chr
324 ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp
328 list lslice splice push pop shift unshift reverse
330 cond_expr flip flop andassign orassign and or xor
332 warn die lineseq nextstate unstack scope enter leave
334 rv2cv anoncode prototype
336 entersub leavesub return method -- XXX loops via recursion?
338 leaveeval -- needed for Safe to operate, is safe without entereval
342 These memory related ops are not included in :base_core because they
343 can easily be used to implement a resource attack (e.g., consume all
346 concat repeat join range
350 Note that despite the existance of this optag a memory resource attack
351 may still be possible using only :base_core ops.
353 Disabling these ops is a I<very> heavy handed way to attempt to prevent
354 a memory resource attack. It's probable that a specific memory limit
355 mechanism will be added to perl in the near future.
359 These loop ops are not included in :base_core because they can easily be
360 used to implement a resource attack (e.g., consume all available CPU time).
371 These ops enable I<filehandle> (rather than filename) based input and
372 output. These are safe on the assumption that only pre-existing
373 filehandles are available for use. To create new filehandles other ops
374 such as open would need to be enabled.
376 readline rcatline getc read
378 formline enterwrite leavewrite
380 print sysread syswrite send recv eof tell seek
382 readdir telldir seekdir rewinddir
386 These are a hotchpotch of opcodes still waiting to be considered
390 padsv padav padhv padany
392 rv2gv refgen srefgen ref
394 bless -- could be used to change ownership of objects (reblessing)
398 pushre regcmaybe regcomp subst substcont
400 sprintf prtf -- can core dump
410 getppid getpgrp setpgrp getpriority setpriority localtime gmtime
412 entertry leavetry -- can be used to 'hide' fatal errors
416 These ops are not included in :base_core because of the risk of them being
417 used to generate floating point exceptions (which would have to be caught
418 using a $SIG{FPE} handler).
420 atan2 sin cos exp log sqrt
422 These ops are not included in :base_core because they have an effect
423 beyond the scope of the compartment.
429 A handy tag name for a I<reasonable> default set of ops. (The current ops
430 allowed are unstable while development continues. It will change.)
432 :base_core :base_mem :base_loop :base_io :base_orig
434 If safety matters to you (and why else would you be using the Opcode module?)
435 then you should not rely on the definition of this, or indeed any other, optag!
442 ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread
443 ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned
444 ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx
452 ghbyname ghbyaddr ghostent shostent ehostent -- hosts
453 gnbyname gnbyaddr gnetent snetent enetent -- networks
454 gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols
455 gsbyname gsbyport gservent sservent eservent -- services
457 gpwnam gpwuid gpwent spwent epwent getlogin -- users
458 ggrnam ggrgid ggrent sgrent egrent -- groups
462 A handy tag name for a I<reasonable> default set of ops beyond the
463 :default optag. Like :default (and indeed all the other optags) its
464 current definition is unstable while development continues. It will change.
466 The :browse tag represents the next step beyond :default. It it a
467 superset of the :default ops and adds :filesys_read the :sys_db.
468 The intent being that scripts can access more (possibly sensitive)
469 information about your system but not be able to change it.
471 :default :filesys_read :sys_db
478 open_dir closedir -- other dir ops are in :base_io
482 link unlink rename symlink truncate
488 fcntl -- not strictly filesys related, but possibly as dangerous?
502 time tms -- could be used for timing attacks (paranoid?)
506 This tag holds groups of assorted specialist opcodes that don't warrant
507 having optags defined for them.
509 SystemV Interprocess Communications:
511 msgctl msgget msgrcv msgsnd
515 shmctl shmget shmread shmwrite
517 =item :still_to_be_decided
522 socket getpeername ssockopt
523 bind connect listen accept shutdown gsockopt getsockname
525 sleep alarm -- changes global timer state and signal handling
526 sort -- assorted problems including core dumps
527 tied -- can be used to access object implementing a tie
528 pack unpack -- can be used to create/use memory pointers
530 entereval -- can be used to hide code from initial compile
533 caller -- get info about calling environment and args
537 dbstate -- perl -d version of nextstate(ment) opcode
541 This tag is simply a bucket for opcodes that are unlikely to be used via
542 a tag name but need to be tagged for completness and documentation.
551 ops(3) -- perl pragma interface to Opcode module.
553 Safe(3) -- Opcode and namespace limited execution compartments
557 Originally designed and implemented by Malcolm Beattie,
558 mbeattie@sable.ox.ac.uk as part of Safe version 1.
560 Split out from Safe module version 1, named opcode tags and other
561 changes added by Tim Bunce <Tim.Bunce@ig.co.uk>.