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
30 bootstrap Opcode $VERSION;
34 sub ops_to_opset { opset @_ } # alias for old name
36 sub opset_to_hex ($) {
37 return "(invalid opset)" unless verify_opset($_[0]);
43 # handy utility: perl -MOpcode=opdump -e 'opdump File'
44 foreach(opset_to_ops(full_opset)) {
45 my $op = sprintf " %12s %s\n", $_, opdesc($_);
46 next if defined $pat and $op !~ m/$pat/i;
55 @all{opset_to_ops(full_opset)} = (); # keys only
58 local($/) = "\n=cut"; # skip to optags definition section
60 $/ = "\n="; # now read in 'pod section' chunks
62 next unless m/^item\s+(:\w+)/;
65 # Split into lines, keep only indented lines
66 my @lines = grep { m/^\s/ } split(/\n/);
67 foreach (@lines) { s/--.*// } # delete comments
68 my @ops = map { split ' ' } @lines; # get op words
71 warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_};
75 # opset will croak on invalid names
76 define_optag($tag, opset(@ops));
79 warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all;
89 Opcode - Disable named opcodes when compiling perl code
98 Perl code is always compiled into an internal format before execution.
100 Evaluating perl code (e.g. via "eval" or "do 'file'") causes
101 the code to be compiled into an internal format and then,
102 provided there was no error in the compilation, executed.
103 The internal format is based on many distinct I<opcodes>.
105 By default no opmask is in effect and any code can be compiled.
107 The Opcode module allow you to define an I<operator mask> to be in
108 effect when perl I<next> compiles any code. Attempting to compile code
109 which contains a masked opcode will cause the compilation to fail
110 with an error. The code will not be executed.
114 The Opcode module is not usually used directly. See the ops pragma and
115 Safe modules for more typical uses.
119 The authors make B<no warranty>, implied or otherwise, about the
120 suitability of this software for safety or security purposes.
122 The authors shall not in any case be liable for special, incidental,
123 consequential, indirect or other similar damages arising from the use
126 Your mileage will vary. If in any doubt B<do not use it>.
129 =head1 Operator Names and Operator Lists
131 The canonical list of operator names is the contents of the array
132 op_name defined and initialised in file F<opcode.h> of the Perl
133 source distribution (and installed into the perl library).
135 Each operator has both a terse name (its opname) and a more verbose or
136 recognisable descriptive name. The opdesc function can be used to
137 return a list of descriptions for a list of operators.
139 Many of the functions and methods listed below take a list of
140 operators as parameters. Most operator lists can be made up of several
141 types of element. Each element can be one of
145 =item an operator name (opname)
147 Operator names are typically small lowercase words like enterloop,
148 leaveloop, last, next, redo etc. Sometimes they are rather cryptic
149 like gv2cv, i_ncmp and ftsvtx.
151 =item an operator tag name (optag)
153 Operator tags can be used to refer to groups (or sets) of operators.
154 Tag names always being with a colon. The Opcode module defines several
155 optags and the user can define others using the define_optag function.
157 =item a negated opname or optag
159 An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir.
160 Negating an opname or optag means remove the corresponding ops from the
161 accumulated set of ops at that point.
163 =item an operator set (opset)
165 An I<opset> as a binary string of approximately 43 bytes which holds a
166 set or zero or more operators.
168 The opset and opset_to_ops functions can be used to convert from
169 a list of operators to an opset and I<vice versa>.
171 Wherever a list of operators can be given you can use one or more opsets.
172 See also Manipulating Opsets below.
177 =head1 Opcode Functions
179 The Opcode package contains functions for manipulating operator names
180 tags and sets. All are available for export by the package.
186 In a scalar context opcodes returns the number of opcodes in this
187 version of perl (around 340 for perl5.002).
189 In a list context it returns a list of all the operator names.
190 (Not yet implemented, use @names = opset_to_ops(full_opset).)
192 =item opset (OP, ...)
194 Returns an opset containing the listed operators.
196 =item opset_to_ops (OPSET)
198 Returns a list of operator names corresponding to those operators in
201 =item opset_to_hex (OPSET)
203 Returns a string representation of an opset. Can be handy for debugging.
207 Returns an opset which includes all operators.
211 Returns an opset which contains no operators.
213 =item invert_opset (OPSET)
215 Returns an opset which is the inverse set of the one supplied.
217 =item verify_opset (OPSET, ...)
219 Returns true if the supplied opset looks like a valid opset (is the
220 right length etc) otherwise it returns false. If an optional second
221 parameter is true then verify_opset will croak on an invalid opset
222 instead of returning false.
224 Most of the other Opcode functions call verify_opset automatically
225 and will croak if given an invalid opset.
227 =item define_optag (OPTAG, OPSET)
229 Define OPTAG as a symbolic name for OPSET. Optag names always start
232 The optag name used must not be defined already (define_optag will
233 croak if it is already defined). Optag names are global to the perl
234 process and optag definitions cannot be altered or deleted once
237 It is strongly recommended that applications using Opcode should use a
238 leading capital letter on their tag names since lowercase names are
239 reserved for use by the Opcode module. If using Opcode within a module
240 you should prefix your tags names with the name of your module to
241 ensure uniqueness and thus avoid clashes with other modules.
243 =item opmask_add (OPSET)
245 Adds the supplied opset to the current opmask. Note that there is
246 currently I<no> mechanism for unmasking ops once they have been masked.
251 Returns an opset corresponding to the current opmask.
253 =item opdesc (OP, ...)
255 This takes a list of operator names and returns the corresponding list
256 of operator descriptions.
260 Dumps to STDOUT a two column list of op names and op descriptions.
261 If an optional pattern is given then only lines which match the
262 (case insensitive) pattern will be output.
264 It's designed to be used as a handy command line utility:
266 perl -MOpcode=opdump -e opdump
267 perl -MOpcode=opdump -e 'opdump Eval'
271 =head1 Manipulating Opsets
273 Opsets may be manipulated using the perl bit vector operators & (and), | (or),
274 ^ (xor) and ~ (negate/invert).
276 However you should never rely on the numerical position of any opcode
277 within the opset. In other words both sides of a bit vector operator
278 should be opsets returned from Opcode functions.
280 Also, since the number of opcodes in your current version of perl might
281 not be an exact multiple of eight, there may be unused bits in the last
282 byte of an upset. This should not cause any problems (Opcode functions
283 ignore those extra bits) but it does mean that using the ~ operator
284 will typically not produce the same 'physical' opset 'string' as the
285 invert_opset function.
290 $bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv
292 $yes = opset_can($opset, @ops) true if $opset has all @ops set
294 @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...)
298 # the =cut above is used by _init_optags() to get here quickly
300 =head1 Predefined Opcode Tags
306 null stub scalar pushmark wantarray const defined undef
310 rv2av aassign aelem aelemfast aslice av2arylen
312 rv2hv helem hslice each values keys exists delete
314 preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec
315 int hex oct abs pow multiply i_multiply divide i_divide
316 modulo i_modulo add i_add subtract i_subtract
318 left_shift right_shift bit_and bit_xor bit_or negate i_negate
321 lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
322 slt sgt sle sge seq sne scmp
324 substr vec stringify study pos length index rindex ord chr
326 ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp
330 list lslice splice push pop shift unshift reverse
332 cond_expr flip flop andassign orassign and or xor
334 warn die lineseq nextstate unstack scope enter leave
336 rv2cv anoncode prototype
338 entersub leavesub return method -- XXX loops via recursion?
340 leaveeval -- needed for Safe to operate, is safe without entereval
344 These memory related ops are not included in :base_core because they
345 can easily be used to implement a resource attack (e.g., consume all
348 concat repeat join range
352 Note that despite the existance of this optag a memory resource attack
353 may still be possible using only :base_core ops.
355 Disabling these ops is a I<very> heavy handed way to attempt to prevent
356 a memory resource attack. It's probable that a specific memory limit
357 mechanism will be added to perl in the near future.
361 These loop ops are not included in :base_core because they can easily be
362 used to implement a resource attack (e.g., consume all available CPU time).
373 These ops enable I<filehandle> (rather than filename) based input and
374 output. These are safe on the assumption that only pre-existing
375 filehandles are available for use. To create new filehandles other ops
376 such as open would need to be enabled.
378 readline rcatline getc read
380 formline enterwrite leavewrite
382 print sysread syswrite send recv eof tell seek
384 readdir telldir seekdir rewinddir
388 These are a hotchpotch of opcodes still waiting to be considered
392 padsv padav padhv padany
394 rv2gv refgen srefgen ref
396 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?
498 glob -- access to Cshell via <`rm *`>
504 time tms -- could be used for timing attacks (paranoid?)
508 This tag holds groups of assorted specialist opcodes that don't warrant
509 having optags defined for them.
511 SystemV Interprocess Communications:
513 msgctl msgget msgrcv msgsnd
517 shmctl shmget shmread shmwrite
519 =item :still_to_be_decided
524 socket getpeername ssockopt
525 bind connect listen accept shutdown gsockopt getsockname
527 sleep alarm -- changes global timer state and signal handling
528 sort -- assorted problems including core dumps
529 tied -- can be used to access object implementing a tie
530 pack unpack -- can be used to create/use memory pointers
532 entereval -- can be used to hide code from initial compile
535 caller -- get info about calling environment and args
539 dbstate -- perl -d version of nextstate(ment) opcode
543 This tag is simply a bucket for opcodes that are unlikely to be used via
544 a tag name but need to be tagged for completness and documentation.
553 ops(3) -- perl pragma interface to Opcode module.
555 Safe(3) -- Opcode and namespace limited execution compartments
559 Originally designed and implemented by Malcolm Beattie,
560 mbeattie@sable.ox.ac.uk as part of Safe version 1.
562 Split out from Safe module version 1, named opcode tags and other
563 changes added by Tim Bunce E<lt>F<Tim.Bunce@ig.co.uk>E<gt>.