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
57 local($/) = "\n=cut"; # skip to optags definition section
59 $/ = "\n="; # now read in 'pod section' chunks
61 next unless m/^item\s+(:\w+)/;
64 # Split into lines, keep only indented lines
65 my @lines = grep { m/^\s/ } split(/\n/);
66 foreach (@lines) { s/--.*// } # delete comments
67 my @ops = map { split ' ' } @lines; # get op words
70 warn "$tag - $_ already tagged in $seen{$_}\n" if $seen{$_};
74 # opset will croak on invalid names
75 define_optag($tag, opset(@ops));
78 warn "Untagged opnames: ".join(' ',keys %all)."\n" if %all;
88 Opcode - Disable named opcodes when compiling perl code
97 Perl code is always compiled into an internal format before execution.
99 Evaluating perl code (e.g. via "eval" or "do 'file'") causes
100 the code to be compiled into an internal format and then,
101 provided there was no error in the compilation, executed.
102 The internal format is based on many distinct I<opcodes>.
104 By default no opmask is in effect and any code can be compiled.
106 The Opcode module allow you to define an I<operator mask> to be in
107 effect when perl I<next> compiles any code. Attempting to compile code
108 which contains a masked opcode will cause the compilation to fail
109 with an error. The code will not be executed.
113 The Opcode module is not usually used directly. See the ops pragma and
114 Safe modules for more typical uses.
118 The authors make B<no warranty>, implied or otherwise, about the
119 suitability of this software for safety or security purposes.
121 The authors shall not in any case be liable for special, incidental,
122 consequential, indirect or other similar damages arising from the use
125 Your mileage will vary. If in any doubt B<do not use it>.
128 =head1 Operator Names and Operator Lists
130 The canonical list of operator names is the contents of the array
131 op_name defined and initialised in file F<opcode.h> of the Perl
132 source distribution (and installed into the perl library).
134 Each operator has both a terse name (its opname) and a more verbose or
135 recognisable descriptive name. The opdesc function can be used to
136 return a list of descriptions for a list of operators.
138 Many of the functions and methods listed below take a list of
139 operators as parameters. Most operator lists can be made up of several
140 types of element. Each element can be one of
144 =item an operator name (opname)
146 Operator names are typically small lowercase words like enterloop,
147 leaveloop, last, next, redo etc. Sometimes they are rather cryptic
148 like gv2cv, i_ncmp and ftsvtx.
150 =item an operator tag name (optag)
152 Operator tags can be used to refer to groups (or sets) of operators.
153 Tag names always being with a colon. The Opcode module defines several
154 optags and the user can define others using the define_optag function.
156 =item a negated opname or optag
158 An opname or optag can be prefixed with an exclamation mark, e.g., !mkdir.
159 Negating an opname or optag means remove the corresponding ops from the
160 accumulated set of ops at that point.
162 =item an operator set (opset)
164 An I<opset> as a binary string of approximately 43 bytes which holds a
165 set or zero or more operators.
167 The opset and opset_to_ops functions can be used to convert from
168 a list of operators to an opset and I<vice versa>.
170 Wherever a list of operators can be given you can use one or more opsets.
171 See also Manipulating Opsets below.
176 =head1 Opcode Functions
178 The Opcode package contains functions for manipulating operator names
179 tags and sets. All are available for export by the package.
185 In a scalar context opcodes returns the number of opcodes in this
186 version of perl (around 340 for perl5.002).
188 In a list context it returns a list of all the operator names.
189 (Not yet implemented, use @names = opset_to_ops(full_opset).)
191 =item opset (OP, ...)
193 Returns an opset containing the listed operators.
195 =item opset_to_ops (OPSET)
197 Returns a list of operator names corresponding to those operators in
200 =item opset_to_hex (OPSET)
202 Returns a string representation of an opset. Can be handy for debugging.
206 Returns an opset which includes all operators.
210 Returns an opset which contains no operators.
212 =item invert_opset (OPSET)
214 Returns an opset which is the inverse set of the one supplied.
216 =item verify_opset (OPSET, ...)
218 Returns true if the supplied opset looks like a valid opset (is the
219 right length etc) otherwise it returns false. If an optional second
220 parameter is true then verify_opset will croak on an invalid opset
221 instead of returning false.
223 Most of the other Opcode functions call verify_opset automatically
224 and will croak if given an invalid opset.
226 =item define_optag (OPTAG, OPSET)
228 Define OPTAG as a symbolic name for OPSET. Optag names always start
231 The optag name used must not be defined already (define_optag will
232 croak if it is already defined). Optag names are global to the perl
233 process and optag definitions cannot be altered or deleted once
236 It is strongly recommended that applications using Opcode should use a
237 leading capital letter on their tag names since lowercase names are
238 reserved for use by the Opcode module. If using Opcode within a module
239 you should prefix your tags names with the name of your module to
240 ensure uniqueness and thus avoid clashes with other modules.
242 =item opmask_add (OPSET)
244 Adds the supplied opset to the current opmask. Note that there is
245 currently I<no> mechanism for unmasking ops once they have been masked.
250 Returns an opset corresponding to the current opmask.
252 =item opdesc (OP, ...)
254 This takes a list of operator names and returns the corresponding list
255 of operator descriptions.
259 Dumps to STDOUT a two column list of op names and op descriptions.
260 If an optional pattern is given then only lines which match the
261 (case insensitive) pattern will be output.
263 It's designed to be used as a handy command line utility:
265 perl -MOpcode=opdump -e opdump
266 perl -MOpcode=opdump -e 'opdump Eval'
270 =head1 Manipulating Opsets
272 Opsets may be manipulated using the perl bit vector operators & (and), | (or),
273 ^ (xor) and ~ (negate/invert).
275 However you should never rely on the numerical position of any opcode
276 within the opset. In other words both sides of a bit vector operator
277 should be opsets returned from Opcode functions.
279 Also, since the number of opcodes in your current version of perl might
280 not be an exact multiple of eight, there may be unused bits in the last
281 byte of an upset. This should not cause any problems (Opcode functions
282 ignore those extra bits) but it does mean that using the ~ operator
283 will typically not produce the same 'physical' opset 'string' as the
284 invert_opset function.
289 $bool = opset_eq($opset1, $opset2) true if opsets are logically eqiv
291 $yes = opset_can($opset, @ops) true if $opset has all @ops set
293 @diff = opset_diff($opset1, $opset2) => ('foo', '!bar', ...)
297 # the =cut above is used by _init_optags() to get here quickly
299 =head1 Predefined Opcode Tags
305 null stub scalar pushmark wantarray const defined undef
309 rv2av aassign aelem aelemfast aslice av2arylen
311 rv2hv helem hslice each values keys exists delete
313 preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec
314 int hex oct abs pow multiply i_multiply divide i_divide
315 modulo i_modulo add i_add subtract i_subtract
317 left_shift right_shift bit_and bit_xor bit_or negate i_negate
320 lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
321 slt sgt sle sge seq sne scmp
323 substr vec stringify study pos length index rindex ord chr
325 ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp
329 list lslice splice push pop shift unshift reverse
331 cond_expr flip flop andassign orassign and or xor
333 warn die lineseq nextstate unstack scope enter leave
335 rv2cv anoncode prototype
337 entersub leavesub return method -- XXX loops via recursion?
339 leaveeval -- needed for Safe to operate, is safe without entereval
343 These memory related ops are not included in :base_core because they
344 can easily be used to implement a resource attack (e.g., consume all
347 concat repeat join range
351 Note that despite the existance of this optag a memory resource attack
352 may still be possible using only :base_core ops.
354 Disabling these ops is a I<very> heavy handed way to attempt to prevent
355 a memory resource attack. It's probable that a specific memory limit
356 mechanism will be added to perl in the near future.
360 These loop ops are not included in :base_core because they can easily be
361 used to implement a resource attack (e.g., consume all available CPU time).
372 These ops enable I<filehandle> (rather than filename) based input and
373 output. These are safe on the assumption that only pre-existing
374 filehandles are available for use. To create new filehandles other ops
375 such as open would need to be enabled.
377 readline rcatline getc read
379 formline enterwrite leavewrite
381 print sysread syswrite send recv eof tell seek
383 readdir telldir seekdir rewinddir
387 These are a hotchpotch of opcodes still waiting to be considered
391 padsv padav padhv padany
393 rv2gv refgen srefgen ref
395 bless -- could be used to change ownership of objects (reblessing)
397 pushre regcmaybe regcomp subst substcont
399 sprintf prtf -- can core dump
409 getppid getpgrp setpgrp getpriority setpriority localtime gmtime
411 entertry leavetry -- can be used to 'hide' fatal errors
415 These ops are not included in :base_core because of the risk of them being
416 used to generate floating point exceptions (which would have to be caught
417 using a $SIG{FPE} handler).
419 atan2 sin cos exp log sqrt
421 These ops are not included in :base_core because they have an effect
422 beyond the scope of the compartment.
428 A handy tag name for a I<reasonable> default set of ops. (The current ops
429 allowed are unstable while development continues. It will change.)
431 :base_core :base_mem :base_loop :base_io :base_orig
433 If safety matters to you (and why else would you be using the Opcode module?)
434 then you should not rely on the definition of this, or indeed any other, optag!
441 ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread
442 ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned
443 ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx
451 ghbyname ghbyaddr ghostent shostent ehostent -- hosts
452 gnbyname gnbyaddr gnetent snetent enetent -- networks
453 gpbyname gpbynumber gprotoent sprotoent eprotoent -- protocols
454 gsbyname gsbyport gservent sservent eservent -- services
456 gpwnam gpwuid gpwent spwent epwent getlogin -- users
457 ggrnam ggrgid ggrent sgrent egrent -- groups
461 A handy tag name for a I<reasonable> default set of ops beyond the
462 :default optag. Like :default (and indeed all the other optags) its
463 current definition is unstable while development continues. It will change.
465 The :browse tag represents the next step beyond :default. It it a
466 superset of the :default ops and adds :filesys_read the :sys_db.
467 The intent being that scripts can access more (possibly sensitive)
468 information about your system but not be able to change it.
470 :default :filesys_read :sys_db
477 open_dir closedir -- other dir ops are in :base_io
481 link unlink rename symlink truncate
487 fcntl -- not strictly filesys related, but possibly as dangerous?
497 glob -- access to Cshell via <`rm *`>
503 time tms -- could be used for timing attacks (paranoid?)
507 This tag holds groups of assorted specialist opcodes that don't warrant
508 having optags defined for them.
510 SystemV Interprocess Communications:
512 msgctl msgget msgrcv msgsnd
516 shmctl shmget shmread shmwrite
518 =item :still_to_be_decided
523 socket getpeername ssockopt
524 bind connect listen accept shutdown gsockopt getsockname
526 sleep alarm -- changes global timer state and signal handling
527 sort -- assorted problems including core dumps
528 tied -- can be used to access object implementing a tie
529 pack unpack -- can be used to create/use memory pointers
531 entereval -- can be used to hide code from initial compile
534 caller -- get info about calling environment and args
538 dbstate -- perl -d version of nextstate(ment) opcode
542 This tag is simply a bucket for opcodes that are unlikely to be used via
543 a tag name but need to be tagged for completness and documentation.
552 ops(3) -- perl pragma interface to Opcode module.
554 Safe(3) -- Opcode and namespace limited execution compartments
558 Originally designed and implemented by Malcolm Beattie,
559 mbeattie@sable.ox.ac.uk as part of Safe version 1.
561 Split out from Safe module version 1, named opcode tags and other
562 changes added by Tim Bunce E<lt>F<Tim.Bunce@ig.co.uk>E<gt>.