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1 | package Fatal; |
2 | |
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3 | use 5.008; # 5.8.x needed for autodie |
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4 | use Carp; |
5 | use strict; |
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6 | use warnings; |
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7 | use Tie::RefHash; # To cache subroutine refs |
8 | |
9 | use constant PERL510 => ( $] >= 5.010 ); |
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10 | |
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11 | use constant LEXICAL_TAG => q{:lexical}; |
12 | use constant VOID_TAG => q{:void}; |
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13 | use constant INSIST_TAG => q{!}; |
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14 | |
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15 | use constant ERROR_NOARGS => 'Cannot use lexical %s with no arguments'; |
16 | use constant ERROR_VOID_LEX => VOID_TAG.' cannot be used with lexical scope'; |
17 | use constant ERROR_LEX_FIRST => LEXICAL_TAG.' must be used as first argument'; |
18 | use constant ERROR_NO_LEX => "no %s can only start with ".LEXICAL_TAG; |
19 | use constant ERROR_BADNAME => "Bad subroutine name for %s: %s"; |
20 | use constant ERROR_NOTSUB => "%s is not a Perl subroutine"; |
21 | use constant ERROR_NOT_BUILT => "%s is neither a builtin, nor a Perl subroutine"; |
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22 | use constant ERROR_NOHINTS => "No user hints defined for %s"; |
23 | |
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24 | use constant ERROR_CANT_OVERRIDE => "Cannot make the non-overridable builtin %s fatal"; |
25 | |
26 | use constant ERROR_NO_IPC_SYS_SIMPLE => "IPC::System::Simple required for Fatalised/autodying system()"; |
27 | |
28 | use constant ERROR_IPC_SYS_SIMPLE_OLD => "IPC::System::Simple version %f required for Fatalised/autodying system(). We only have version %f"; |
29 | |
30 | use constant ERROR_AUTODIE_CONFLICT => q{"no autodie '%s'" is not allowed while "use Fatal '%s'" is in effect}; |
31 | |
32 | use constant ERROR_FATAL_CONFLICT => q{"use Fatal '%s'" is not allowed while "no autodie '%s'" is in effect}; |
33 | |
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34 | use constant ERROR_58_HINTS => q{Non-subroutine %s hints for %s are not supported under Perl 5.8.x}; |
35 | |
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36 | # Older versions of IPC::System::Simple don't support all the |
37 | # features we need. |
38 | |
39 | use constant MIN_IPC_SYS_SIMPLE_VER => 0.12; |
40 | |
41 | # All the Fatal/autodie modules share the same version number. |
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42 | our $VERSION = '2.06'; |
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43 | |
44 | our $Debug ||= 0; |
45 | |
46 | # EWOULDBLOCK values for systems that don't supply their own. |
47 | # Even though this is defined with our, that's to help our |
48 | # test code. Please don't rely upon this variable existing in |
49 | # the future. |
50 | |
51 | our %_EWOULDBLOCK = ( |
52 | MSWin32 => 33, |
53 | ); |
54 | |
55 | # We have some tags that can be passed in for use with import. |
56 | # These are all assumed to be CORE:: |
57 | |
58 | my %TAGS = ( |
59 | ':io' => [qw(:dbm :file :filesys :ipc :socket |
60 | read seek sysread syswrite sysseek )], |
61 | ':dbm' => [qw(dbmopen dbmclose)], |
62 | ':file' => [qw(open close flock sysopen fcntl fileno binmode |
63 | ioctl truncate)], |
64 | ':filesys' => [qw(opendir closedir chdir link unlink rename mkdir |
65 | symlink rmdir readlink umask)], |
66 | ':ipc' => [qw(:msg :semaphore :shm pipe)], |
67 | ':msg' => [qw(msgctl msgget msgrcv msgsnd)], |
68 | ':threads' => [qw(fork)], |
69 | ':semaphore'=>[qw(semctl semget semop)], |
70 | ':shm' => [qw(shmctl shmget shmread)], |
71 | ':system' => [qw(system exec)], |
72 | |
73 | # Can we use qw(getpeername getsockname)? What do they do on failure? |
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74 | # TODO - Can socket return false? |
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75 | ':socket' => [qw(accept bind connect getsockopt listen recv send |
76 | setsockopt shutdown socketpair)], |
77 | |
78 | # Our defaults don't include system(), because it depends upon |
79 | # an optional module, and it breaks the exotic form. |
80 | # |
81 | # This *may* change in the future. I'd love IPC::System::Simple |
82 | # to be a dependency rather than a recommendation, and hence for |
83 | # system() to be autodying by default. |
84 | |
85 | ':default' => [qw(:io :threads)], |
86 | |
87 | # Version specific tags. These allow someone to specify |
88 | # use autodie qw(:1.994) and know exactly what they'll get. |
89 | |
90 | ':1.994' => [qw(:default)], |
91 | ':1.995' => [qw(:default)], |
92 | ':1.996' => [qw(:default)], |
93 | ':1.997' => [qw(:default)], |
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94 | ':1.998' => [qw(:default)], |
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95 | ':1.999' => [qw(:default)], |
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96 | ':1.999_01' => [qw(:default)], |
97 | ':2.00' => [qw(:default)], |
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98 | ':2.01' => [qw(:default)], |
99 | ':2.02' => [qw(:default)], |
100 | ':2.03' => [qw(:default)], |
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101 | ':2.04' => [qw(:default)], |
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102 | ':2.05' => [qw(:default)], |
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103 | ':2.06' => [qw(:default)], |
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104 | ); |
105 | |
106 | $TAGS{':all'} = [ keys %TAGS ]; |
107 | |
108 | # This hash contains subroutines for which we should |
109 | # subroutine() // die() rather than subroutine() || die() |
110 | |
111 | my %Use_defined_or; |
112 | |
113 | # CORE::open returns undef on failure. It can legitimately return |
114 | # 0 on success, eg: open(my $fh, '-|') || exec(...); |
115 | |
116 | @Use_defined_or{qw( |
117 | CORE::fork |
118 | CORE::recv |
119 | CORE::send |
120 | CORE::open |
121 | CORE::fileno |
122 | CORE::read |
123 | CORE::readlink |
124 | CORE::sysread |
125 | CORE::syswrite |
126 | CORE::sysseek |
127 | CORE::umask |
128 | )} = (); |
129 | |
130 | # Cached_fatalised_sub caches the various versions of our |
131 | # fatalised subs as they're produced. This means we don't |
132 | # have to build our own replacement of CORE::open and friends |
133 | # for every single package that wants to use them. |
134 | |
135 | my %Cached_fatalised_sub = (); |
136 | |
137 | # Every time we're called with package scope, we record the subroutine |
138 | # (including package or CORE::) in %Package_Fatal. This allows us |
139 | # to detect illegal combinations of autodie and Fatal, and makes sure |
140 | # we don't accidently make a Fatal function autodying (which isn't |
141 | # very useful). |
142 | |
143 | my %Package_Fatal = (); |
144 | |
145 | # The first time we're called with a user-sub, we cache it here. |
146 | # In the case of a "no autodie ..." we put back the cached copy. |
147 | |
148 | my %Original_user_sub = (); |
149 | |
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150 | # Is_fatalised_sub simply records a big map of fatalised subroutine |
151 | # refs. It means we can avoid repeating work, or fatalising something |
152 | # we've already processed. |
153 | |
154 | my %Is_fatalised_sub = (); |
155 | tie %Is_fatalised_sub, 'Tie::RefHash'; |
156 | |
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157 | # We use our package in a few hash-keys. Having it in a scalar is |
158 | # convenient. The "guard $PACKAGE" string is used as a key when |
159 | # setting up lexical guards. |
160 | |
161 | my $PACKAGE = __PACKAGE__; |
162 | my $PACKAGE_GUARD = "guard $PACKAGE"; |
163 | my $NO_PACKAGE = "no $PACKAGE"; # Used to detect 'no autodie' |
164 | |
165 | # Here's where all the magic happens when someone write 'use Fatal' |
166 | # or 'use autodie'. |
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167 | |
168 | sub import { |
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169 | my $class = shift(@_); |
170 | my $void = 0; |
171 | my $lexical = 0; |
172 | my $insist_hints = 0; |
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173 | |
174 | my ($pkg, $filename) = caller(); |
175 | |
176 | @_ or return; # 'use Fatal' is a no-op. |
177 | |
178 | # If we see the :lexical flag, then _all_ arguments are |
179 | # changed lexically |
180 | |
181 | if ($_[0] eq LEXICAL_TAG) { |
182 | $lexical = 1; |
183 | shift @_; |
184 | |
185 | # If we see no arguments and :lexical, we assume they |
186 | # wanted ':default'. |
187 | |
188 | if (@_ == 0) { |
189 | push(@_, ':default'); |
190 | } |
191 | |
192 | # Don't allow :lexical with :void, it's needlessly confusing. |
193 | if ( grep { $_ eq VOID_TAG } @_ ) { |
194 | croak(ERROR_VOID_LEX); |
195 | } |
196 | } |
197 | |
198 | if ( grep { $_ eq LEXICAL_TAG } @_ ) { |
199 | # If we see the lexical tag as the non-first argument, complain. |
200 | croak(ERROR_LEX_FIRST); |
201 | } |
202 | |
203 | my @fatalise_these = @_; |
204 | |
205 | # Thiese subs will get unloaded at the end of lexical scope. |
206 | my %unload_later; |
207 | |
208 | # This hash helps us track if we've alredy done work. |
209 | my %done_this; |
210 | |
211 | # NB: we're using while/shift rather than foreach, since |
212 | # we'll be modifying the array as we walk through it. |
213 | |
214 | while (my $func = shift @fatalise_these) { |
215 | |
216 | if ($func eq VOID_TAG) { |
217 | |
218 | # When we see :void, set the void flag. |
219 | $void = 1; |
220 | |
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221 | } elsif ($func eq INSIST_TAG) { |
222 | |
223 | $insist_hints = 1; |
224 | |
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225 | } elsif (exists $TAGS{$func}) { |
226 | |
227 | # When it's a tag, expand it. |
228 | push(@fatalise_these, @{ $TAGS{$func} }); |
229 | |
230 | } else { |
231 | |
232 | # Otherwise, fatalise it. |
233 | |
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234 | # Check to see if there's an insist flag at the front. |
235 | # If so, remove it, and insist we have hints for this sub. |
236 | my $insist_this; |
237 | |
238 | if ($func =~ s/^!//) { |
239 | $insist_this = 1; |
240 | } |
241 | |
242 | # TODO: Even if we've already fatalised, we should |
243 | # check we've done it with hints (if $insist_hints). |
244 | |
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245 | # If we've already made something fatal this call, |
246 | # then don't do it twice. |
247 | |
248 | next if $done_this{$func}; |
249 | |
250 | # We're going to make a subroutine fatalistic. |
251 | # However if we're being invoked with 'use Fatal qw(x)' |
252 | # and we've already been called with 'no autodie qw(x)' |
253 | # in the same scope, we consider this to be an error. |
254 | # Mixing Fatal and autodie effects was considered to be |
255 | # needlessly confusing on p5p. |
256 | |
257 | my $sub = $func; |
258 | $sub = "${pkg}::$sub" unless $sub =~ /::/; |
259 | |
260 | # If we're being called as Fatal, and we've previously |
261 | # had a 'no X' in scope for the subroutine, then complain |
262 | # bitterly. |
263 | |
264 | if (! $lexical and $^H{$NO_PACKAGE}{$sub}) { |
265 | croak(sprintf(ERROR_FATAL_CONFLICT, $func, $func)); |
266 | } |
267 | |
268 | # We're not being used in a confusing way, so make |
269 | # the sub fatal. Note that _make_fatal returns the |
270 | # old (original) version of the sub, or undef for |
271 | # built-ins. |
272 | |
273 | my $sub_ref = $class->_make_fatal( |
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274 | $func, $pkg, $void, $lexical, $filename, |
275 | ( $insist_this || $insist_hints ) |
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276 | ); |
277 | |
278 | $done_this{$func}++; |
279 | |
280 | $Original_user_sub{$sub} ||= $sub_ref; |
281 | |
282 | # If we're making lexical changes, we need to arrange |
283 | # for them to be cleaned at the end of our scope, so |
284 | # record them here. |
285 | |
286 | $unload_later{$func} = $sub_ref if $lexical; |
287 | } |
288 | } |
289 | |
290 | if ($lexical) { |
291 | |
292 | # Dark magic to have autodie work under 5.8 |
293 | # Copied from namespace::clean, that copied it from |
294 | # autobox, that found it on an ancient scroll written |
295 | # in blood. |
296 | |
297 | # This magic bit causes %^H to be lexically scoped. |
298 | |
299 | $^H |= 0x020000; |
300 | |
301 | # Our package guard gets invoked when we leave our lexical |
302 | # scope. |
303 | |
304 | push(@ { $^H{$PACKAGE_GUARD} }, autodie::Scope::Guard->new(sub { |
305 | $class->_install_subs($pkg, \%unload_later); |
306 | })); |
307 | |
308 | } |
309 | |
310 | return; |
311 | |
312 | } |
313 | |
314 | # The code here is originally lifted from namespace::clean, |
315 | # by Robert "phaylon" Sedlacek. |
316 | # |
317 | # It's been redesigned after feedback from ikegami on perlmonks. |
318 | # See http://perlmonks.org/?node_id=693338 . Ikegami rocks. |
319 | # |
320 | # Given a package, and hash of (subname => subref) pairs, |
321 | # we install the given subroutines into the package. If |
322 | # a subref is undef, the subroutine is removed. Otherwise |
323 | # it replaces any existing subs which were already there. |
324 | |
325 | sub _install_subs { |
326 | my ($class, $pkg, $subs_to_reinstate) = @_; |
327 | |
328 | my $pkg_sym = "${pkg}::"; |
329 | |
330 | while(my ($sub_name, $sub_ref) = each %$subs_to_reinstate) { |
331 | |
332 | my $full_path = $pkg_sym.$sub_name; |
333 | |
334 | # Copy symbols across to temp area. |
335 | |
336 | no strict 'refs'; ## no critic |
337 | |
338 | local *__tmp = *{ $full_path }; |
339 | |
340 | # Nuke the old glob. |
341 | { no strict; delete $pkg_sym->{$sub_name}; } ## no critic |
342 | |
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343 | # Copy innocent bystanders back. Note that we lose |
344 | # formats; it seems that Perl versions up to 5.10.0 |
345 | # have a bug which causes copying formats to end up in |
346 | # the scalar slot. Thanks to Ben Morrow for spotting this. |
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347 | |
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348 | foreach my $slot (qw( SCALAR ARRAY HASH IO ) ) { |
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349 | next unless defined *__tmp{ $slot }; |
350 | *{ $full_path } = *__tmp{ $slot }; |
351 | } |
352 | |
353 | # Put back the old sub (if there was one). |
354 | |
355 | if ($sub_ref) { |
356 | |
357 | no strict; ## no critic |
358 | *{ $pkg_sym . $sub_name } = $sub_ref; |
359 | } |
360 | } |
361 | |
362 | return; |
363 | } |
364 | |
365 | sub unimport { |
366 | my $class = shift; |
367 | |
368 | # Calling "no Fatal" must start with ":lexical" |
369 | if ($_[0] ne LEXICAL_TAG) { |
370 | croak(sprintf(ERROR_NO_LEX,$class)); |
371 | } |
372 | |
373 | shift @_; # Remove :lexical |
374 | |
375 | my $pkg = (caller)[0]; |
376 | |
377 | # If we've been called with arguments, then the developer |
378 | # has explicitly stated 'no autodie qw(blah)', |
379 | # in which case, we disable Fatalistic behaviour for 'blah'. |
380 | |
381 | my @unimport_these = @_ ? @_ : ':all'; |
382 | |
383 | while (my $symbol = shift @unimport_these) { |
384 | |
385 | if ($symbol =~ /^:/) { |
386 | |
387 | # Looks like a tag! Expand it! |
388 | push(@unimport_these, @{ $TAGS{$symbol} }); |
389 | |
390 | next; |
391 | } |
392 | |
393 | my $sub = $symbol; |
394 | $sub = "${pkg}::$sub" unless $sub =~ /::/; |
395 | |
396 | # If 'blah' was already enabled with Fatal (which has package |
397 | # scope) then, this is considered an error. |
398 | |
399 | if (exists $Package_Fatal{$sub}) { |
400 | croak(sprintf(ERROR_AUTODIE_CONFLICT,$symbol,$symbol)); |
401 | } |
402 | |
403 | # Record 'no autodie qw($sub)' as being in effect. |
404 | # This is to catch conflicting semantics elsewhere |
405 | # (eg, mixing Fatal with no autodie) |
406 | |
407 | $^H{$NO_PACKAGE}{$sub} = 1; |
408 | |
409 | if (my $original_sub = $Original_user_sub{$sub}) { |
410 | # Hey, we've got an original one of these, put it back. |
411 | $class->_install_subs($pkg, { $symbol => $original_sub }); |
412 | next; |
413 | } |
414 | |
415 | # We don't have an original copy of the sub, on the assumption |
416 | # it's core (or doesn't exist), we'll just nuke it. |
417 | |
418 | $class->_install_subs($pkg,{ $symbol => undef }); |
419 | |
420 | } |
421 | |
422 | return; |
423 | |
424 | } |
425 | |
426 | # TODO - This is rather terribly inefficient right now. |
427 | |
428 | # NB: Perl::Critic's dump-autodie-tag-contents depends upon this |
429 | # continuing to work. |
430 | |
431 | { |
432 | my %tag_cache; |
433 | |
434 | sub _expand_tag { |
435 | my ($class, $tag) = @_; |
436 | |
437 | if (my $cached = $tag_cache{$tag}) { |
438 | return $cached; |
439 | } |
440 | |
441 | if (not exists $TAGS{$tag}) { |
442 | croak "Invalid exception class $tag"; |
443 | } |
444 | |
445 | my @to_process = @{$TAGS{$tag}}; |
446 | |
447 | my @taglist = (); |
448 | |
449 | while (my $item = shift @to_process) { |
450 | if ($item =~ /^:/) { |
451 | push(@to_process, @{$TAGS{$item}} ); |
452 | } else { |
453 | push(@taglist, "CORE::$item"); |
454 | } |
455 | } |
456 | |
457 | $tag_cache{$tag} = \@taglist; |
458 | |
459 | return \@taglist; |
460 | |
461 | } |
462 | |
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463 | } |
464 | |
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465 | # This code is from the original Fatal. It scares me. |
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466 | # It is 100% compatible with the 5.10.0 Fatal module, right down |
467 | # to the scary 'XXXX' comment. ;) |
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468 | |
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469 | sub fill_protos { |
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470 | my $proto = shift; |
471 | my ($n, $isref, @out, @out1, $seen_semi) = -1; |
472 | while ($proto =~ /\S/) { |
473 | $n++; |
474 | push(@out1,[$n,@out]) if $seen_semi; |
475 | push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//; |
476 | push(@out, "\$_[$n]"), next if $proto =~ s/^\s*([_*\$&])//; |
477 | push(@out, "\@_[$n..\$#_]"), last if $proto =~ s/^\s*(;\s*)?\@//; |
478 | $seen_semi = 1, $n--, next if $proto =~ s/^\s*;//; # XXXX ???? |
479 | die "Internal error: Unknown prototype letters: \"$proto\""; |
480 | } |
481 | push(@out1,[$n+1,@out]); |
482 | return @out1; |
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483 | } |
484 | |
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485 | # This is a backwards compatible version of _write_invocation. It's |
486 | # recommended you don't use it. |
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487 | |
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488 | sub write_invocation { |
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489 | my ($core, $call, $name, $void, @args) = @_; |
490 | |
491 | return Fatal->_write_invocation( |
492 | $core, $call, $name, $void, |
493 | 0, # Lexical flag |
494 | undef, # Sub, unused in legacy mode |
495 | undef, # Subref, unused in legacy mode. |
496 | @args |
497 | ); |
498 | } |
499 | |
500 | # This version of _write_invocation is used internally. It's not |
501 | # recommended you call it from external code, as the interface WILL |
502 | # change in the future. |
503 | |
504 | sub _write_invocation { |
505 | |
506 | my ($class, $core, $call, $name, $void, $lexical, $sub, $sref, @argvs) = @_; |
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507 | |
508 | if (@argvs == 1) { # No optional arguments |
509 | |
510 | my @argv = @{$argvs[0]}; |
511 | shift @argv; |
512 | |
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513 | return $class->_one_invocation($core,$call,$name,$void,$sub,! $lexical, $sref, @argv); |
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514 | |
515 | } else { |
516 | my $else = "\t"; |
517 | my (@out, @argv, $n); |
518 | while (@argvs) { |
519 | @argv = @{shift @argvs}; |
520 | $n = shift @argv; |
521 | |
522 | push @out, "${else}if (\@_ == $n) {\n"; |
523 | $else = "\t} els"; |
524 | |
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525 | push @out, $class->_one_invocation($core,$call,$name,$void,$sub,! $lexical, $sref, @argv); |
0b09a93a |
526 | } |
9b657a62 |
527 | push @out, qq[ |
0b09a93a |
528 | } |
9b657a62 |
529 | die "Internal error: $name(\@_): Do not expect to get ", scalar(\@_), " arguments"; |
0b09a93a |
530 | ]; |
531 | |
532 | return join '', @out; |
533 | } |
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534 | } |
535 | |
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536 | |
537 | # This is a slim interface to ensure backward compatibility with |
538 | # anyone doing very foolish things with old versions of Fatal. |
539 | |
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540 | sub one_invocation { |
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541 | my ($core, $call, $name, $void, @argv) = @_; |
542 | |
543 | return Fatal->_one_invocation( |
544 | $core, $call, $name, $void, |
545 | undef, # Sub. Unused in back-compat mode. |
546 | 1, # Back-compat flag |
547 | undef, # Subref, unused in back-compat mode. |
548 | @argv |
549 | ); |
550 | |
551 | } |
552 | |
553 | # This is the internal interface that generates code. |
554 | # NOTE: This interface WILL change in the future. Please do not |
555 | # call this subroutine directly. |
556 | |
557 | # TODO: Whatever's calling this code has already looked up hints. Pass |
558 | # them in, rather than look them up a second time. |
559 | |
560 | sub _one_invocation { |
561 | my ($class, $core, $call, $name, $void, $sub, $back_compat, $sref, @argv) = @_; |
562 | |
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563 | |
564 | # If someone is calling us directly (a child class perhaps?) then |
565 | # they could try to mix void without enabling backwards |
566 | # compatibility. We just don't support this at all, so we gripe |
567 | # about it rather than doing something unwise. |
568 | |
569 | if ($void and not $back_compat) { |
570 | Carp::confess("Internal error: :void mode not supported with $class"); |
571 | } |
572 | |
573 | # @argv only contains the results of the in-built prototype |
574 | # function, and is therefore safe to interpolate in the |
575 | # code generators below. |
576 | |
577 | # TODO - The following clobbers context, but that's what the |
578 | # old Fatal did. Do we care? |
579 | |
580 | if ($back_compat) { |
581 | |
9b657a62 |
582 | # Use Fatal qw(system) will never be supported. It generated |
583 | # a compile-time error with legacy Fatal, and there's no reason |
584 | # to support it when autodie does a better job. |
0b09a93a |
585 | |
586 | if ($call eq 'CORE::system') { |
587 | return q{ |
9b657a62 |
588 | croak("UNIMPLEMENTED: use Fatal qw(system) not supported."); |
0b09a93a |
589 | }; |
590 | } |
591 | |
592 | local $" = ', '; |
593 | |
594 | if ($void) { |
595 | return qq/return (defined wantarray)?$call(@argv): |
596 | $call(@argv) || croak "Can't $name(\@_)/ . |
597 | ($core ? ': $!' : ', \$! is \"$!\"') . '"' |
598 | } else { |
599 | return qq{return $call(@argv) || croak "Can't $name(\@_)} . |
600 | ($core ? ': $!' : ', \$! is \"$!\"') . '"'; |
601 | } |
602 | } |
603 | |
604 | # The name of our original function is: |
605 | # $call if the function is CORE |
606 | # $sub if our function is non-CORE |
607 | |
608 | # The reason for this is that $call is what we're actualling |
609 | # calling. For our core functions, this is always |
610 | # CORE::something. However for user-defined subs, we're about to |
611 | # replace whatever it is that we're calling; as such, we actually |
612 | # calling a subroutine ref. |
613 | |
9b657a62 |
614 | my $human_sub_name = $core ? $call : $sub; |
615 | |
616 | # Should we be testing to see if our result is defined, or |
617 | # just true? |
618 | |
619 | my $use_defined_or; |
620 | |
621 | my $hints; # All user-sub hints, including list hints. |
622 | |
623 | if ( $core ) { |
624 | |
625 | # Core hints are built into autodie. |
626 | |
627 | $use_defined_or = exists ( $Use_defined_or{$call} ); |
628 | |
629 | } |
630 | else { |
631 | |
632 | # User sub hints are looked up using autodie::hints, |
633 | # since users may wish to add their own hints. |
634 | |
635 | require autodie::hints; |
636 | |
637 | $hints = autodie::hints->get_hints_for( $sref ); |
eb8d423f |
638 | |
639 | # We'll look up the sub's fullname. This means we |
640 | # get better reports of where it came from in our |
641 | # error messages, rather than what imported it. |
642 | |
643 | $human_sub_name = autodie::hints->sub_fullname( $sref ); |
644 | |
9b657a62 |
645 | } |
0b09a93a |
646 | |
9b657a62 |
647 | # Checks for special core subs. |
0b09a93a |
648 | |
649 | if ($call eq 'CORE::system') { |
650 | |
651 | # Leverage IPC::System::Simple if we're making an autodying |
652 | # system. |
653 | |
654 | local $" = ", "; |
655 | |
656 | # We need to stash $@ into $E, rather than using |
657 | # local $@ for the whole sub. If we don't then |
658 | # any exceptions from internal errors in autodie/Fatal |
659 | # will mysteriously disappear before propogating |
660 | # upwards. |
661 | |
662 | return qq{ |
663 | my \$retval; |
664 | my \$E; |
665 | |
666 | |
667 | { |
668 | local \$@; |
669 | |
670 | eval { |
671 | \$retval = IPC::System::Simple::system(@argv); |
672 | }; |
673 | |
674 | \$E = \$@; |
675 | } |
676 | |
677 | if (\$E) { |
678 | |
9b657a62 |
679 | # TODO - This can't be overridden in child |
0b09a93a |
680 | # classes! |
681 | |
682 | die autodie::exception::system->new( |
683 | function => q{CORE::system}, args => [ @argv ], |
684 | message => "\$E", errno => \$!, |
685 | ); |
686 | } |
687 | |
688 | return \$retval; |
689 | }; |
690 | |
691 | } |
692 | |
0b09a93a |
693 | local $" = ', '; |
694 | |
695 | # If we're going to throw an exception, here's the code to use. |
696 | my $die = qq{ |
697 | die $class->throw( |
9b657a62 |
698 | function => q{$human_sub_name}, args => [ @argv ], |
0b09a93a |
699 | pragma => q{$class}, errno => \$!, |
eb8d423f |
700 | context => \$context, return => \$retval, |
0b09a93a |
701 | ) |
702 | }; |
703 | |
704 | if ($call eq 'CORE::flock') { |
705 | |
706 | # flock needs special treatment. When it fails with |
707 | # LOCK_UN and EWOULDBLOCK, then it's not really fatal, it just |
708 | # means we couldn't get the lock right now. |
709 | |
710 | require POSIX; # For POSIX::EWOULDBLOCK |
711 | |
712 | local $@; # Don't blat anyone else's $@. |
713 | |
714 | # Ensure that our vendor supports EWOULDBLOCK. If they |
715 | # don't (eg, Windows), then we use known values for its |
716 | # equivalent on other systems. |
717 | |
718 | my $EWOULDBLOCK = eval { POSIX::EWOULDBLOCK(); } |
719 | || $_EWOULDBLOCK{$^O} |
720 | || _autocroak("Internal error - can't overload flock - EWOULDBLOCK not defined on this system."); |
721 | |
722 | require Fcntl; # For Fcntl::LOCK_NB |
723 | |
724 | return qq{ |
725 | |
eb8d423f |
726 | my \$context = wantarray() ? "list" : "scalar"; |
727 | |
0b09a93a |
728 | # Try to flock. If successful, return it immediately. |
729 | |
730 | my \$retval = $call(@argv); |
731 | return \$retval if \$retval; |
732 | |
733 | # If we failed, but we're using LOCK_NB and |
734 | # returned EWOULDBLOCK, it's not a real error. |
735 | |
736 | if (\$_[1] & Fcntl::LOCK_NB() and \$! == $EWOULDBLOCK ) { |
737 | return \$retval; |
738 | } |
739 | |
740 | # Otherwise, we failed. Die noisily. |
741 | |
742 | $die; |
743 | |
744 | }; |
745 | } |
746 | |
747 | # AFAIK everything that can be given an unopned filehandle |
748 | # will fail if it tries to use it, so we don't really need |
749 | # the 'unopened' warning class here. Especially since they |
750 | # then report the wrong line number. |
751 | |
eb8d423f |
752 | # Other warnings are disabled because they produce excessive |
753 | # complaints from smart-match hints under 5.10.1. |
754 | |
9b657a62 |
755 | my $code = qq[ |
eb8d423f |
756 | no warnings qw(unopened uninitialized numeric); |
0b09a93a |
757 | |
758 | if (wantarray) { |
759 | my \@results = $call(@argv); |
eb8d423f |
760 | my \$retval = \\\@results; |
761 | my \$context = "list"; |
9b657a62 |
762 | |
763 | ]; |
764 | |
765 | if ( $hints and ( ref($hints->{list} ) || "" ) eq 'CODE' ) { |
766 | |
767 | # NB: Subroutine hints are passed as a full list. |
768 | # This differs from the 5.10.0 smart-match behaviour, |
769 | # but means that context unaware subroutines can use |
770 | # the same hints in both list and scalar context. |
771 | |
772 | $code .= qq{ |
773 | if ( \$hints->{list}->(\@results) ) { $die }; |
774 | }; |
775 | } |
776 | elsif ( PERL510 and $hints ) { |
777 | $code .= qq{ |
778 | if ( \@results ~~ \$hints->{list} ) { $die }; |
779 | }; |
780 | } |
781 | elsif ( $hints ) { |
782 | croak sprintf(ERROR_58_HINTS, 'list', $sub); |
783 | } |
784 | else { |
785 | $code .= qq{ |
786 | # An empty list, or a single undef is failure |
0b09a93a |
787 | if (! \@results or (\@results == 1 and ! defined \$results[0])) { |
788 | $die; |
9b657a62 |
789 | } |
790 | } |
791 | } |
792 | |
793 | # Tidy up the end of our wantarray call. |
794 | |
795 | $code .= qq[ |
0b09a93a |
796 | return \@results; |
797 | } |
9b657a62 |
798 | ]; |
0b09a93a |
799 | |
0b09a93a |
800 | |
9b657a62 |
801 | # Otherwise, we're in scalar context. |
802 | # We're never in a void context, since we have to look |
803 | # at the result. |
804 | |
805 | $code .= qq{ |
eb8d423f |
806 | my \$retval = $call(@argv); |
807 | my \$context = "scalar"; |
9b657a62 |
808 | }; |
809 | |
810 | if ( $hints and ( ref($hints->{scalar} ) || "" ) eq 'CODE' ) { |
811 | |
812 | # We always call code refs directly, since that always |
813 | # works in 5.8.x, and always works in 5.10.1 |
814 | |
815 | return $code .= qq{ |
eb8d423f |
816 | if ( \$hints->{scalar}->(\$retval) ) { $die }; |
817 | return \$retval; |
9b657a62 |
818 | }; |
0b09a93a |
819 | |
9b657a62 |
820 | } |
821 | elsif (PERL510 and $hints) { |
822 | return $code . qq{ |
823 | |
eb8d423f |
824 | if ( \$retval ~~ \$hints->{scalar} ) { $die }; |
9b657a62 |
825 | |
eb8d423f |
826 | return \$retval; |
9b657a62 |
827 | }; |
828 | } |
829 | elsif ( $hints ) { |
830 | croak sprintf(ERROR_58_HINTS, 'scalar', $sub); |
831 | } |
832 | |
833 | return $code . |
834 | ( $use_defined_or ? qq{ |
0b09a93a |
835 | |
eb8d423f |
836 | $die if not defined \$retval; |
0b09a93a |
837 | |
eb8d423f |
838 | return \$retval; |
0b09a93a |
839 | |
840 | } : qq{ |
841 | |
eb8d423f |
842 | return \$retval || $die; |
0b09a93a |
843 | |
844 | } ) ; |
845 | |
e92e55da |
846 | } |
847 | |
0b09a93a |
848 | # This returns the old copy of the sub, so we can |
849 | # put it back at end of scope. |
850 | |
851 | # TODO : Check to make sure prototypes are restored correctly. |
852 | |
853 | # TODO: Taking a huge list of arguments is awful. Rewriting to |
854 | # take a hash would be lovely. |
855 | |
9b657a62 |
856 | # TODO - BACKCOMPAT - This is not yet compatible with 5.10.0 |
857 | |
e92e55da |
858 | sub _make_fatal { |
9b657a62 |
859 | my($class, $sub, $pkg, $void, $lexical, $filename, $insist) = @_; |
860 | my($name, $code, $sref, $real_proto, $proto, $core, $call, $hints); |
e92e55da |
861 | my $ini = $sub; |
862 | |
863 | $sub = "${pkg}::$sub" unless $sub =~ /::/; |
0b09a93a |
864 | |
865 | # Figure if we're using lexical or package semantics and |
866 | # twiddle the appropriate bits. |
867 | |
868 | if (not $lexical) { |
869 | $Package_Fatal{$sub} = 1; |
870 | } |
871 | |
872 | # TODO - We *should* be able to do skipping, since we know when |
873 | # we've lexicalised / unlexicalised a subroutine. |
874 | |
e92e55da |
875 | $name = $sub; |
876 | $name =~ s/.*::// or $name =~ s/^&//; |
0b09a93a |
877 | |
878 | warn "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug; |
879 | croak(sprintf(ERROR_BADNAME, $class, $name)) unless $name =~ /^\w+$/; |
880 | |
881 | if (defined(&$sub)) { # user subroutine |
882 | |
9b657a62 |
883 | # NOTE: Previously we would localise $@ at this point, so |
884 | # the following calls to eval {} wouldn't interfere with anything |
885 | # that's already in $@. Unfortunately, it would also stop |
886 | # any of our croaks from triggering(!), which is even worse. |
887 | |
0b09a93a |
888 | # This could be something that we've fatalised that |
889 | # was in core. |
890 | |
9b657a62 |
891 | if ( $Package_Fatal{$sub} and do { local $@; eval { prototype "CORE::$name" } } ) { |
0b09a93a |
892 | |
893 | # Something we previously made Fatal that was core. |
894 | # This is safe to replace with an autodying to core |
895 | # version. |
896 | |
897 | $core = 1; |
898 | $call = "CORE::$name"; |
899 | $proto = prototype $call; |
900 | |
901 | # We return our $sref from this subroutine later |
902 | # on, indicating this subroutine should be placed |
903 | # back when we're finished. |
904 | |
905 | $sref = \&$sub; |
906 | |
907 | } else { |
908 | |
9b657a62 |
909 | # If this is something we've already fatalised or played with, |
910 | # then look-up the name of the original sub for the rest of |
911 | # our processing. |
912 | |
913 | $sub = $Is_fatalised_sub{\&$sub} || $sub; |
914 | |
0b09a93a |
915 | # A regular user sub, or a user sub wrapping a |
916 | # core sub. |
917 | |
918 | $sref = \&$sub; |
919 | $proto = prototype $sref; |
920 | $call = '&$sref'; |
9b657a62 |
921 | require autodie::hints; |
922 | |
923 | $hints = autodie::hints->get_hints_for( $sref ); |
924 | |
925 | # If we've insisted on hints, but don't have them, then |
926 | # bail out! |
927 | |
928 | if ($insist and not $hints) { |
929 | croak(sprintf(ERROR_NOHINTS, $name)); |
930 | } |
931 | |
932 | # Otherwise, use the default hints if we don't have |
933 | # any. |
934 | |
935 | $hints ||= autodie::hints::DEFAULT_HINTS(); |
0b09a93a |
936 | |
937 | } |
938 | |
910ad8dd |
939 | } elsif ($sub eq $ini && $sub !~ /^CORE::GLOBAL::/) { |
0b09a93a |
940 | # Stray user subroutine |
941 | croak(sprintf(ERROR_NOTSUB,$sub)); |
942 | |
943 | } elsif ($name eq 'system') { |
944 | |
945 | # If we're fatalising system, then we need to load |
946 | # helper code. |
947 | |
9b657a62 |
948 | # The business with $E is to avoid clobbering our caller's |
949 | # $@, and to avoid $@ being localised when we croak. |
0b09a93a |
950 | |
9b657a62 |
951 | my $E; |
0b09a93a |
952 | |
9b657a62 |
953 | { |
954 | local $@; |
955 | |
956 | eval { |
957 | require IPC::System::Simple; # Only load it if we need it. |
958 | require autodie::exception::system; |
959 | }; |
960 | $E = $@; |
961 | } |
962 | |
963 | if ($E) { croak ERROR_NO_IPC_SYS_SIMPLE; } |
964 | |
965 | # Make sure we're using a recent version of ISS that actually |
966 | # support fatalised system. |
967 | if ($IPC::System::Simple::VERSION < MIN_IPC_SYS_SIMPLE_VER) { |
968 | croak sprintf( |
969 | ERROR_IPC_SYS_SIMPLE_OLD, MIN_IPC_SYS_SIMPLE_VER, |
970 | $IPC::System::Simple::VERSION |
971 | ); |
972 | } |
0b09a93a |
973 | |
974 | $call = 'CORE::system'; |
975 | $name = 'system'; |
db4e6d09 |
976 | $core = 1; |
0b09a93a |
977 | |
978 | } elsif ($name eq 'exec') { |
979 | # Exec doesn't have a prototype. We don't care. This |
980 | # breaks the exotic form with lexical scope, and gives |
981 | # the regular form a "do or die" beaviour as expected. |
982 | |
983 | $call = 'CORE::exec'; |
984 | $name = 'exec'; |
985 | $core = 1; |
986 | |
987 | } else { # CORE subroutine |
9b657a62 |
988 | my $E; |
989 | { |
990 | local $@; |
991 | $proto = eval { prototype "CORE::$name" }; |
992 | $E = $@; |
993 | } |
994 | croak(sprintf(ERROR_NOT_BUILT,$name)) if $E; |
0b09a93a |
995 | croak(sprintf(ERROR_CANT_OVERRIDE,$name)) if not defined $proto; |
996 | $core = 1; |
997 | $call = "CORE::$name"; |
e92e55da |
998 | } |
0b09a93a |
999 | |
e92e55da |
1000 | if (defined $proto) { |
0b09a93a |
1001 | $real_proto = " ($proto)"; |
e92e55da |
1002 | } else { |
0b09a93a |
1003 | $real_proto = ''; |
1004 | $proto = '@'; |
1005 | } |
1006 | |
1007 | my $true_name = $core ? $call : $sub; |
1008 | |
1009 | # TODO: This caching works, but I don't like using $void and |
1010 | # $lexical as keys. In particular, I suspect our code may end up |
1011 | # wrapping already wrapped code when autodie and Fatal are used |
1012 | # together. |
1013 | |
1014 | # NB: We must use '$sub' (the name plus package) and not |
1015 | # just '$name' (the short name) here. Failing to do so |
1016 | # results code that's in the wrong package, and hence has |
1017 | # access to the wrong package filehandles. |
1018 | |
1019 | if (my $subref = $Cached_fatalised_sub{$class}{$sub}{$void}{$lexical}) { |
1020 | $class->_install_subs($pkg, { $name => $subref }); |
1021 | return $sref; |
e92e55da |
1022 | } |
0b09a93a |
1023 | |
1024 | $code = qq[ |
1025 | sub$real_proto { |
1026 | local(\$", \$!) = (', ', 0); # TODO - Why do we do this? |
1027 | ]; |
1028 | |
1029 | # Don't have perl whine if exec fails, since we'll be handling |
1030 | # the exception now. |
1031 | $code .= "no warnings qw(exec);\n" if $call eq "CORE::exec"; |
1032 | |
e92e55da |
1033 | my @protos = fill_protos($proto); |
9b657a62 |
1034 | $code .= $class->_write_invocation($core, $call, $name, $void, $lexical, $sub, $sref, @protos); |
e92e55da |
1035 | $code .= "}\n"; |
0b09a93a |
1036 | warn $code if $Debug; |
1037 | |
1038 | # I thought that changing package was a monumental waste of |
1039 | # time for CORE subs, since they'll always be the same. However |
1040 | # that's not the case, since they may refer to package-based |
1041 | # filehandles (eg, with open). |
1042 | # |
1043 | # There is potential to more aggressively cache core subs |
1044 | # that we know will never want to interact with package variables |
1045 | # and filehandles. |
1046 | |
2ba6ecf4 |
1047 | { |
0b09a93a |
1048 | no strict 'refs'; ## no critic # to avoid: Can't use string (...) as a symbol ref ... |
0b09a93a |
1049 | |
9b657a62 |
1050 | my $E; |
1051 | |
1052 | { |
1053 | local $@; |
1054 | $code = eval("package $pkg; use Carp; $code"); ## no critic |
1055 | $E = $@; |
1056 | } |
0b09a93a |
1057 | |
9b657a62 |
1058 | if (not $code) { |
1059 | croak("Internal error in autodie/Fatal processing $true_name: $E"); |
0b09a93a |
1060 | |
1061 | } |
1062 | } |
1063 | |
1064 | # Now we need to wrap our fatalised sub inside an itty bitty |
1065 | # closure, which can detect if we've leaked into another file. |
1066 | # Luckily, we only need to do this for lexical (autodie) |
1067 | # subs. Fatal subs can leak all they want, it's considered |
1068 | # a "feature" (or at least backwards compatible). |
1069 | |
1070 | # TODO: Cache our leak guards! |
1071 | |
1072 | # TODO: This is pretty hairy code. A lot more tests would |
1073 | # be really nice for this. |
1074 | |
1075 | my $leak_guard; |
1076 | |
1077 | if ($lexical) { |
1078 | |
1079 | $leak_guard = qq< |
1080 | package $pkg; |
1081 | |
1082 | sub$real_proto { |
1083 | |
db4e6d09 |
1084 | # If we're inside a string eval, we can end up with a |
1085 | # whacky filename. The following code allows autodie |
1086 | # to propagate correctly into string evals. |
1087 | |
1088 | my \$caller_level = 0; |
1089 | |
b0745470 |
1090 | my \$caller; |
1091 | |
1092 | while ( (\$caller = (caller \$caller_level)[1]) =~ m{^\\(eval \\d+\\)\$} ) { |
1093 | |
1094 | # If our filename is actually an eval, and we |
1095 | # reach it, then go to our autodying code immediatately. |
1096 | |
1097 | goto &\$code if (\$caller eq \$filename); |
db4e6d09 |
1098 | \$caller_level++; |
1099 | } |
1100 | |
b0745470 |
1101 | # We're now out of the eval stack. |
1102 | |
0b09a93a |
1103 | # If we're called from the correct file, then use the |
1104 | # autodying code. |
db4e6d09 |
1105 | goto &\$code if ((caller \$caller_level)[1] eq \$filename); |
0b09a93a |
1106 | |
1107 | # Oh bother, we've leaked into another file. Call the |
1108 | # original code. Note that \$sref may actually be a |
1109 | # reference to a Fatalised version of a core built-in. |
1110 | # That's okay, because Fatal *always* leaks between files. |
1111 | |
1112 | goto &\$sref if \$sref; |
1113 | >; |
1114 | |
1115 | |
1116 | # If we're here, it must have been a core subroutine called. |
1117 | # Warning: The following code may disturb some viewers. |
1118 | |
1119 | # TODO: It should be possible to combine this with |
1120 | # write_invocation(). |
1121 | |
1122 | foreach my $proto (@protos) { |
1123 | local $" = ", "; # So @args is formatted correctly. |
1124 | my ($count, @args) = @$proto; |
1125 | $leak_guard .= qq< |
1126 | if (\@_ == $count) { |
1127 | return $call(@args); |
1128 | } |
1129 | >; |
1130 | } |
1131 | |
1132 | $leak_guard .= qq< croak "Internal error in Fatal/autodie. Leak-guard failure"; } >; |
1133 | |
1134 | # warn "$leak_guard\n"; |
1135 | |
9b657a62 |
1136 | my $E; |
1137 | { |
1138 | local $@; |
1139 | |
1140 | $leak_guard = eval $leak_guard; ## no critic |
0b09a93a |
1141 | |
9b657a62 |
1142 | $E = $@; |
1143 | } |
0b09a93a |
1144 | |
9b657a62 |
1145 | die "Internal error in $class: Leak-guard installation failure: $E" if $E; |
0b09a93a |
1146 | } |
1147 | |
9b657a62 |
1148 | my $installed_sub = $leak_guard || $code; |
1149 | |
1150 | $class->_install_subs($pkg, { $name => $installed_sub }); |
1151 | |
1152 | $Cached_fatalised_sub{$class}{$sub}{$void}{$lexical} = $installed_sub; |
1153 | |
1154 | # Cache that we've now overriddent this sub. If we get called |
1155 | # again, we may need to find that find subroutine again (eg, for hints). |
0b09a93a |
1156 | |
9b657a62 |
1157 | $Is_fatalised_sub{$installed_sub} = $sref; |
0b09a93a |
1158 | |
1159 | return $sref; |
1160 | |
1161 | } |
1162 | |
1163 | # This subroutine exists primarily so that child classes can override |
1164 | # it to point to their own exception class. Doing this is significantly |
1165 | # less complex than overriding throw() |
1166 | |
1167 | sub exception_class { return "autodie::exception" }; |
1168 | |
1169 | { |
1170 | my %exception_class_for; |
1171 | my %class_loaded; |
1172 | |
1173 | sub throw { |
1174 | my ($class, @args) = @_; |
1175 | |
1176 | # Find our exception class if we need it. |
1177 | my $exception_class = |
1178 | $exception_class_for{$class} ||= $class->exception_class; |
1179 | |
1180 | if (not $class_loaded{$exception_class}) { |
1181 | if ($exception_class =~ /[^\w:']/) { |
1182 | confess "Bad exception class '$exception_class'.\nThe '$class->exception_class' method wants to use $exception_class\nfor exceptions, but it contains characters which are not word-characters or colons."; |
1183 | } |
1184 | |
1185 | # Alas, Perl does turn barewords into modules unless they're |
1186 | # actually barewords. As such, we're left doing a string eval |
1187 | # to make sure we load our file correctly. |
1188 | |
1189 | my $E; |
1190 | |
1191 | { |
1192 | local $@; # We can't clobber $@, it's wrong! |
1193 | eval "require $exception_class"; ## no critic |
1194 | $E = $@; # Save $E despite ending our local. |
1195 | } |
1196 | |
1197 | # We need quotes around $@ to make sure it's stringified |
1198 | # while still in scope. Without them, we run the risk of |
1199 | # $@ having been cleared by us exiting the local() block. |
1200 | |
1201 | confess "Failed to load '$exception_class'.\nThis may be a typo in the '$class->exception_class' method,\nor the '$exception_class' module may not exist.\n\n $E" if $E; |
1202 | |
1203 | $class_loaded{$exception_class}++; |
1204 | |
1205 | } |
1206 | |
1207 | return $exception_class->new(@args); |
2ba6ecf4 |
1208 | } |
e92e55da |
1209 | } |
1210 | |
0b09a93a |
1211 | # For some reason, dying while replacing our subs doesn't |
1212 | # kill our calling program. It simply stops the loading of |
1213 | # autodie and keeps going with everything else. The _autocroak |
1214 | # sub allows us to die with a vegence. It should *only* ever be |
1215 | # used for serious internal errors, since the results of it can't |
1216 | # be captured. |
1217 | |
1218 | sub _autocroak { |
1219 | warn Carp::longmess(@_); |
1220 | exit(255); # Ugh! |
1221 | } |
1222 | |
1223 | package autodie::Scope::Guard; |
1224 | |
1225 | # This code schedules the cleanup of subroutines at the end of |
1226 | # scope. It's directly inspired by chocolateboy's excellent |
1227 | # Scope::Guard module. |
1228 | |
1229 | sub new { |
1230 | my ($class, $handler) = @_; |
1231 | |
1232 | return bless $handler, $class; |
1233 | } |
1234 | |
1235 | sub DESTROY { |
1236 | my ($self) = @_; |
1237 | |
1238 | $self->(); |
1239 | } |
1240 | |
e92e55da |
1241 | 1; |
1242 | |
1243 | __END__ |
1244 | |
1245 | =head1 NAME |
1246 | |
0b09a93a |
1247 | Fatal - Replace functions with equivalents which succeed or die |
e92e55da |
1248 | |
1249 | =head1 SYNOPSIS |
1250 | |
1251 | use Fatal qw(open close); |
1252 | |
0b09a93a |
1253 | open(my $fh, "<", $filename); # No need to check errors! |
1254 | |
1255 | use File::Copy qw(move); |
1256 | use Fatal qw(move); |
1257 | |
1258 | move($file1, $file2); # No need to check errors! |
1259 | |
e92e55da |
1260 | sub juggle { . . . } |
0b09a93a |
1261 | Fatal->import('juggle'); |
1262 | |
1263 | =head1 BEST PRACTICE |
1264 | |
1265 | B<Fatal has been obsoleted by the new L<autodie> pragma.> Please use |
1266 | L<autodie> in preference to C<Fatal>. L<autodie> supports lexical scoping, |
1267 | throws real exception objects, and provides much nicer error messages. |
1268 | |
1269 | The use of C<:void> with Fatal is discouraged. |
e92e55da |
1270 | |
1271 | =head1 DESCRIPTION |
1272 | |
0b09a93a |
1273 | C<Fatal> provides a way to conveniently replace |
1274 | functions which normally return a false value when they fail with |
1275 | equivalents which raise exceptions if they are not successful. This |
1276 | lets you use these functions without having to test their return |
1277 | values explicitly on each call. Exceptions can be caught using |
1278 | C<eval{}>. See L<perlfunc> and L<perlvar> for details. |
e92e55da |
1279 | |
1280 | The do-or-die equivalents are set up simply by calling Fatal's |
1281 | C<import> routine, passing it the names of the functions to be |
1282 | replaced. You may wrap both user-defined functions and overridable |
0b09a93a |
1283 | CORE operators (except C<exec>, C<system>, C<print>, or any other |
1284 | built-in that cannot be expressed via prototypes) in this way. |
e92e55da |
1285 | |
91c7a880 |
1286 | If the symbol C<:void> appears in the import list, then functions |
1287 | named later in that import list raise an exception only when |
1288 | these are called in void context--that is, when their return |
1289 | values are ignored. For example |
1290 | |
0b09a93a |
1291 | use Fatal qw/:void open close/; |
91c7a880 |
1292 | |
0b09a93a |
1293 | # properly checked, so no exception raised on error |
9b657a62 |
1294 | if (not open(my $fh, '<', '/bogotic') { |
0b09a93a |
1295 | warn "Can't open /bogotic: $!"; |
1296 | } |
91c7a880 |
1297 | |
0b09a93a |
1298 | # not checked, so error raises an exception |
1299 | close FH; |
1300 | |
1301 | The use of C<:void> is discouraged, as it can result in exceptions |
1302 | not being thrown if you I<accidentally> call a method without |
1303 | void context. Use L<autodie> instead if you need to be able to |
1304 | disable autodying/Fatal behaviour for a small block of code. |
1305 | |
1306 | =head1 DIAGNOSTICS |
1307 | |
1308 | =over 4 |
1309 | |
1310 | =item Bad subroutine name for Fatal: %s |
1311 | |
1312 | You've called C<Fatal> with an argument that doesn't look like |
1313 | a subroutine name, nor a switch that this version of Fatal |
1314 | understands. |
1315 | |
1316 | =item %s is not a Perl subroutine |
1317 | |
1318 | You've asked C<Fatal> to try and replace a subroutine which does not |
1319 | exist, or has not yet been defined. |
1320 | |
1321 | =item %s is neither a builtin, nor a Perl subroutine |
1322 | |
1323 | You've asked C<Fatal> to replace a subroutine, but it's not a Perl |
1324 | built-in, and C<Fatal> couldn't find it as a regular subroutine. |
1325 | It either doesn't exist or has not yet been defined. |
1326 | |
1327 | =item Cannot make the non-overridable %s fatal |
1328 | |
1329 | You've tried to use C<Fatal> on a Perl built-in that can't be |
1330 | overridden, such as C<print> or C<system>, which means that |
1331 | C<Fatal> can't help you, although some other modules might. |
1332 | See the L</"SEE ALSO"> section of this documentation. |
1333 | |
1334 | =item Internal error: %s |
1335 | |
1336 | You've found a bug in C<Fatal>. Please report it using |
1337 | the C<perlbug> command. |
1338 | |
1339 | =back |
91c7a880 |
1340 | |
a6fd7f3f |
1341 | =head1 BUGS |
1342 | |
0b09a93a |
1343 | C<Fatal> clobbers the context in which a function is called and always |
1344 | makes it a scalar context, except when the C<:void> tag is used. |
1345 | This problem does not exist in L<autodie>. |
a6fd7f3f |
1346 | |
3776a202 |
1347 | "Used only once" warnings can be generated when C<autodie> or C<Fatal> |
1348 | is used with package filehandles (eg, C<FILE>). It's strongly recommended |
1349 | you use scalar filehandles instead. |
1350 | |
e92e55da |
1351 | =head1 AUTHOR |
1352 | |
0b09a93a |
1353 | Original module by Lionel Cons (CERN). |
e92e55da |
1354 | |
10af26ed |
1355 | Prototype updates by Ilya Zakharevich <ilya@math.ohio-state.edu>. |
e92e55da |
1356 | |
0b09a93a |
1357 | L<autodie> support, bugfixes, extended diagnostics, C<system> |
1358 | support, and major overhauling by Paul Fenwick <pjf@perltraining.com.au> |
1359 | |
1360 | =head1 LICENSE |
1361 | |
1362 | This module is free software, you may distribute it under the |
1363 | same terms as Perl itself. |
1364 | |
1365 | =head1 SEE ALSO |
1366 | |
1367 | L<autodie> for a nicer way to use lexical Fatal. |
1368 | |
1369 | L<IPC::System::Simple> for a similar idea for calls to C<system()> |
1370 | and backticks. |
1371 | |
e92e55da |
1372 | =cut |