source: for-distributions/trunk/bin/windows/perl/lib/diagnostics.pm@ 14489

Last change on this file since 14489 was 14489, checked in by oranfry, 17 years ago

upgrading to perl 5.8
File size: 16.9 KB
Line 
1package diagnostics;
2
3=head1 NAME
4
5diagnostics, splain - produce verbose warning diagnostics
6
7=head1 SYNOPSIS
8
9Using the C<diagnostics> pragma:
10
11 use diagnostics;
12 use diagnostics -verbose;
13
14 enable diagnostics;
15 disable diagnostics;
16
17Using the C<splain> standalone filter program:
18
19 perl program 2>diag.out
20 splain [-v] [-p] diag.out
21
22Using diagnostics to get stack traces from a misbehaving script:
23
24 perl -Mdiagnostics=-traceonly my_script.pl
25
26=head1 DESCRIPTION
27
28=head2 The C<diagnostics> Pragma
29
30This module extends the terse diagnostics normally emitted by both the
31perl compiler and the perl interpreter (from running perl with a -w
32switch or C<use warnings>), augmenting them with the more
33explicative and endearing descriptions found in L<perldiag>. Like the
34other pragmata, it affects the compilation phase of your program rather
35than merely the execution phase.
36
37To use in your program as a pragma, merely invoke
38
39 use diagnostics;
40
41at the start (or near the start) of your program. (Note
42that this I<does> enable perl's B<-w> flag.) Your whole
43compilation will then be subject(ed :-) to the enhanced diagnostics.
44These still go out B<STDERR>.
45
46Due to the interaction between runtime and compiletime issues,
47and because it's probably not a very good idea anyway,
48you may not use C<no diagnostics> to turn them off at compiletime.
49However, you may control their behaviour at runtime using the
50disable() and enable() methods to turn them off and on respectively.
51
52The B<-verbose> flag first prints out the L<perldiag> introduction before
53any other diagnostics. The $diagnostics::PRETTY variable can generate nicer
54escape sequences for pagers.
55
56Warnings dispatched from perl itself (or more accurately, those that match
57descriptions found in L<perldiag>) are only displayed once (no duplicate
58descriptions). User code generated warnings a la warn() are unaffected,
59allowing duplicate user messages to be displayed.
60
61This module also adds a stack trace to the error message when perl dies.
62This is useful for pinpointing what caused the death. The B<-traceonly> (or
63just B<-t>) flag turns off the explanations of warning messages leaving just
64the stack traces. So if your script is dieing, run it again with
65
66 perl -Mdiagnostics=-traceonly my_bad_script
67
68to see the call stack at the time of death. By supplying the B<-warntrace>
69(or just B<-w>) flag, any warnings emitted will also come with a stack
70trace.
71
72=head2 The I<splain> Program
73
74While apparently a whole nuther program, I<splain> is actually nothing
75more than a link to the (executable) F<diagnostics.pm> module, as well as
76a link to the F<diagnostics.pod> documentation. The B<-v> flag is like
77the C<use diagnostics -verbose> directive.
78The B<-p> flag is like the
79$diagnostics::PRETTY variable. Since you're post-processing with
80I<splain>, there's no sense in being able to enable() or disable() processing.
81
82Output from I<splain> is directed to B<STDOUT>, unlike the pragma.
83
84=head1 EXAMPLES
85
86The following file is certain to trigger a few errors at both
87runtime and compiletime:
88
89 use diagnostics;
90 print NOWHERE "nothing\n";
91 print STDERR "\n\tThis message should be unadorned.\n";
92 warn "\tThis is a user warning";
93 print "\nDIAGNOSTIC TESTER: Please enter a <CR> here: ";
94 my $a, $b = scalar <STDIN>;
95 print "\n";
96 print $x/$y;
97
98If you prefer to run your program first and look at its problem
99afterwards, do this:
100
101 perl -w test.pl 2>test.out
102 ./splain < test.out
103
104Note that this is not in general possible in shells of more dubious heritage,
105as the theoretical
106
107 (perl -w test.pl >/dev/tty) >& test.out
108 ./splain < test.out
109
110Because you just moved the existing B<stdout> to somewhere else.
111
112If you don't want to modify your source code, but still have on-the-fly
113warnings, do this:
114
115 exec 3>&1; perl -w test.pl 2>&1 1>&3 3>&- | splain 1>&2 3>&-
116
117Nifty, eh?
118
119If you want to control warnings on the fly, do something like this.
120Make sure you do the C<use> first, or you won't be able to get
121at the enable() or disable() methods.
122
123 use diagnostics; # checks entire compilation phase
124 print "\ntime for 1st bogus diags: SQUAWKINGS\n";
125 print BOGUS1 'nada';
126 print "done with 1st bogus\n";
127
128 disable diagnostics; # only turns off runtime warnings
129 print "\ntime for 2nd bogus: (squelched)\n";
130 print BOGUS2 'nada';
131 print "done with 2nd bogus\n";
132
133 enable diagnostics; # turns back on runtime warnings
134 print "\ntime for 3rd bogus: SQUAWKINGS\n";
135 print BOGUS3 'nada';
136 print "done with 3rd bogus\n";
137
138 disable diagnostics;
139 print "\ntime for 4th bogus: (squelched)\n";
140 print BOGUS4 'nada';
141 print "done with 4th bogus\n";
142
143=head1 INTERNALS
144
145Diagnostic messages derive from the F<perldiag.pod> file when available at
146runtime. Otherwise, they may be embedded in the file itself when the
147splain package is built. See the F<Makefile> for details.
148
149If an extant $SIG{__WARN__} handler is discovered, it will continue
150to be honored, but only after the diagnostics::splainthis() function
151(the module's $SIG{__WARN__} interceptor) has had its way with your
152warnings.
153
154There is a $diagnostics::DEBUG variable you may set if you're desperately
155curious what sorts of things are being intercepted.
156
157 BEGIN { $diagnostics::DEBUG = 1 }
158
159
160=head1 BUGS
161
162Not being able to say "no diagnostics" is annoying, but may not be
163insurmountable.
164
165The C<-pretty> directive is called too late to affect matters.
166You have to do this instead, and I<before> you load the module.
167
168 BEGIN { $diagnostics::PRETTY = 1 }
169
170I could start up faster by delaying compilation until it should be
171needed, but this gets a "panic: top_level" when using the pragma form
172in Perl 5.001e.
173
174While it's true that this documentation is somewhat subserious, if you use
175a program named I<splain>, you should expect a bit of whimsy.
176
177=head1 AUTHOR
178
179Tom Christiansen <F<[email protected]>>, 25 June 1995.
180
181=cut
182
183use strict;
184use 5.006;
185use Carp;
186$Carp::Internal{__PACKAGE__.""}++;
187
188our $VERSION = 1.15;
189our $DEBUG;
190our $VERBOSE;
191our $PRETTY;
192our $TRACEONLY = 0;
193our $WARNTRACE = 0;
194
195use Config;
196my($privlib, $archlib) = @Config{qw(privlibexp archlibexp)};
197if ($^O eq 'VMS') {
198 require VMS::Filespec;
199 $privlib = VMS::Filespec::unixify($privlib);
200 $archlib = VMS::Filespec::unixify($archlib);
201}
202my @trypod = (
203 "$archlib/pod/perldiag.pod",
204 "$privlib/pod/perldiag-$Config{version}.pod",
205 "$privlib/pod/perldiag.pod",
206 "$archlib/pods/perldiag.pod",
207 "$privlib/pods/perldiag-$Config{version}.pod",
208 "$privlib/pods/perldiag.pod",
209 );
210# handy for development testing of new warnings etc
211unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod";
212(my $PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0];
213
214if ($^O eq 'MacOS') {
215 # just updir one from each lib dir, we'll find it ...
216 ($PODFILE) = grep { -e } map { "$_:pod:perldiag.pod" } @INC;
217}
218
219
220$DEBUG ||= 0;
221my $WHOAMI = ref bless []; # nobody's business, prolly not even mine
222
223local $| = 1;
224local $_;
225
226my $standalone;
227my(%HTML_2_Troff, %HTML_2_Latin_1, %HTML_2_ASCII_7);
228
229CONFIG: {
230 our $opt_p = our $opt_d = our $opt_v = our $opt_f = '';
231
232 unless (caller) {
233 $standalone++;
234 require Getopt::Std;
235 Getopt::Std::getopts('pdvf:')
236 or die "Usage: $0 [-v] [-p] [-f splainpod]";
237 $PODFILE = $opt_f if $opt_f;
238 $DEBUG = 2 if $opt_d;
239 $VERBOSE = $opt_v;
240 $PRETTY = $opt_p;
241 }
242
243 if (open(POD_DIAG, $PODFILE)) {
244 warn "Happy happy podfile from real $PODFILE\n" if $DEBUG;
245 last CONFIG;
246 }
247
248 if (caller) {
249 INCPATH: {
250 for my $file ( (map { "$_/$WHOAMI.pm" } @INC), $0) {
251 warn "Checking $file\n" if $DEBUG;
252 if (open(POD_DIAG, $file)) {
253 while (<POD_DIAG>) {
254 next unless
255 /^__END__\s*# wish diag dbase were more accessible/;
256 print STDERR "podfile is $file\n" if $DEBUG;
257 last INCPATH;
258 }
259 }
260 }
261 }
262 } else {
263 print STDERR "podfile is <DATA>\n" if $DEBUG;
264 *POD_DIAG = *main::DATA;
265 }
266}
267if (eof(POD_DIAG)) {
268 die "couldn't find diagnostic data in $PODFILE @INC $0";
269}
270
271
272%HTML_2_Troff = (
273 'amp' => '&', # ampersand
274 'lt' => '<', # left chevron, less-than
275 'gt' => '>', # right chevron, greater-than
276 'quot' => '"', # double quote
277
278 "Aacute" => "A\\*'", # capital A, acute accent
279 # etc
280
281);
282
283%HTML_2_Latin_1 = (
284 'amp' => '&', # ampersand
285 'lt' => '<', # left chevron, less-than
286 'gt' => '>', # right chevron, greater-than
287 'quot' => '"', # double quote
288
289 "Aacute" => "\xC1" # capital A, acute accent
290
291 # etc
292);
293
294%HTML_2_ASCII_7 = (
295 'amp' => '&', # ampersand
296 'lt' => '<', # left chevron, less-than
297 'gt' => '>', # right chevron, greater-than
298 'quot' => '"', # double quote
299
300 "Aacute" => "A" # capital A, acute accent
301 # etc
302);
303
304our %HTML_Escapes;
305*HTML_Escapes = do {
306 if ($standalone) {
307 $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7;
308 } else {
309 \%HTML_2_Latin_1;
310 }
311};
312
313*THITHER = $standalone ? *STDOUT : *STDERR;
314
315my %transfmt = ();
316my $transmo = <<EOFUNC;
317sub transmo {
318 #local \$^W = 0; # recursive warnings we do NOT need!
319 study;
320EOFUNC
321
322my %msg;
323{
324 print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG;
325 local $/ = '';
326 local $_;
327 my $header;
328 my $for_item;
329 while (<POD_DIAG>) {
330
331 unescape();
332 if ($PRETTY) {
333 sub noop { return $_[0] } # spensive for a noop
334 sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; }
335 sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; }
336 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/bold($+)/ges;
337 s/[LIF]<(.*?)>/italic($1)/ges;
338 } else {
339 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/$+/gs;
340 s/[LIF]<(.*?)>/$1/gs;
341 }
342 unless (/^=/) {
343 if (defined $header) {
344 if ( $header eq 'DESCRIPTION' &&
345 ( /Optional warnings are enabled/
346 || /Some of these messages are generic./
347 ) )
348 {
349 next;
350 }
351 s/^/ /gm;
352 $msg{$header} .= $_;
353 undef $for_item;
354 }
355 next;
356 }
357 unless ( s/=item (.*?)\s*\z//) {
358
359 if ( s/=head1\sDESCRIPTION//) {
360 $msg{$header = 'DESCRIPTION'} = '';
361 undef $for_item;
362 }
363 elsif( s/^=for\s+diagnostics\s*\n(.*?)\s*\z// ) {
364 $for_item = $1;
365 }
366 next;
367 }
368
369 if( $for_item ) { $header = $for_item; undef $for_item }
370 else {
371 $header = $1;
372 while( $header =~ /[;,]\z/ ) {
373 <POD_DIAG> =~ /^\s*(.*?)\s*\z/;
374 $header .= ' '.$1;
375 }
376 }
377
378 # strip formatting directives from =item line
379 $header =~ s/[A-Z]<(.*?)>/$1/g;
380
381 my @toks = split( /(%l?[dx]|%c|%(?:\.\d+)?s)/, $header );
382 if (@toks > 1) {
383 my $conlen = 0;
384 for my $i (0..$#toks){
385 if( $i % 2 ){
386 if( $toks[$i] eq '%c' ){
387 $toks[$i] = '.';
388 } elsif( $toks[$i] eq '%d' ){
389 $toks[$i] = '\d+';
390 } elsif( $toks[$i] eq '%s' ){
391 $toks[$i] = $i == $#toks ? '.*' : '.*?';
392 } elsif( $toks[$i] =~ '%.(\d+)s' ){
393 $toks[$i] = ".{$1}";
394 } elsif( $toks[$i] =~ '^%l*x$' ){
395 $toks[$i] = '[\da-f]+';
396 }
397 } elsif( length( $toks[$i] ) ){
398 $toks[$i] =~ s/^.*$/\Q$&\E/;
399 $conlen += length( $toks[$i] );
400 }
401 }
402 my $lhs = join( '', @toks );
403 $transfmt{$header}{pat} =
404 " s{^$lhs}\n {\Q$header\E}s\n\t&& return 1;\n";
405 $transfmt{$header}{len} = $conlen;
406 } else {
407 $transfmt{$header}{pat} =
408 " m{^\Q$header\E} && return 1;\n";
409 $transfmt{$header}{len} = length( $header );
410 }
411
412 print STDERR "$WHOAMI: Duplicate entry: \"$header\"\n"
413 if $msg{$header};
414
415 $msg{$header} = '';
416 }
417
418
419 close POD_DIAG unless *main::DATA eq *POD_DIAG;
420
421 die "No diagnostics?" unless %msg;
422
423 # Apply patterns in order of decreasing sum of lengths of fixed parts
424 # Seems the best way of hitting the right one.
425 for my $hdr ( sort { $transfmt{$b}{len} <=> $transfmt{$a}{len} }
426 keys %transfmt ){
427 $transmo .= $transfmt{$hdr}{pat};
428 }
429 $transmo .= " return 0;\n}\n";
430 print STDERR $transmo if $DEBUG;
431 eval $transmo;
432 die $@ if $@;
433}
434
435if ($standalone) {
436 if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" }
437 while (defined (my $error = <>)) {
438 splainthis($error) || print THITHER $error;
439 }
440 exit;
441}
442
443my $olddie;
444my $oldwarn;
445
446sub import {
447 shift;
448 $^W = 1; # yup, clobbered the global variable;
449 # tough, if you want diags, you want diags.
450 return if defined $SIG{__WARN__} && ($SIG{__WARN__} eq \&warn_trap);
451
452 for (@_) {
453
454 /^-d(ebug)?$/ && do {
455 $DEBUG++;
456 next;
457 };
458
459 /^-v(erbose)?$/ && do {
460 $VERBOSE++;
461 next;
462 };
463
464 /^-p(retty)?$/ && do {
465 print STDERR "$0: I'm afraid it's too late for prettiness.\n";
466 $PRETTY++;
467 next;
468 };
469
470 /^-t(race)?$/ && do {
471 $TRACEONLY++;
472 next;
473 };
474 /^-w(arntrace)?$/ && do {
475 $WARNTRACE++;
476 next;
477 };
478
479 warn "Unknown flag: $_";
480 }
481
482 $oldwarn = $SIG{__WARN__};
483 $olddie = $SIG{__DIE__};
484 $SIG{__WARN__} = \&warn_trap;
485 $SIG{__DIE__} = \&death_trap;
486}
487
488sub enable { &import }
489
490sub disable {
491 shift;
492 return unless $SIG{__WARN__} eq \&warn_trap;
493 $SIG{__WARN__} = $oldwarn || '';
494 $SIG{__DIE__} = $olddie || '';
495}
496
497sub warn_trap {
498 my $warning = $_[0];
499 if (caller eq $WHOAMI or !splainthis($warning)) {
500 if ($WARNTRACE) {
501 print STDERR Carp::longmess($warning);
502 } else {
503 print STDERR $warning;
504 }
505 }
506 goto &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap;
507};
508
509sub death_trap {
510 my $exception = $_[0];
511
512 # See if we are coming from anywhere within an eval. If so we don't
513 # want to explain the exception because it's going to get caught.
514 my $in_eval = 0;
515 my $i = 0;
516 while (my $caller = (caller($i++))[3]) {
517 if ($caller eq '(eval)') {
518 $in_eval = 1;
519 last;
520 }
521 }
522
523 splainthis($exception) unless $in_eval;
524 if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; }
525 &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap;
526
527 return if $in_eval;
528
529 # We don't want to unset these if we're coming from an eval because
530 # then we've turned off diagnostics.
531
532 # Switch off our die/warn handlers so we don't wind up in our own
533 # traps.
534 $SIG{__DIE__} = $SIG{__WARN__} = '';
535
536 # Have carp skip over death_trap() when showing the stack trace.
537 local($Carp::CarpLevel) = 1;
538
539 confess "Uncaught exception from user code:\n\t$exception";
540 # up we go; where we stop, nobody knows, but i think we die now
541 # but i'm deeply afraid of the &$olddie guy reraising and us getting
542 # into an indirect recursion loop
543};
544
545my %exact_duplicate;
546my %old_diag;
547my $count;
548my $wantspace;
549sub splainthis {
550 return 0 if $TRACEONLY;
551 local $_ = shift;
552 local $\;
553 ### &finish_compilation unless %msg;
554 s/\.?\n+$//;
555 my $orig = $_;
556 # return unless defined;
557
558 # get rid of the where-are-we-in-input part
559 s/, <.*?> (?:line|chunk).*$//;
560
561 # Discard 1st " at <file> line <no>" and all text beyond
562 # but be aware of messsages containing " at this-or-that"
563 my $real = 0;
564 my @secs = split( / at / );
565 $_ = $secs[0];
566 for my $i ( 1..$#secs ){
567 if( $secs[$i] =~ /.+? (?:line|chunk) \d+/ ){
568 $real = 1;
569 last;
570 } else {
571 $_ .= ' at ' . $secs[$i];
572 }
573 }
574
575 # remove parenthesis occurring at the end of some messages
576 s/^\((.*)\)$/$1/;
577
578 if ($exact_duplicate{$orig}++) {
579 return &transmo;
580 } else {
581 return 0 unless &transmo;
582 }
583
584 $orig = shorten($orig);
585 if ($old_diag{$_}) {
586 autodescribe();
587 print THITHER "$orig (#$old_diag{$_})\n";
588 $wantspace = 1;
589 } else {
590 autodescribe();
591 $old_diag{$_} = ++$count;
592 print THITHER "\n" if $wantspace;
593 $wantspace = 0;
594 print THITHER "$orig (#$old_diag{$_})\n";
595 if ($msg{$_}) {
596 print THITHER $msg{$_};
597 } else {
598 if (0 and $standalone) {
599 print THITHER " **** Error #$old_diag{$_} ",
600 ($real ? "is" : "appears to be"),
601 " an unknown diagnostic message.\n\n";
602 }
603 return 0;
604 }
605 }
606 return 1;
607}
608
609sub autodescribe {
610 if ($VERBOSE and not $count) {
611 print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"),
612 "\n$msg{DESCRIPTION}\n";
613 }
614}
615
616sub unescape {
617 s {
618 E<
619 ( [A-Za-z]+ )
620 >
621 } {
622 do {
623 exists $HTML_Escapes{$1}
624 ? do { $HTML_Escapes{$1} }
625 : do {
626 warn "Unknown escape: E<$1> in $_";
627 "E<$1>";
628 }
629 }
630 }egx;
631}
632
633sub shorten {
634 my $line = $_[0];
635 if (length($line) > 79 and index($line, "\n") == -1) {
636 my $space_place = rindex($line, ' ', 79);
637 if ($space_place != -1) {
638 substr($line, $space_place, 1) = "\n\t";
639 }
640 }
641 return $line;
642}
643
644
6451 unless $standalone; # or it'll complain about itself
646__END__ # wish diag dbase were more accessible
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