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 diagnostics->enable; 15 diagnostics->disable; 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 50C<disable()> and C<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 $diagnostics::PRETTY variable can generate nicer 54escape sequences for pagers. 55 56Warnings dispatched from perl itself (or more accurately, those that match 57descriptions found in L<perldiag>) are only displayed once (no duplicate 58descriptions). User code generated warnings a la warn() are unaffected, 59allowing duplicate user messages to be displayed. 60 61This module also adds a stack trace to the error message when perl dies. 62This is useful for pinpointing what 63caused the death. The B<-traceonly> (or 64just B<-t>) flag turns off the explanations of warning messages leaving just 65the stack traces. So if your script is dieing, run it again with 66 67 perl -Mdiagnostics=-traceonly my_bad_script 68 69to see the call stack at the time of death. By supplying the B<-warntrace> 70(or just B<-w>) flag, any warnings emitted will also come with a stack 71trace. 72 73=head2 The I<splain> Program 74 75Another program, I<splain> is actually nothing 76more than a link to the (executable) F<diagnostics.pm> module, as well as 77a link to the F<diagnostics.pod> documentation. The B<-v> flag is like 78the C<use diagnostics -verbose> directive. 79The B<-p> flag is like the 80$diagnostics::PRETTY variable. Since you're post-processing with 81I<splain>, there's no sense in being able to enable() or disable() processing. 82 83Output from I<splain> is directed to B<STDOUT>, unlike the pragma. 84 85=head1 EXAMPLES 86 87The following file is certain to trigger a few errors at both 88runtime and compiletime: 89 90 use diagnostics; 91 print NOWHERE "nothing\n"; 92 print STDERR "\n\tThis message should be unadorned.\n"; 93 warn "\tThis is a user warning"; 94 print "\nDIAGNOSTIC TESTER: Please enter a <CR> here: "; 95 my $a, $b = scalar <STDIN>; 96 print "\n"; 97 print $x/$y; 98 99If you prefer to run your program first and look at its problem 100afterwards, do this: 101 102 perl -w test.pl 2>test.out 103 ./splain < test.out 104 105Note that this is not in general possible in shells of more dubious heritage, 106as the theoretical 107 108 (perl -w test.pl >/dev/tty) >& test.out 109 ./splain < test.out 110 111Because you just moved the existing B<stdout> to somewhere else. 112 113If you don't want to modify your source code, but still have on-the-fly 114warnings, do this: 115 116 exec 3>&1; perl -w test.pl 2>&1 1>&3 3>&- | splain 1>&2 3>&- 117 118Nifty, eh? 119 120If you want to control warnings on the fly, do something like this. 121Make sure you do the C<use> first, or you won't be able to get 122at the enable() or disable() methods. 123 124 use diagnostics; # checks entire compilation phase 125 print "\ntime for 1st bogus diags: SQUAWKINGS\n"; 126 print BOGUS1 'nada'; 127 print "done with 1st bogus\n"; 128 129 diagnostics->disable; # only turns off runtime warnings 130 print "\ntime for 2nd bogus: (squelched)\n"; 131 print BOGUS2 'nada'; 132 print "done with 2nd bogus\n"; 133 134 diagnostics->enable; # turns back on runtime warnings 135 print "\ntime for 3rd bogus: SQUAWKINGS\n"; 136 print BOGUS3 'nada'; 137 print "done with 3rd bogus\n"; 138 139 diagnostics->disable; 140 print "\ntime for 4th bogus: (squelched)\n"; 141 print BOGUS4 'nada'; 142 print "done with 4th bogus\n"; 143 144=head1 INTERNALS 145 146Diagnostic messages derive from the F<perldiag.pod> file when available at 147runtime. Otherwise, they may be embedded in the file itself when the 148splain package is built. See the F<Makefile> for details. 149 150If an extant $SIG{__WARN__} handler is discovered, it will continue 151to be honored, but only after the diagnostics::splainthis() function 152(the module's $SIG{__WARN__} interceptor) has had its way with your 153warnings. 154 155There is a $diagnostics::DEBUG variable you may set if you're desperately 156curious what sorts of things are being intercepted. 157 158 BEGIN { $diagnostics::DEBUG = 1 } 159 160 161=head1 BUGS 162 163Not being able to say "no diagnostics" is annoying, but may not be 164insurmountable. 165 166The C<-pretty> directive is called too late to affect matters. 167You have to do this instead, and I<before> you load the module. 168 169 BEGIN { $diagnostics::PRETTY = 1 } 170 171I could start up faster by delaying compilation until it should be 172needed, but this gets a "panic: top_level" when using the pragma form 173in Perl 5.001e. 174 175While it's true that this documentation is somewhat subserious, if you use 176a program named I<splain>, you should expect a bit of whimsy. 177 178=head1 AUTHOR 179 180Tom Christiansen <F<tchrist@mox.perl.com>>, 25 June 1995. 181 182=cut 183 184use strict; 185use 5.009001; 186use Carp; 187$Carp::Internal{__PACKAGE__.""}++; 188 189our $VERSION = '1.40'; 190our $DEBUG; 191our $VERBOSE; 192our $PRETTY; 193our $TRACEONLY = 0; 194our $WARNTRACE = 0; 195 196use Config; 197use Text::Tabs 'expand'; 198my $privlib = $Config{privlibexp}; 199if ($^O eq 'VMS') { 200 require VMS::Filespec; 201 $privlib = VMS::Filespec::unixify($privlib); 202} 203my @trypod = ( 204 "$privlib/pod/perldiag.pod", 205 "$privlib/pods/perldiag.pod", 206 ); 207# handy for development testing of new warnings etc 208unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod"; 209(my $PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0]; 210 211$DEBUG ||= 0; 212 213local $| = 1; 214local $_; 215local $.; 216 217my $standalone; 218my(%HTML_2_Troff, %HTML_2_Latin_1, %HTML_2_ASCII_7); 219 220CONFIG: { 221 our $opt_p = our $opt_d = our $opt_v = our $opt_f = ''; 222 223 unless (caller) { 224 $standalone++; 225 require Getopt::Std; 226 Getopt::Std::getopts('pdvf:') 227 or die "Usage: $0 [-v] [-p] [-f splainpod]"; 228 $PODFILE = $opt_f if $opt_f; 229 $DEBUG = 2 if $opt_d; 230 $VERBOSE = $opt_v; 231 $PRETTY = $opt_p; 232 } 233 234 if (open(POD_DIAG, '<', $PODFILE)) { 235 warn "Happy happy podfile from real $PODFILE\n" if $DEBUG; 236 last CONFIG; 237 } 238 239 if (caller) { 240 INCPATH: { 241 for my $file ( (map { "$_/".__PACKAGE__.".pm" } @INC), $0) { 242 warn "Checking $file\n" if $DEBUG; 243 if (open(POD_DIAG, '<', $file)) { 244 while (<POD_DIAG>) { 245 next unless 246 /^__END__\s*# wish diag dbase were more accessible/; 247 print STDERR "podfile is $file\n" if $DEBUG; 248 last INCPATH; 249 } 250 } 251 } 252 } 253 } else { 254 print STDERR "podfile is <DATA>\n" if $DEBUG; 255 *POD_DIAG = *main::DATA; 256 } 257} 258if (eof(POD_DIAG)) { 259 die "couldn't find diagnostic data in $PODFILE @INC $0"; 260} 261 262 263%HTML_2_Troff = ( 264 'amp' => '&', # ampersand 265 'lt' => '<', # left chevron, less-than 266 'gt' => '>', # right chevron, greater-than 267 'quot' => '"', # double quote 268 'sol' => '/', # forward slash / solidus 269 'verbar' => '|', # vertical bar 270 271 "Aacute" => "A\\*'", # capital A, acute accent 272 # etc 273 274); 275 276%HTML_2_Latin_1 = ( 277 'amp' => '&', # ampersand 278 'lt' => '<', # left chevron, less-than 279 'gt' => '>', # right chevron, greater-than 280 'quot' => '"', # double quote 281 'sol' => '/', # Forward slash / solidus 282 'verbar' => '|', # vertical bar 283 284 # # capital A, acute accent 285 "Aacute" => chr utf8::unicode_to_native(0xC1) 286 287 # etc 288); 289 290%HTML_2_ASCII_7 = ( 291 'amp' => '&', # ampersand 292 'lt' => '<', # left chevron, less-than 293 'gt' => '>', # right chevron, greater-than 294 'quot' => '"', # double quote 295 'sol' => '/', # Forward slash / solidus 296 'verbar' => '|', # vertical bar 297 298 "Aacute" => "A" # capital A, acute accent 299 # etc 300); 301 302our %HTML_Escapes; 303*HTML_Escapes = do { 304 if ($standalone) { 305 $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7; 306 } else { 307 \%HTML_2_Latin_1; 308 } 309}; 310 311*THITHER = $standalone ? *STDOUT : *STDERR; 312 313my %transfmt = (); 314my $transmo = <<EOFUNC; 315sub transmo { 316 #local \$^W = 0; # recursive warnings we do NOT need! 317EOFUNC 318 319my %msg; 320my $over_level = 0; # We look only at =item lines at the first =over level 321{ 322 print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG; 323 local $/ = ''; 324 local $_; 325 my $header; 326 my @headers; 327 my $for_item; 328 my $seen_body; 329 while (<POD_DIAG>) { 330 331 sub _split_pod_link { 332 $_[0] =~ m'(?:([^|]*)\|)?([^/]*)(?:/("?)(.*)\3)?'s; 333 ($1,$2,$4); 334 } 335 336 unescape(); 337 if ($PRETTY) { 338 sub noop { return $_[0] } # spensive for a noop 339 sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; } 340 sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; } 341 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/bold($+)/ges; 342 s/[IF]<(.*?)>/italic($1)/ges; 343 s/L<(.*?)>/ 344 my($text,$page,$sect) = _split_pod_link($1); 345 defined $text 346 ? $text 347 : defined $sect 348 ? italic($sect) . ' in ' . italic($page) 349 : italic($page) 350 /ges; 351 s/S<(.*?)>/ 352 $1 353 /ges; 354 } else { 355 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/$+/gs; 356 s/[IF]<(.*?)>/$1/gs; 357 s/L<(.*?)>/ 358 my($text,$page,$sect) = _split_pod_link($1); 359 defined $text 360 ? $text 361 : defined $sect 362 ? qq '"$sect" in $page' 363 : $page 364 /ges; 365 s/S<(.*?)>/ 366 $1 367 /ges; 368 } 369 unless (/^=/) { 370 if (defined $header) { 371 if ( $header eq 'DESCRIPTION' && 372 ( /Optional warnings are enabled/ 373 || /Some of these messages are generic./ 374 ) ) 375 { 376 next; 377 } 378 $_ = expand $_; 379 s/^/ /gm; 380 $msg{$header} .= $_; 381 for my $h(@headers) { $msg{$h} .= $_ } 382 ++$seen_body; 383 undef $for_item; 384 } 385 next; 386 } 387 388 # If we have not come across the body of the description yet, then 389 # the previous header needs to share the same description. 390 if ($seen_body) { 391 @headers = (); 392 } 393 else { 394 push @headers, $header if defined $header; 395 } 396 397 if ( ! s/=item (.*?)\s*\z//s || $over_level != 1) { 398 399 if ( s/=head1\sDESCRIPTION//) { 400 $msg{$header = 'DESCRIPTION'} = ''; 401 undef $for_item; 402 } 403 elsif( s/^=for\s+diagnostics\s*\n(.*?)\s*\z// ) { 404 $for_item = $1; 405 } 406 elsif( /^=over\b/ ) { 407 $over_level++; 408 } 409 elsif( /^=back\b/ ) { # Stop processing body here 410 $over_level--; 411 if ($over_level == 0) { 412 undef $header; 413 undef $for_item; 414 $seen_body = 0; 415 next; 416 } 417 } 418 next; 419 } 420 421 if( $for_item ) { $header = $for_item; undef $for_item } 422 else { 423 $header = $1; 424 425 $header =~ s/\n/ /gs; # Allow multi-line headers 426 } 427 428 # strip formatting directives from =item line 429 $header =~ s/[A-Z]<(.*?)>/$1/g; 430 431 # Since we strip "(\.\s*)\n" when we search a warning, strip it here as well 432 $header =~ s/(\.\s*)?$//; 433 434 my @toks = split( /(%l?[dxX]|%[ucp]|%(?:\.\d+)?[fs])/, $header ); 435 if (@toks > 1) { 436 my $conlen = 0; 437 for my $i (0..$#toks){ 438 if( $i % 2 ){ 439 if( $toks[$i] eq '%c' ){ 440 $toks[$i] = '.'; 441 } elsif( $toks[$i] =~ /^%(?:d|u)$/ ){ 442 $toks[$i] = '\d+'; 443 } elsif( $toks[$i] =~ '^%(?:s|.*f)$' ){ 444 $toks[$i] = $i == $#toks ? '.*' : '.*?'; 445 } elsif( $toks[$i] =~ '%.(\d+)s' ){ 446 $toks[$i] = ".{$1}"; 447 } elsif( $toks[$i] =~ '^%l*([pxX])$' ){ 448 $toks[$i] = $1 eq 'X' ? '[\dA-F]+' : '[\da-f]+'; 449 } 450 } elsif( length( $toks[$i] ) ){ 451 $toks[$i] = quotemeta $toks[$i]; 452 $conlen += length( $toks[$i] ); 453 } 454 } 455 my $lhs = join( '', @toks ); 456 $lhs =~ s/(\\\s)+/\\s+/g; # Replace lit space with multi-space match 457 $transfmt{$header}{pat} = 458 " s^\\s*$lhs\\s*\Q$header\Es\n\t&& return 1;\n"; 459 $transfmt{$header}{len} = $conlen; 460 } else { 461 my $lhs = "\Q$header\E"; 462 $lhs =~ s/(\\\s)+/\\s+/g; # Replace lit space with multi-space match 463 $transfmt{$header}{pat} = 464 " s^\\s*$lhs\\s*\Q$header\E\n\t && return 1;\n"; 465 $transfmt{$header}{len} = length( $header ); 466 } 467 468 print STDERR __PACKAGE__.": Duplicate entry: \"$header\"\n" 469 if $msg{$header}; 470 471 $msg{$header} = ''; 472 $seen_body = 0; 473 } 474 475 476 close POD_DIAG unless *main::DATA eq *POD_DIAG; 477 478 die "No diagnostics?" unless %msg; 479 480 # Apply patterns in order of decreasing sum of lengths of fixed parts 481 # Seems the best way of hitting the right one. 482 for my $hdr ( sort { $transfmt{$b}{len} <=> $transfmt{$a}{len} } 483 keys %transfmt ){ 484 $transmo .= $transfmt{$hdr}{pat}; 485 } 486 $transmo .= " return 0;\n}\n"; 487 print STDERR $transmo if $DEBUG; 488 eval $transmo; 489 die $@ if $@; 490} 491 492if ($standalone) { 493 if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" } 494 while (defined (my $error = <>)) { 495 splainthis($error) || print THITHER $error; 496 } 497 exit; 498} 499 500my $olddie; 501my $oldwarn; 502 503sub import { 504 shift; 505 $^W = 1; # yup, clobbered the global variable; 506 # tough, if you want diags, you want diags. 507 return if defined $SIG{__WARN__} && ($SIG{__WARN__} eq \&warn_trap); 508 509 for (@_) { 510 511 /^-d(ebug)?$/ && do { 512 $DEBUG++; 513 next; 514 }; 515 516 /^-v(erbose)?$/ && do { 517 $VERBOSE++; 518 next; 519 }; 520 521 /^-p(retty)?$/ && do { 522 print STDERR "$0: I'm afraid it's too late for prettiness.\n"; 523 $PRETTY++; 524 next; 525 }; 526 # matches trace and traceonly for legacy doc mixup reasons 527 /^-t(race(only)?)?$/ && do { 528 $TRACEONLY++; 529 next; 530 }; 531 /^-w(arntrace)?$/ && do { 532 $WARNTRACE++; 533 next; 534 }; 535 536 warn "Unknown flag: $_"; 537 } 538 539 $oldwarn = $SIG{__WARN__}; 540 $olddie = $SIG{__DIE__}; 541 $SIG{__WARN__} = \&warn_trap; 542 $SIG{__DIE__} = \&death_trap; 543} 544 545sub enable { &import } 546 547sub disable { 548 shift; 549 return unless $SIG{__WARN__} eq \&warn_trap; 550 $SIG{__WARN__} = $oldwarn || ''; 551 $SIG{__DIE__} = $olddie || ''; 552} 553 554sub warn_trap { 555 my $warning = $_[0]; 556 if (caller eq __PACKAGE__ or !splainthis($warning)) { 557 if ($WARNTRACE) { 558 print STDERR Carp::longmess($warning); 559 } else { 560 print STDERR $warning; 561 } 562 } 563 goto &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap; 564}; 565 566sub death_trap { 567 my $exception = $_[0]; 568 569 # See if we are coming from anywhere within an eval. If so we don't 570 # want to explain the exception because it's going to get caught. 571 my $in_eval = 0; 572 my $i = 0; 573 while (my $caller = (caller($i++))[3]) { 574 if ($caller eq '(eval)') { 575 $in_eval = 1; 576 last; 577 } 578 } 579 580 splainthis($exception) unless $in_eval; 581 if (caller eq __PACKAGE__) { 582 print STDERR "INTERNAL EXCEPTION: $exception"; 583 } 584 &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap; 585 586 return if $in_eval; 587 588 # We don't want to unset these if we're coming from an eval because 589 # then we've turned off diagnostics. 590 591 # Switch off our die/warn handlers so we don't wind up in our own 592 # traps. 593 $SIG{__DIE__} = $SIG{__WARN__} = ''; 594 595 $exception =~ s/\n(?=.)/\n\t/gas; 596 597 die Carp::longmess("__diagnostics__") 598 =~ s/^__diagnostics__.*?line \d+\.?\n/ 599 "Uncaught exception from user code:\n\t$exception" 600 /re; 601 # up we go; where we stop, nobody knows, but i think we die now 602 # but i'm deeply afraid of the &$olddie guy reraising and us getting 603 # into an indirect recursion loop 604}; 605 606my %exact_duplicate; 607my %old_diag; 608my $count; 609my $wantspace; 610sub splainthis { 611 return 0 if $TRACEONLY; 612 for (my $tmp = shift) { 613 local $\; 614 local $!; 615 ### &finish_compilation unless %msg; 616 s/(\.\s*)?\n+$//; 617 my $orig = $_; 618 # return unless defined; 619 620 # get rid of the where-are-we-in-input part 621 s/, <.*?> (?:line|chunk).*$//; 622 623 # Discard 1st " at <file> line <no>" and all text beyond 624 # but be aware of messages containing " at this-or-that" 625 my $real = 0; 626 my @secs = split( / at / ); 627 return unless @secs; 628 $_ = $secs[0]; 629 for my $i ( 1..$#secs ){ 630 if( $secs[$i] =~ /.+? (?:line|chunk) \d+/ ){ 631 $real = 1; 632 last; 633 } else { 634 $_ .= ' at ' . $secs[$i]; 635 } 636 } 637 638 # remove parenthesis occurring at the end of some messages 639 s/^\((.*)\)$/$1/; 640 641 if ($exact_duplicate{$orig}++) { 642 return &transmo; 643 } else { 644 return 0 unless &transmo; 645 } 646 647 my $short = shorten($orig); 648 if ($old_diag{$_}) { 649 autodescribe(); 650 print THITHER "$short (#$old_diag{$_})\n"; 651 $wantspace = 1; 652 } elsif (!$msg{$_} && $orig =~ /\n./s) { 653 # A multiline message, like "Attempt to reload / 654 # Compilation failed" 655 my $found; 656 for (split /^/, $orig) { 657 splainthis($_) and $found = 1; 658 } 659 return $found; 660 } else { 661 autodescribe(); 662 $old_diag{$_} = ++$count; 663 print THITHER "\n" if $wantspace; 664 $wantspace = 0; 665 print THITHER "$short (#$old_diag{$_})\n"; 666 if ($msg{$_}) { 667 print THITHER $msg{$_}; 668 } else { 669 if (0 and $standalone) { 670 print THITHER " **** Error #$old_diag{$_} ", 671 ($real ? "is" : "appears to be"), 672 " an unknown diagnostic message.\n\n"; 673 } 674 return 0; 675 } 676 } 677 return 1; 678 } 679} 680 681sub autodescribe { 682 if ($VERBOSE and not $count) { 683 print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"), 684 "\n$msg{DESCRIPTION}\n"; 685 } 686} 687 688sub unescape { 689 s { 690 E< 691 ( [A-Za-z]+ ) 692 > 693 } { 694 do { 695 exists $HTML_Escapes{$1} 696 ? do { $HTML_Escapes{$1} } 697 : do { 698 warn "Unknown escape: E<$1> in $_"; 699 "E<$1>"; 700 } 701 } 702 }egx; 703} 704 705sub shorten { 706 my $line = $_[0]; 707 if (length($line) > 79 and index($line, "\n") == -1) { 708 my $space_place = rindex($line, ' ', 79); 709 if ($space_place != -1) { 710 substr($line, $space_place, 1) = "\n\t"; 711 } 712 } 713 return $line; 714} 715 716 7171 unless $standalone; # or it'll complain about itself 718__END__ # wish diag dbase were more accessible 719