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 $diagnostics::PRETTY variable can generate nicer 54escape sequences for pagers. 55 56Warnings dispatched from perl itself (or more accurately, those that match 57descriptions found in L<perldiag>) are only displayed once (no duplicate 58descriptions). User code generated warnings a la warn() are unaffected, 59allowing duplicate user messages to be displayed. 60 61This module also adds a stack trace to the error message when perl dies. 62This is useful for pinpointing what 63caused the death. The B<-traceonly> (or 64just B<-t>) flag turns off the explanations of warning messages leaving just 65the stack traces. So if your script is dieing, run it again with 66 67 perl -Mdiagnostics=-traceonly my_bad_script 68 69to see the call stack at the time of death. By supplying the B<-warntrace> 70(or just B<-w>) flag, any warnings emitted will also come with a stack 71trace. 72 73=head2 The I<splain> Program 74 75While apparently a whole nuther program, I<splain> is actually nothing 76more than a link to the (executable) F<diagnostics.pm> module, as well as 77a link to the F<diagnostics.pod> documentation. The B<-v> flag is like 78the C<use diagnostics -verbose> directive. 79The B<-p> flag is like the 80$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 disable diagnostics; # 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 enable diagnostics; # 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 disable diagnostics; 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 = '1.31'; 190our $DEBUG; 191our $VERBOSE; 192our $PRETTY; 193our $TRACEONLY = 0; 194our $WARNTRACE = 0; 195 196use Config; 197my $privlib = $Config{privlibexp}; 198if ($^O eq 'VMS') { 199 require VMS::Filespec; 200 $privlib = VMS::Filespec::unixify($privlib); 201} 202my @trypod = ( 203 "$privlib/pod/perldiag.pod", 204 "$privlib/pods/perldiag.pod", 205 ); 206# handy for development testing of new warnings etc 207unshift @trypod, "./pod/perldiag.pod" if -e "pod/perldiag.pod"; 208(my $PODFILE) = ((grep { -e } @trypod), $trypod[$#trypod])[0]; 209 210$DEBUG ||= 0; 211my $WHOAMI = ref bless []; # nobody's business, prolly not even mine 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 $file ( (map { "$_/$WHOAMI.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 $0"; 260} 261 262 263%HTML_2_Troff = ( 264 'amp' => '&', # ampersand 265 'lt' => '<', # left chevron, less-than 266 'gt' => '>', # right chevron, greater-than 267 'quot' => '"', # double quote 268 269 "Aacute" => "A\\*'", # capital A, acute accent 270 # etc 271 272); 273 274%HTML_2_Latin_1 = ( 275 'amp' => '&', # ampersand 276 'lt' => '<', # left chevron, less-than 277 'gt' => '>', # right chevron, greater-than 278 'quot' => '"', # double quote 279 280 "Aacute" => "\xC1" # capital A, acute accent 281 282 # etc 283); 284 285%HTML_2_ASCII_7 = ( 286 'amp' => '&', # ampersand 287 'lt' => '<', # left chevron, less-than 288 'gt' => '>', # right chevron, greater-than 289 'quot' => '"', # double quote 290 291 "Aacute" => "A" # capital A, acute accent 292 # etc 293); 294 295our %HTML_Escapes; 296*HTML_Escapes = do { 297 if ($standalone) { 298 $PRETTY ? \%HTML_2_Latin_1 : \%HTML_2_ASCII_7; 299 } else { 300 \%HTML_2_Latin_1; 301 } 302}; 303 304*THITHER = $standalone ? *STDOUT : *STDERR; 305 306my %transfmt = (); 307my $transmo = <<EOFUNC; 308sub transmo { 309 #local \$^W = 0; # recursive warnings we do NOT need! 310EOFUNC 311 312my %msg; 313{ 314 print STDERR "FINISHING COMPILATION for $_\n" if $DEBUG; 315 local $/ = ''; 316 local $_; 317 my $header; 318 my @headers; 319 my $for_item; 320 my $seen_body; 321 while (<POD_DIAG>) { 322 323 sub _split_pod_link { 324 $_[0] =~ '(?:([^|]*)\|)?([^/]*)(?:/("?)(.*)\3)?'; 325 ($1,$2,$4); 326 } 327 328 unescape(); 329 if ($PRETTY) { 330 sub noop { return $_[0] } # spensive for a noop 331 sub bold { my $str =$_[0]; $str =~ s/(.)/$1\b$1/g; return $str; } 332 sub italic { my $str = $_[0]; $str =~ s/(.)/_\b$1/g; return $str; } 333 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/bold($+)/ges; 334 s/[IF]<(.*?)>/italic($1)/ges; 335 s/L<(.*?)>/ 336 my($text,$page,$sect) = _split_pod_link($1); 337 defined $text 338 ? $text 339 : defined $sect 340 ? italic($sect) . ' in ' . italic($page) 341 : italic($page) 342 /ges; 343 s/S<(.*?)>/ 344 $1 345 /ges; 346 } else { 347 s/C<<< (.*?) >>>|C<< (.*?) >>|[BC]<(.*?)>/$+/gs; 348 s/[IF]<(.*?)>/$1/gs; 349 s/L<(.*?)>/ 350 my($text,$page,$sect) = _split_pod_link($1); 351 defined $text 352 ? $text 353 : defined $sect 354 ? qq '"$sect" in $page' 355 : $page 356 /ges; 357 s/S<(.*?)>/ 358 $1 359 /ges; 360 } 361 unless (/^=/) { 362 if (defined $header) { 363 if ( $header eq 'DESCRIPTION' && 364 ( /Optional warnings are enabled/ 365 || /Some of these messages are generic./ 366 ) ) 367 { 368 next; 369 } 370 s/^/ /gm; 371 $msg{$header} .= $_; 372 for my $h(@headers) { $msg{$h} .= $_ } 373 ++$seen_body; 374 undef $for_item; 375 } 376 next; 377 } 378 379 # If we have not come across the body of the description yet, then 380 # the previous header needs to share the same description. 381 if ($seen_body) { 382 @headers = (); 383 } 384 else { 385 push @headers, $header if defined $header; 386 } 387 388 unless ( s/=item (.*?)\s*\z//s) { 389 390 if ( s/=head1\sDESCRIPTION//) { 391 $msg{$header = 'DESCRIPTION'} = ''; 392 undef $for_item; 393 } 394 elsif( s/^=for\s+diagnostics\s*\n(.*?)\s*\z// ) { 395 $for_item = $1; 396 } 397 next; 398 } 399 400 if( $for_item ) { $header = $for_item; undef $for_item } 401 else { 402 $header = $1; 403 404 $header =~ s/\n/ /gs; # Allow multi-line headers 405 } 406 407 # strip formatting directives from =item line 408 $header =~ s/[A-Z]<(.*?)>/$1/g; 409 410 # Since we strip "(\.\s*)\n" when we search a warning, strip it here as well 411 $header =~ s/(\.\s*)?$//; 412 413 my @toks = split( /(%l?[dxX]|%[ucp]|%(?:\.\d+)?[fs])/, $header ); 414 if (@toks > 1) { 415 my $conlen = 0; 416 for my $i (0..$#toks){ 417 if( $i % 2 ){ 418 if( $toks[$i] eq '%c' ){ 419 $toks[$i] = '.'; 420 } elsif( $toks[$i] =~ /^%(?:d|u)$/ ){ 421 $toks[$i] = '\d+'; 422 } elsif( $toks[$i] =~ '^%(?:s|.*f)$' ){ 423 $toks[$i] = $i == $#toks ? '.*' : '.*?'; 424 } elsif( $toks[$i] =~ '%.(\d+)s' ){ 425 $toks[$i] = ".{$1}"; 426 } elsif( $toks[$i] =~ '^%l*([pxX])$' ){ 427 $toks[$i] = $1 eq 'X' ? '[\dA-F]+' : '[\da-f]+'; 428 } 429 } elsif( length( $toks[$i] ) ){ 430 $toks[$i] = quotemeta $toks[$i]; 431 $conlen += length( $toks[$i] ); 432 } 433 } 434 my $lhs = join( '', @toks ); 435 $lhs =~ s/(\\\s)+/\\s+/g; # Replace lit space with multi-space match 436 $transfmt{$header}{pat} = 437 " s^\\s*$lhs\\s*\Q$header\Es\n\t&& return 1;\n"; 438 $transfmt{$header}{len} = $conlen; 439 } else { 440 my $lhs = "\Q$header\E"; 441 $lhs =~ s/(\\\s)+/\\s+/g; # Replace lit space with multi-space match 442 $transfmt{$header}{pat} = 443 " s^\\s*$lhs\\s*\Q$header\E\n\t && return 1;\n"; 444 $transfmt{$header}{len} = length( $header ); 445 } 446 447 print STDERR "$WHOAMI: Duplicate entry: \"$header\"\n" 448 if $msg{$header}; 449 450 $msg{$header} = ''; 451 $seen_body = 0; 452 } 453 454 455 close POD_DIAG unless *main::DATA eq *POD_DIAG; 456 457 die "No diagnostics?" unless %msg; 458 459 # Apply patterns in order of decreasing sum of lengths of fixed parts 460 # Seems the best way of hitting the right one. 461 for my $hdr ( sort { $transfmt{$b}{len} <=> $transfmt{$a}{len} } 462 keys %transfmt ){ 463 $transmo .= $transfmt{$hdr}{pat}; 464 } 465 $transmo .= " return 0;\n}\n"; 466 print STDERR $transmo if $DEBUG; 467 eval $transmo; 468 die $@ if $@; 469} 470 471if ($standalone) { 472 if (!@ARGV and -t STDIN) { print STDERR "$0: Reading from STDIN\n" } 473 while (defined (my $error = <>)) { 474 splainthis($error) || print THITHER $error; 475 } 476 exit; 477} 478 479my $olddie; 480my $oldwarn; 481 482sub import { 483 shift; 484 $^W = 1; # yup, clobbered the global variable; 485 # tough, if you want diags, you want diags. 486 return if defined $SIG{__WARN__} && ($SIG{__WARN__} eq \&warn_trap); 487 488 for (@_) { 489 490 /^-d(ebug)?$/ && do { 491 $DEBUG++; 492 next; 493 }; 494 495 /^-v(erbose)?$/ && do { 496 $VERBOSE++; 497 next; 498 }; 499 500 /^-p(retty)?$/ && do { 501 print STDERR "$0: I'm afraid it's too late for prettiness.\n"; 502 $PRETTY++; 503 next; 504 }; 505 # matches trace and traceonly for legacy doc mixup reasons 506 /^-t(race(only)?)?$/ && do { 507 $TRACEONLY++; 508 next; 509 }; 510 /^-w(arntrace)?$/ && do { 511 $WARNTRACE++; 512 next; 513 }; 514 515 warn "Unknown flag: $_"; 516 } 517 518 $oldwarn = $SIG{__WARN__}; 519 $olddie = $SIG{__DIE__}; 520 $SIG{__WARN__} = \&warn_trap; 521 $SIG{__DIE__} = \&death_trap; 522} 523 524sub enable { &import } 525 526sub disable { 527 shift; 528 return unless $SIG{__WARN__} eq \&warn_trap; 529 $SIG{__WARN__} = $oldwarn || ''; 530 $SIG{__DIE__} = $olddie || ''; 531} 532 533sub warn_trap { 534 my $warning = $_[0]; 535 if (caller eq $WHOAMI or !splainthis($warning)) { 536 if ($WARNTRACE) { 537 print STDERR Carp::longmess($warning); 538 } else { 539 print STDERR $warning; 540 } 541 } 542 goto &$oldwarn if defined $oldwarn and $oldwarn and $oldwarn ne \&warn_trap; 543}; 544 545sub death_trap { 546 my $exception = $_[0]; 547 548 # See if we are coming from anywhere within an eval. If so we don't 549 # want to explain the exception because it's going to get caught. 550 my $in_eval = 0; 551 my $i = 0; 552 while (my $caller = (caller($i++))[3]) { 553 if ($caller eq '(eval)') { 554 $in_eval = 1; 555 last; 556 } 557 } 558 559 splainthis($exception) unless $in_eval; 560 if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; } 561 &$olddie if defined $olddie and $olddie and $olddie ne \&death_trap; 562 563 return if $in_eval; 564 565 # We don't want to unset these if we're coming from an eval because 566 # then we've turned off diagnostics. 567 568 # Switch off our die/warn handlers so we don't wind up in our own 569 # traps. 570 $SIG{__DIE__} = $SIG{__WARN__} = ''; 571 572 $exception =~ s/\n(?=.)/\n\t/gas; 573 574 die Carp::longmess("__diagnostics__") 575 =~ s/^__diagnostics__.*?line \d+\.?\n/ 576 "Uncaught exception from user code:\n\t$exception" 577 /re; 578 # up we go; where we stop, nobody knows, but i think we die now 579 # but i'm deeply afraid of the &$olddie guy reraising and us getting 580 # into an indirect recursion loop 581}; 582 583my %exact_duplicate; 584my %old_diag; 585my $count; 586my $wantspace; 587sub splainthis { 588 return 0 if $TRACEONLY; 589 for (my $tmp = shift) { 590 local $\; 591 local $!; 592 ### &finish_compilation unless %msg; 593 s/(\.\s*)?\n+$//; 594 my $orig = $_; 595 # return unless defined; 596 597 # get rid of the where-are-we-in-input part 598 s/, <.*?> (?:line|chunk).*$//; 599 600 # Discard 1st " at <file> line <no>" and all text beyond 601 # but be aware of messages containing " at this-or-that" 602 my $real = 0; 603 my @secs = split( / at / ); 604 return unless @secs; 605 $_ = $secs[0]; 606 for my $i ( 1..$#secs ){ 607 if( $secs[$i] =~ /.+? (?:line|chunk) \d+/ ){ 608 $real = 1; 609 last; 610 } else { 611 $_ .= ' at ' . $secs[$i]; 612 } 613 } 614 615 # remove parenthesis occurring at the end of some messages 616 s/^\((.*)\)$/$1/; 617 618 if ($exact_duplicate{$orig}++) { 619 return &transmo; 620 } else { 621 return 0 unless &transmo; 622 } 623 624 my $short = shorten($orig); 625 if ($old_diag{$_}) { 626 autodescribe(); 627 print THITHER "$short (#$old_diag{$_})\n"; 628 $wantspace = 1; 629 } elsif (!$msg{$_} && $orig =~ /\n./s) { 630 # A multiline message, like "Attempt to reload / 631 # Compilation failed" 632 my $found; 633 for (split /^/, $orig) { 634 splainthis($_) and $found = 1; 635 } 636 return $found; 637 } else { 638 autodescribe(); 639 $old_diag{$_} = ++$count; 640 print THITHER "\n" if $wantspace; 641 $wantspace = 0; 642 print THITHER "$short (#$old_diag{$_})\n"; 643 if ($msg{$_}) { 644 print THITHER $msg{$_}; 645 } else { 646 if (0 and $standalone) { 647 print THITHER " **** Error #$old_diag{$_} ", 648 ($real ? "is" : "appears to be"), 649 " an unknown diagnostic message.\n\n"; 650 } 651 return 0; 652 } 653 } 654 return 1; 655 } 656} 657 658sub autodescribe { 659 if ($VERBOSE and not $count) { 660 print THITHER &{$PRETTY ? \&bold : \&noop}("DESCRIPTION OF DIAGNOSTICS"), 661 "\n$msg{DESCRIPTION}\n"; 662 } 663} 664 665sub unescape { 666 s { 667 E< 668 ( [A-Za-z]+ ) 669 > 670 } { 671 do { 672 exists $HTML_Escapes{$1} 673 ? do { $HTML_Escapes{$1} } 674 : do { 675 warn "Unknown escape: E<$1> in $_"; 676 "E<$1>"; 677 } 678 } 679 }egx; 680} 681 682sub shorten { 683 my $line = $_[0]; 684 if (length($line) > 79 and index($line, "\n") == -1) { 685 my $space_place = rindex($line, ' ', 79); 686 if ($space_place != -1) { 687 substr($line, $space_place, 1) = "\n\t"; 688 } 689 } 690 return $line; 691} 692 693 6941 unless $standalone; # or it'll complain about itself 695__END__ # wish diag dbase were more accessible 696