5 B<CGI::Carp> - CGI routines for writing to the HTTPD (or other) error log
11 croak "We're outta here!";
12 confess "It was my fault: $!";
13 carp "It was your fault!";
17 use CGI::Carp qw(cluck);
18 cluck "I wouldn't do that if I were you";
20 use CGI::Carp qw(fatalsToBrowser);
21 die "Fatal error messages are now sent to browser";
25 CGI scripts have a nasty habit of leaving warning messages in the error
26 logs that are neither time stamped nor fully identified. Tracking down
27 the script that caused the error is a pain. This fixes that. Replace
36 And the standard warn(), die (), croak(), confess() and carp() calls
37 will automagically be replaced with functions that write out nicely
38 time-stamped messages to the HTTP server error log.
42 [Fri Nov 17 21:40:43 1995] test.pl: I'm confused at test.pl line 3.
43 [Fri Nov 17 21:40:43 1995] test.pl: Got an error message: Permission denied.
44 [Fri Nov 17 21:40:43 1995] test.pl: I'm dying.
46 =head1 REDIRECTING ERROR MESSAGES
48 By default, error messages are sent to STDERR. Most HTTPD servers
49 direct STDERR to the server's error log. Some applications may wish
50 to keep private error logs, distinct from the server's error log, or
51 they may wish to direct error messages to STDOUT so that the browser
54 The C<carpout()> function is provided for this purpose. Since
55 carpout() is not exported by default, you must import it explicitly by
58 use CGI::Carp qw(carpout);
60 The carpout() function requires one argument, which should be a
61 reference to an open filehandle for writing errors. It should be
62 called in a C<BEGIN> block at the top of the CGI application so that
63 compiler errors will be caught. Example:
66 use CGI::Carp qw(carpout);
67 open(LOG, ">>/usr/local/cgi-logs/mycgi-log") or
68 die("Unable to open mycgi-log: $!\n");
72 carpout() does not handle file locking on the log for you at this point.
74 The real STDERR is not closed -- it is moved to CGI::Carp::SAVEERR. Some
75 servers, when dealing with CGI scripts, close their connection to the
76 browser when the script closes STDOUT and STDERR. CGI::Carp::SAVEERR is there to
77 prevent this from happening prematurely.
79 You can pass filehandles to carpout() in a variety of ways. The "correct"
80 way according to Tom Christiansen is to pass a reference to a filehandle
85 This looks weird to mere mortals however, so the following syntaxes are
92 carpout(\'main::LOG');
96 FileHandle and other objects work as well.
98 Use of carpout() is not great for performance, so it is recommended
99 for debugging purposes or for moderate-use applications. A future
100 version of this module may delay redirecting STDERR until one of the
101 CGI::Carp methods is called to prevent the performance hit.
103 =head1 MAKING PERL ERRORS APPEAR IN THE BROWSER WINDOW
105 If you want to send fatal (die, confess) errors to the browser, ask to
106 import the special "fatalsToBrowser" subroutine:
108 use CGI::Carp qw(fatalsToBrowser);
109 die "Bad error here";
111 Fatal errors will now be echoed to the browser as well as to the log. CGI::Carp
112 arranges to send a minimal HTTP header to the browser so that even errors that
113 occur in the early compile phase will be seen.
114 Nonfatal errors will still be directed to the log file only (unless redirected
117 Note that fatalsToBrowser does B<not> work with mod_perl version 2.0
120 =head2 Changing the default message
122 By default, the software error message is followed by a note to
123 contact the Webmaster by e-mail with the time and date of the error.
124 If this message is not to your liking, you can change it using the
125 set_message() routine. This is not imported by default; you should
126 import it on the use() line:
128 use CGI::Carp qw(fatalsToBrowser set_message);
129 set_message("It's not a bug, it's a feature!");
131 You may also pass in a code reference in order to create a custom
132 error message. At run time, your code will be called with the text
133 of the error message that caused the script to die. Example:
135 use CGI::Carp qw(fatalsToBrowser set_message);
139 print "<h1>Oh gosh</h1>";
140 print "<p>Got an error: $msg</p>";
142 set_message(\&handle_errors);
145 In order to correctly intercept compile-time errors, you should call
146 set_message() from within a BEGIN{} block.
148 =head1 MAKING WARNINGS APPEAR AS HTML COMMENTS
150 It is now also possible to make non-fatal errors appear as HTML
151 comments embedded in the output of your program. To enable this
152 feature, export the new "warningsToBrowser" subroutine. Since sending
153 warnings to the browser before the HTTP headers have been sent would
154 cause an error, any warnings are stored in an internal buffer until
155 you call the warningsToBrowser() subroutine with a true argument:
157 use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
158 use CGI qw(:standard);
160 warningsToBrowser(1);
162 You may also give a false argument to warningsToBrowser() to prevent
163 warnings from being sent to the browser while you are printing some
164 content where HTML comments are not allowed:
166 warningsToBrowser(0); # disable warnings
167 print "<script type=\"text/javascript\"><!--\n";
168 print_some_javascript_code();
169 print "//--></script>\n";
170 warningsToBrowser(1); # re-enable warnings
172 Note: In this respect warningsToBrowser() differs fundamentally from
173 fatalsToBrowser(), which you should never call yourself!
175 =head1 OVERRIDING THE NAME OF THE PROGRAM
177 CGI::Carp includes the name of the program that generated the error or
178 warning in the messages written to the log and the browser window.
179 Sometimes, Perl can get confused about what the actual name of the
180 executed program was. In these cases, you can override the program
181 name that CGI::Carp will use for all messages.
183 The quick way to do that is to tell CGI::Carp the name of the program
184 in its use statement. You can do that by adding
185 "name=cgi_carp_log_name" to your "use" statement. For example:
187 use CGI::Carp qw(name=cgi_carp_log_name);
189 . If you want to change the program name partway through the program,
190 you can use the C<set_progname()> function instead. It is not
191 exported by default, you must import it explicitly by saying
193 use CGI::Carp qw(set_progname);
195 Once you've done that, you can change the logged name of the program
196 at any time by calling
198 set_progname(new_program_name);
200 You can set the program back to the default by calling
204 Note that this override doesn't happen until after the program has
205 compiled, so any compile-time errors will still show up with the
206 non-overridden program name
210 1.29 Patch from Peter Whaite to fix the unfixable problem of CGI::Carp
211 not behaving correctly in an eval() context.
213 1.05 carpout() added and minor corrections by Marc Hedlund
214 <hedlund@best.com> on 11/26/95.
216 1.06 fatalsToBrowser() no longer aborts for fatal errors within
219 1.08 set_message() added and carpout() expanded to allow for FileHandle
222 1.09 set_message() now allows users to pass a code REFERENCE for
223 really custom error messages. croak and carp are now
224 exported by default. Thanks to Gunther Birznieks for the
227 1.10 Patch from Chris Dean (ctdean@cogit.com) to allow
228 module to run correctly under mod_perl.
230 1.11 Changed order of > and < escapes.
232 1.12 Changed die() on line 217 to CORE::die to avoid B<-w> warning.
234 1.13 Added cluck() to make the module orthogonal with Carp.
235 More mod_perl related fixes.
237 1.20 Patch from Ilmari Karonen (perl@itz.pp.sci.fi): Added
238 warningsToBrowser(). Replaced <CODE> tags with <PRE> in
239 fatalsToBrowser() output.
241 1.23 ineval() now checks both $^S and inspects the message for the "eval" pattern
242 (hack alert!) in order to accommodate various combinations of Perl and
245 1.24 Patch from Scott Gifford (sgifford@suspectclass.com): Add support
246 for overriding program name.
248 1.26 Replaced CORE::GLOBAL::die with the evil $SIG{__DIE__} because the
249 former isn't working in some people's hands. There is no such thing
250 as reliable exception handling in Perl.
252 1.27 Replaced tell STDOUT with bytes=tell STDOUT.
256 Copyright 1995-2002, Lincoln D. Stein. All rights reserved.
258 This library is free software; you can redistribute it and/or modify
259 it under the same terms as Perl itself.
261 Address bug reports and comments to: lstein@cshl.org
265 Carp, CGI::Base, CGI::BasePlus, CGI::Request, CGI::MiniSvr, CGI::Form,
267 if (defined($CGI::Carp::PROGNAME))
269 $file = $CGI::Carp::PROGNAME;
279 *CORE::GLOBAL::die = \&CGI::Carp::die;
285 @EXPORT = qw(confess croak carp);
286 @EXPORT_OK = qw(carpout fatalsToBrowser warningsToBrowser wrap set_message set_progname cluck ^name= die);
288 $main::SIG{__WARN__}=\&CGI::Carp::warn;
290 $CGI::Carp::VERSION = '1.29';
291 $CGI::Carp::CUSTOM_MSG = undef;
294 # fancy import routine detects and handles 'errorWrap' specially.
299 if (@name=grep(/^name=/,@_))
301 my($n) = (split(/=/,$name[0]))[1];
303 @_=grep(!/^name=/,@_);
306 grep($routines{$_}++,@_,@EXPORT);
307 $WRAP++ if $routines{'fatalsToBrowser'} || $routines{'wrap'};
308 $WARN++ if $routines{'warningsToBrowser'};
309 my($oldlevel) = $Exporter::ExportLevel;
310 $Exporter::ExportLevel = 1;
311 Exporter::import($pkg,keys %routines);
312 $Exporter::ExportLevel = $oldlevel;
313 $main::SIG{__DIE__} =\&CGI::Carp::die if $routines{'fatalsToBrowser'};
314 # $pkg->export('CORE::GLOBAL','die');
317 # These are the originals
318 sub realwarn { CORE::warn(@_); }
319 sub realdie { CORE::die(@_); }
323 my($pack,$file,$line,$sub) = caller($level);
324 my($dev,$dirs,$id) = File::Spec->splitpath($file);
325 return ($file,$line,$id);
329 my $time = scalar(localtime);
331 my ($id,$pack,$file,$dev,$dirs);
332 if (defined($CGI::Carp::PROGNAME)) {
333 $id = $CGI::Carp::PROGNAME;
337 ($pack,$file) = caller($frame++);
340 ($dev,$dirs,$id) = File::Spec->splitpath($id);
341 return "[$time] $id: ";
345 $CGI::Carp::PROGNAME = shift;
346 return $CGI::Carp::PROGNAME;
352 my($file,$line,$id) = id(1);
353 $message .= " at $file line $line.\n" unless $message=~/\n$/;
354 _warn($message) if $WARN;
356 $message=~s/^/$stamp/gm;
362 if ($EMIT_WARNINGS) {
363 # We need to mangle the message a bit to make it a valid HTML
364 # comment. This is done by substituting similar-looking ISO
365 # 8859-1 characters for <, > and -. This is a hack.
366 $msg =~ tr/<>-/\253\273\255/;
368 print STDOUT "<!-- warning: $msg -->\n";
370 push @WARNINGS, $msg;
375 # The mod_perl package Apache::Registry loads CGI programs by calling
376 # eval. These evals don't count when looking at the stack backtrace.
378 my $message = Carp::longmess();
379 $message =~ s,eval[^\n]+(ModPerl|Apache)/(?:Registry|Dispatch)\w*\.pm.*,,s
380 if exists $ENV{MOD_PERL};
385 (exists $ENV{MOD_PERL} ? 0 : $^S) || _longmess() =~ /eval [\{\']/m
389 my ($arg,@rest) = @_;
393 $arg = join("",($arg,@rest)) || "Died";
394 my($file,$line,$id) = id(1);
395 $arg .= " at $file line $line.\n" unless $arg=~/\n$/;
404 $arg = join("", ($arg,@rest));
405 my($file,$line,$id) = id(1);
406 $arg .= " at $file line $line." unless $arg=~/\n$/;
407 &fatalsToBrowser($arg) if $WRAP;
408 if (($arg =~ /\n$/) || !exists($ENV{MOD_PERL})) {
420 $CGI::Carp::CUSTOM_MSG = shift;
421 return $CGI::Carp::CUSTOM_MSG;
424 sub confess { CGI::Carp::die Carp::longmess @_; }
425 sub croak { CGI::Carp::die Carp::shortmess @_; }
426 sub carp { CGI::Carp::warn Carp::shortmess @_; }
427 sub cluck { CGI::Carp::warn Carp::longmess @_; }
429 # We have to be ready to accept a filehandle as a reference
433 my($no) = fileno(to_filehandle($in));
434 realdie("Invalid filehandle $in\n") unless defined $no;
436 open(SAVEERR, ">&STDERR");
437 open(STDERR, ">&$no") or
438 ( print SAVEERR "Unable to redirect STDERR: $!\n" and exit(1) );
441 sub warningsToBrowser {
442 $EMIT_WARNINGS = @_ ? shift : 1;
443 _warn(shift @WARNINGS) while $EMIT_WARNINGS and @WARNINGS;
447 sub fatalsToBrowser {
453 my($wm) = $ENV{SERVER_ADMIN} ?
454 qq[the webmaster (<a href="mailto:$ENV{SERVER_ADMIN}">$ENV{SERVER_ADMIN}</a>)] :
455 "this site's webmaster";
456 my ($outer_message) = <<END;
457 For help, please send mail to $wm, giving this error message
458 and the time and date of the error.
461 my $mod_perl = exists $ENV{MOD_PERL};
464 if (ref($CUSTOM_MSG) eq 'CODE') {
465 print STDOUT "Content-type: text/html\n\n"
467 &$CUSTOM_MSG($msg); # nicer to perl 5.003 users
470 $outer_message = $CUSTOM_MSG;
475 <h1>Software error:</h1>
485 if ($ENV{MOD_PERL_API_VERSION} && $ENV{MOD_PERL_API_VERSION} == 2) {
487 require Apache2::RequestRec;
488 require Apache2::RequestIO;
489 require Apache2::RequestUtil;
491 require ModPerl::Util;
492 require Apache2::Response;
493 $r = Apache2::RequestUtil->request;
496 $r = Apache->request;
498 # If bytes have already been sent, then
499 # we print the message out directly.
500 # Otherwise we make a custom error
501 # handler to produce the doc for us.
502 if ($r->bytes_sent) {
504 $mod_perl == 2 ? ModPerl::Util::exit(0) : $r->exit;
506 # MSIE won't display a custom 500 response unless it is >512 bytes!
507 if ($ENV{HTTP_USER_AGENT} =~ /MSIE/) {
508 $mess = "<!-- " . (' ' x 513) . " -->\n$mess";
510 $r->custom_response(500,$mess);
513 my $bytes_written = eval{tell STDOUT};
514 if (defined $bytes_written && $bytes_written > 0) {
518 print STDOUT "Content-type: text/html\n\n";
523 warningsToBrowser(1); # emit warnings before dying
526 # Cut and paste from CGI.pm so that we don't have the overhead of
527 # always loading the entire CGI module.
530 return undef unless $thingy;
531 return $thingy if UNIVERSAL::isa($thingy,'GLOB');
532 return $thingy if UNIVERSAL::isa($thingy,'FileHandle');
535 while (my $package = caller($caller++)) {
536 my($tmp) = $thingy=~/[\':]/ ? $thingy : "$package\:\:$thingy";
537 return $tmp if defined(fileno($tmp));