add CGI.pm v2.66 (from Lincoln Stein)
[p5sagit/p5-mst-13.2.git] / lib / CGI / Carp.pm
CommitLineData
54310121 1package CGI::Carp;
2
3=head1 NAME
4
5B<CGI::Carp> - CGI routines for writing to the HTTPD (or other) error log
6
7=head1 SYNOPSIS
8
9 use CGI::Carp;
10
11 croak "We're outta here!";
12 confess "It was my fault: $!";
13 carp "It was your fault!";
14 warn "I'm confused";
15 die "I'm dying.\n";
16
71f3e297 17 use CGI::Carp qw(cluck);
18 cluck "I wouldn't do that if I were you";
19
20 use CGI::Carp qw(fatalsToBrowser);
21 die "Fatal error messages are now sent to browser";
22
54310121 23=head1 DESCRIPTION
24
25CGI scripts have a nasty habit of leaving warning messages in the error
26logs that are neither time stamped nor fully identified. Tracking down
27the script that caused the error is a pain. This fixes that. Replace
28the usual
29
30 use Carp;
31
32with
33
34 use CGI::Carp
35
36And the standard warn(), die (), croak(), confess() and carp() calls
37will automagically be replaced with functions that write out nicely
38time-stamped messages to the HTTP server error log.
39
40For example:
41
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.
45
46=head1 REDIRECTING ERROR MESSAGES
47
48By default, error messages are sent to STDERR. Most HTTPD servers
49direct STDERR to the server's error log. Some applications may wish
50to keep private error logs, distinct from the server's error log, or
51they may wish to direct error messages to STDOUT so that the browser
52will receive them.
53
54The C<carpout()> function is provided for this purpose. Since
55carpout() is not exported by default, you must import it explicitly by
56saying
57
58 use CGI::Carp qw(carpout);
59
60The carpout() function requires one argument, which should be a
61reference to an open filehandle for writing errors. It should be
62called in a C<BEGIN> block at the top of the CGI application so that
63compiler errors will be caught. Example:
64
65 BEGIN {
66 use CGI::Carp qw(carpout);
67 open(LOG, ">>/usr/local/cgi-logs/mycgi-log") or
68 die("Unable to open mycgi-log: $!\n");
69 carpout(LOG);
70 }
71
72carpout() does not handle file locking on the log for you at this point.
73
74The real STDERR is not closed -- it is moved to SAVEERR. Some
75servers, when dealing with CGI scripts, close their connection to the
76browser when the script closes STDOUT and STDERR. SAVEERR is used to
77prevent this from happening prematurely.
78
79You can pass filehandles to carpout() in a variety of ways. The "correct"
80way according to Tom Christiansen is to pass a reference to a filehandle
81GLOB:
82
83 carpout(\*LOG);
84
85This looks weird to mere mortals however, so the following syntaxes are
86accepted as well:
87
88 carpout(LOG);
89 carpout(main::LOG);
90 carpout(main'LOG);
91 carpout(\LOG);
92 carpout(\'main::LOG');
93
94 ... and so on
95
424ec8fa 96FileHandle and other objects work as well.
97
54310121 98Use of carpout() is not great for performance, so it is recommended
99for debugging purposes or for moderate-use applications. A future
100version of this module may delay redirecting STDERR until one of the
101CGI::Carp methods is called to prevent the performance hit.
102
103=head1 MAKING PERL ERRORS APPEAR IN THE BROWSER WINDOW
104
105If you want to send fatal (die, confess) errors to the browser, ask to
106import the special "fatalsToBrowser" subroutine:
107
108 use CGI::Carp qw(fatalsToBrowser);
109 die "Bad error here";
110
111Fatal errors will now be echoed to the browser as well as to the log. CGI::Carp
112arranges to send a minimal HTTP header to the browser so that even errors that
113occur in the early compile phase will be seen.
114Nonfatal errors will still be directed to the log file only (unless redirected
115with carpout).
116
424ec8fa 117=head2 Changing the default message
118
119By default, the software error message is followed by a note to
120contact the Webmaster by e-mail with the time and date of the error.
121If this message is not to your liking, you can change it using the
122set_message() routine. This is not imported by default; you should
123import it on the use() line:
124
125 use CGI::Carp qw(fatalsToBrowser set_message);
126 set_message("It's not a bug, it's a feature!");
127
128You may also pass in a code reference in order to create a custom
129error message. At run time, your code will be called with the text
130of the error message that caused the script to die. Example:
131
132 use CGI::Carp qw(fatalsToBrowser set_message);
133 BEGIN {
134 sub handle_errors {
135 my $msg = shift;
136 print "<h1>Oh gosh</h1>";
137 print "Got an error: $msg";
138 }
139 set_message(\&handle_errors);
140 }
141
142In order to correctly intercept compile-time errors, you should call
143set_message() from within a BEGIN{} block.
144
54310121 145=head1 CHANGE LOG
146
1471.05 carpout() added and minor corrections by Marc Hedlund
148 <hedlund@best.com> on 11/26/95.
149
1501.06 fatalsToBrowser() no longer aborts for fatal errors within
151 eval() statements.
152
424ec8fa 1531.08 set_message() added and carpout() expanded to allow for FileHandle
154 objects.
155
1561.09 set_message() now allows users to pass a code REFERENCE for
157 really custom error messages. croak and carp are now
158 exported by default. Thanks to Gunther Birznieks for the
159 patches.
160
1611.10 Patch from Chris Dean (ctdean@cogit.com) to allow
162 module to run correctly under mod_perl.
163
71f3e297 1641.11 Changed order of &gt; and &lt; escapes.
165
1661.12 Changed die() on line 217 to CORE::die to avoid B<-w> warning.
167
1681.13 Added cluck() to make the module orthogonal with Carp.
169 More mod_perl related fixes.
170
54310121 171=head1 AUTHORS
172
71f3e297 173Copyright 1995-1998, Lincoln D. Stein. All rights reserved.
174
175This library is free software; you can redistribute it and/or modify
176it under the same terms as Perl itself.
54310121 177
71f3e297 178Address bug reports and comments to: lstein@cshl.org
54310121 179
180=head1 SEE ALSO
181
182Carp, CGI::Base, CGI::BasePlus, CGI::Request, CGI::MiniSvr, CGI::Form,
183CGI::Response
184
185=cut
186
187require 5.000;
188use Exporter;
189use Carp;
190
191@ISA = qw(Exporter);
192@EXPORT = qw(confess croak carp);
71f3e297 193@EXPORT_OK = qw(carpout fatalsToBrowser wrap set_message cluck);
54310121 194
3538e1d5 195BEGIN {
196 $] >= 5.005
3d1a2ec4 197 ? eval q#sub ineval { defined $^S ? $^S : _longmess() =~ /eval [\{\']/m }#
198 : eval q#sub ineval { _longmess() =~ /eval [\{\']/m }#;
3538e1d5 199 $@ and die;
200}
201
54310121 202$main::SIG{__WARN__}=\&CGI::Carp::warn;
203$main::SIG{__DIE__}=\&CGI::Carp::die;
3d1a2ec4 204$CGI::Carp::VERSION = '1.16';
424ec8fa 205$CGI::Carp::CUSTOM_MSG = undef;
54310121 206
207# fancy import routine detects and handles 'errorWrap' specially.
208sub import {
209 my $pkg = shift;
210 my(%routines);
424ec8fa 211 grep($routines{$_}++,@_,@EXPORT);
212 $WRAP++ if $routines{'fatalsToBrowser'} || $routines{'wrap'};
54310121 213 my($oldlevel) = $Exporter::ExportLevel;
214 $Exporter::ExportLevel = 1;
215 Exporter::import($pkg,keys %routines);
216 $Exporter::ExportLevel = $oldlevel;
217}
218
219# These are the originals
9014bb8e 220sub realwarn { CORE::warn(@_); }
221sub realdie { CORE::die(@_); }
54310121 222
223sub id {
224 my $level = shift;
225 my($pack,$file,$line,$sub) = caller($level);
14a089c5 226 my($id) = $file=~m|([^/]+)\z|;
54310121 227 return ($file,$line,$id);
228}
229
230sub stamp {
231 my $time = scalar(localtime);
232 my $frame = 0;
233 my ($id,$pack,$file);
234 do {
235 $id = $file;
236 ($pack,$file) = caller($frame++);
237 } until !$file;
14a089c5 238 ($id) = $id=~m|([^/]+)\z|;
54310121 239 return "[$time] $id: ";
240}
241
242sub warn {
243 my $message = shift;
244 my($file,$line,$id) = id(1);
245 $message .= " at $file line $line.\n" unless $message=~/\n$/;
246 my $stamp = stamp;
247 $message=~s/^/$stamp/gm;
248 realwarn $message;
249}
250
424ec8fa 251# The mod_perl package Apache::Registry loads CGI programs by calling
252# eval. These evals don't count when looking at the stack backtrace.
253sub _longmess {
254 my $message = Carp::longmess();
71f3e297 255 my $mod_perl = exists $ENV{MOD_PERL};
424ec8fa 256 $message =~ s,eval[^\n]+Apache/Registry\.pm.*,,s if $mod_perl;
257 return( $message );
258}
259
54310121 260sub die {
3538e1d5 261 realdie @_ if ineval;
262 my $message = shift;
263 my $time = scalar(localtime);
264 my($file,$line,$id) = id(1);
265 $message .= " at $file line $line." unless $message=~/\n$/;
266 &fatalsToBrowser($message) if $WRAP;
267 my $stamp = stamp;
268 $message=~s/^/$stamp/gm;
269 realdie $message;
54310121 270}
271
424ec8fa 272sub set_message {
273 $CGI::Carp::CUSTOM_MSG = shift;
274 return $CGI::Carp::CUSTOM_MSG;
275}
276
54310121 277# Avoid generating "subroutine redefined" warnings with the following
278# hack:
279{
280 local $^W=0;
281 eval <<EOF;
282sub confess { CGI::Carp::die Carp::longmess \@_; }
71f3e297 283sub croak { CGI::Carp::die Carp::shortmess \@_; }
284sub carp { CGI::Carp::warn Carp::shortmess \@_; }
285sub cluck { CGI::Carp::warn Carp::longmess \@_; }
54310121 286EOF
287 ;
288}
289
290# We have to be ready to accept a filehandle as a reference
291# or a string.
292sub carpout {
293 my($in) = @_;
424ec8fa 294 my($no) = fileno(to_filehandle($in));
71f3e297 295 realdie("Invalid filehandle $in\n") unless defined $no;
54310121 296
297 open(SAVEERR, ">&STDERR");
298 open(STDERR, ">&$no") or
299 ( print SAVEERR "Unable to redirect STDERR: $!\n" and exit(1) );
300}
301
302# headers
303sub fatalsToBrowser {
304 my($msg) = @_;
71f3e297 305 $msg=~s/&/&amp;/g;
54310121 306 $msg=~s/>/&gt;/g;
307 $msg=~s/</&lt;/g;
424ec8fa 308 $msg=~s/\"/&quot;/g;
309 my($wm) = $ENV{SERVER_ADMIN} ?
310 qq[the webmaster (<a href="mailto:$ENV{SERVER_ADMIN}">$ENV{SERVER_ADMIN}</a>)] :
311 "this site's webmaster";
312 my ($outer_message) = <<END;
313For help, please send mail to $wm, giving this error message
314and the time and date of the error.
315END
316 ;
71f3e297 317 my $mod_perl = exists $ENV{MOD_PERL};
318 print STDOUT "Content-type: text/html\n\n"
319 unless $mod_perl;
424ec8fa 320
321 if ($CUSTOM_MSG) {
322 if (ref($CUSTOM_MSG) eq 'CODE') {
323 &$CUSTOM_MSG($msg); # nicer to perl 5.003 users
324 return;
325 } else {
326 $outer_message = $CUSTOM_MSG;
327 }
328 }
329
71f3e297 330 my $mess = <<END;
54310121 331<H1>Software error:</H1>
332<CODE>$msg</CODE>
333<P>
71f3e297 334$outer_message
54310121 335END
424ec8fa 336 ;
71f3e297 337
3d1a2ec4 338 if ($mod_perl && (my $r = Apache->request)) {
71f3e297 339 # If bytes have already been sent, then
340 # we print the message out directly.
341 # Otherwise we make a custom error
342 # handler to produce the doc for us.
343 if ($r->bytes_sent) {
344 $r->print($mess);
345 $r->exit;
346 } else {
347 $r->status(500);
348 $r->custom_response(500,$mess);
349 }
350 } else {
351 print STDOUT $mess;
352 }
424ec8fa 353}
354
355# Cut and paste from CGI.pm so that we don't have the overhead of
356# always loading the entire CGI module.
357sub to_filehandle {
358 my $thingy = shift;
359 return undef unless $thingy;
360 return $thingy if UNIVERSAL::isa($thingy,'GLOB');
361 return $thingy if UNIVERSAL::isa($thingy,'FileHandle');
362 if (!ref($thingy)) {
363 my $caller = 1;
364 while (my $package = caller($caller++)) {
365 my($tmp) = $thingy=~/[\':]/ ? $thingy : "$package\:\:$thingy";
366 return $tmp if defined(fileno($tmp));
367 }
368 }
369 return undef;
54310121 370}
371
3721;