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54310121 |
1 | package CGI::Carp; |
2 | |
3 | =head1 NAME |
4 | |
5 | B<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 | |
17 | =head1 DESCRIPTION |
18 | |
19 | CGI scripts have a nasty habit of leaving warning messages in the error |
20 | logs that are neither time stamped nor fully identified. Tracking down |
21 | the script that caused the error is a pain. This fixes that. Replace |
22 | the usual |
23 | |
24 | use Carp; |
25 | |
26 | with |
27 | |
28 | use CGI::Carp |
29 | |
30 | And the standard warn(), die (), croak(), confess() and carp() calls |
31 | will automagically be replaced with functions that write out nicely |
32 | time-stamped messages to the HTTP server error log. |
33 | |
34 | For example: |
35 | |
36 | [Fri Nov 17 21:40:43 1995] test.pl: I'm confused at test.pl line 3. |
37 | [Fri Nov 17 21:40:43 1995] test.pl: Got an error message: Permission denied. |
38 | [Fri Nov 17 21:40:43 1995] test.pl: I'm dying. |
39 | |
40 | =head1 REDIRECTING ERROR MESSAGES |
41 | |
42 | By default, error messages are sent to STDERR. Most HTTPD servers |
43 | direct STDERR to the server's error log. Some applications may wish |
44 | to keep private error logs, distinct from the server's error log, or |
45 | they may wish to direct error messages to STDOUT so that the browser |
46 | will receive them. |
47 | |
48 | The C<carpout()> function is provided for this purpose. Since |
49 | carpout() is not exported by default, you must import it explicitly by |
50 | saying |
51 | |
52 | use CGI::Carp qw(carpout); |
53 | |
54 | The carpout() function requires one argument, which should be a |
55 | reference to an open filehandle for writing errors. It should be |
56 | called in a C<BEGIN> block at the top of the CGI application so that |
57 | compiler errors will be caught. Example: |
58 | |
59 | BEGIN { |
60 | use CGI::Carp qw(carpout); |
61 | open(LOG, ">>/usr/local/cgi-logs/mycgi-log") or |
62 | die("Unable to open mycgi-log: $!\n"); |
63 | carpout(LOG); |
64 | } |
65 | |
66 | carpout() does not handle file locking on the log for you at this point. |
67 | |
68 | The real STDERR is not closed -- it is moved to SAVEERR. Some |
69 | servers, when dealing with CGI scripts, close their connection to the |
70 | browser when the script closes STDOUT and STDERR. SAVEERR is used to |
71 | prevent this from happening prematurely. |
72 | |
73 | You can pass filehandles to carpout() in a variety of ways. The "correct" |
74 | way according to Tom Christiansen is to pass a reference to a filehandle |
75 | GLOB: |
76 | |
77 | carpout(\*LOG); |
78 | |
79 | This looks weird to mere mortals however, so the following syntaxes are |
80 | accepted as well: |
81 | |
82 | carpout(LOG); |
83 | carpout(main::LOG); |
84 | carpout(main'LOG); |
85 | carpout(\LOG); |
86 | carpout(\'main::LOG'); |
87 | |
88 | ... and so on |
89 | |
424ec8fa |
90 | FileHandle and other objects work as well. |
91 | |
54310121 |
92 | Use of carpout() is not great for performance, so it is recommended |
93 | for debugging purposes or for moderate-use applications. A future |
94 | version of this module may delay redirecting STDERR until one of the |
95 | CGI::Carp methods is called to prevent the performance hit. |
96 | |
97 | =head1 MAKING PERL ERRORS APPEAR IN THE BROWSER WINDOW |
98 | |
99 | If you want to send fatal (die, confess) errors to the browser, ask to |
100 | import the special "fatalsToBrowser" subroutine: |
101 | |
102 | use CGI::Carp qw(fatalsToBrowser); |
103 | die "Bad error here"; |
104 | |
105 | Fatal errors will now be echoed to the browser as well as to the log. CGI::Carp |
106 | arranges to send a minimal HTTP header to the browser so that even errors that |
107 | occur in the early compile phase will be seen. |
108 | Nonfatal errors will still be directed to the log file only (unless redirected |
109 | with carpout). |
110 | |
424ec8fa |
111 | =head2 Changing the default message |
112 | |
113 | By default, the software error message is followed by a note to |
114 | contact the Webmaster by e-mail with the time and date of the error. |
115 | If this message is not to your liking, you can change it using the |
116 | set_message() routine. This is not imported by default; you should |
117 | import it on the use() line: |
118 | |
119 | use CGI::Carp qw(fatalsToBrowser set_message); |
120 | set_message("It's not a bug, it's a feature!"); |
121 | |
122 | You may also pass in a code reference in order to create a custom |
123 | error message. At run time, your code will be called with the text |
124 | of the error message that caused the script to die. Example: |
125 | |
126 | use CGI::Carp qw(fatalsToBrowser set_message); |
127 | BEGIN { |
128 | sub handle_errors { |
129 | my $msg = shift; |
130 | print "<h1>Oh gosh</h1>"; |
131 | print "Got an error: $msg"; |
132 | } |
133 | set_message(\&handle_errors); |
134 | } |
135 | |
136 | In order to correctly intercept compile-time errors, you should call |
137 | set_message() from within a BEGIN{} block. |
138 | |
54310121 |
139 | =head1 CHANGE LOG |
140 | |
141 | 1.05 carpout() added and minor corrections by Marc Hedlund |
142 | <hedlund@best.com> on 11/26/95. |
143 | |
144 | 1.06 fatalsToBrowser() no longer aborts for fatal errors within |
145 | eval() statements. |
146 | |
424ec8fa |
147 | 1.08 set_message() added and carpout() expanded to allow for FileHandle |
148 | objects. |
149 | |
150 | 1.09 set_message() now allows users to pass a code REFERENCE for |
151 | really custom error messages. croak and carp are now |
152 | exported by default. Thanks to Gunther Birznieks for the |
153 | patches. |
154 | |
155 | 1.10 Patch from Chris Dean (ctdean@cogit.com) to allow |
156 | module to run correctly under mod_perl. |
157 | |
54310121 |
158 | =head1 AUTHORS |
159 | |
160 | Lincoln D. Stein <lstein@genome.wi.mit.edu>. Feel free to redistribute |
161 | this under the Perl Artistic License. |
162 | |
163 | |
164 | =head1 SEE ALSO |
165 | |
166 | Carp, CGI::Base, CGI::BasePlus, CGI::Request, CGI::MiniSvr, CGI::Form, |
167 | CGI::Response |
168 | |
169 | =cut |
170 | |
171 | require 5.000; |
172 | use Exporter; |
173 | use Carp; |
174 | |
175 | @ISA = qw(Exporter); |
176 | @EXPORT = qw(confess croak carp); |
424ec8fa |
177 | @EXPORT_OK = qw(carpout fatalsToBrowser wrap set_message); |
54310121 |
178 | |
179 | $main::SIG{__WARN__}=\&CGI::Carp::warn; |
180 | $main::SIG{__DIE__}=\&CGI::Carp::die; |
9014bb8e |
181 | $CGI::Carp::VERSION = '1.101'; |
424ec8fa |
182 | $CGI::Carp::CUSTOM_MSG = undef; |
54310121 |
183 | |
184 | # fancy import routine detects and handles 'errorWrap' specially. |
185 | sub import { |
186 | my $pkg = shift; |
187 | my(%routines); |
424ec8fa |
188 | grep($routines{$_}++,@_,@EXPORT); |
189 | $WRAP++ if $routines{'fatalsToBrowser'} || $routines{'wrap'}; |
54310121 |
190 | my($oldlevel) = $Exporter::ExportLevel; |
191 | $Exporter::ExportLevel = 1; |
192 | Exporter::import($pkg,keys %routines); |
193 | $Exporter::ExportLevel = $oldlevel; |
194 | } |
195 | |
196 | # These are the originals |
9014bb8e |
197 | # XXX Why not just use CORE::die etc., instead of these two? GSAR |
198 | sub realwarn { CORE::warn(@_); } |
199 | sub realdie { CORE::die(@_); } |
54310121 |
200 | |
201 | sub id { |
202 | my $level = shift; |
203 | my($pack,$file,$line,$sub) = caller($level); |
204 | my($id) = $file=~m|([^/]+)$|; |
205 | return ($file,$line,$id); |
206 | } |
207 | |
208 | sub stamp { |
209 | my $time = scalar(localtime); |
210 | my $frame = 0; |
211 | my ($id,$pack,$file); |
212 | do { |
213 | $id = $file; |
214 | ($pack,$file) = caller($frame++); |
215 | } until !$file; |
216 | ($id) = $id=~m|([^/]+)$|; |
217 | return "[$time] $id: "; |
218 | } |
219 | |
220 | sub warn { |
221 | my $message = shift; |
222 | my($file,$line,$id) = id(1); |
223 | $message .= " at $file line $line.\n" unless $message=~/\n$/; |
224 | my $stamp = stamp; |
225 | $message=~s/^/$stamp/gm; |
226 | realwarn $message; |
227 | } |
228 | |
424ec8fa |
229 | # The mod_perl package Apache::Registry loads CGI programs by calling |
230 | # eval. These evals don't count when looking at the stack backtrace. |
231 | sub _longmess { |
232 | my $message = Carp::longmess(); |
233 | my $mod_perl = ($ENV{'GATEWAY_INTERFACE'} |
234 | && $ENV{'GATEWAY_INTERFACE'} =~ /^CGI-Perl\//); |
235 | $message =~ s,eval[^\n]+Apache/Registry\.pm.*,,s if $mod_perl; |
236 | return( $message ); |
237 | } |
238 | |
54310121 |
239 | sub die { |
240 | my $message = shift; |
241 | my $time = scalar(localtime); |
242 | my($file,$line,$id) = id(1); |
54310121 |
243 | $message .= " at $file line $line.\n" unless $message=~/\n$/; |
424ec8fa |
244 | &fatalsToBrowser($message) if $WRAP && _longmess() !~ /eval [{\']/m; |
54310121 |
245 | my $stamp = stamp; |
246 | $message=~s/^/$stamp/gm; |
247 | realdie $message; |
248 | } |
249 | |
424ec8fa |
250 | sub set_message { |
251 | $CGI::Carp::CUSTOM_MSG = shift; |
252 | return $CGI::Carp::CUSTOM_MSG; |
253 | } |
254 | |
54310121 |
255 | # Avoid generating "subroutine redefined" warnings with the following |
256 | # hack: |
257 | { |
258 | local $^W=0; |
259 | eval <<EOF; |
260 | sub confess { CGI::Carp::die Carp::longmess \@_; } |
261 | sub croak { CGI::Carp::die Carp::shortmess \@_; } |
262 | sub carp { CGI::Carp::warn Carp::shortmess \@_; } |
263 | EOF |
264 | ; |
265 | } |
266 | |
267 | # We have to be ready to accept a filehandle as a reference |
268 | # or a string. |
269 | sub carpout { |
270 | my($in) = @_; |
424ec8fa |
271 | my($no) = fileno(to_filehandle($in)); |
9014bb8e |
272 | realdie "Invalid filehandle $in\n" unless defined $no; |
54310121 |
273 | |
274 | open(SAVEERR, ">&STDERR"); |
275 | open(STDERR, ">&$no") or |
276 | ( print SAVEERR "Unable to redirect STDERR: $!\n" and exit(1) ); |
277 | } |
278 | |
279 | # headers |
280 | sub fatalsToBrowser { |
281 | my($msg) = @_; |
282 | $msg=~s/>/>/g; |
283 | $msg=~s/</</g; |
424ec8fa |
284 | $msg=~s/&/&/g; |
285 | $msg=~s/\"/"/g; |
286 | my($wm) = $ENV{SERVER_ADMIN} ? |
287 | qq[the webmaster (<a href="mailto:$ENV{SERVER_ADMIN}">$ENV{SERVER_ADMIN}</a>)] : |
288 | "this site's webmaster"; |
289 | my ($outer_message) = <<END; |
290 | For help, please send mail to $wm, giving this error message |
291 | and the time and date of the error. |
292 | END |
293 | ; |
54310121 |
294 | print STDOUT "Content-type: text/html\n\n"; |
424ec8fa |
295 | |
296 | if ($CUSTOM_MSG) { |
297 | if (ref($CUSTOM_MSG) eq 'CODE') { |
298 | &$CUSTOM_MSG($msg); # nicer to perl 5.003 users |
299 | return; |
300 | } else { |
301 | $outer_message = $CUSTOM_MSG; |
302 | } |
303 | } |
304 | |
54310121 |
305 | print STDOUT <<END; |
306 | <H1>Software error:</H1> |
307 | <CODE>$msg</CODE> |
308 | <P> |
424ec8fa |
309 | $outer_message; |
54310121 |
310 | END |
424ec8fa |
311 | ; |
312 | } |
313 | |
314 | # Cut and paste from CGI.pm so that we don't have the overhead of |
315 | # always loading the entire CGI module. |
316 | sub to_filehandle { |
317 | my $thingy = shift; |
318 | return undef unless $thingy; |
319 | return $thingy if UNIVERSAL::isa($thingy,'GLOB'); |
320 | return $thingy if UNIVERSAL::isa($thingy,'FileHandle'); |
321 | if (!ref($thingy)) { |
322 | my $caller = 1; |
323 | while (my $package = caller($caller++)) { |
324 | my($tmp) = $thingy=~/[\':]/ ? $thingy : "$package\:\:$thingy"; |
325 | return $tmp if defined(fileno($tmp)); |
326 | } |
327 | } |
328 | return undef; |
54310121 |
329 | } |
330 | |
331 | 1; |