EvanK has asked for the wisdom of the Perl Monks concerning the following question:

This might sound like a strange one, but I need to have all the errors that display in the CGI interface of my program to NOT have the script name or line numbers. For example, I'm using CGI::Carp to intercept any fatal errors: 
use strict;
use CGI::Carp qw/fatalsToBrowser set_message/;

BEGIN {
  sub die_nice { # this will intercept any fatals
    my $err = shift;
    print "<html>\n<body>\n<h1>Custom CGI Error</h1>\n";
    print "<pre>$err</pre>\n";
    print "[script-specific error/dump info goes here]\n";
    print "</body>\n</html>\n";
    warningsToBrowser(1);
  }
  set_message(\&die_nice);
}

die('[this is the message passed to die]');

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Now, running this code would (more or less) produce this in my browser: 
[this is the message passed to die] at /home/evan/dietest.cgi line 18.

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The thing is, once I put it into production, I'd only want the users to see [this is the message passed to die] while the full error would still appear in the apache error log. the only way I can think of doing this is to filter the error message like so: 
sub die_nice {
  my $err = shift;
  $err =~ s/ at \S+ line \d+//g
  
  print "<html>\n<body>\n<h1>Custom CGI Error</h1>\n";
  print "<pre>$err</pre>\n";
  print "[script-specific error/dump info goes here]\n";
  print "</body>\n</html>\n";
  warningsToBrowser(1);
}

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This will work, mind you (im using it right now), but it seems like a hacky solution, plus what if the regex matches some other part of a strangely worded error...is there a Better Way™?

__________
Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
- Terry Pratchett

Replies are listed 'Best First'.
Re: error messages without program names or line numbers
by BrowserUk (Patriarch) on Aug 04, 2006 at 15:50 UTC

    If you append a newline to the message you pass to die then it will not append the extra info. This convention is honoured by Carp and by implication probably by CGI::Carp also.

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]

      If you append a newline to the message you pass to die then it will not append the extra info.

      But then the extra info won't be in the log either. Still ... I suppose you can have some variation of this? 

      warn($_), die "$_\n" for 'my error message';

      [download]

      print "Just another Perl ${\(trickster and hacker)},"
      The Sidhekin proves Sidhe did it!

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[d/l]
[select]
        Both excellent points, ++ to both of you, but the bigger problem (as I admittedly should have elaborated on) is how to catch errors I don't have dominion over?

        For instance, a database error with RaiseError turned on will display a whole mess of crap.

        of course, i think compile-time and/or syntax errors may occur before CGI::Carp can catch them, but I'm more concerned with outside forces, such as assorted modules.

        __________
        Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
        - Terry Pratchett

[reply]
[d/l]
Re: error messages without program names or line numbers
by perladdict (Chaplain) on Aug 04, 2006 at 20:31 UTC
    Hi EvanK,
    premature death in a CGI script tends to cause server errors when the proper HTTP header doesn't get out to the server before the program pegs out.
    . the function carpout redirects the warnings & errors to the filehandle specified in script.
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      From Chapter 32.5 of Programming Perl Version 3 "CGI::Carp":

      The module is also kinder to web surfers, since premature death in a CGI script tends to cause inscrutable "Server 500" errors when the proper HTTP header doesn't get out to the server before your program pegs out, and this module makes sure that doesn't happen.  The carpout function redirects all warnings and errors to the filehandle specified.

      perladdict, please be careful to attribute sources when you are quoting them, otherwise it might tend to appear that you are taking credit for words which were not originally yours.

      s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/
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