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我運行的Apache2 CGI腳本，我在error.log中這個警戒線（我刪除從輸出所有類似行）：爲什麼在mod_perl下使用「使用常量」來獲得「重新定義」警告？
[Thu Jul 30 09:39:37 2009] upload.pl: Constant subroutine ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::UPLOAD_DIR redefined at /usr/share/perl/5.10/constant.pm line 115, line 133.
Constant subroutine
ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::BUFFER_SIZE redefined at /usr/share/perl/5.10/constant.pm line 115, line 133 (#1)
[Thu Jul 30 09:39:37 2009] upload.pl: Constant subroutine ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::BUFFER_SIZE redefined at /usr/share/perl/5.10/constant.pm line 115, line 133.
Constant subroutine
ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::MAX_FILE_SIZE redefined at /usr/share/perl/5.10/constant.pm line 115, line 133 (#1)
[Thu Jul 30 09:39:37 2009] upload.pl: Constant subroutine ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::MAX_FILE_SIZE redefined at /usr/share/perl/5.10/constant.pm line 115, line 133.
Constant subroutine
ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::MAX_DIR_SIZE redefined at /usr/share/perl/5.10/constant.pm line 115, line 133 (#1)
[Thu Jul 30 09:39:37 2009] upload.pl: Constant subroutine ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::MAX_DIR_SIZE redefined at /usr/share/perl/5.10/constant.pm line 115, line 133.
Constant subroutine
ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::MAX_OPEN_TRIES redefined at /usr/share/perl/5.10/constant.pm line 115, line 133 (#1)
[Thu Jul 30 09:39:37 2009] upload.pl: Constant subroutine ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::MAX_OPEN_TRIES redefined at /usr/share/perl/5.10/constant.pm line 115, line 133.
Subroutine dir_size redefined at /home/stanislav/cgi/perl/upload.pl line 79,
line 133 (#2)
[Thu Jul 30 09:39:37 2009] upload.pl: Subroutine dir_size redefined at /home/stanislav/cgi/perl/upload.pl line 79, line 133.
Subroutine error redefined at /home/stanislav/cgi/perl/upload.pl line 90,
line 133 (#2)
[Thu Jul 30 09:39:37 2009] upload.pl: Subroutine error redefined at /home/stanislav/cgi/perl/upload.pl line 90, line 133.
Argument "" isn't numeric in numeric ge (>=) at
/home/stanislav/cgi/perl/upload.pl line 62 (#4)
[Thu Jul 30 09:39:37 2009] -e: Argument "" isn't numeric in numeric ge (>=) at /home/stanislav/cgi/perl/upload.pl line 62.
Filehandle OUTPUT opened only for input at /home/stanislav/cgi/perl/upload.pl
line 69 (#5)
[Thu Jul 30 09:39:37 2009] -e: Filehandle OUTPUT opened only for input at /home/stanislav/cgi/perl/upload.pl line 69.
Constant subroutine
ModPerl::ROOT::ModPerl::Registry::home_stanislav_cgi_perl_upload_2epl::UPLOAD_DIR redefined at /usr/share/perl/5.10/constant.pm line 115, line 133 (#1)
爲什麼這行是有，是有辦法阻止他們？使這個警告
代碼（從書「用Perl CGI編程」拍攝，修正了一些錯誤 ）：
#!/usr/bin/perl
use strict;
use warnings;
use CGI;
use CGI::Carp;
#use diagnostics qw/-verbose/;
use Fcntl qw(:DEFAULT :flock);
use constant UPLOAD_DIR => "/tmp/test_upload/";
use constant BUFFER_SIZE => 16_384;
use constant MAX_FILE_SIZE => 1_048_576; # Limit each upload to 1 MB
use constant MAX_DIR_SIZE => 100 * 1_048_576; # Limit total uploads to 100 MB
use constant MAX_OPEN_TRIES => 100;
$CGI::DISABLE_UPLOADS = 0;
$CGI::POST_MAX = MAX_FILE_SIZE;
my $q = new CGI;
$q->cgi_error and error($q, "Error transferring file: " . $q->cgi_error);
my $file = $q->param("file") || error($q, "No file received.");
my $filename = $q->param("filename") || error($q, "No filename entered.");
my $fh = $q->upload("file") || error($q, "Something is wrong with file handle.");
#my $fh = $q->upload($file);
my $buffer = "";
if (dir_size(UPLOAD_DIR) + $ENV{CONTENT_LENGTH} > MAX_DIR_SIZE) {
error($q, "Upload directory is full.");
}
# Allow letters, digits, periods, underscores, dashes
# Convert anything else to an underscore
$filename =~ s/[^\w.-]/_/g;
if ($filename =~ /^(\w[\w.-]*)/) {
$filename = $1;
}
else {
error($q, "Invalid file name; files must start with a letter or number.");
}
# Open output file, making sure the name is unique
until (sysopen OUTPUT, UPLOAD_DIR . $filename, O_CREAT | O_EXCL) {
$filename =~ s/(\d*)(\.\w+)$/($1||0) + 1 . $2/e;
$1 >= MAX_OPEN_TRIES and error($q, "Unable to save your file.");
}
# This is necessary for non-Unix systems; does nothing on Unix
binmode $fh;
binmode OUTPUT;
# Write contents to output file
while (read($fh, $buffer, BUFFER_SIZE)) {
print OUTPUT $buffer;
}
close OUTPUT;
if (-T $fh) {
print $q->header("text/plain");
seek $fh, 0, 0;
map { print } ;
}
sub dir_size {
my $dir = shift;
my $dir_size = 0;
# Loop through files and sum the sizes; doesn't descend down subdirs
opendir DIR, $dir or die "Unable to open $dir: $!";
while ($_ = readdir DIR) {
$dir_size += -s "$dir/$_";
}
return $dir_size;
}
sub error {
my($q, $reason) = @_;
print $q->header("text/html"),
$q->start_html("Error"),
$q->h1("Error"),
$q->p("Your upload was not procesed because the following error ",
"occured: "),
$q->p($q->i($reason)),
$q->end_html;
exit;
}
這段代碼有類似的輸出： $ perl -e 'sub FOO() { 1 } BEGIN{ *FOO = sub() { 2 }; } print FOO;'
Constant subroutine main::FOO redefined at -e line 1.
I did put no warnings qw/redefine/但它並沒有幫助。