Re^9: CGI-Upload / Bad File Number

I tried your example just to see what happens, but i can't find any strange behaviour.
The code passes my whole script as a string without beeing executed. In the end it appears as a post on the message-board without any changes.

I think the point is, that i use single-' characters. So no execution is performed.

But i have to admit:
In the current version it is possible to manipulate the execution by combinations of ' and \ chars or if \ is the last character at all. In this case, the evaluated string will look like this: 'foo\\'bar' or like this: 'foo\';.
In the first case 'bar' will be executed, if it contains perl-code. (I tried this one 6\'+7+\'3. so the evaluated string is '6\\'+7+\\'3'. The result was - as expected - '16').

To avoid this, i sometimes have to protect some \-characters by doubeling them, or simply remove every \-char followed by a '-char...

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Re^10: CGI-Upload / Bad File Number by Anonymous Monk on Jul 19, 2016 at 00:17 UTC
:) I tried your example just to see what happens, but i can't find any strange behaviour. so a taxi is on its way down the road driver asks passanger, where now? passanger says BANANA, and the cars wheel is replaced with a BANANA, and they crash and burn. Thats not strange? that is a feature to look for in a taxi? Same same `#!/usr/bin/perl -- #~ use strict; #~ use warnings; use CGI; my $query = CGI->new( { 'query; system q{echo deleting files}; $query +', 'BANANA', 'z','z' } ); my @names = $query->param; for( @names ){ $val = $query->param($_); eval "\$$_ = '$val';" or warn $@; } __END__ deleting files Can't locate object method "param" via package "BANANA" (perhaps you f +orgot to load "BANANA"?) at - line 8.` [download] Whoops, all the messages are lost ... is the data important? worth money? Red flags are red, where there is one, there are more ...	[reply] [d/l]

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Re^10: CGI-Upload / Bad File Number
by Anonymous Monk on Jul 19, 2016 at 00:17 UTC

I tried your example just to see what happens, but i can't find any strange behaviour.

so a taxi is on its way down the road driver asks passanger, where now?

passanger says BANANA, and the cars wheel is replaced with a BANANA, and they crash and burn.

Thats not strange? that is a feature to look for in a taxi?

Same same

#!/usr/bin/perl --
#~ use strict;
#~ use warnings;
use CGI;
my $query = CGI->new( { 'query; system q{echo deleting files}; $query 
+', 'BANANA', 'z','z' } );
my @names = $query->param;
for( @names ){
    $val = $query->param($_);
    eval "\$$_ = '$val';" or warn $@;
}
__END__
deleting files
Can't locate object method "param" via package "BANANA" (perhaps you f
+orgot to load "BANANA"?) at - line 8.
[download]

Whoops, all the messages are lost ... is the data important? worth money?

Red flags are red, where there is one, there are more ...

[reply]
[d/l]