Re: Taint problem opening file to write

From what I gather, your tainting is not from the filename (because you SEEM to have untainted it). However, you should be very wary of this:

open(FILE,">$file"); vs. open(FILE,"> $file");

The first one (if untainted properly), will make sure there are no leading spaces in the filename. The second, may or may not work how you suspect, and just MIGHT be the cause of the problem. I don't think I've read any book that uses open(F,"> $file");.

Looking at your code a third time, I noticed that you don't bother to look for leading or trailing spaces (regex \s) in $file_out. So, let's just eliminate part of that problem with a: $file_out =~ s/\s+//;.

Hope that helps some...

Theodore Charles III
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(jeffa) Re: Taint problem opening file to write by jeffa (Bishop) on Apr 30, 2002 at 14:26 UTC
Here is where i recommend the 3-arg form of open. From the docs: Use 3-argument form to open a file with arbitrary weird characters in it, `open(FILE, '<', $file);` [download] otherwise it's necessary to protect any leading and trailing whitespace: `$file =~ s#^(\s)#./$1#; open(FOO, "< $file\0");` [download] jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l] [select]
Re: Re: Taint problem opening file to write by derby (Abbot) on Apr 30, 2002 at 14:37 UTC
Necos, from my version of the open documention (perl 5.6.1) but not the online monks version of the open doc - In the 2-arguments (and 1-argument) form of the call the mode and filename should be concatenated (in this order), possibly separated by spaces. so you can separate the mode from the filename by a space (and the code in doio.c backs that up) but you're right, it's not idiomatic. -derby	[reply]


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