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Re: Creating a file with Open
by Jouke (Curate) on Oct 03, 2000 at 11:32 UTC
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brrr...next time try to format the code like this:
open (UPLOAD, "+>$user_name" ) || print_error_page ("Can't open your s
+ubmit directory.");
flock(UPLOAD, $LOCK_EX) || print_error_page("Can't flock your submit d
+irectory.");
It's possible that the permissions on the directory you are writing in are not sufficient. It's a good idea to include $! (the system-errormessage) in the string you're printing with print_error_page(). In that case you can tell why the file is not created. (it should be possible to do this...)
HTH
Jouke Visser, Perl 'Adept'
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(jcwren) Re: Creating a file with Open
by jcwren (Prior) on Oct 03, 2000 at 15:28 UTC
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Most likely it's a problem with file permissions. The webserver typically runs with a userid of 'nobody', and is not permitted to write most places. If you're trying to write a file to the user's home directory, for example, it's highly unlikely (and would be highly improper) if the webserver were allowed to write there.
Often, people create a directory off of /home/httpd/, and give 'nobody' special permission to write there.
--Chris
e-mail jcwren | [reply] |
RE (tilly) 1: Creating a file with Open
by tilly (Archbishop) on Oct 03, 2000 at 16:04 UTC
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Everyone has already said to include $! in the error
message. This is important but it is only a start.
You should also do as perlstyle says and include
$user_name.
And personally I would begin sweating at trusting user input
for filenames. Have you verified that the name looks like
what you think it should? See perlsec for more on that
issue.
And btw that code for flocking will not give you the
protection you want, open it "+<$user_name" or else it
gets wiped out before you try to lock it. | [reply] |
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And btw that code for flocking will not give you the protection you want, open it "+<$user_name" or else it gets wiped out before you try to lock it.
I'm confused here. Everyone else has been saying "+>$user_name" which makes sense to me. Is your suggestion a typo, or am I missing something fundamental here?
Guildenstern
Negaterd character class uber alles!
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My point is not a typo.
Both "+<$user_name" and "+>$user_name" open the file for both reading and writing, but the first opens it for reading, and you can also write, while the second opens it for writing, but you can also read. Therefore the second wipes out the possibly existing file for you, while the first does not.
Wiping out the file before you lock it and ensure it is not in use is unlikely to be desired. I call that, ERACE. (Sorry, didn't even try to hold that one back. :-)
If this confuses you, just use sentinel files as in Simple Locking since I already dealt with all of this there.
EDIT
Somehow I said "suggestion" where I meant "typo". Fixed.
EDIT 2
Some days I should not post. Thanks isotope for pointing out I meant "while the first does not". *sigh*
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Opening the file "+>" will wipe it out, so flocking it
is then pretty pointless - you destroy the file before
you've gained the lock on it.
You need to open the file "+<", if that failed then
open it "+>" then flock it then truncate it if
you want to be safe with your flocking in the presence of
other readers.
Note that if you want to read the file back in with flocking you
need to use "+<" so that you open the file with
write intent otherwise the flocking may not work properly
(I don't understand the reasons for this but that is what
it says in the man pages!)
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Re: Creating a file with Open
by c-era (Curate) on Oct 03, 2000 at 15:32 UTC
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If you want to get the error change your code to this:
open (UPLOAD, "+>$user_name" ) || print_error_page ("Can't open your s
+ubmit directory.<br>$!");
flock(UPLOAD, $LOCK_EX) || print_error_page("Can't flock your submit d
+irectory.<br>$!");
The $! will print out the error for you. | [reply]
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