The purpose of the program is to write data files into a specific subdirectory of the users' home directories, e.g. /home/username/datadir/datafile.timestamp.txt.

datadir is only writable by the program and readable by the user. But since it's inside the user's home directory the user could rename it an replace it with a symlink or re-create it and put a symlink with the datafile name inside.

Of course, the obvious solution is to change the filesystem layout but that is currently not an option. So the program needs to open the directory and the data file with O_NOFOLLOW to avoid writing to the wrong places.

The desired behavior when encountering a symlink is to refuse writing the data and produce a warning message. This case is rare enough that it's not too much hassle.

The readdir() part is just a minor issue and it might get removed in the future but it feels a bit clumsy right now. And since fdopendir() is part of POSIX.1-2008 one might hope to find it in a current Perl version.

Anyway, thanks for all your replies. I guess I'll put up with the chdir() solution.

In reply to Re^2: readdir() on a sysopen() handle? by perlhuhn
in thread readdir() on a sysopen() handle? by perlhuhn

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