IIRC files must be readable o+r, directories read and executable o+rx

r is not strictly required for directories, missing read permissions on a directory only prevent you from listing the directory (ls and opendir will fail). To access items in a directory, you only need "cross" (executable) permissions on the directory, and sufficient permissions on the directory items.

For shared libraries (*.so), it actually depends on the OS implementation. Some Unix systems require them to be executable, for others, read permissions are sufficient. On Linux, you can have both variants, depending on the distribution.

Alexander

So is Perl accessing modules without checking the surrounding directory?

Probably...

At least in the case of perldoc - which is not relevant here - r would be needed on directories.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}

So is Perl accessing modules without checking the surrounding directory?

Probably...

Yes. Why should it be done in any other way? Perl needs to read some files with known names. So for each file, it calls open(), perhaps through several layers of libraries. That may succeed or fail. Why should perl (or any other application) check directories for that? Even stat() and lstat() only need execute permission on all of the directories leading to the file passed to stat()/lstat(), no read permissions.

The operating system does check the directories, like the desired file, for sufficient permissions and other things. See "ERRORS" in open() and path_resolution.

The only reason for needing read permissions on a directory is when you need a list of file names, e.g. for an (insecure) plugin system that loads all files as plugins that match some criteria on file names.

Nevertheless, directories commonly have either both r and x bits sets, or none of them. Having only the r bit set does not make much sense, having only the x bit set may be useful in some security-related scenarios.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

So is Perl accessing modules without checking the surrounding directory?

Perl is asking the operating system for the files. If the OS thinks it's OK it returns the contents of the files, otherwise it doesn't and one gets permission denied. In my linux, reading a file is permitted when the surrounding directory has "x" set (executable bit) for the reader user.