According to perlport's note on stat, the device and inode information returned by stat are not meaningful or reliable on some systems. Is there a way of knowing if they are meaningful on the current system? Perhaps a Config variable contains this information?

Update: Background info:

I'm trying to determine if a given file has already been read and processed. If it has, I'll just use the data in memory instead of processing the file a second time. False negatives are acceptable. False positives are not. 

sub canonize_file_name {
   ???
}

my $id = canonize_file_name($file_name);
if (not exists $forest{$id}) {
   $forest{$id} = Tree->new($file_name);
}
return $forest{$id};

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I plan to use File::Spec's rel2abs and case_tolerant, but I thought I might use the device+inode on systems where it is supported. Is it possible to determine if this is such a system? Is there an existing module that does any of this?

Update: Progress:

Cache::AgainstFile looks good. Still need to handle canonisation.

In reply to Is device+inode meaningful? by ikegami

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