[Dovecot] Re: Bug#224092: Dovecot IMAP: detection of folders

[Miquel van Smoorenburg]

On Sat, 20 Dec 2003 17:47:20, Timo Sirainen wrote:
> On Dec 20, 2003, at 2:20 PM, Jeroen van Disseldorp wrote:
> 
> > On Saturday 20 December 2003 04:40, Timo Sirainen wrote:
> >> If I did add special check for ".imap", it would mean that you
> >> couldn't create a root folder called "imap" which I think some people
> >> might actually do.
> >
> > I understand. However, making a simple check for being a file or
> > directory wouldn't harm anyone. As .subscriptions, .customflags
> > and .imap* are all files, interpreting them as folders would generate
> > errors anyhow. If .imap* is somehow renamed to .whatever or
> > dovecot-whatever, the check would still hold as files would never be
> > interpreted as mail folders.
> 
> It would hurt performance with very little gain. Now I can just do it 
> all with opendir() and readdir() which is usually 2-3 syscalls. If I 
> wanted to know if each entry is file or directory, I'd have to call 
> stat() for each entry. This could be done for those few special cases I 
> guess, but I wouldn't add it for everything..

Modern filesystems return more info from readdir() than just the
filename. Check out the d_type field of the direct struct. If it's
DT_REG it's a file; it it's DT_DIR it's a directory; if it's DT_UNKNOWN
the file system doesn't support it and you have to do a stat().

Mike.