Re: gtags and symbolic links

[Petr Uzel]

Hi again,

On Thu, May 14, 2009 at 07:44:50PM +0900, Shigio YAMAGUCHI wrote:
> Hi,
> > First of all, I'm thinking about implementing the nofollow option for 
> > gtags, as
> > proposed on [2]. My question is, how exactly should this behave: should that
> > only omit symbolic links that point to a directory or should that ignore
> > symbolic links completely (e.g. ./foo.c pointing to ./bar.c) ?
> 
> I have not thought about details yet.
> Is there something proposal?

My proposal is to introduce new 'nofollow' option for gtags that would
make gtags not to descend to symbolic links pointing to directories.

> 
> > When thinking about it and looking into the code, I don't quite understand 
> > the
> > following part of find_read_traverse()  (libutil/find.c):
> ...
> > To be specific, what's the purpose of lines 539-551? If I'm not mistaken, 
> > the
> > test at line 545 can never succeed because it is the opposite of the test at
> > line 538.
> 
> It might be so. But at present, this code is harmless.

OK, that's what I've thought.

> 
> > Next, is there any benefit of determining the type of a file in getdirs()
> > function (I mean prefixing the filename with f,d) instead of determining =
> > the
> > type directly in the find_read_traverse() function?
> 
> This is due to a historical reason.
> In some systems like BSD, dirent structure has a member named 'd_type' which
> describes file type. Determining type by it, we can avoid to calling stat(2)
> for each files.  But another systems like GNU/Linux doesn't has it.
> I wanted to hide the difference in a basic function, getdirs().
> 
> By the way, GLOBAL doesn't use the 'd_type' currently due to the following 
> bug:
> [http://lists.gnu.org/archive/html/bug-global/2003-08/msg00002.html]

Thanks for clarifiction. Manpage for linux readdir states that the
d_type isn't supported by all filesystems, so it IMHO means that you
can't rely on that (IOW it's not a bug but a feature). Is the
performance gain of using d_type on BSD's worth the trouble with
maintaining getdirs() ?

> 
> > And finally: what actually made me start thinking about this is fact that 
> > gtags
> > can not treat recursive links, like in [3]. This actually makes it 
> > difficult to
> > use gtags on directories created by quilt setup, because quilt creates 
> > exactly
> > this type of directory structure (for a good reason). This could be worked
> > around by the nofollow option, but IMHO the recursive link detection should 
> > be
> > done also in default mode - what do you think?
> 
> What is quilt setup?

http://linux.die.net/man/1/quilt

quilt setup is a 'quilt subcommand' intended to help maintaining
RPM's. Given a specfile and a tarball with sources, it extracts the
tarball, cds to this directory and creates symbolic link pointing to
'..' -> so running gtags in the directory with sources fails.

> What should GLOBAL do?

It should detect and ignore recursive links (like find,ctags,cscope,.... do).


Thanks,

-- 
Best regards / s pozdravem

Petr Uzel, Packages maintainer
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