Re: [PATCH 3/5] read_config: don't try to open file beginning with '.'

From: Yann Droneaud <ydroneaud-RlY5vtjFyJ3QT0dZR+AlfA@public.gmane.org>
To: Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 3/5] read_config: don't try to open file beginning with '.'
Date: Tue, 31 May 2011 23:23:12 +0200	[thread overview]
Message-ID: <1306876992.4475.11.camel@dworkin.quest-ce.net> (raw)
In-Reply-To: <BANLkTimPvmNzOHn8JRkmu=iBU88nNEq9_A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

Hi,

Le mardi 31 mai 2011 à 11:42 -0700, Roland Dreier a écrit :
> On Thu, Mar 31, 2011 at 2:29 AM, Yann Droneaud <ydroneaud-RlY5vtjFyJ3QT0dZR+AlfA@public.gmane.org> wrote:
> > Files beginning with a dot are mostly current and parent directories or,
> > by convention, hidden files.
> >
> > Those path are skipped in find_sysfs_dev().
> 
> Not sure we want to do this. We already skip non-regular files, and
> I'm not sure we want to exclude certain file names.

For example, while testing libibverbs config parsing, I've used emacs to
edit drivers file. And, when emacs open a buffer, it create a lock file
with a leading dot.

So running a libibverbs program prints
libibverbs: Warning: couldn't stat config file
'/tmp/ib/etc/libibverbs.d/.#test'.

Here's a strace output:

open("/tmp/ib/etc/libibverbs.d", O_RDONLY|O_NONBLOCK|O_DIRECTORY|
O_CLOEXEC) = 3
getdents(3, /* 3 entries */, 32768)     = 80
stat("/tmp/ib/etc/libibverbs.d/.#test", 0x7fffe11e8c60) = -1 ENOENT (No
such file or directory)
write(2, "libibverbs: Warning: couldn't st"..., 82) = 82
stat("/tmp/ib/etc/libibverbs.d/.", {st_mode=S_IFDIR|0775,
st_size=4096, ...}) = 0
stat("/tmp/ib/etc/libibverbs.d/..", {st_mode=S_IFDIR|0775,
st_size=4096, ...}) = 0
getdents(3, /* 0 entries */, 32768)     = 0
close(3)                                = 0

Skipping that "normally" hidden file seems a good behavior. Same thing
for those backup files with ~ suffix.

It's mostly harmless, but code which load dynamic modules makes me a
little angry :)

For example, directory libibverbs.d should be owned by root with write
limited write permission, likewise for the driver files.

Regards.

-- 
Yann Droneaud

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