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Date: Tue, 18 Sep 2012 19:47:29 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Roland McGrath <roland@hack.frob.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>, linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Amerigo Wang <amwang@redhat.com>,
        "Jonathan M. Foote" <jmfoote@cert.org>,
        Pedro Alves <palves@redhat.com>
Subject: Re: [PATCH -mm v2] coredump: extend core dump note section to
	contain file names of mapped files
Message-ID: <20120918174729.GA27841@redhat.com>
References: <1347980129-1510-1-git-send-email-vda.linux@googlemail.com> <20120918165819.583252C0A4@topped-with-meat.com> <20120918172720.GA26606@redhat.com>
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On 09/18, Oleg Nesterov wrote:
>
> Or perhaps 'filename = ""' case can handle this case itself. In this
> case we do not even need strlen(), remaining = name - filename.

IOW. Denys, this is up to you and _iirc_ this was already discussed
(just I don't remember the result), but perhaps

	if (IS_ERR(filename)) {
		if (-ENAMETOOLONG) {
			...
			goto retry;
		}
		remaining--;
		*name++ = 0;
	} else {
		remaining = name - filename;
		strcpy(name, filename);
	}

Hmm. And I just noticed that 'filename = ""' case does not verify
there is a room to write a single '\0' :/

So, afaics you also need

	- if (-ENAMETOOLONG)
	+ if (-ENAMETOOLONG || !remaining)

or I missed something.

Oleg.