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From: Junio C Hamano <gitster@pobox•com>
To: Jeff King <peff@peff•net>
Cc: Jorge <griffin@gmx•es>, git@vger•kernel.org
Subject: Re: [PATCH 4/4] config.c: rewrite ENODEV into EISDIR when mmap fails
Date: Thu, 28 May 2015 10:11:55 -0700	[thread overview]
Message-ID: <xmqq7frsiq3o.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20150528080300.GD23395@peff.net> (Jeff King's message of "Thu, 28 May 2015 04:03:01 -0400")

Jeff King <peff@peff•net> writes:

> If we try to mmap a directory, we'll get ENODEV. This
> translates to "no such device" for the user, which is not
> very helpful. Since we've just fstat()'d the file, we can
> easily check whether the problem was a directory to give a
> better message.
>
> Signed-off-by: Jeff King <peff@peff•net>
> ---
> It feels a bit wrong to put this magic conversion here, and not in
> xmmap. But of course xmmap does not have the stat information.
> ...
> diff --git a/config.c b/config.c
> index e7dc155..29fa012 100644
> --- a/config.c
> +++ b/config.c
> @@ -2056,6 +2056,8 @@ int git_config_set_multivar_in_file(const char *config_filename,
>  		contents = xmmap_gently(NULL, contents_sz, PROT_READ,
>  					MAP_PRIVATE, in_fd, 0);
>  		if (contents == MAP_FAILED) {
> +			if (errno == ENODEV && S_ISDIR(st.st_mode))
> +				errno = EISDIR;
>  			error("unable to mmap '%s': %s",
>  			      config_filename, strerror(errno));
>  			ret = CONFIG_INVALID_FILE;

I think this patch places the "magic" at the right place, but I
would have preferred to see something more like this:

	if (contents == MAP_FAILED) {
        	if (errno == ENODEV && S_ISDIR(st.st_mode))
			error("unable to mmap a directory '%s',
                        	config_filename);
		else
                	error("unable to mmap '%s': %s",
                        	config_filename, strerror(errno));
		ret = CONFIG_INVALID_FILE;

But that is a very minor preference.  I am OK with relying on our
knowledge that strerror(EISDIR) would give something that says "the
thing is a directory which is not appropriate for the operation", as
nobody after that strerror() refers to 'errno' in this codepath.

Thanks.  The patches were a pleasant read.

next prev parent reply	other threads:[~2015-05-28 17:12 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-27 13:29 Bug: .gitconfig folder Jorge
2015-05-27 20:30 ` Junio C Hamano
2015-05-27 22:18   ` Jeff King
2015-05-27 22:24     ` Stefan Beller
2015-05-28  6:13       ` Jeff King
2015-05-27 22:38     ` Junio C Hamano
2015-05-28  7:51       ` Jeff King
2015-05-28  7:54         ` [PATCH 1/4] read-cache.c: drop PROT_WRITE from mmap of index Jeff King
2015-05-28  7:54         ` [PATCH 2/4] config.c: fix mmap leak when writing config Jeff King
2015-06-30 14:34           ` [PATCH] config.c: fix writing config files on Windows network shares Karsten Blees
2015-06-30 14:46             ` Torsten Bögershausen
2015-06-30 16:01               ` Jeff King
2015-06-30 14:52             ` Johannes Schindelin
2015-06-30 16:00             ` Jeff King
2015-05-28  7:56         ` [PATCH 3/4] config.c: avoid xmmap error messages Jeff King
2015-05-28  8:03         ` [PATCH 4/4] config.c: rewrite ENODEV into EISDIR when mmap fails Jeff King
2015-05-28 17:11           ` Junio C Hamano [this message]
2015-05-28 20:44             ` Jeff King
2015-05-28 21:11               ` Junio C Hamano
2015-05-28 17:06         ` Bug: .gitconfig folder Junio C Hamano

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