From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, Lars Schneider <larsxschneider@gmail.com>,
Eric Wong <e@80x24.org>,
Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH v3 2/3] sha1_file: open window into packfiles with O_CLOEXEC
Date: Wed, 26 Oct 2016 00:25:55 -0400 [thread overview]
Message-ID: <20161026042555.neaxvnmggtcku5cc@sigill.intra.peff.net> (raw)
In-Reply-To: <20161025181621.4201-3-gitster@pobox.com>
On Tue, Oct 25, 2016 at 11:16:20AM -0700, Junio C Hamano wrote:
> diff --git a/sha1_file.c b/sha1_file.c
> index 5d2bcd3ed1..09045df1dc 100644
> --- a/sha1_file.c
> +++ b/sha1_file.c
> @@ -1571,12 +1571,17 @@ int git_open(const char *name)
> if (fd >= 0)
> return fd;
>
> - /* Might the failure be due to O_NOATIME? */
> - if (errno != ENOENT && sha1_file_open_flag) {
> - sha1_file_open_flag = 0;
> + /* Try again w/o O_CLOEXEC: the kernel might not support it */
> + if ((sha1_file_open_flag & O_CLOEXEC) && errno == EINVAL) {
> + sha1_file_open_flag &= ~O_CLOEXEC;
> continue;
> }
So if we start with O_CLOEXEC|O_NOATIME, we drop CLOEXEC here and try
again with just O_NOATIME. And then if _that_ fails...
> + /* Might the failure be due to O_NOATIME? */
> + if (errno != ENOENT && (sha1_file_open_flag & O_NOATIME)) {
> + sha1_file_open_flag &= ~O_NOATIME;
> + continue;
> + }
We drop O_NOATIME, and end up with an empty flag field.
But we will never have tried just O_CLOEXEC, which might have worked.
Because of the order here, this would not be a regression (i.e., any
system that used to work will still eventually find a working comb), but
it does mean that systems without O_NOATIME do not get the benefit of
the new O_CLOEXEC protection.
Unfortunately, I think covering all of the cases would be 2^nr_flags.
That's only 4 right now, but it does not bode well as a pattern.
I'm not sure it's worth worrying about or not; I don't know which
systems are actually lacking either of the flags, or if they tend to
have both.
-Peff
next prev parent reply other threads:[~2016-10-26 4:26 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-24 18:02 [PATCH v2 0/2] Use CLOEXEC to avoid fd leaks larsxschneider
2016-10-24 18:02 ` [PATCH v2 1/2] sha1_file: open window into packfiles with CLOEXEC larsxschneider
2016-10-25 10:27 ` Johannes Schindelin
2016-10-25 16:58 ` Junio C Hamano
2016-10-24 18:03 ` [PATCH v2 2/2] read-cache: make sure file handles are not inherited by child processes larsxschneider
2016-10-24 18:39 ` Eric Wong
2016-10-24 19:53 ` Junio C Hamano
2016-10-25 10:33 ` Johannes Schindelin
2016-10-25 17:02 ` Junio C Hamano
2016-10-24 19:22 ` Johannes Sixt
2016-10-24 19:53 ` Lars Schneider
2016-10-25 21:39 ` Johannes Sixt
2016-10-24 18:23 ` [PATCH v2 0/2] Use CLOEXEC to avoid fd leaks Junio C Hamano
2016-10-25 11:27 ` Johannes Schindelin
2016-10-25 18:16 ` [PATCH v3 0/3] quick reroll of Lars's git_open() w/ O_CLOEXEC Junio C Hamano
2016-10-25 18:16 ` [PATCH v3 1/3] sha1_file: rename git_open_noatime() to git_open() Junio C Hamano
2016-10-25 18:16 ` [PATCH v3 2/3] sha1_file: open window into packfiles with O_CLOEXEC Junio C Hamano
2016-10-26 4:25 ` Jeff King [this message]
2016-10-26 16:23 ` Junio C Hamano
2016-10-26 16:47 ` Jeff King
2016-10-26 17:52 ` Junio C Hamano
2016-10-26 20:17 ` Jeff King
2016-10-26 21:15 ` Junio C Hamano
2016-10-27 10:24 ` Jeff King
2016-10-27 21:49 ` Junio C Hamano
2016-10-27 22:38 ` Linus Torvalds
2016-10-27 22:56 ` Junio C Hamano
2016-10-27 23:09 ` Linus Torvalds
2016-10-27 23:19 ` Linus Torvalds
2016-10-27 23:36 ` Junio C Hamano
2016-10-27 23:44 ` Linus Torvalds
2016-10-28 1:08 ` Junio C Hamano
2016-10-28 2:37 ` Junio C Hamano
2016-10-28 5:51 ` Eric Wong
2016-10-28 11:11 ` Johannes Schindelin
2016-10-28 16:13 ` Linus Torvalds
2016-10-28 16:48 ` Junio C Hamano
2016-10-28 17:38 ` Linus Torvalds
2016-10-28 17:47 ` Junio C Hamano
2016-10-29 1:26 ` Junio C Hamano
2016-10-29 8:25 ` Johannes Schindelin
2016-10-29 17:06 ` Linus Torvalds
2016-10-31 17:37 ` Junio C Hamano
2016-10-31 13:56 ` Jeff King
2016-10-31 17:55 ` Junio C Hamano
2016-10-31 18:05 ` Jeff King
2016-10-28 13:32 ` Junio C Hamano
2016-10-28 13:33 ` Junio C Hamano
2016-10-28 7:51 ` Jeff King
2016-10-25 18:16 ` [PATCH v3 3/3] read-cache: make sure file handles are not inherited by child processes Junio C Hamano
2016-10-25 21:33 ` Eric Wong
2016-10-25 22:54 ` Junio C Hamano
2016-10-25 21:48 ` [PATCH v3 0/3] quick reroll of Lars's git_open() w/ O_CLOEXEC Lars Schneider
2016-10-25 22:56 ` Junio C Hamano
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