From: Junio C Hamano <gitster@pobox.com>
To: "Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Han-Wen Nienhuys <hanwen@google.com>,
Han-Wen Nienhuys <hanwenn@gmail.com>
Subject: Re: [PATCH v2 2/3] refs/files-backend: stop setting errno from lock_ref_oid_basic
Date: Wed, 28 Apr 2021 13:20:51 +0900 [thread overview]
Message-ID: <xmqqzgxjavks.fsf@gitster.g> (raw)
In-Reply-To: <db5da7d7fb5178c14c1f5733d35bb69813c9c644.1619191907.git.gitgitgadget@gmail.com> (Han-Wen Nienhuys via GitGitGadget's message of "Fri, 23 Apr 2021 15:31:46 +0000")
"Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com> writes:
> From: Han-Wen Nienhuys <hanwen@google.com>
>
> Errno is a global variable written by almost all system calls, and therefore it
> is hard to reason about its state.
>
> This is a functional noop, because calls to lock_ref_oid_basic() in this file
> are followed by:
>
> * lock_ref_oid_basic (copy/rename rollback error path)
>
> * write_ref_to_lockfile (both in the rollback path and the success path of
> copy/rename)
>
> * create_symref_locked (files_create_symref)
>
> * refs_reflog_exists (reflog expiry)
>
> These calls do I/O and therefore clobber errno. They are not inspecting the
> incoming errno.
Hmph, are you saying that these calls do I/O and always the I/O
would fail? A system call that is successfull don't touch errno;
only the calls that resulted in failure do.
next prev parent reply other threads:[~2021-04-28 4:20 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 10:24 [PATCH] refs: remove EINVAL specification from the errno sideband in read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-04-23 12:57 ` Jeff King
2021-04-23 15:25 ` Han-Wen Nienhuys
2021-04-23 15:31 ` [PATCH v2 0/3] refs: cleanup errno sideband ref related functions Han-Wen Nienhuys via GitGitGadget
2021-04-23 15:31 ` [PATCH v2 1/3] refs: remove EINVAL specification from the errno sideband in read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-04-23 15:31 ` [PATCH v2 2/3] refs/files-backend: stop setting errno from lock_ref_oid_basic Han-Wen Nienhuys via GitGitGadget
2021-04-28 4:20 ` Junio C Hamano [this message]
2021-04-28 10:55 ` Han-Wen Nienhuys
2021-04-29 1:55 ` Junio C Hamano
2021-04-29 8:52 ` Han-Wen Nienhuys
2021-04-23 15:31 ` [PATCH v2 3/3] refs: make errno output explicit for read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
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