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From: Junio C Hamano <gitster@pobox.com>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: Kim Gybels <kgybels@infogroep.be>,
	Johannes Schindelin <johannes.schindelin@gmx.de>,
	git@vger.kernel.org
Subject: Re: [PATCH 0/3] Supplements to "packed_ref_cache: don't use mmap() for small files"
Date: Wed, 17 Jan 2018 13:52:51 -0800	[thread overview]
Message-ID: <xmqqvag0qhjg.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <cover.1516017331.git.mhagger@alum.mit.edu> (Michael Haggerty's message of "Mon, 15 Jan 2018 13:17:32 +0100")

Michael Haggerty <mhagger@alum.mit.edu> writes:

> So I will follow up this email with three patches:
>
> 1. Mention that `snapshot::buf` can be NULL for empty files
>
>    I suggest squashing this into your patch, to make it clear that
>    `snapshot::buf` and `snapshot::eof` can also be NULL if the
>    `packed-refs` file is empty.
>
> 2. create_snapshot(): exit early if the file was empty
>
>    Avoid undefined behavior by returning early if `snapshot->buf` is
>    NULL.
>
> 3. find_reference_location(): don't invoke if `snapshot->buf` is NULL
>
>    Avoid undefined behavior and confusing semantics by not calling
>    `find_reference_location()` when `snapshot->buf` is NULL.

These look all sensible with today's code and with v2 from this
thread.

With the v3, i.e. "do the xmalloc() even for size==0", however,
snapshot->buf would never be NULL, so I'd shelve them for now,
though.

Thanks.

  parent reply	other threads:[~2018-01-17 21:52 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-13 16:11 [PATCH] packed_ref_cache: don't use mmap() for small files Kim Gybels
2018-01-13 18:56 ` Johannes Schindelin
2018-01-14 19:14 ` [PATCH v2] " Kim Gybels
2018-01-15 12:17   ` [PATCH 0/3] Supplements to "packed_ref_cache: don't use mmap() for small files" Michael Haggerty
2018-01-15 12:17     ` [PATCH 1/3] SQUASH? Mention that `snapshot::buf` can be NULL for empty files Michael Haggerty
2018-01-15 12:17     ` [PATCH 2/3] create_snapshot(): exit early if the file was empty Michael Haggerty
2018-01-15 12:17     ` [PATCH 3/3] find_reference_location(): don't invoke if `snapshot->buf` is NULL Michael Haggerty
2018-01-17 20:23     ` [PATCH 0/3] Supplements to "packed_ref_cache: don't use mmap() for small files" Johannes Schindelin
2018-01-17 21:52     ` Junio C Hamano [this message]
2018-01-15 21:15 ` [PATCH] packed_ref_cache: don't use mmap() for small files Jeff King
2018-01-15 23:37   ` Kim Gybels
2018-01-15 23:52     ` Jeff King
2018-01-16 19:38       ` [PATCH v3] " Kim Gybels
2018-01-17 22:09         ` Jeff King
2018-01-21  4:41           ` Michael Haggerty
2018-01-22 19:31             ` Junio C Hamano
2018-01-24 11:05               ` Michael Haggerty
2018-01-24 11:14                 ` [PATCH 0/6] Yet another approach to handling empty snapshots Michael Haggerty
2018-01-24 11:14                   ` [PATCH 1/6] struct snapshot: store `start` rather than `header_len` Michael Haggerty
2018-01-24 20:36                     ` Jeff King
2018-01-24 11:14                   ` [PATCH 2/6] create_snapshot(): use `xmemdupz()` rather than a strbuf Michael Haggerty
2018-01-24 11:14                   ` [PATCH 3/6] find_reference_location(): make function safe for empty snapshots Michael Haggerty
2018-01-24 20:27                     ` Jeff King
2018-01-24 21:11                       ` Junio C Hamano
2018-01-24 21:34                         ` Jeff King
2018-01-24 11:14                   ` [PATCH 4/6] packed_ref_iterator_begin(): make optimization more general Michael Haggerty
2018-01-24 20:32                     ` Jeff King
2018-01-24 11:14                   ` [PATCH 5/6] load_contents(): don't try to mmap an empty file Michael Haggerty
2018-01-24 11:14                   ` [PATCH 6/6] packed_ref_cache: don't use mmap() for small files Michael Haggerty
2018-01-24 20:38                   ` [PATCH 0/6] Yet another approach to handling empty snapshots Jeff King
2018-01-24 20:54                   ` Junio C Hamano
2018-02-15 16:54                   ` Johannes Schindelin
2018-01-24 18:05                 ` [PATCH v3] packed_ref_cache: don't use mmap() for small files Junio C Hamano

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