From: Junio C Hamano <gitster@pobox.com>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Stefan Beller" <sbeller@google.com>, "Jeff King" <peff@peff.net>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"David Turner" <novalis@novalis.org>,
git@vger.kernel.org
Subject: Re: [PATCH 04/23] prefix_ref_iterator: don't trim too much
Date: Thu, 18 May 2017 13:19:31 +0900 [thread overview]
Message-ID: <xmqq1srmvlt8.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <eecc015af8d7ed71223b591b13847fdb56ee69f0.1495014840.git.mhagger@alum.mit.edu> (Michael Haggerty's message of "Wed, 17 May 2017 14:05:27 +0200")
Michael Haggerty <mhagger@alum.mit.edu> writes:
> The `trim` parameter can be set independently of `prefix`. So if some
> caller were to set `trim` to be greater than `strlen(prefix)`, we
> could end up pointing the `refname` field of the iterator past the NUL
> of the actual reference name string.
>
> That can't happen currently, because `trim` is always set either to
> zero or to `strlen(prefix)`. But even the latter could lead to
> confusion, if a refname is exactly equal to the prefix, because then
> we would set the outgoing `refname` to the empty string.
>
> And we're about to decouple the `prefix` and `trim` arguments even
> more, so let's be cautious here. Skip over any references whose names
> are not longer than `trim`.
Should we be silently continuing, or should we use die("BUG") here
instead, if the motivation is to be cautions? Personally, I do not
find this memchr() implementation too bad, especially when our
objective is to play cautious, but strlen() based one is fine, too.
It's not like refname field would point at a run of non-NUL bytes at
the end of the last-mapped page and taking strlen() would segfault,
right?
> + if (iter->trim) {
> + /*
> + * If there wouldn't be at least one character
> + * left in the refname after trimming, skip
> + * over it:
> + */
> + if (memchr(iter->iter0->refname, '\0', iter->trim + 1))
> + continue;
> + iter->base.refname = iter->iter0->refname + iter->trim;
> + } else {
> + iter->base.refname = iter->iter0->refname;
> + }
> +
> iter->base.oid = iter->iter0->oid;
> iter->base.flags = iter->iter0->flags;
> return ITER_OK;
next prev parent reply other threads:[~2017-05-18 4:19 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-17 12:05 [PATCH 00/23] Prepare to separate out a packed_ref_store Michael Haggerty
2017-05-17 12:05 ` [PATCH 01/23] t3600: clean up permissions test properly Michael Haggerty
2017-05-17 12:42 ` Jeff King
2017-05-17 14:01 ` Michael Haggerty
2017-05-18 4:10 ` Junio C Hamano
2017-05-19 3:37 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 02/23] refs.h: clarify docstring for the ref_transaction_update()-related fns Michael Haggerty
2017-05-17 16:46 ` Stefan Beller
2017-05-18 4:13 ` Junio C Hamano
2017-05-17 12:05 ` [PATCH 03/23] ref_iterator_begin_fn(): fix docstring Michael Haggerty
2017-05-17 12:05 ` [PATCH 04/23] prefix_ref_iterator: don't trim too much Michael Haggerty
2017-05-17 12:55 ` Jeff King
2017-05-17 14:11 ` Michael Haggerty
2017-05-17 14:22 ` Jeff King
2017-05-18 4:19 ` Junio C Hamano [this message]
2017-05-18 4:50 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 05/23] refs_ref_iterator_begin(): don't check prefixes redundantly Michael Haggerty
2017-05-17 12:59 ` Jeff King
2017-05-17 14:21 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 06/23] refs: use `size_t` indexes when iterating over ref transaction updates Michael Haggerty
2017-05-17 16:59 ` Stefan Beller
2017-05-18 4:55 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 07/23] ref_store: take `logmsg` parameter when deleting references Michael Haggerty
2017-05-17 13:12 ` Jeff King
2017-05-17 15:01 ` Michael Haggerty
2017-05-17 15:03 ` Jeff King
2017-05-17 12:05 ` [PATCH 08/23] lockfile: add a new method, is_lock_file_locked() Michael Haggerty
2017-05-17 13:12 ` Jeff King
2017-05-17 12:05 ` [PATCH 09/23] files-backend: move `lock` member to `files_ref_store` Michael Haggerty
2017-05-17 13:15 ` Jeff King
2017-05-17 15:49 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 10/23] files_ref_store: put the packed files lock directly in this struct Michael Haggerty
2017-05-17 13:17 ` Jeff King
2017-05-17 15:05 ` Michael Haggerty
2017-05-17 17:18 ` Stefan Beller
2017-05-18 0:18 ` Brandon Williams
2017-05-19 4:00 ` Michael Haggerty
2017-05-18 0:17 ` Brandon Williams
2017-05-18 1:11 ` Jeff King
2017-05-18 15:42 ` Brandon Williams
2017-05-17 12:05 ` [PATCH 11/23] files_transaction_cleanup(): new helper function Michael Haggerty
2017-05-17 13:19 ` Jeff King
2017-05-19 4:49 ` Michael Haggerty
2017-05-17 17:26 ` Stefan Beller
2017-05-19 4:42 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 12/23] ref_transaction_commit(): break into multiple functions Michael Haggerty
2017-05-17 17:44 ` Stefan Beller
2017-05-19 7:58 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 13/23] ref_update_reject_duplicates(): expose function to whole refs module Michael Haggerty
2017-05-17 12:05 ` [PATCH 14/23] ref_update_reject_duplicates(): use `size_t` rather than `int` Michael Haggerty
2017-05-17 12:05 ` [PATCH 15/23] ref_update_reject_duplicates(): add a sanity check Michael Haggerty
2017-05-17 12:05 ` [PATCH 16/23] should_pack_ref(): new function, extracted from `files_pack_refs()` Michael Haggerty
2017-05-17 12:05 ` [PATCH 17/23] get_packed_ref_cache(): assume "packed-refs" won't change while locked Michael Haggerty
2017-05-17 17:57 ` Stefan Beller
2017-05-18 1:15 ` Jeff King
2017-05-18 16:58 ` Stefan Beller
2017-05-17 12:05 ` [PATCH 18/23] read_packed_refs(): do more of the work of reading packed refs Michael Haggerty
2017-05-17 12:05 ` [PATCH 19/23] read_packed_refs(): report unexpected fopen() failures Michael Haggerty
2017-05-17 13:28 ` Jeff King
2017-05-17 15:27 ` Michael Haggerty
2017-05-18 4:57 ` Junio C Hamano
2017-05-18 5:08 ` Jeff King
2017-05-17 12:05 ` [PATCH 20/23] refs_ref_iterator_begin(): handle `GIT_REF_PARANOIA` Michael Haggerty
2017-05-17 13:29 ` Jeff King
2017-05-17 12:05 ` [PATCH 21/23] create_ref_entry(): remove `check_name` option Michael Haggerty
2017-05-17 12:05 ` [PATCH 22/23] ref-filter: limit traversal to prefix Michael Haggerty
2017-05-17 13:38 ` Jeff King
2017-05-19 10:02 ` Michael Haggerty
2017-05-17 12:05 ` [PATCH 23/23] cache_ref_iterator_begin(): avoid priming unneeded directories Michael Haggerty
2017-05-17 13:42 ` [PATCH 00/23] Prepare to separate out a packed_ref_store Jeff King
2017-05-17 18:14 ` Stefan Beller
2017-05-18 17:14 ` Johannes Sixt
2017-05-18 17:22 ` Jeff King
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